Layered transition metal oxides prepared by plasma-enhanced sintering technique as environmentally stable cathode for potassium-ion batteries

Layered transition metal oxides are deemed the most promising cathode materials for potassium-ion batteries owing to their high energy density and scalable design. However, their inherent moisture sensitivity thwarts their potential commercial realization. Herein, we show the efficacy of plasma-enhanced sintering technique in enhancing the environmental stability of K0.6Ni0.2Co0.3Mn0.5O2 layered oxide. The attained K0.6Ni0.2Co0.3Mn0.5O2 microspheres manifest a potassium-deficient surface layer that significantly suppresses surface hygroscopicity. Consequently, K0.6Ni0.2Co0.3Mn0.5O2 can be kept and handled in ambient air condition, while yet achieve competitive potassium-ion storage performance compared with other reported layered cathode materials with similar composition and microstructures. Overall, this work accentuates plasma-enhanced sintering techniques as an effective strategy to circumvent the moisture sensitivity of potassium-containing layered metal oxides, leverageable to hygroscopic layered metal oxides for other energy storage systems.