Covalent sulfur as stable anode for potassium ion battery

The potassium bis(fluoro-sulfonyl)imide(KFSI)-based electrolyte has great application prospects in potassium ion batteries (PIBs). However, their development has been limited by the decomposition of electrolytes and the corrosion of Al foils (current collector) at high potential. Here, a N-doping, sulfur-rich chemically bonded porphyrin organic framework (SPOF) with a high potential plateau were synthesized as an anode to lower the redox potential of full cells and further inhibit the corrosion of Al foils. SPOF as anode delivers high reversible capacity (557 mAh g(-1) at 50 mA g(-1)), excellent cycling performance (94% capacity retention over 1000 cycles at 500 mA g(-1)), and superior rate performance. Meanwhile, the ex situ FTIR, Raman, and HRTEM revealed the stability of N-doping and the reversible covalent sulfur and S-S bonds changes during potassiation/depotassiation. In addition, full cells using SPOF anode and PTCDA cathode showed outstanding performance (high capacity of 300 mAh g(-1) at 200 mA g(-1)). And the Al current collector of the full cell was not corroded after 150 cycles. Yet, the Al foils with PTCDA as cathode were seriously corroded. This work provides a new strategy for realizing ultra-high reversible capacity and cyclic stability of PIBs, and also accelerates the process of early commercial application of PIBs. (C) 2021 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

This study synthesized a novel SPOF organic framework as an anode for potassium ion batteries, successfully increasing the reversible capacity and cyclic stability of the battery, while inhibiting the corrosion of aluminum foils. In full cells, the system composed of SPOF anode and PTCDA cathode exhibited excellent performance.