Ionic Liquid‐Directed Nanoporous TiNb 2 O 7 Anodes with Superior Performance for Fast‐Rechargeable Lithium‐Ion Batteries

Abstract Nanoporous TiNb 2 O 7 (NPTNO) material is synthesized by a sol–gel method with an ionic liquid (IL) as the nanoporous structure directing template. NPTNO exhibits a high reversible capacity of 210 mAh g –1 even at the charging rate of 50 C and an excellent cyclability of half‐cell capacity retention of 74% for 1000 cycles at 5 C and LiNi 0.5 Mn 1.5 O 4 ‐coupled full‐cell capacity retentions of 81% and 87% for 1000 cycles at 1 C and 2 C, respectively. The studies of the 1000 cycled NPTNO electrode illustrate that the IL‐directed mesoporous structure can enhance the cyclability of NPTNO cells due to the alleviation of repetitive mechanical stress and volume fluctuation induced by the repetitive Li + insertion‐extraction processes. The measured Li + diffusion coefficients from the galvanostatic intermittent titration technique suggest that the IL‐templating strategy indeed ensures the fast rechargeability of NPTNO cells based on the fast Li + diffusion kinetics. Benefitting from the nanoporous structure, NPTNO with unhindered Li + diffusion pathways achieves a superior rate capability in the titanium‐based oxide materials and the best full‐cell cyclability in the TNO materials. Therefore, the templating potential of IL is demonstrated, and the superb electrochemical performance establishes the IL‐directed NPTNO as a promising anode candidate for fast‐rechargeable LIBs.