Observation of ZrNb14O37 Nanowires as a Lithium Container via In Situ and Ex Situ Techniques for High-Performance Lithium-Ion Batteries

Micron-Sized Cobalt Niobium Oxide with Multiscale Porous Sponge-Like Structure Boosting High-Rate and Long-Life Lithium Storage

Niobium-based oxides show great potential as intercalation-type anodes in lithium-ion batteries due to their relatively high theoretical specific capacity. Nevertheless, their electrochemical properties are unsatisfactorily restricted by the poor electronic conductivity. Here, micron-sized Co0.5Nb24.5O62 with multiscale sponge-like structure is synthesized and demonstrated to be a fast-charging anode material. It can deliver a remarkable capacity of 287 mA h g-1 with a safe average working potential of ≈1.55 V vs Li+/Li and a high initial Coulombic efficiency of 91.1% at 0.1C. Owing to the fast electronic/ionic transport derived from the multiscale porous sponge-like structure, Co0.5Nb24.5O62 exhibits a superior rate capability of 142 mA h g-1 even at 10C. In addition, its maximum volume change during the charge/discharge process is determined to be 9.18%, thus exhibiting excellent cycling stability with 75.3% capacity retention even after 3000 cycles at 10C. The LiFePO4//Co0.5Nb24.5O62 full cells also achieve good rate performance of 101 mA h g-1 at 10C, as well as an excellent cycling performance of 81% capacity retention after 1200 cycles at 5C, further proving the promising application prospect of Co0.5Nb24.5O62.

Synthesis of a full range Fe-doped ZnFexCo2-xO4 and its application as anode material for lithium-ion battery

Fe-Doped ZnFe_xCo_2-xO₄ (x = 0.00, 0.17, 0.33, 0.47, 0.67, 0.87, 1.17, 1.37, 1.67, 1.87, 2.00) compounds were prepared by a sol-gel method. X-ray diffraction measurements show that Fe-doping does not change the crystal structure of ZnCo₂O₄ and dopant Fe successfully occupies the 16c Co site. Because of the bigger radius of the doping ion, the cell parameters and cell volumes of ZnFe_xCo_2-xO₄ compounds present an obvious linear increase with increasing Fe content. In addition, attributed to the similar crystal structures for ZnFe₂O₄ and ZnCo₂O₄, a full range (0 ≤ x ≤ 2) of ZnFe_xCo_2-xO₄ solid solution phases was obtained. V/I measurement results show that a small Fe doping content obviously improved the electronic conductivity of the sample. In addition, due to the smaller particles size and uniform particle distribution caused by Fe doping, the lithium ion diffusion coefficient of the sample was increased by 2 orders of magnitude. Based on the improved electronic conductivity combined with the significantly increased lithium-ion diffusion coefficient, a sample with Fe doping content of x = 0.33, ZnFe_0.33Co_1.67O₄, presents a high reversible specific capacity and excellent rate cycle stability. At a rate of 100 mA g^-1, a relatively high discharge capacity of 850 mA h g^-1 can still be obtained after 100 cycles, which is obviously higher than that of pure ZnCo₂O₄ (only 295 mA h g^-1). Even at a higher discharge rate of 500 mA g^-1, a discharge capacity of 450 mA h g^-1 with a capacity retention of nearly 100% was obtained. Based on its excellent electrochemical properties, ZnFe_0.33Co_1.67O₄ will be a promising anode material for rechargeable lithium-ion batteries.

Wadsley-Roth Crystallographic Shear Structure Niobium-Based Oxides: Promising Anode Materials for High-Safety Lithium-Ion Batteries

Wadsley-Roth crystallographic shear structure niobium-based oxides are of great interest in fast Li+ storage due to their unique 3D open tunnel structures that offer facile Li+ diffusion paths. Their moderate lithiation potential and reversible redox couples hold the great promise in the development of next-generation lithium-ion batteries (LIBs) that are characterized by high power density, long lifespan, and high safety. Despite these outstanding merits, there is still extensive advancement space for further enhancing their electrochemical kinetics. And the industrial feasibility of Wadsley-Roth crystallographic shear structure niobium-based oxides as anode materials for LIBs requires more systematic research. In this review, recent progress in this field is summarized with the aim of realizing the practical applications of Wadsley-Roth phase anode materials in commercial LIBs. The review focuses on research toward the crystalline structure analyses, electrochemical reaction mechanisms, modification strategies, and full cell performance. In addition to highlighting the current research advances, the outlook and perspective on Wadsley-Roth anode materials is also concisely provided.

Copper, zinc, and manganese niobates (CuNb2O6, ZnNb2O6, and MnNb2O6): structural characteristics, Li+ storage properties, and working mechanisms

Niobium-based oxides are considered promising anode materials for Li-ion batteries due to their high capacities, good cyclability, and excellent safety.