Mildly-expanded graphite with adjustable interlayer distance as high-performance anode for potassium-ion batteries

As a promising anode for potassium-ion batteries (PIBs), graphite has drawn great attention due to easy availability, low cost and formation of potassium-based intercalation compound. However, poor cyclic and rate performances due to severe structural degradation limit the practical application of graphite anode. Herein, a low cost mildly-expanded graphite (MEG) with adjustable interlayer lattice distance is synthesized through a wet chemical oxidation route. As anode for PIBs, the MEG exhibited stable intercalation/deintercalation plateaus, outstanding cyclic stability and rate performance. By optimizing the mass ratio between graphite and potassium permanganate oxidant, the MEG anode retaining longrange-ordered domains of graphite delivers a capacity of 88 mAh/g at 1500 mA/g and a capacity retention of 72.3% after 200 cycles at 100 mA/g. The potassium ion full cell assembled with MEGs anode exhibites high energy density and outstanding cyclic stability. Our results demonstrate a promising graphite-based anode for PIBs and provide guidance for the designing of novel carbonic electrodes for PIBs. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

A low cost mildly-expanded graphite anode with adjustable interlayer lattice distance was synthesized for potassium-ion batteries, showing stable intercalation/deintercalation plateaus and outstanding cyclic stability and rate performance. By optimizing the mass ratio, the anode delivered high capacity and retention rate under different current densities, demonstrating promising potential for PIBs.