Uniform carbon coating and solid electrolyte interphase synergistically enhanced exceptional anodic K‐ion storage properties of stable KTiOPO4 single crystals

Abstract Searching for low‐cost, high‐capacity, high‐power, high‐stability, high‐tap‐density, and inherently safe materials for developing cheap, safe, and high‐performance batteries has always been a research hotspot. Herein, an inherently safe, low‐cost, and low‐strain KTiOPO 4 (KTOP) submicron single crystals with a uniform thin layer carbon coating are developed using a ball‐mill assisted solid‐state method. Uniform solid electrolyte interphase, carbon coating, and inherently stable structure synergistically help compact KTOP submicron single crystals achieve an exceptional anodic K‐ion storage performance. The carbon‐coated KTOP single crystals obtained under the carbonization temperature of 400°C (KTOP‐C‐400) can deliver an exceptional potassium ion storage performance of 253.3, 224.0, 175.5, and 131.1 mA h g −1 at the current density of 100, 200, 500, and 1000 mA g −1 , respectively, in the electrolyte of 5 M potassium bis(fluorosulfonyl)imide (KFSI) in DIGLYME electrolytes. Even after being cycled at 1000 mA g −1 for 1000 cycles, the capacity was maintained at 182.5 mA h g −1 with a coulombic efficiency of 99.9%.