TiNb 2 O 7 (TNO) is regarded as a potential fast-charging anode for lithium-ion batteries due to its fast reversible phase transition and safe working potential, but it suffers from unsatisfactory electronic conductivity, sluggish ion kinetics, and poor structural stability under high rates. Herein, tantalum (Ta) with strong Ta–O bonds is doped into TNO to enhance its fast-charging property and structural stability. Proper amount of Ta doping not only increases the interlayer spacing for fast Li + transport, but also improves the electrical conductivity, being successfully proved by experimental analyses. Density functional theory (DFT) calculation verifies that the lattice distortion induced by the incorporation of strong Ta-O bonds can effectively strengthen the structural stability. Notably, in situ X-ray diffraction (XRD) technology reveals that Ta doping relieves volumetric strain during lithiation and de-lithiation. Thus, the optimized Ta 0.1 -TNO sample owns impressive long-term cycling stability even at a high current density of 10C, which delivers a high-capacity retention of 85.12% (a capacity decay of less than 0.01% per cycle) after 1500 cycles. This work provides a fast-charging anode material with superior structural stability for lithium-ion batteries. Graphical abstract
Wellars Utetiwabo,Lei Zhou,Muhammad Khurram Tufail,Xintao Zuo,Le Yang,Jinfeng Zeng,Ruiwen Shao,Wen Yang
Defect engineering through induction of dislocations is an efficient strategy to design and develop an electrode material with enhanced electrochemical performance in energy storage technology. Yet, synthesis, comprehension, identification, and effect of dislocation in electrode materials for lithium-ion batteries (LIBs) are still elusive. Herein, we propose an ethanol-thermal method mediated with surfactant-template and subsequent annealing under air atmosphere to induce dislocation into titanium niobium oxide (Ti 2 Nb 14 O 39 ), resultant nanoscale-dislocated-Ti 2 Nb 14 O 39 (Nano- dl -TNO). High-resolution transmission electron microscope (HRTEM), fast Fourier transform (FFT), and Geometrical phase analysis (GPA) denote that the high dislocation density engraved with stacking faults forms into the Ti 2 Nb 14 O 39 lattice. The presence of dislocation could offer an additional active site for lithium-ion storage and tune the electrical and ionic properties of the Ti 2 Nb 14 O 39 . The resultant Nano- dl -TNO delivers superior rate capability, high specific capacity, better cycling stability, and making Ti 2 Nb 14 O 39 a suitable candidate among fast-charging anode materials for lithium-ion batteries. Moreover, In-situ High-resolution transmission electron microscope (HRTEM) and Geometrical phase analysis (GPA) evinces that the removal of the dislocated area in the Nano- dl -TNO leads to the contraction of the lattice, alleviation of the total volume expansion, causing the symmetrization and preserves structural stability. The present findings and designed approach reveal the rose-colored perspective of dislocation engineering into mixed transition metal oxides as next-generation anodes for advanced lithium-ion batteries and all-solid-state lithium-ion batteries.
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