Shell Modulation of Hollow Metal Sulfide Nanocomposite for Stable Potassium Storage at Room and High Temperature

The large size of K‐ion makes the pursuit of stable high‐capacity anodes for K‐ion batteries (KIBs) a formidable challenge, particularly for high temperature KIBs as the electrode instability becomes more aggravated with temperature climbing. Herein, we demonstrate that a hollow ZnS@C nanocomposite (h‐ZnS@C) with a precise shell modulation can resist electrode disintegration to enable stable high‐capacity potassium storage at room and high temperature. Based on a model electrode, we identify an interesting structure‐function correlation of the h‐ZnS@C: with an increase in the shell thickness, the cyclability increases while the rate and capacity decreases, shedding light on the design of high‐performance h‐ZnS@C anodes via engineering the shell thickness. Typically, the h‐ZnS@C anode with a shell thickness of 60 nm can deliver an impressive comprehensive performance at room temperature; the h‐ZnS@C with shell thickness increasing to 75 nm can achieve an extraordinary stability (88.6% capacity retention over 450 cycles) with a high capacity (450 mAh g‐1) and a superb rate even at an extreme temperature of 60 ℃, which is much superior than those reported anodes. This contribution envisions new perspectives on rational design of functional metal sulfides composite toward high‐performance KIBs with insights into the significant structure‐function correlation.