Co-activated Conversion Reaction of MoO2:CoMoO3 as a Negative Electrode Material for Lithium-Ion Batteries

Heterostructured CoO/MoB MBene composites for high performance lithium-ion batteries anode

Transition metal oxide CoO has attracted extensive attention as a potential anode material for lithium-ion batteries (LIBs) due to its impressive theoretical specific capacity. However, pristine CoO often suffers from structural collapse during cycling, resulting in reduced capacity. To address these challenges, we developed a method to in situ grow octahedral CoO nanoparticles on hierarchical multilayer MoB MBene. The matched layer gradients and heterojunction formation between CoO and MoB MBene effectively accommodate the volume expansion of CoO. Following 200 cycles at 100 mA/g, the CoO/MoB MBene electrode achieves a capacity of 819.8 mAh/g, a significant 2.58-fold performance improvement over pristine CoO. Even at 1000 mA/g, the composite retains a capacity of 601.3 mAh/g after 600 cycles, while the pristine material retains only 142.4 mAh/g. This breakthrough suggests CoO/MoB MBene composite holds great promise in improving the performance of LIBs and may pave the way for the development of advanced materials.

Tailoring the Surface of Natural Graphite with Functional Metal Oxides via Facile Crystallization for Lithium-Ion Batteries

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.

Complementary combinative strategy of defect engineering and graphene coupling for efficient energy-functional materials

The synergetic combination of defect engineering and graphene coupling enables to develop an effective way of exploring efficient bifunctional electrocatalyst/electrode materials. Defect-engineered amorphous MoO₂ -reduced graphene oxide (rGO) nanohybrid was synthesized by soft-chemical reduction of K₂ MoO₄ in graphene oxide colloids. Mo K-edge X-ray absorption spectroscopy clearly demonstrates the rutile-type local atomic structure of amorphous MoO₂ with significant oxygen vacancies and intimate electronic coupling with rGO. The defect-introduced MoO₂ -rGO nanohybrid shows excellent bifunctionality as electrocatalyst for hydrogen evolution reaction and electrode for sodium-ion batteries, which are superior to those of crystalline MoO₂ -rGO homologue. The beneficial effect of simultaneous defect control and rGO coupling can be ascribed to the provision of oxygen vacancies acting as active sites, the increase of electrical conductivity, and the improvement of reaction kinetics.