Design and synthesis of NiCo-NiCoO₂@C composites with improved lithium storage performance as the anode materials

The rapid capacity decay severely limits the commercial applications of metal oxide-based electrodes. Exploring innovative materials with enhanced lithium storage performance is urgent and challenging. Herein, we propose a strategy for the synthesis of NiCo-NiCoO₂@C composites using layered double hydroxide (LDH) precursors. When used as the anode materials, the composites deliver enhanced capacity throughout the continuous charge-discharge process. In our design, the electrochemically active NiCoO₂ nanoparticles pulverize the NiCo phases via a conversion reaction. The NiCo phases can increase capacity by reacting with the Li₂O yielded from the conversion of NiCoO₂ and participating in the reversible transformation of solid-electrolyte interface (SEI) films, thus ensuring fast charge transfer. Voids that appear with the consumption of NiCo phases can provide abundant channels for Li⁺ transportation. Carbon matrices can effectively alleviate the stress generated during repeated cycles of expansion and shrinkage. Benefiting from these features, NiCo-NiCoO₂@C anode delivers a highly enhanced reversible capacity of 961.6 mAh g^-1 after 300 cycles at 200 mA g^-1. This LDH-based strategy may be extended to the design and synthesis of various enhanced anode materials for lithium-ion batteries (LIBs).