Elucidating the Impact of Cobalt Doping on the Lithium Storage Mechanism in Conversion/Alloying‐Type Zinc Oxide Anodes

Abstract Herein, an in‐depth investigation of the influence of transition‐metal doping on the structural and electrochemical characteristics of a hybrid conversion/alloying‐type lithium‐ion anode material is presented. Therefore, pure zinc oxide (ZnO) and cobalt‐doped ZnO (Zn 0.9 Co 0.1 O) were investigated comparatively. Characterization by using X‐ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) confirmed the successful incorporation of the cobalt (Co) dopant into the wurtzite ZnO structure, which led to a decreased particle size for the doped compound. The in situ electrochemical XRD analysis of the first de‐/lithiation of ZnO and Zn 0.9 Co 0.1 O revealed the highly beneficial impact of the transition‐metal dopant on the reversible degradation of lithium oxide (Li 2 O) and suppression of zinc crystallite growth upon lithiation; both effects are essential for greatly improved electrochemical performance. As a result, Co doping leads to a substantially increased specific capacity from 326 mAh g −1 for pure ZnO to 789 mAh g −1 for Zn 0.9 Co 0.1 O after 75 full charge–discharge cycles.