RESUMEN
Graphite is the most popular anode material for lithium-ion batteries (LIBs) owing to its high reversibility and stable cycling performance. With the rapid growth of the global electric vehicle (EV) market, it has become necessary to improve the quick-charge performance of graphite to reduce the charging time of LIBs. Therefore, from a structural viewpoint, it is crucial to control interfacial reactions and stabilize the surface of graphite to improve the sluggish interfacial kinetics. Herein, we propose a facile approach for integrating functional metal oxides on the surface of natural graphite (NG) via a surface-coating technique in combination with a facile-crystallization process. The functionality of the metal oxides, i.e., MoO2 and Fe3O4, on the surface of NG was thoroughly investigated based on various structural and electrochemical analyses. The results demonstrate that the metal oxides play critical roles in stabilizing the surface of NG and facilitating faster Li+ migration at the interface between NG and the electrolyte during cycling. In particular, the full cell configured with the c-Fe3O4-NG anode shows remarkably improved charging behavior (3 C charging-1 C discharging) without any significant loss of reversible capacity during 300 cycles. This study has conclusively established that tailoring the surface of NG with functional metal oxides would be a utilitarian way to improve the charging capability of NG. We are confident that the study results would provide utilitarian insights into the development of advanced LIBs for successful implementation in EV applications in the future.
RESUMEN
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 MoOx-MoPx promoter improves the charging rate and suppresses Li plating without compromising energy density. We design and synthesise MoOx-MoPx/graphite via controllable and scalable surface engineering, i.e., the deposition of a MoOx nanolayer on the graphite surface, followed by vapour-induced partial phase transformation of MoOx to MoPx. A variety of analytical studies combined with thermodynamic calculations demonstrate that MoOx effectively mitigates the formation of resistive films on the graphite surface, while MoPx hosts Li+ at relatively high potentials via a fast intercalation reaction and plays a dominant role in lowering the Li+ adsorption energy. The MoOx-MoPx/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 LiNi0.6Co0.2Mn0.2O2 cathode. Thus, the developed approach paves the way to the design of advanced anode materials for fast-charging Li-ion batteries.
