Uniform carbon coating mediated multiphase interface in submicron sized rodlike cobalt ditelluride anodes for high-capacity and fast lithium storage. (20th January 2023) - Fan, Huilin
Research highlights: The CoTe2 submicron-rod coated by carbon layer was synthesized by a green method. The CoTe2 phase transition is controlled by the surface derived carbon layer. The abundant multiphase interfaces promote the electrons/ions transport. The optimized sample shows an excellent lithium storage performance. 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. Graphical abstract: Introducing abundant inner heterogeneous (carbon/CoTe2 ) and homogeneous (orthorhombic/hexagonal CoTe2 ) interfaces in submicron-rod CoTe2, instead of exposing the high external surface in nanoscale electrodes, is proposed. The electrode possesses excellent lithium storage performance due to the strengthened structure stability, and promoted electrons/ions transport. Image, graphical abstract