Realizing the enhanced cyclability of a cactus-like NiCoO nanocrystal anode fabricated by molecular layer deposition.

Lithium-ion batteries with conversion-type anode electrodes have attracted increasing interest in providing higher energy storage density than those with commercial intercalation-type electrodes. However, conversion-type materials exhibit severe structural instability and capacity fade during cycling. In this work, a molecular layer deposition (MLD)-derived conductive AlO/carbon layer was employed to stabilize the structure of the cactus-like NiCoO nanocrystal (NC) anode. The conductive AlO/carbon network and cactus-like NiCoO NCs are beneficial for fast Li/e transport. Moreover, the AlO/carbon buffer-layer can prevent the NiCoO NCs from agglomeration and form a steady solid electrolyte interphase (SEI), thus hampering the penetration of the electrolyte. Owing to these advantages, the assembled NiCoO@AlO/carbon half battery shows a high reversible capacity (931.2 mA h g at 2 A g) and long-term stability of 290 mA h g at 5 A g over 500 cycles. Quantitative analyses further reveal the fast kinetics and the capacitance-battery dual model mechanism in the 3D core-shell structures. The design and introduction of MLD-derived hybrid coating may open a new way to conversion-type and alloy-type anode materials beyond NiCoO to achieve high cyclability.