Synergistically enhanced structural, thermal and interfacial stability of K0.45MnO2 via tailoring the local structure for high-energy and high-power potassium-ion batteries

Abstract

Mn-based layered oxides are widely considered as cost-effective cathodes for K-ion batteries (KIBs), whereas the local lattice distortion induced by the Jahn-Teller effect of Mn3+ usually results in limited capacity and unsatisfactory cycling lives. Herein, a new P3-type K0.45Mn0.9Al0.1O2 material is designed via riveting electrochemical inactive Al3+ in the octahedral Mn3+ sites, which is experimentally proved to play a key role in suppressing misfit dislocations at the atomic scale, enlarging the spacing of K+ layers, relieving exothermic phase transition at elevated temperature and helping to form a stable and uniform cathode electrolyte interphase (CEI) layer synergistically. Thanks to these inherent merits, K0.45Mn0.9Al0.1O2 delivers a high specific capacity of 152 mAh/g at 20 mA g−1 and excellent cyclic performance with capacity retention of 67 % over 1000 cycles, much superior to K0.45MnO2. Impressively, the full battery achieves a high energy (291 Wh kg−1) and power (843 W kg−1) densities over state-of-the-art layered cathodes for KIBs. This study not only provides a facile and effective strategy to jointly enhance the structural, thermal and interfacial stability of Mn-based layered cathodes, but also the underlying mechanism revealed here sheds light on designing novel cathodes via tailoring the local structural environments.