Abstract Potassium‐based layered transition metal oxides, one of the most promising cathodes for potassium‐ion batteries (PIBs), suffer from detrimental intrinsic phase transitions and sluggish K + ‐diffusion kinetics, resulting in inferior fast‐charging capability. Herein, a facile bimetallic substitution strategy is proposed to synthesize Ni/Cu substituted manganese‐based layered oxide (KMNCO) cathode with exceptional fast‐charging capability. Benefiting from the precise substitution of Ni/Cu for Mn, KMNCO features suppressed high‐spin Mn 3+ concentration and enhanced potassium content. As expected, KMNCO demonstrates a high reversible specific capacity, extraordinary fast‐charging specific capacity, and cycling stability. In situ X‐ray diffraction combined with in situ kinetics analysis and microstructural characterization elucidates a highly reversible, solid‐solution mechanism governing K + intercalation/deintercalation in KMNCO. In‐depth electrochemical analysis and theoretical calculations confirm that Ni/Cu substitution eliminates the K + ‐vacancy ordered structure, thereby enhancing potassium storage kinetics of KMNCO. In addition, full‐cells based on the KMNCO cathode deliver a reversible specific capacity of 93 mAh g −1 and satisfactory cycling stability. This work provides an alternative route for precisely engineering fast‐charging cathode materials for PIBs.
Zeng et al. (Wed,) studied this question.