Synthesis of highly crumpled carbon-graphene composite for adsorption-controlled potassium-ion anode materials

Abstract

Potassium-ion batteries (PIBs) are very suitable for large-scale energy storage due to their extensive resources. Nevertheless, the anodes of PIBs suffer from larger volume expansion, sluggish reaction kinetics, and tardy ion diffusion rate due to the larger ion radius and molecular weight of potassium ions. In order to solve above issues, we synthesized a carbon-graphene composite using a physical mixing strategy, which is different from previous heteroatom doping methods. The F127 is used as a soft template to prepare a mixture of carbon materials (named as FRC). The unique structure of FRC consists of a RGO with corrugated surface and F127-derived hard carbon with a lot of holes. Through the half-cell test, FRC delivers a high reversible specific capacity of 476.2 mA h g−1 at 100 mA g−1 after 200 cycles and excellent rate capacity (323.7 mA h g−1 at 5000 mA g−1). Systematic characterizations demonstrate that F127 can not only be used as an intermediate separator between RGO layers to prevent RGO agglomeration, but also increase the surface wrinkle and improve the porosity of RGO, so that the electrolyte can quickly penetrate, which are beneficial for the pseudocapacitive effect and diffusion coefficient.