Uniform carbon coating mediated multiphase interface in submicron sized rodlike cobalt ditelluride anodes for high-capacity and fast lithium storage

Abstract

Cobalt ditelluride (CoTe2) is an attractive anode material for lithium-ion batteries due to its unique metallic characteristic, multiple crystal structure, and high density. However, the poor stability and slow-charging capability limit the practical application. While the effective strategy of nano-engineering brings lower volumetric capacity and more irreversible side reactions. In this work, a strategy of constructing abundant inner heterogeneous (carbon/CoTe2) and homogeneous (orthorhombic/hexagonal CoTe2) interfaces in submicron-scale electrode, instead of exposing the high external surface in nanoscale electrodes, is proposed. Structural, morphology, and composition characterization, combined with the electrochemical analysis reveal the multiphase interface in CoTe2 mediated by uniform carbon coating can remarkably strengthen the structure stability and promote the electrons/ions transport. The resultant optimal electrode exhibits a superb electrochemical performance with a rising discharge capacity up to 807 mA h g−1 (600.2 mA h cm−3) at 0.2 C (1 C = 600 mA g−1) after 200 cycles, as well as a stabilized capacity of 438 mA h g−1 (325.7 mA h cm−3) at 1 C after 400 cycles. This success can expand to other anode materials with multiple crystal phases to promote the energy storage.