Interlayer-Engineering and Surface-Substituting Manganese-Based Self-Evolution for High-Performance Potassium Cathode

摘要

Manganese-based layered oxides cathodes have attracted enormous interestdue to their advantages in cost and energy density. The significant challengesof Mn-based layered oxides for potassium-ion batteries (PIBs) are complexphase transition and Mn dissolution upon K~+ intercalation/deintercalation.Here, a P3-type K_(0.45)Rb_(0.05)Mn_(0.85)Mg_(0.15)O_2 (KRMMO) cathode material isproposed to address the above challenges. The results show that rubidiumacts as a pillar to expand interlayer spacing and stabilize the structure,while magnesium partially replaces Mn to suppress the Jahn–Teller distortionof the Mn~(3+). The KRMMO cathode exhibits high capacity of 108.0 and77.3 mAh g~(?1) at 20 and 500 mA g~(?1), respectively, and retains 98.2 of itsinitial capacity after 200 cycles. Compared with P3-K_(0.5)MnO_2, the capacityfading of P3-KRMMO is effectively suppressed, which is mainly due to thesynergistic contribution of Rb and Mg ions in the alleviation of volumechange and suppression of phase transition. This work may open a newavenue for the design and optimization of layered cathode materials for PIBsand beyond.