Impact of Sb‐Doping on the Reversible Li⁺ and Na⁺ Storage in CeO₂‐Type Negative Electrodes

Insertion-type metal oxide anode materials for lithium-ion and sodium-ion batteries commonly offer excellent cycling stability. However, their reversible capacity is eventually constrained by the finite number of available active sites within their crystal structures. Herein, the effect of introducing Sb into insertion-type CeO2 (Sb-CeO2) is investigated as an effective strategy to overcome this intrinsic limitation. Compared to neat CeO2, it shows a substantially increased capacity owing to the extended redox activity of the Sb dopant while generally maintaining the insertion-type reaction mechanism of the CeO2 host matrix. Interestingly, Sb-CeO2 demonstrates promising performance in both Li-cells and Na-cells. Although the capacity contribution of Sb is slightly reduced in Na-cells compared to Li-cells, the former benefit from a highly stable solid electrolyte interphase layer and a remarkable rate capability in combination with an ether-based electrolyte. This is demonstrated also in sodium-ion cells comprising an Sb-CeO2 anode and a Na3V2(PO4)3 cathode, showing excellent power performance up to a dis-/charge rate of 50C.