Chemical-etching strategy tailoring hollow carbon confined highly dispersed CoP nanoparticles for durable potassium storage

Abstract

Implanting nano-scaled CoP particles into hollow carbon is usually regarded as an effective strategy to improve structural stability for potassium ion batteries (PIBs). Hence, we employ tannic acid (TA) as the chemical-etching agent to elaborately synthesize a novel hollow hybrid composite composed of highly dispersed CoP nanoparticles (10-20 nm) embedded in well-developed carbon shell (CoP/C-2). The nano-sized CoP significantly shortens the diffusion distance of K-ions within electrode, while the highly dispersed features can expose more active surface to electrolyte by avoiding self-agglomeration, endowing improved reaction kinetics. Besides, the presence of carbon shell provides sufficient buffer space for volume variation, all of which are conducive to maintaining structural integrity against pulverization upon repeated cycling. When used as an anode for PIBs, the optimized CoP/C-2 exhibits an extraordinary cycling stability by keeping a high reversible capacity of 103.4 mAh g−1 after 1000 cycles at 2 A g−1, outperforming most previously reported literatures. The strategy presented in this work may provide a reference for constructing other advanced CoP-based abodes for PIBs.