Cation-vacancy induced Li+ intercalation pseudocapacitance at atomically thin heterointerface for high capacity and high power lithium-ion batteries

It is challenging to create cation vacancies in electrode materials for enhancing the performance of rechargeable lithium ion batteries (LIBs). Herein, we utilized a strong alkaline etching method to successfully create Co vacancies at the interface of atomically thin Co3-xO4/graphene@CNT heterostructure for high-energy/power lithium storage. The creation of Co-vacancies in the sample was confirmed by high-resolution scanning transmission electron microscope (HRSTEM), X-ray photoelectron spectroscopy (XPS) and electron energy loss near-edge structures (ELNES). The obtained Co3-xO4/graphene@CNT delivers an ultra-high capacity of 1688.2 mAh g(-1) at 0.2 C, excellent rate capability of 83.7% capacity retention at 1 C, and an ultralong life up to 1500 cycles with a reversible capacity of 1066.3 mAh g(-1). Reaction kinetic study suggests a significant contribution from pseudocapacitive storage induced by the Co-vacancies at the Co3-xO4/graphene@CNT interface. Density functional theory confirms that the Co-vacancies could dramatically enhance the Li adsorption and provide an additional pathway with a lower energy barrier for Li diffusion, which results in an intercalation pseudocapacitive behavior and high-capacity/rate energy storage. (C) 2021 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

This study successfully created Co vacancies in the interface of atomically thin Co3-xO4/graphene@CNT heterostructure by using a strong alkaline etching method, leading to enhanced performance and energy storage capability of lithium-ion batteries. Experimental results demonstrated ultra-high capacity, excellent rate capability, and long cycle life of the material. Density functional theory confirmed that Co vacancies could improve lithium adsorption and provide a lower energy barrier for lithium diffusion.