Synthesis, Electrochemistry, and Thermal Stability of High‐Energy Ball‐Milled Silicon‐based Alloy Anodes in Lithium‐Ion Batteries**

Abstract The fast capacity degradation of silicon‐based anodes significantly limits the application in lithium‐ion battery (LIB) industries. Recently, Si−CuO composites have been reported as promising anodes in terms of being cost‐effective and technically feasible, but improved cycle stability is still desired. This work introduces a proper amount of NiO into the Si−CuO composites via a facile high‐energy ball‐milling method. The study reveals that compared to the binary Si‐CuO composites, Si−CuO−NiO samples have less pronounced volume change during the cycles due to the formation of rich‐Si NiSi 2 . More specifically, Si 87.5 (CuO) 3.4 (NiO) 9.1 shows the highest 100‐cycle capacity retention of ∼86.9 % at 0.2 C with an average coulombic efficiency of ∼99.4 %. Moreover, the thermal stability investigation demonstrates that the temperature of 600 °C is suitable to coat a carbon layer on Si 87.5 (CuO) 3.4 (NiO) 9.1 , where the microstructure and the uniform element distribution produced in the milling process as well as the suppression to the cr‐Li 3.75 Si formation can be maintained to the maximum extent, thus with further enhanced electrochemical performance.