Flexible Three-Dimensional Heterostructured ZnO-Co 3 O 4 on Carbon Cloth as Free-Standing Anode with Outstanding Li/Na Storage Performance

Abstract

Herein, a facile and binder-free method was developed to prepare a flexible electrode for dual battery applications, which was achieved by fabricating nanosheets of ZnO-Co3O4 heterostructures attached on the surface of highly conductive carbon cloth (CC). Remarkably, for Li-ion batteries, the combined effects of two dimensional (2D) heterostructural and three dimensional (3D) carbon fiber substrate offered an excellent reversible capacity rate of approximately 1785 mAh g(-1) at a current density of 200 mA g(-1). Even at a charge-discharge rate of 2000 mA g(-1), the ZnO-Co3O4@CC composite exhibited a reversible capacity of 491 mAh g(-1) after 400 cycles. For sodium-ion batteries, the composite exhibited a reversible specific capacity of 684 mAh g(-1) at a current density of 200 mA g(-1) and a capacity of 265 mAh g(-1) after 500 cycles at a current density of 1000 mA g(-1). Flexible half-cells were also constructed, which exhibited high flexibility and excellent electrochemical performance. The excellent performance is mainly due to the in situ growth of ZnO-Co3O4 nanosheets on the CC, which provided a large contact area between the active material and the flexible and conductive substrate, ultimately facilitating rapid electron transport and preventing the aggregation of large surface area nanosheets. (C) 2018 The Electrochemical Society.