Insight of K-deficient layered KxMnO2 cathode for potassium-ions batteries

Potassium-ions batteries (PIBs) are attracting increasing attention as up-and-coming youngster in large-scale grid-level energy storage benefiting from its low-cost and high energy density. Nevertheless, enough researches regarding indispensable cathode materials for PIBs are badly absent. Herein, we synthesize K-deficient layered manganese-based oxides (P2-K0.21MnO2 and P3-K0.23MnO2) and investigate them as cathode of PIBs for the first time. As the newcomer of potassium-containing layered manganese-based oxides (KxMnO2) group, P2-K0.21MnO2 delivers high discharge capacity of 99.3 mAh g(-1) and P3-K0.23MnO2 exhibits remarkable capacity retention rate of 75.5%. Besides, in-situ XRD and ex-situ XRD measurements reveal the reversible phase transition of P2-K0.21MnO2 and P3-K0.23MnO2 with the potassium-ions extraction and reinsertion, respectively. This work contributes to a better understanding for the potassium storage in K-deficient layered KxMnO2 (x <= 0.23), possessing an important basic scientific significance for the exploitation and application of layered KxMnO2 in 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

K-deficient layered manganese-based oxides are synthesized and investigated as cathodes for potassium-ions batteries (PIBs) for the first time, showing high discharge capacity and remarkable capacity retention rate. The reversible phase transition during potassium-ions extraction and reinsertion provides a better understanding for potassium storage in K-deficient layered KxMnO2, contributing to the development and application of layered KxMnO2 in PIBs.