Graphene collage on Ni-rich layered oxide cathodes for advanced lithium-ion batteries

Abstract

The energy storage performance of lithium-ion batteries (LIBs) depends on the electrode capacity and electrode/cell design parameters, which have previously been addressed separately, leading to a failure in practical implementation. Here, we show how conformal graphene (Gr) coating on Ni-rich oxides enables the fabrication of highly packed cathodes containing a high content of active material (~99 wt%) without conventional conducting agents. With 99 wt% LiNi_0.8Co_0.15Al_0.05O₂ (NCA) and electrode density of ~4.3 g cm^-3, the Gr-coated NCA cathode delivers a high areal capacity, ~5.4 mAh cm⁻² (~38% increase) and high volumetric capacity, ~863 mAh cm^-3 (~34% increase) at a current rate of 0.2 C (~1.1 mA cm^-2); this surpasses the bare electrode approaching a commercial level of electrode setting (96 wt% NCA; ~3.3 g cm^-3). Our findings offer a combinatorial avenue for materials engineering and electrode design toward advanced LIB cathodes.

Li-ion battery electrodes contain inactive materials, such as conducting agents and polymeric binders, which limit the energy density. Here, the authors demonstrate highly dense Ni-rich cathodes with improved volumetric capacities by coating graphene and minimizing the inactive components.