A cooperative biphasic MoOx–MoPx promoter enables a fast-charging lithium-ion battery

Abstract

The realisation of fast-charging lithium-ion batteries with long cycle lifetimes is hindered by the uncontrollable plating of metallic Li on the graphite anode during high-rate charging. Here we report that surface engineering of graphite with a cooperative biphasic MoO_x–MoP_x promoter improves the charging rate and suppresses Li plating without compromising energy density. We design and synthesise MoO_x–MoP_x/graphite via controllable and scalable surface engineering, i.e., the deposition of a MoO_x nanolayer on the graphite surface, followed by vapour-induced partial phase transformation of MoO_x to MoP_x. A variety of analytical studies combined with thermodynamic calculations demonstrate that MoO_x effectively mitigates the formation of resistive films on the graphite surface, while MoP_x hosts Li⁺ at relatively high potentials via a fast intercalation reaction and plays a dominant role in lowering the Li⁺ adsorption energy. The MoO_x–MoP_x/graphite anode exhibits a fast-charging capability (<10 min charging for 80% of the capacity) and stable cycling performance without any signs of Li plating over 300 cycles when coupled with a LiNi_0.6Co_0.2Mn_0.2O₂ cathode. Thus, the developed approach paves the way to the design of advanced anode materials for fast-charging Li-ion batteries.

Fast-charging of lithium-ion batteries is hindered by the uncontrollable plating of metallic Li on the graphite anode during cycling. Here, the authors demonstrate the fast chargeability and long cycle lifetimes via surface engineering of graphite with a cooperative biphasic MoO_x–MoP_x promoter.