Cobalt-doping-induced ultrathin solid-electrolyte interphase construction and shuttle effect inhibition in Cu3PS4-carbon nanotube hybrid enabling superior potassium-ion storage

Ternary transition-metal phosphorus chalcogenides have intriguing properties as anodes for K-ion batteries, such as diverse compositions, abundant resources, high theoretical capacities, and multiplex redox reactions. However, they mostly suffer from intermediate polysulfides shuttling, huge volume variations, sluggish kinetics, and poor conductivity, leading to rapid decay of electrochemical performance. To efficiently exploit their advantages, we introduce a simple heteroatom transition-metal (Co, Fe, Ni) doping strategy to a Cu3PS4-carbon nanotube heterostructure for the first time. The doping of Co particles into Cu3PS4-carbon nanotube (CPSC/Co) hybrid concurrently alleviates volumetric changes, causes the formation of a thin solid-electrolyte interphase film, suppresses the dissolution of soluble potassium polysulfides into the electrolyte, hinders the agglomeration of discharging/recharging products, and boosts the reversibility of redox reactions during potassiation/depotassiation processes. The CPSC/Co hybrid thus delivers an excellent initial Coulombic efficiency (86.1%), outstanding cyclic stability (489 mAh g-1 after 300 cycles at 0.2 A g-1), and high rate capability (291 mAh g- 1 at 2 A g-1). Our findings demonstrate that transition-metal doping can rationally modulate the morphology and composition of solid-electrolyte interphase films and alter the discharging/charging reactions in metal-ion batteries.