AbstractThe development of high‐performance sulfur‐based composite cathodes is a promising strategy to accelerate the reaction kinetics of sulfur and decelerate the irreversible loss of polysulfides. Herein, a strategy for fabricating high‐performance metal‐sulfur composite cathodes is proposed to achieve a facile synthesis process, adjustable high sulfur content, and excellent electrochemical performance. Electroless nickel plating is applied to achieve a nickel‐sulfur nanocomposite with metallic nickel to inhibit the high resistance of the active solid‐state materials (i. e., sulfur and lithium sulfide) and the rapid diffusion of the active liquid‐state materials (i. e., lithium polysulfides). Therefore, the electroless nickel‐plated sulfur (ENS) composite cathode attains high, tunable sulfur contents of 60 wt %–95 wt %, large sulfur loadings of 2–10 mg cm−2, and excellent charge‐storage capacity values of 822–1,362 mAh g−1, corresponding to high areal capacity and energy density values of 8.2 mAh cm−2 and 17.3 mWh cm−2, respectively.