Design and synthesis of Janus-structured mutually doped SnO2-Co3O4 hollow nanostructures as superior anode materials for lithium-ion batteries

摘要

Janus-structured materials composed of mutually doped SnO2-Co3O4 hollow nanostructures were designed and synthesized for use as an efficient anode material for lithium-ion batteries. The Janusstructured powder consisting of Co-doped SnSe nanoplates and Sn-doped CoSex polyhedral structures was synthesized by a one-pot spray pyrolysis process. Similarly, the structured SnO2-Co3O4 powder consisting of Co-doped SnO2 hollow nanoplates and Sn-doped Co3O4 hollow polyhedral structures was prepared by a nanoscale Kirkendall diffusion process. The doping of both materials in the hollow SnO2 nanoplates and Co3O4 polyhedral structures improved the reversible capacities and cycling performances of the Janus-structured SnO2-Co3O4 composite powder. This was achieved by minimizing the growth of metallic Sn and Co nanocrystals during cycling, improving the decomposition of Li2O, and facilitating the conversion of Sn to SnO2 during the delithiation process through a catalytic effect of metallic Co. The discharge capacity of the Janus-structured SnO2-Co3O4 hollow powder with a Sn : Co ratio of 1 : 2 at a current density of 1 A g(-1) for the 1000th cycle was 1058.7 mA h g(-1). This Janus-structured mutually doped SnO2-Co3O4 composite powder showed extraordinary cycling and rate performances for lithium ion storage.