Wadsley–Roth phase CoNb11O29 as a high-performance anode for lithium-ion batteries

Abstract

Owing to their high capacity, suitable operating potential, and remarkable rate performance, niobium-based oxides attract increasing attention as a new class of intercalation-type anodes for lithium-ion batteries (LIBs). However, limited by the inferior electronic and Li⁺ conductivities, their electrochemical performance is not satisfactory. Here, micron-sized CoNb₁₁O₂₉ (CNO) is designed and proved as a prominent anode. With an average operating potential of 1.55 V, CNO possesses a high specific capacity of 265 mA h g⁻¹ and a high initial Coulombic efficiency of 92% at 0.1C (1C = 400 mA g⁻¹). Through galvanostatic intermittent titration technique (GITT) measurements and cyclic voltammetry (CV) tests, large pseudocapacitive contribution as well as fast Li⁺ diffusion are confirmed. Moreover, in situ X-ray diffraction (XRD) verified the simple solid-solution mechanism, and the maximum volume change is determined to be 4.06%. Therefore, CNO shows excellent rate performance (113 mA h g⁻¹ at 10C) and extreme cycling performance (73% capacity retention after 5000 cycles at 10C). The excellent cycling stability (96.4% capacity retention after 900 cycles at 5C) of the LiFePO₄//CNO full cell further demonstrates its great application prospects.