Zinc‐Doping Strategy on P2‐Type Mn‐Based Layered Oxide Cathode for High‐Performance Potassium‐ion Batteries

Abstract Mn‐based layered oxide is extensively investigated as a promising cathode material for potassium‐ion batteries due to its high theoretical capacity and natural abundance of manganese. However, the Jahn–Teller distortion caused by high‐spin Mn 3+ (t 2g 3 e g 1 ) destabilizes the host structure and reduces the cycling stability. Here, K 0.02 Na 0.55 Mn 0.70 Ni 0.25 Zn 0.05 O 2 (denoted as KNMNO‐Z) is reported to inhibit the Jahn–Teller effect and reduce the irreversible phase transition. Through the implementation of a Zn‐doping strategy, higher Mn valence is achieved in the KNMNO‐Z electrode, resulting in a reduction of Mn 3+ amount and subsequently leading to an improvement in cyclic stability. Specifically, after 1000 cycles, a high retention rate of 97% is observed. Density functional theory calculations reveals that low‐valence Zn 2+ ions substituting the transition metal position of Mn regulated the electronic structure around the MnO bonding, thereby alleviating the anisotropic coupling between oxidized O 2− and Mn 4+ and improving the structural stability. K 0.02 Na 0.55 Mn 0.70 Ni 0.25 Zn 0.05 O 2 provided an initial discharge capacity of 57 mAh g −1 at 100 mA g −1 and a decay rate of only 0.003% per cycle, indicating that the Zn‐doped strategy is effective for developing high‐performance Mn‐based layered oxide cathode materials in PIBs.