Introduction
Global energy consumption is continuously increasing with population growth and rapid industrialization, which requires sustainable advancements in both energy generation and energy-storage technologies.[1] While bringing great prosperity to human society, the increasing energy demand creates challenges for energy resources and the consumption of conventional fossil fuels causes increasing greenhouse gas emission.[2] Therefore, for a sustainable energy future, new technologies and new ways of thinking are needed with respect to energy generation, storage, delivery, and consumption.[3] To enhance energy security and reduce the negative health and environmental impacts of fossil fuels, there has been growing focus on the exploration of renewable energy sources, among which solar, wind, tide, and wave energies represent successful sectors at present.[4] However, the renewable energies are usually not continuously available due to external factors that cannot be controlled. The requirements of addressing the intermittency issue of these clean energies have triggered a very rapidly developing area of research—electricity (or energy) storage.[5]
Battery storage systems are emerging as one of the key solutions to effectively integrate intermittent renewable energies in power systems.[6] Setting power cable-free, rechargeable batteries have powered extensive types of mobile electronics that are supporting our modern life.[7] High-power-density and high-energy-density rechargeable battery technologies are also presently under vigorous development for vehicle electrification.[8] Utility-scale batteries are expected to enable a great feed-in of renewables into the grid by storing excess generation and firming renewable energy output.[9] Scaling up from portable power sources to transportation-scale and grid-scale applications, the design of electrochemical storage systems needs to take into account the cost/abundance of materials, environmental/eco efficiency of cell chemistries, as well as the life cycle and safety analysis.[10] A number of currently existing rechargeable battery technologies can possibly fulfil some of the aforementioned sustainability requirements. However, existing intrinsic limitations of energy-storage capacity or technological hurdles are hampering the deployment toward large-scale applications.[11]
In this perspective, we first give an overview of the currently existing rechargeable battery technologies from a sustainability point of view. With regard to energy-storage performance, lithium-ion batteries are leading all the other rechargeable battery chemistries in terms of both energy density and power density. However long-term sustainability concerns of lithium-ion technology are also obvious when examining the materials toxicity and the feasibility, cost, and availability of elemental resources. Based off of recent research advances, strategies and approaches toward the enhancement of sustainability of lithium-ion technologies are first discussed. Then, emerging and cutting-edge battery technologies beyond lithium with affordable and nontoxic chemistries and materials that present great economic and environmental incentives for sustainability are highlighted and prospected.
Sustainability of Currently Available Rechargeable Battery Technologies
In general, batteries are designed to provide ideal solutions for compact and cost-effective energy storage, portable and pollution-free operation without moving parts and toxic components exposed, sufficiently high energy and power densities, high overall round-trip energy efficiency, long cycle life, sufficient service life, and shelf life.[12] Commercial batteries available today use a diverse range of battery chemistries and materials in either an inorganic or an organic nature.[13] All battery systems could be classified as primary (nonrechargeable) and secondary (rechargeable) systems. Nonrechargeable batteries are not suitable for electric vehicles or grid storage purposes and are out of the scope of this Review. Through decades of competition in consumer markets, three types of rechargeable battery technologies have survived and are currently dominating the electrochemical energy-storage market. They are lead–acid (Pb–acid) batteries, nickel–metal hydride (Ni–MH) batteries, and lithium-ion batteries.[14]
A conceptual assessment framework that can be used to evaluate the sustainability of battery technologies is shown in Figure 1, in which the key criteria are defined according to the environmental and social impact categories. Figure 2 shows the comprehensive operational characteristics and sustainability levels of the three batteries currently dominating the market. In terms of operational parameters, Li+-ion batteries show significant superiority to Pb–acid and Ni–MH batteries across most metrics (Figure 2), which make it easy to understand the immense commercial and academic interest in this cell system.
[IMAGE OMITTED. SEE PDF]
[IMAGE OMITTED. SEE PDF]
Pb–acid batteries are presently the mostly used rechargeable batteries all over the world because of their superior merit of low cost.[15] Other advantages of Pb–acid batteries include low self-discharge rates and low-temperature operation.[16] From the perspective of sustainability, Pb–acid batteries meet the requirements of materials availability and cost efficiency. However, lead is known as a toxic element and sulfuric acid is generally regarded as a hazardous material. Although the use of toxic elements and hazardous sulfuric acid makes Pb–acid batteries internally unsustainable, these types of batteries have been used for more than a century and are applied in nearly every vehicle on the road today.[17] It has not practically caused a serious and unbearable environmental sustainability problem so far, due to the fact that Pb–acid batteries have achieved more than 99% recovery and recycling rates globally.[18] Most ongoing research work on Pb–acid batteries are aiming at extending their cycle life, enhancing their charge rate, and improving other operation parameters.[19] But their materials toxicity issue is intrinsic and cannot be overcome through technological innovation.
Ni–MH batteries were commercially introduced in 1989 and could offer superior operational performance to Pb–acid batteries in many categories (as shown in Figure 2).[20] However, the high-cost hydride-storage metal alloys make Ni–MH systems expensive. Some elements of hydride-storage materials are less abundant in nature. With the cost reduction of Li+-ion batteries, Ni–MH batteries are the most expensive one at present among the three dominating rechargeable battery technologies.[21] As Li+-ion batteries offer higher energy density and Pb–acid batteries are less expensive, Ni–MH batteries do not show significant metrics for the emerging grid energy storage. However, the Ni–MH couple represent a green cell chemistry as there are no toxic materials used.[22] In addition, the use of low-reactivity electrode materials and aqueous-based electrolytes makes Ni–MH batteries naturally safer in contrast to Pb–acid and Li+-ion systems.[23] Their safer operation advantages offer them opportunities to be used in special places where safety is highly required. Based on the earlier discussion, both the Pb–acid and the Ni–MH batteries have their own inherent limitations with respect to long-term sustainability. The sustainability issues of Li+-ion batteries will be discussed in the next section.
Strategies toward Enhancing the Sustainability of Li+-Ion Batteries
Sustainability Issues of Li+-Ion Batteries
The development of Li+-ion batteries has primarily been oriented by the market demand in pursuing optimized cell performances. However, materials in Li+-ion batteries are leading to more concerns with respect to sustainability and environmental aspects.[24] A typical Li+-ion cell unit is fabricated with six major components, including anode, electrolyte, separator, cathode, current collectors, and accessories. In general, accessories, separators, and electrolytes can be conveniently separated and recycled relative to other cell components.[25] However, it is extremely challenging to recycle the electrode units (anode, current collectors, and cathode) that are economically valuable.[26] Figure 3a shows the major ecological concerns pertaining to Li+-ion technologies, including 1) recycling efficiency of cell components, 2) energy-intensive production of battery materials (including metal oxide cathodes, graphite anodes, polymer separators, and metal current collectors), 3) costly processing of electrodes, 4) expensive production of unit cells and cell stacks, and 5) toxicity of battery materials and compounds (such as nonaqueous electrolytes, organic binders, and transition metal oxide cathodes).
[IMAGE OMITTED. SEE PDF]
Enhancing the Sustainability of Li+-Ion Batteries
To overcome the sustainability issues of Li+-ion batteries, many strategical research approaches have been continuously pursued in exploring sustainable material alternatives (cathodes, anodes, electrolytes, and other inactive cell compartments) and optimizing ecofriendly approaches that are relevant to the energy balance and sustainability of Li+-ion technologies.
Anode Materials
Graphitic carbon serves as a standard anode in present Li+-ion batteries, which could be classified as natural graphite and synthetic graphite.[27] In comparison to the cathode materials, the graphite anode generally has a much lower cost. Nevertheless, the costs of natural graphite and synthetic graphite are quite different (natural graphite: ≈$4–8 kg−1; synthetic graphite: ≈$12–13 kg−1).[28] The cost difference between two kinds of graphite materials is caused by the energy-intensive production of synthetic graphite and the rich resources of natural graphite.[28] Undoubtedly, natural graphite presents significantly lower costs than synthetic graphite in the long run. Therefore, there is an onward trend in replacing synthetic graphite anodes with natural graphite materials.[29] The current market shares of natural graphite and synthetic graphite are, respectively, 35% and 56% in Li+-ion battery anodes.[30] Synthetic graphite materials are typically made from petroleum-based precursors (such as coke) through high-energy-consumption processes.[31] Strategies under development now toward reducing the manufacturing cost include the use of catalysts to reduce the graphitization temperature, which could significantly reduce the energy consumption for producing synthetic graphite materials.[32] To reduce the reliance on petroleum products (as precursors) and enhance the materials sustainability, there is increasing interest in the development of synthetic graphite from biomass materials or industrial waste.[33] Natural graphite materials originate from ores, but the resource is geographically distributed in limited regions and the product processing causes serious environmental concerns.[34] New environmentally friendly and energy-efficient processing techniques for producing high-purity natural graphite materials are actively investigated.[35] The addition of Si to graphite-based materials (graphite/silicon blends) has been regarded as a promising strategy to improve the overall energy density of Li+-ion batteries.[36] Though Si incorporation also induces a sequence of problems, a small amount of Si has been used in commercial cells.[37] Precursor materials for producing Si-based anodes are naturally abundant. However, Si comes from sand and there are a host of environmental issues associated with sand mining that are not yet well regulated.[38] Therefore, there are also increasing research interests in producing Si-based materials from biomass or industrial waste.[39]
In addition to graphite and silicon, the current market shares of other anode materials only cover ≈5% (e.g., amorphous carbons: ≈2%, lithium titanate spinel oxide (LTO): ≈3%).[30] Amorphous carbon can store large reversible capacity but is also accompanied with large irreversible capacity.[40] Spinel-structured LTO offers excellent safety characteristics and long lifetime.[41] As these two materials do not represent the main stream of anode materials for Li+-ion batteries, they are not discussed in detail here.
Cathode Materials
Layer-structured LiMO2 (with M = Ni, Mn, Co, Al) metal oxides represent one of the current cathode materials for Li+-ion batteries to couple with a graphite anode.[42] Various configurations of LiNi1−x−yMnxCoyAlzO2 layered cathodes, such as LiNi1−x−yMnxCozO2 NMC (NMC) and LiNi0.8Co0.15Al0.05O2 (NCA), could offer critical properties (practical capacity, cell voltage, material density, and rate capability), outperforming other candidate cathode materials.[43] Li, Co, and Ni are regarded as critical elements in the raw materials of Li+-ion batteries, which contribute ≈1/3 the total cost of NMC (and/or NCA)-based Li+-ion batteries.[44] Among the major elements in a Li+-ion battery, resources of lithium and cobalt pose the highest concerns. At the beginning of this century, only a small percentage of lithium and cobalt went into batteries. However, by 2015, 32% of lithium and 46% of cobalt were used for Li+-ion batteries production.[45] On the other hand, other elements, viz., graphite, copper, aluminum, manganese, and nickel, have not been affected significantly. Therefore, finding sufficient supply of lithium has geared up mining industries for higher production.[46] With the increasing interests in the deployment of large-scale energy-storage systems, lithium shortage is foreseen. Although the price of lithium fluctuated over the past decade according to supply and demand, concerns about the shortage of lithium resource have been increasingly spreading. In addition to being a cost driver, Co is recognized as a toxic element (Ni is a suspected human carcinogen) and the production of Co increases serious environmental concerns.[47] Environmental effects of cobalt mining have been assessed in detail.[48] It has raised both environmental and moral concerns, which originate from questionable mining conditions in central Africa and those allegedly involving child labor.[49] The price of Co fluctuates frequently due to the insecure supply chain.[50] Within the past decade, the price of Co has actually increased markedly.[29] The increasing cost of Co has led to multiple efforts to increase Ni and decrease Co in layered materials, from LiNi1/3Mn1/3Co1/3O2 (NMC-111) to LiNi0.6Mn0.2Co0.2O2 (NMC-622), to LiNi0.8Mn0.1Co0.1O2 (NMC-811).[51] So far, the high-Ni approach has not only led to increasing energy contents but also led to lower costs (e.g., NMC-622: $25 kg−1; NMC-811, $24 kg−1; NCA (LiNi0.8Co0.15Al0.05O2): $26 kg−1; LMR–NMC (lithium- or manganese-rich NMC): $20 kg−1).[29] Industries have started to introduce NCA with Ni contents >90% and NMC-811 into commercial batteries. Academia is now actively investigating NMC cathodes with Ni > 80% or even Co-free LiNixMyO2 (x > 0.8, M = Mg, Mn, Al) cathodes, such as the recently reported LiNi1−x−yMnxAlyO2 (NMA).[52]
While the high-Ni approach can lower the cost and the hazardous concern, it also degrades the cycle life of Li+-ion batteries. To improve cycling stability, the development of single-crystal-layered cathode materials may be a promising strategy.[53]
In addition to layered cathodes, other Co-free cathodes also provide opportunities to reduce the concerns regarding materials scarcity.[54] High-voltage spinel LiNi0.5Mn1.5O4, Li/Mn-rich layered oxide Li1.2Ni0.2Mn0.6O2, or spinel Li4Mn2O5 are gaining considerable attention as potential alternative sustainable cathodes.[55] However, their cycling performances have to be intensively improved.[56]
Olivine-structured cathode materials with chemistries of LiFePO4 (LFP) or LiFe1−xMnxPO4 (LFMP) are more sustainable than other cathode materials because these polyanionic materials are composed of abundant elements.[57] In addition to the advantage of low materials cost, LFP-based Li+-ion batteries also present long shelf life and long cycle life due to the stable structure of the polyanionic phosphate framework. The drawback of current LiFePO4-based materials lies in their relatively low energy content and relatively high production cost, which are promisingly overcome by continuous engineering endeavors.[58]
Electrolytes and Separators
Electrolytes in the state-of-the-art Li+-ion batteries are popularly on the basis of lithium hexafluorophosphate (LiPF6) salt dissolved in carbonate-based organic solvents.[59] Depending on the composition and purity, prices for carbonate-based electrolytes range from $7 to $20 kg−1.[60] From a sustainable perspective, carbonate organic solvents are available in abundance, pose low toxicity, and can be synthesized from renewable resources, such as urea and alcohols.[61] From a safety and a recycling point of view, carbonate-based electrolytes exhibit flammable and volatile features as well as poor thermal stability, which could result in potential hazard risks and poor recyclability.[62] Active research directions at present are going into multiple directions. One field is the exploration of fluorinated additives and solvents. However, the improved performance of these types of electrolytes is acquired by a sacrifice of environmental friendliness.[63] Another interesting direction is going into ethylene carbonate (EC)-free electrolyte, which allows the operation of high-voltage cathodes. However, most of these EC-free electrolytes rely on either fluorinated additives, highly expensive lithium salts, or organosulfur compounds, which result in potential environmental and sustainability impacts.[64] Ionic liquids (ILs) possess low flammability, a broad electrochemical window, high thermal stability, and low volatility.[65] These properties make them promising alternative electrolytes for Li+-ion batteries and can enhance battery safety.[66] However, ecotoxicity studies of ILs have also highlighted environmental concerns of some ILs.[67] Actually, the toxicity of an IL depends on the chemical nature of the anions and cations present. Therefore, ecofriendly and biodegradable ILs may be feasible in the future.
In addition to organic solvents, Li salts are another major component of electrolytes. LiPF6 possesses multiple advantageous properties, such as high solubility, ionic mobility, conductivity, and electrochemical stability, and acts as a primary option in current Li+-ion batteries.[68] However, its natural toxicity, poor chemical, and thermal stability pose sustainability concerns.[69] Many efforts have been made toward getting rid of the ecounfriendly and high-cost LiPF6, but no perfect alternative to LiPF6 has been discovered so far. A boron-based popular lithium bis(oxalato)borate (LiBOB) shows interesting properties but cannot be operated at cell voltages > 4.2 V. However, it is promising to be applied in LiFePO4 cells to build fluorine-free and sustainable Li+-ion batteries.[70]
A new conceptual electrolyte, “water-in-salt,” has also attracted considerable attention for the advancement in sustainable electrolytes.[71] The resulting aqueous-based Li+-ion batteries are attracting more attention, as these electrolyte are environmentally friendly and safe.[72] Reducing water content is a key to expanding the narrow electrochemical window (due to the low water-splitting potential) of these types of electrolytes.[73] The low (or free) water content can also be reduced using room-temperature Li salt hydrate melts.[74] Although these electrolyte approaches use water as a green solvent, the use of a large amount of lithium salts makes them less desirable at the current development stage from an economic point of view. Recently, a so-called “water-in-ionomer” gel electrolyte was proposed, which exhibits a more sustainable feature than the water-in-salt electrolyte.[75] The water-in-ionomer electrolyte, comprising fluorine-free ionomers with a low concentration lithium salt, could possibly keep pace with the performances of highly concentrated water-in-salt electrolyte.[75] This novel electrolyte concept may be able to open a path for fluorine-free aqueous electrolytes for Li+-ion batteries, which could improve the carbon footprint consideration of the battery technology.
A separator is an essential component in liquid electrolyte Li+-ion batteries. Oil-derived low-cost polyolefines, such as polyethylene and polypropylene, are dominating separator materials in commercial Li+-ion batteries.[76] Toward ecofriendly and biocompatible targets, cellulose-based separators are of great interest.[77] Cellulose is a biopolymer and is naturally abundant. The separators with cellulose as a starting material can be manufactured through environmentally benign and low-cost processes.[78] Separators made of chitin, alginate, and silk fibroin biomaterials are also promising choices for the advancement of future sustainable Li+-ion batteries.[79]
Solid-state electrolytes (SSE) can serve as both a separator and an electrolyte, which provide great possibility to circumvent the safety issues of Li+-ion batteries.[80] SSEs can be classified into two groups: polymeric SSEs and ceramic SSEs. In view of sustainability, many research interests with respect to polymeric solid electrolytes are in the direction of producing ionic polymers from renewable resources to replace those synthesized from fossil fuels.[81] However, there is concern that enormous amounts of energy are needed to produce monomers from renewable resources, which leads to a debate on whether or not the production of Li+-ion polymers from renewable resources is really beneficial for sustainability impact.[82] It is possible to recycle polymer electrolyte materials, but the processes are presumably energy consuming and expensive.[83]
So far, various classes of ceramic solid electrolytes have been developed including LISICON-type, NASICON-type, garnet-type, perovskite-type, sulfide electrolyte, oxy-nitride electrolyte, etc.[84] While impressive Li+-ion conductivities are achieved, ceramic solid electrolytes present critical drawbacks, such as poor compatibility with the Li anode, poor mechanical property, and poor interfacial stability.[85] Apart from these problems, some ceramic solid electrolytes comprise sparse elements, such as lanthanum in perovskite-type Li3.3La0.56TiO3 (LLTO) and garnet-type Li7La3Zr2O12 (LLZO) materials.[86] The production of all-oxide ceramic electrolytes involves energy-intensive and costly processing, which challenge the large-scale production of these ceramic solid electrolytes.[87] In contrast to oxide ceramics, sulfide-type glass–solid electrolytes contain mainly abundant elements (S and P). The production of glass sulfide-type electrolytes can be accessed with cold pressing, which does not consume much energy. However, due to their sensitivity to H2O, it requires a moisture-free condition for processing sulfide-type electrolyte materials.[88] In view of the earlier discussion, due to the high processing efforts and the need for a high lithium content, SSEs at present are difficult to compete with liquid electrolytes with regard to sustainability and due to other properties.
Summing up the earlier discussion, Figure 3b shows a schematic interpretation of the key strategies to be taken toward enhancing the sustainability of the current Li+-ion battery technologies: 1) development of battery materials with abundant, nontoxic, low-cost raw materials, 2) reduction in production cost and reduction in energy consumption involved in processing, and 3) enhancement in the recycling efficiency of key elements and components involved. We mainly discussed here the materials development. The energy-efficient processing of battery materials and the recycling of battery components/elements can be viewed in the recent relevant publications.[89]
Toward Sustainable Batteries Beyond Lithium-Ion Technologies
Lithium–Air, Lithium–Carbon Dioxide, and Lithium–Sulfur Batteries
Lithium–air and lithium–sulfur batteries are presently among the most attractive electrochemical energy-storage technologies because of their exceptionally high energy content in contrast to insertion-electrode Li+-ion batteries.[90] Especially, they can reduce the Li+-ion battery problems with respect to environmental and cost concerns, as more sustainable and less cost cathode materials are used.[91]
Li–air batteries can theoretically offer energy densities about a magnitude higher than today's Li+-ion batteries, but only two-fold enhancement has been demonstrated with very limited cycle numbers in research labs so far. With respect to the electrolyte used, Li–air batteries can be classified into three groups: nonaqueous, aqueous, and solid–electrolyte systems. Over the past two decades, most research efforts have been focused on nonaqueous Li–air batteries. However, there still exist critical issues, such as low energy efficiency, low areal capacity, poisoning of air electrodes by impurities, etc.[92] The aqueous systems and solid Li–air batteries are not able to sustain a high power density and deep cycling for practical applications.[93] From a cell chemistry perspective, the use of the air cathode to replace metal oxides offers great sustainability. However, the sustainability of Li–air batteries also depends on the electrolytes and cathode catalysts used. Nonaqueous electrolytes and solid electrolytes in Li–O2 batteries share similar sustainability issues to those in Li+-ion batteries, as discussed in the previous section. In the long run, only low-cost, nonprecious metal catalysts would make practical sense for the development of sustainable Li–air batteries (Figure 4a).[94] In addition, the use of Li-metal anode poses both performance degradation and safety concerns. Therefore, the incorporation of Li+-ion anode materials with air cathode might be worthy of further work, aiming at addressing unsolved cycle life and safety issues (Figure 4a).
[IMAGE OMITTED. SEE PDF]
On the other hand, most Li–air batteries studied so far were usually operated under a pure oxygen atmosphere.[95] CO2 in ambient air is an active gas when operating real Li–air batteries and its solubility in nonaqueous electrolytes is even higher than that of oxygen. Recently, the investigation of the impact of CO2 on Li–air batteries has triggered immense interests in the development of Li–CO2 (with a CO2 gaseous cathode) and Li–O2/CO2 batteries (with a mixture of O2/CO2 gaseous cathode).[96] Li-CO2 and Li–O2/CO2 batteries not only serve as an energy-storage technology but also represent a CO2 capture system offering more sustainable advantages (Figure 4a). At present, it is generally realized among the battery community that the commercialization of either Li–O2, Li–O2/CO2, or Li–CO2 technologies has a long way to go, not only at the applied level, but also on the fundamental level.
Moving forward from Li–air systems, the community is now focusing more on Li–S systems. Sulfur is an abundant element and is well known as a sustainable cathode with very low cost (≈$50 per ton).[97] The production of sulfur materials is already a well-developed business and the development of sulfur-based batteries leads to both ecologic and economic significance.[98] Research progress in Li–S batteries has been reviewed timely and can be accessed in quite a few publications.[99] We herein discuss the sustainable aspects of Li–S batteries. Current research toward increasing the sustainability of Li–S batteries includes the simplification of sulfur–carbon composite cathodes with low-cost processes and with renewable resources (as shown in Figure 4b).[100] To address the safety issue of Li-metal anode, a combination of an alloy anode, a silicon-based anode, or a carbonous anode with a Li2S composite cathode is now being actively investigated.[101] Due to the polysulfide shuttle concerns, the development of biomass-derived polymer electrolytes would provide both a sustainable advantage and an effective way to prevent the migration of soluble polysulfide.[102]
Next-Generation Battery Technologies Based on Lithium-Alternative Anode Chemistries
Beyond lithium, negative electrodes with other metal or metal-ion chemistries have long been studied for electrochemical energy storage, even before the commercialization of Li+-ion batteries.[103] Rechargeable batteries with sodium, potassium, magnesium, calcium, aluminum, zinc, and iron anode chemistries have been revived based on the splendid success of Li+-ion batteries as alternatives, considering the shortage of lithium resource.[104] These Li-alternative anode chemistries are for the development of next-generation battery technologies. Figure 5 shows these promising negative electrode elements in terms of various categories with respect to their energy-storage properties as well as their economic characteristics.
[IMAGE OMITTED. SEE PDF]
The high natural abundance and global distribution of alkali-metal elements Na and K highlight their potential as alternative anodes to Li. Neither of these two alkali metal elements pose health and environmental concerns.[105] Considering their production cost, K is less attractive than Na in regard to sustainability. Research on Na-based batteries, including both Na-metal batteries and Na+-ion batteries, is now flourishing worldwide and many negative and positive electrode materials with attractive properties have been demonstrated.[106] While cost and environmental advantages have prompted the focus on Na-based batteries, research on K-based batteries is relatively limited. With an insertion-type Prussian blue or conversion-type O2 or sulfur cathodes, K batteries have shown promising results.[107] These cell chemistries are interesting in view of an ecological point as all active material elements are highly abundant. However, there are serious safety concerns on K metal anode due to the formation of K dendrites which can result in cell short and thermal runaway.
Alkaline earth metals Ca and Mg are Earth-abundant elements. Their bivalent feature offers an advantage of two-electron transfer per atom. The safety concerns are to a lesser extent with metallic Mg or Ca anodes.[108] These characteristics favor the possibility of developing sustainable, high-energy batteries. However, the complexity of the metal–electrolyte interface and the lack of reliable electrolytes hinder alkaline Earth-based energy-storage technologies getting into the market.[109] In addition, suitable conversion-type cathodes are required to harness the high energy density and the high elemental abundancy of these two interesting anode materials for real energy-storage applications.
Zn and Al are also interesting anode chemistries for developing sustainable energy-storage technologies, due to their elemental abundancy, high theoretical capacity, and environmentally friendly nature.[110] Al possesses multiple advantages of high elemental abundance, high charge capacity (multiple-electron transfer), high safety, and small ionic size, all of which are promising properties for high energy-storage applications. Insertion-type cathodes for aluminum-ion batteries are on the basis of V, Mn, Ti, or Mo oxides or Prussian blue materials.[111] Conversion-type cathodes, such as sulfur and oxygen, have also been demonstrated with Al-metal anodes, but the resulting Al-metal batteries suffer from many reversibility and cycling stability problems.[112] From a sustainable viewpoint, zinc-based batteries are green energy-storage technologies considering the high material availability of zinc and its operability with aqueous-based electrolytes. While the high atomic weight of Zn and the low discharge voltage limit the practical energy density, Zn-based batteries are still a highly attracting sustainable energy-storage concept for grid-scale energy storage where the weight of a battery is not a serious concern. Rechargeable zinc–air batteries are good examples of a low-cost energy-storage system with high environmental friendliness and safety.[113]
Organic Electrode Batteries
Electrochemically active organics are potentially promising to be used as electrode materials in batteries. There have been many organic electrode materials reported, showing excellent electrochemical reversibility so far. However, among them, most are produced from nonrenewable fossil resources (petrochemical precursors), which cannot be considered as “green” electrode materials. Nowadays, many efforts are focusing on organic electrode compounds originating from renewable sources.[114] Organics with any sizes ranging from small molecules to macromolecules to polymers can be used as battery electrodes. Low soluble polymers are prone to provide long cycle life, whereas small-molecule organics can usually offer high-energy-storage capacities.
Figure 6 shows the possible biogenic resource routes for producing organic electrode materials and designing electrode structures for green battery concepts with two exemplary representatives.[115] There are many types of electrochemically active biomolecules existing in nature, which provide great advantages to harness their natural electrochemical reaction activities to design novel battery chemistries and battery electrode materials.[116] C, H, O, N, P, and S are general elements in these bio-derived electrochemically reactive materials, which are ecofriendly. Particularly, biomolecules are usually light, implying the advantage of biomolecule electrode materials with high gravimetric energy density. The structure of biomolecules is also tunable, which provides possibilities to eliminate any electrochemically inactive section in a biomolecule or functionalize the molecules with other desired groups. Furthermore, these organic materials usually exhibit a moderate working potential, adequate ionic/electronic conductivity, less volume change, and exceptionally high specific capacity, all of which help them stand out to compete with other types of electrode materials. In addition to full organic electrode batteries,[117] a wide range of metallic anodes (Li, Na, K, Ca, Mg, and Zn) can be coupled to organic cathodes.[118] The above exceptional versatility inspires the research of diverse sustainable energy-storage systems for different application purposes. Like that for developing other types of batteries, organic electrode batteries have to overcome some critical barriers before standing out for practical applications. The challenges include both the mechanistic understanding of the electron/ion transport in organic electrodes and the technical development of high-performance battery electrodes.
[IMAGE OMITTED. SEE PDF]
Conclusions and Perspectives
The sustainability of battery-storage technologies has long been a concern that is continuously inspiring the energy-storage community to enhance the cost effectiveness and “green” feature of battery systems through various pathways. The present market-dominating rechargeable batteries are all facing sustainability-related challenges. It is critically important to explore nontoxic (or low-toxic) alternatives to replace the toxic components in future battery technologies.
Lithium-ion batteries represent the state-of-the-art rechargeable battery technology. However, the limited resource of critical cell materials, toxicity of some key elements, and high energy consumption of material production pose serious sustainability concerns for the long run. There is currently a contradiction between the application-oriented cell performance factors (power density and energy density) and the sustainability-oriented materials selection. This contradiction seems that it cannot be solved in the near future. While exploring green material alternatives, one feasible strategy at present to achieve more sustainable high-performance Li+-ion batteries is to explore the second life of the cell materials through effective recycling and recovery of used batteries. Looking over sustainably alternative materials options in the literature, it seems that most cell components and materials in traditional Li+-ion batteries could be possibly replaced with new materials that can fulfil the desired sustainability requirements. However, a “completely sustainable” Li+-ion battery is not promisingly able to offer performances tantamount to commercial Li+-ion batteries. The reason behind lies in that the commercial Li+-ion battery materials have been primarily selected to match the high requirements on energy-storage performances, whereas the evolutionarily developed sustainable material alternatives usually have inherent drawbacks in terms of energy density, cycle stability, and cost competitiveness.
In terms of positive electrodes, lithium–sulfur and lithium–air chemistries present a high potential for sustainable energy-storage technologies. Nevertheless, the commercialization of these two technologies has a long way to go. Furthermore, Li–O2 or Li–S batteries still require quantities of lithium in both the electrodes and electrolyte. Moving beyond lithium, other more sustainable metal elements have drawn increasing attention as alternative anode chemistries. Abundant and low-cost metallic elements of monovalent Na and K, divalent Ca, Mg, and Zn, and trivalent Al are appealing with respect to sustainability for energy-storage technologies. The number of research publications on these beyond-lithium topics have been increasing over the past decade. However, the early-stage research results are neither able to guarantee their future implementation, nor can they foresee which system will succeed first. The commercialization and success of a battery technology depends on both the technical performance factors and its sustainability.
From our viewpoint, development strategies toward achieving more sustainable expectations for electrochemical storage technologies can be projected and executed based on the technological purpose and application field. For mobile and portable applications that require safe and fast-charging batteries with a focus on high energy density and high power, only Li+-ion batteries are realizable hitherto. In this field, besides the incremental improvement of the carbon footprint of Li+-ion batteries (because of ecological advances of the inactive materials and processing), the near-future strategies should focus on the extension of batteries’ lifetime through a combination of a second-life application and an efficient recovery of cell component/materials via stringent recycling. In case the energy density is less critical, Li+-ion components based on more abundant materials (e.g., LiFePO4) are more interesting, e.g., for small-scale home energy or public transport vehicles. In cases where both volume and weight of a battery system are not a concern (e.g., for large stationary storage applications), active battery materials are to be considered based on the criteria of cost, green feature, energy efficiency, material availability, and operation lifetime. This application field is expected to be a promising opportunity for the emerging alternative battery technologies developed on the basis of renewable and/or abundant materials (e.g., Na, S, Mg, Al, Zn, and organic compounds), which are more independent from critical resources, more affordable, and more environmentally compatible although they usually offer lower energy densities than Li+-ion batteries and lithium-metal batteries.
Modern electrochemically active organics derived from biomass or other renewable sources hold a foreseeable potential to enable green and cost-effective battery chemistries. They are expected to accelerate the advancement of high-energy batteries with active metal anodes (Li, Na, K, Ca, Mg, Zn, Al), high-energy/stability aqueous batteries, as well as solid-state batteries that are difficult to access with the popular inorganic electroactive materials. Head-on research on the comprehensive charge-storage mechanisms of these organic species and proper electrode design strategies are to be focused.
To promote the implementation of green battery materials and enhance the sustainable future of electrochemical energy-storage technologies, it is necessary to reduce the big gap between academia and industry. Scientists involved in the academic research of sustainable battery materials achieved fruitful results in the past decades. However, the implementation and commercialization process of these batteries materials and chemistries developed relatively slowly. The reason lies in the fact that the battery materials in the scientific literature is often tested under conditions that are not aligned with practical applications. To build a close connection between academia and industry, it is necessary to establish a set of standards for evaluating battery materials in terms of key performance and sustainability criteria. Academic research labs shall keep attention on the industry standards as a reference for new materials development. Sharing knowledge and experience between academia and industry would be a key to solve these problems and would accelerate the transformation of innovations developed in research labs to industrial applications.
Beyond the technological standpoint, the commercialization and application of battery technologies are also contingent upon societal attributes at different time periods. Undoubtedly, sustainability issues are now more concerned by the society than ever before. Therefore, in addition to technical performance, sustainability must be considered as an extraordinary factor when developing battery-storage technologies. On this wavelength, the establishment of a closed battery life cycle via the recovery of critical battery materials, as well as the exploration of alternative battery-storage systems with greener and more accessible materials are two pathways that our research community shall be actively and continuously engaged in.
Acknowledgements
This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, and Division of Materials Science and Engineering under award number DE-SC0005397.
Conflict of Interest
The authors declare no conflict of interest.
A. Manthiram, Nat. Commun. 2020, 11, 1550.
J. G. Liu, V. Hull, H. C. J. Godfray, D. Tilman, P. Gleick, H. Hoff, C. Pahl-Wostl, Z. C. Xu, M. G. Chung, J. Sun, S. X. Li, Nat. Sustainable 2018, 1, 466.
S. Comello, S. Reichelstein, Nat. Commun. 2019, 10, 2038.
H. S. Boudet, Nat. Energy 2019, 4, 446.
Q. Schiermeier, Nature 2016, 535, 212.
G. Crabtree, Nature 2015, 526, S92.
X. W. Yu, A. Manthiram, Adv. Funct. Mater. 2020, 30, 2004084.
W. D. Li, E. M. Erickson, A. Manthiram, Nat. Energy 2020, 5, 26.
Y. Gogotsi, Nature 2014, 509, 568.
D. Larcher, J. M. Tarascon, Nat. Chem 2015, 7, 19.
T. M. Gur, Energy Environ. Sci. 2018, 11, 2696.
Z. P. Cano, D. Banham, S. Y. Ye, A. Hintennach, J. Lu, M. Fowler, Z. W. Chen, Nat. Energy 2018, 3, 279.
A. Manthiram, X. W. Yu, S. F. Wang, Nat. Rev. Mater. 2017, 2, 16103.
D. Lindley, Nature 2010, 463, 18.
J. Yang, C. Hu, H. Wang, K. Yang, J. B. Liu, H. Yan, Int. J. Energy Res. 2017, 41, 336.
O. Schmidt, A. Hawkes, A. Gambhir, I. Staffell, Nat. Energy 2017, 2, 17110.
Y. X. Yu, J. S. Mao, X. X. Chen, Sci. Total Environ. 2020, 746, 140763.
S. Nemati, G. Pircheraghi, Thermochim. Acta 2020, 693, 178781.
P. T. Moseley, D. A. J. Rand, K. Peters, J. Power Sources 2015, 295, 268.
Q. H. Cheng, D. L. Sun, X. B. Yu, J Alloy Compd 2018, 769, 167.
S. Al-Thyabat, T. Nakamura, E. Shibata, A. Iizuka, Miner. Eng. 2013, 45, 4.
W. H. Zhou, D. Zhu, J. He, J. C. Li, H. Chen, Y. G. Chen, D. L. Chao, Energy Environ. Sci. 2020, 13, 4157.
M. Zielinski, L. Cassayre, P. Floquet, M. Macouin, P. Destrac, N. Coppey, C. Foulet, B. Biscans, Waste Manage. 2020, 118, 677.
a) J. P. Skeete, P. Wells, X. Dong, O. Heidrich, G. Harper, Energy Res. Soc. Sci. 2020, 69, 101581;
b) H. H. Wu, Y. C. Hu, Y. J. Yu, K. Huang, L. Wang, Int. J. Life Cycle Assessment, 2021, 26, 97.
G. Harper, R. Sommerville, E. Kendrick, L. Driscoll, P. Slater, R. Stolkin, A. Walton, P. Christensen, O. Heidrich, S. Lambert, A. Abbott, K. Ryder, L. Gaines, P. Anderson, Nature 2020, 578, E20.
E. S. Fan, L. Li, Z. P. Wang, J. Lin, Y. X. Huang, Y. Yao, R. J. Chen, F. Wu, Chem. Rev. 2020, 120, 7020.
Y. Liu, X. F. Li, L. L. Fan, S. F. Li, H. M. K. Sari, J. Qin, Front. Chem. 2019, 7, 721.
S. Duehnen, J. Betz, M. Kolek, R. Schmuch, M. Winter, T. Placke, Small Methods 2020, 4, 2000039.
R. Schmuch, R. Wagner, G. Horpel, T. Placke, M. Winter, Nat. Energy 2018, 3, 267.
C. X. Yi, Y. Yang, T. Zhang, X. Q. Wu, W. Sun, L. S. Yi, J. Cleaner Prod. 2020, 277, 123585.
S. M. Lee, D. S. Kang, J. S. Roh, Carbon Lett. 2015, 16, 135.
A. Gomez-Martin, J. Martinez-Fernandez, M. Ruttert, A. Heckmann, M. Winter, T. Placke, J. Ramirez-Rico, ChemSusChem 2018, 11, 2776.
L. X. Zhang, Z. H. Liu, G. L. Cui, L. Q. Chen, Prog. Polym. Sci. 2015, 43, 136.
Y. Gao, C. Y. Wang, J. L. Zhang, Q. K. Jing, B. Z. Ma, Y. Q. Chen, W. J. Zhang, ACS Sustain. Chem. Eng. 2020, 8, 9447.
S. C. Chelgani, M. Rudolph, R. Kratzsch, D. Sandmann, J. Gutzmer, Miner. Process. Extr. Metall. Rev. 2016, 37, 58.
H. F. Andersen, C. E. L. Foss, J. Voje, R. Tronstad, T. Mokkelbost, P. ErikVullum, A. Ulvestad, M. Kirkengen, J. P. Maehlen, Sci. Rep. 2019, 9, 14814.
X. X. Zuo, J. Zhu, P. Muller-Buschbaum, Y. J. Cheng, Nano Energy 2017, 31, 113.
B. S. Tubana, T. Babu, L. E. Datnoff, Soil Sci. 2016, 181, 393.
M. J. Yuan, X. T. Guo, Y. Liu, H. Pang, J. Mater. Chem. A 2019, 7, 22123.
S. R. Mukai, T. Hasegawa, M. Takagi, H. Tamon, Carbon 2004, 42, 837.
a) H. J. Hong, G. R. Ban, S. M. Lee, I. S. Park, Y. J. Lee, J. Alloy Compd. 2020, 844, 156203;
b) B. Zhao, R. Ran, M. L. Liu, Z. P. Shao, Mater. Sci. Eng., R 2015, 98, 1.
Q. An, X. H. Sun, J. Z. Guo, S. Cai, C. M. Zheng, J. Electrochem. Soc. 2020, 167, 140528.
W. D. Li, B. H. Song, A. Manthiram, Chem. Soc. Rev. 2017, 46, 3006.
L. Croguennec, M. R. Palacin, J. Am. Chem. Soc. 2015, 137, 3140.
H. Ambrose, A. Kendall, J. Ind. Ecol. 2020, 24, 90.
B. Gourcerol, E. Gloaguen, J. Melleton, J. Tuduri, X. Galiegue, Ore Geol. Rev. 2019, 109, 494.
A. Chagnes, B. Pospiech, J. Chem. Technol. Biotechnol. 2013, 88, 1191.
S. Anwani, R. Methekar, V. Ramadesigan, J. Mater. Cycles Waste Manage. 2020, 22, 2092.
S. H. Farjana, N. Huda, M. A. P. Mahmud, J. Sustainable Min. 2019, 18, 150.
E. A. Olivetti, G. Ceder, G. G. Gaustad, X. K. Fu, Joule 2017, 1, 229.
S. T. Myung, F. Maglia, K. J. Park, C. S. Yoon, P. Lamp, S. J. Kim, Y. K. Sun, ACS Energy Lett. 2017, 2, 196.
W. Li, S. Lee, A. Manthiram, Adv. Mater. 2020, 29, 2002718.
J. Li, H. Y. Li, W. Stone, R. Weber, S. Hy, J. R. Dahn, J. Electrochem. Soc. 2017, 164, A3529.
N. Voronina, Y. K. Sun, S. T. Myung, ACS Energy Lett. 2020, 5, 1814.
G. M. Liang, V. K. Peterson, K. W. See, Z. P. Guo, W. K. Pang, J. Mater. Chem. A 2020, 8, 15373.
Z. X. Chen, W. X. Zhang, Z. H. Yang, Nanotechnology 2020, 31, 012001.
D. Andre, S. J. Kim, P. Lamp, S. F. Lux, F. Maglia, O. Paschos, B. Stiaszny, J. Mater. Chem. A 2015, 3, 6709.
A. Mauger, C. M. Julien, Batteries-Basel 2018, 4, 39.
K. Xu, Chem. Rev. 2014, 114, 11503.
J. L. Schaefer, Y. Lu, S. Moganty, P. Agarwal, N. Jayaprakash, L. A. Archer, Appl. Nanosci. 2012, 2, 91.
F. G. Calvo-Flores, M. J. Monteagudo-Arrebola, J. A. Dobado, J. Isac-Garcia, Top. Curr. Chem. 2018, 376, 18.
E. Quartarone, P. Mustarelli, J. Electrochem. Soc. 2020, 167, 050508.
N. von Aspern, G. V. Roschenthaler, M. Winter, I. Cekic-Laskovic, Angew. Chem., Int. Ed. 2019, 58, 15978.
T. Zhang, E. Paillard, Front. Chem. Sci. Eng. 2018, 12, 577.
K. Karuppasamy, J. Theerthagiri, D. Vikraman, C. J. Yim, S. Hussain, R. Sharma, T. Maiyalagan, J. Q. Qin, H. S. Kim, Polymers 2020, 12, 918.
A. Balducci, S. S. Jeong, G. T. Kim, S. Passerini, M. Winter, M. Schmuck, G. B. Appetecchi, R. Marcilla, D. Mecerreyes, V. Barsukov, V. Khomenko, I. Cantero, I. De Meatza, M. Holzapfel, N. Tran, J. Power Sources 2011, 196, 9719.
M. Petkovic, K. R. Seddon, L. P. N. Rebelo, C. S. Pereira, Chem. Soc. Rev. 2011, 40, 1383.
E. R. Logan, J. R. Dahn, Trends In Chemistry 2020, 2, 354.
L. Terborg, S. Weber, F. Blaske, S. Passerini, M. Winter, U. Karst, S. Nowak, J. Power Sources 2013, 242, 832.
M. Valvo, A. Liivat, H. Eriksson, C. W. Tai, K. Edstrom, ChemSusChem 2017, 10, 2431.
Y. Yamada, K. Usui, K. Sodeyama, S. Ko, Y. Tateyama, A. Yamada, Nat. Energy 2016, 1, 16129.
R. S. Kuhnel, D. Reber, C. Battaglia, J. Electrochem. Soc. 2020, 167, 070544.
K. Xu, C. S. Wang, Nat. Energy 2016, 1, 16161.
a) L. M. Suo, O. Borodin, T. Gao, M. Olguin, J. Ho, X. L. Fan, C. Luo, C. S. Wang, K. Xu, Science 2015, 350, 938;
b) R. S. Kuhnel, D. Reber, A. Remhof, R. Figi, D. Bleiner, C. Battaglia, Chem. Commun. 2016, 52, 10435.
X. He, B. Yan, X. Zhang, Z. G. Liu, D. Bresser, J. Wang, R. Wang, X. Cao, Y. X. Su, H. Jia, C. P. Grey, H. Frielinghaus, D. G. Truhlar, M. Winter, J. Li, E. Paillard, Nat. Commun. 2018, 9, 5320.
H. Lee, M. Yanilmaz, O. Toprakci, K. Fu, X. W. Zhang, Energy Environ. Sci. 2014, 7, 3857.
P. Arora, Z. M. Zhang, Chem. Rev. 2004, 104, 4419.
J. J. Zhang, L. P. Yue, Q. S. Kong, Z. H. Liu, X. H. Zhou, C. J. Zhang, Q. Xu, B. Zhang, G. L. Ding, B. S. Qin, Y. L. Duan, Q. F. Wang, J. H. Yao, G. L. Cui, L. Q. Chen, Sci. Rep. 2014, 4, 3935.
T. W. Zhang, B. Shen, H. B. Yao, T. Ma, L. L. Lu, F. Zhou, S. H. Yu, Nano Lett. 2017, 17, 4894.
X. W. Yu, A. Manthiram, Energy Environ. Sci. 2018, 11, 527.
Y. Lin, J. Li, K. Liu, Y. X. Liu, J. Liu, X. M. Wang, Green Chem. 2016, 18, 3796.
T. A. Hottle, M. M. Bilec, A. E. Landis, Resour Conserv Recy 2017, 122, 295.
F. H. Isikgor, C. R. Becer, Polym. Chem. 2015, 6, 4497.
L. Fan, S. Y. Wei, S. Y. Li, Q. Li, Y. Y. Lu, Adv. Energy Mater. 2018, 8, 1702657.
X. B. Cheng, R. Zhang, C. Z. Zhao, Q. Zhang, Chem. Rev. 2017, 117, 10403.
X. W. Yu, A. Manthiram, Accounts Chem Res 2017, 50, 2653.
N. Haque, A. Hughes, S. Lim, C. Vernon, Resources-Basel 2014, 3, 614.
K. Takada, S. Kondo, Ionics 1998, 4, 42.
a) D. H. S. Tan, P. P. Xu, H. D. Yang, M. C. Kim, H. Nguyen, E. A. Wu, J. M. Doux, A. Banerjee, Y. S. Meng, Z. Chen, Mrs Energy Sustainability 2020, 7, E23;
b) K. M. Winslow, S. J. Laux, T. G. Townsend, Resour. Conserv. Recycle 2018, 129, 263;
c) L. Gaines, Sustainable Mater. Technol. 2018, 17, e00068.
a) X. W. Yu, Z. H. Bi, F. Zhao, A. Manthiram, ACS Appl. Mater. Inter. 2015, 7, 16625;
b) X. W. Yu, M. M. Gross, S. F. Wang, A. Manthiram, Adv. Energy Mater. 2017, 7, 1602454.
a) A. Manthiram, Y. Z. Fu, S. H. Chung, C. X. Zu, Y. S. Su, Chem. Rev. 2014, 114, 11751;
b) N. Imanishi, O. Yamamoto, Mater. Today Adv. 2019, 4, 100031.
K. G. Gallagher, S. Goebel, T. Greszler, M. Mathias, W. Oelerich, D. Eroglu, V. Srinivasan, Energy Environ. Sci. 2014, 7, 1555.
J. P. V. P. V. Tao Liu, E. W. Zhao, J. Lei, N. Garcia-Araez, C. P. Grey, Chem. Rev. 2020, 120, 6558.
Z. W. Chang, J. J. Xu, X. B. Zhang, Adv. Energy Mater. 2017, 7, 1700875.
X. W. Mu, H. Pan, P. He, H. S. Zhou, Adv. Mater. 2019, 31, 1903790.
B. Liu, Y. L. Sun, L. Y. Liu, J. T. Chen, B. J. Yang, S. Xu, X. B. Yan, Energy Environ. Sci. 2019, 12, 887-922.
X. W. Yu, J. Joseph, A. Manthiram, Mater. Horiz. 2016, 3, 314.
M. Pietrzykowski, J. Likus-Cieslik, Sustainability 2018, 10, 2442.
S. H. Chung, A. Manthiram, Adv. Mater. 2019, 31, 1901125.
a) H. D. Yuan, T. F. Liu, Y. J. Liu, J. W. Nai, Y. Wang, W. K. Zhang, X. Y. Tao, Chem. Sci. 2019, 10, 7484;
b) J. T. Li, Z. Y. Wu, Y. Q. Lu, Y. Zhou, Q. S. Huang, L. Huang, S. G. Sun, Adv. Energy Mater. 2017, 7, 1701185.
a) J. Bruckner, S. Thieme, F. Bottger-Hiller, I. Bauer, H. T. Grossmann, P. Strubel, H. Althues, S. Spange, S. Kaskel, Adv. Funct. Mater. 2014, 24, 1284;
b) Y. Yang, M. T. McDowell, A. Jackson, J. J. Cha, S. S. Hong, Y. Cui, Nano Lett. 2010, 10, 1486;
c) M. Agostini, J. Hassoun, Sci. Rep. 2015, 5, 7591.
Y. X. Yin, S. Xin, Y. G. Guo, L. J. Wan, Angew. Chem., Int. Ed. 2013, 52, 13186.
M. Winter, B. Barnett, K. Xu, Chem. Rev. 2018, 118, 11433.
X. W. Yu, A. Manthiram, Small Methods 2017, 1, 1700217.
D. Grasso, K. Strevett, H. Pesari, J. Environ. Syst. 1993, 22, 297.
a) L. Li, Y. Zheng, S. L. Zhang, J. P. Yang, Z. P. Shao, Z. P. Guo, Energy Environ. Sci. 2018, 11, 2310;
b) H. L. Pan, Y. S. Hu, L. Q. Chen, Energy Environ. Sci. 2013, 6, 2338.
a) X. D. Ren, Y. Y. Wu, J. Am. Chem. Soc. 2013, 135, 292300;
b) X. W. Yu, A. Manthiram, Energy Storage Mater 2018, 15, 368;
c) A. Eftekhari, J Power Sources 2004, 126, 221.
a) X. W. Yu, A. Manthiram, Chem 2018, 4, 1200;
b) Z. Zhao-Karger, R. Y. Liu, W. X. Dai, Z. Y. Li, T. Diemant, B. P. Vinayan, C. B. Minella, X. W. Yu, A. Manthiram, R. J. Behm, M. Ruben, M. Fichtner, ACS Energy Lett. 2018, 3, 2005.
a) X. W. Yu, M. J. Boyer, G. S. Hwang, A. Manthiram, Adv Energy Mater. 2019, 9, 1803794;
b) X. W. Yu, A. Manthiram, ACS Energy Lett 2016, 1, 431.
a) J. Muldoon, C. B. Bucur, T. Gregory, Chem. Rev. 2014, 114, 11683;
b) C. J. Xu, Y. Y. Chen, S. Shi, J. Li, F. Y. Kang, D. S. Su, Sci. Rep. 2015, 5, 14120.
Y. Zhang, S. Q. Liu, Y. J. Ji, J. M. Ma, H. J. Yu, Adv. Mater. 2018, 30, 1706310.
a) X. W. Yu, M. J. Boyer, G. S. Hwang, A. Manthiram, Chem 2018, 4, 586;
b) D. R. Egan, C. P. de Leon, R. J. K. Wood, R. L. Jones, K. R. Stokes, F. C. Walsh, J Power Sources 2013, 236, 293.
J. Fu, R. L. Liang, G. H. Liu, A. P. Yu, Z. Y. Bai, L. Yang, Z. W. Chen, Adv. Mater. 2019, 31, 1805230.
Y. L. Liang, Y. Yao, Joule 2018, 2, 1690.
a) B. Lee, Y. Ko, G. Kwon, S. Lee, K. Ku, J. Kim, K. Kang, Joule 2018, 2, 61;
b) N. Patil, C. Jerome, C. Detrembleur, Prog. Polymer Sci. 2018, 82, 34.
L. A. Sazanov, Nat. Rev. Mol. Cell Biol. 2015, 16, 375.
J. A. Luo, B. Hu, M. W. Hu, Y. Zhao, T. L. Liu, ACS Energy Lett. 2019, 4, 2220.
H. N. Chen, G. T. Cong, Y. C. Lu, J. Energy Chem. 2018, 27, 1304.
You have requested "on-the-fly" machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Show full disclaimer
Neither ProQuest nor its licensors make any representations or warranties with respect to the translations. The translations are automatically generated "AS IS" and "AS AVAILABLE" and are not retained in our systems. PROQUEST AND ITS LICENSORS SPECIFICALLY DISCLAIM ANY AND ALL EXPRESS OR IMPLIED WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES FOR AVAILABILITY, ACCURACY, TIMELINESS, COMPLETENESS, NON-INFRINGMENT, MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Your use of the translations is subject to all use restrictions contained in your Electronic Products License Agreement and by using the translation functionality you agree to forgo any and all claims against ProQuest or its licensors for your use of the translation functionality and any output derived there from. Hide full disclaimer
Copyright John Wiley & Sons, Inc. 2021
Abstract
While renewable energy sources are deemed as a preponderant component toward building a sustainable society, their utilization depends on the efficiency and sustainability of energy‐storage technologies. The development of battery‐storage technologies with affordable and environmentally benign chemistries/materials is increasingly considered as an indispensable element of the whole concept of sustainable energy technologies. Lithium‐ion batteries are at the forefront among existing rechargeable battery technologies in terms of operational performance. Considering materials cost, abundance of elements, and toxicity of cell components, there are, however, sustainability concerns for lithium‐ion batteries. Herein, a discussion of the existing rechargeable battery technologies from a sustainability perspective is provided. Then, recent research strategies toward enhancing the sustainability of Li+‐ion technologies are first discussed. After that, emerging novel battery systems, beyond lithium‐ion technology, with sustainable chemistries and materials are highlighted and prospected.
You have requested "on-the-fly" machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Show full disclaimer
Neither ProQuest nor its licensors make any representations or warranties with respect to the translations. The translations are automatically generated "AS IS" and "AS AVAILABLE" and are not retained in our systems. PROQUEST AND ITS LICENSORS SPECIFICALLY DISCLAIM ANY AND ALL EXPRESS OR IMPLIED WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES FOR AVAILABILITY, ACCURACY, TIMELINESS, COMPLETENESS, NON-INFRINGMENT, MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Your use of the translations is subject to all use restrictions contained in your Electronic Products License Agreement and by using the translation functionality you agree to forgo any and all claims against ProQuest or its licensors for your use of the translation functionality and any output derived there from. Hide full disclaimer
Details
1 Materials Science & Engineering Program and Texas Materials Institute, The University of Texas at Austin, Austin, TX, USA