Mesoporous Li4Ti5O12−x/C submicrospheres with comprehensively improved electrochemical performances for high-power lithium-ion batteries

摘要: To comprehensively improve the performance of Li4Ti5O12 (LTO), a synergistic method combining compositing, crystal structure modification and hierarchical particle structuring is employed in this work. Monodispersed/multidispersed mesoporous Li4Ti5O12−x/C submicrospheres were fabricated using monodispersed/multidispersed TiO2 submicrospheres, lithium hydroxide sucrose as precursors. The have well-crystallized spinel structure, no blockages Li+ ion transport pathways, 2.69–3.03% O2− vacancy contents (vs. all 32e sites structure), 12.9–14.6% Ti3+ titanium ions). Thus, electronic conductivity diffusion coefficient particles can be significantly improved, working potential 4.4–4.7 mV lower than that LTO. Furthermore, these contain 1.06–1.44 wt% carbon coatings (2–3 nm thickness) nanoparticles (∼20 size), resulting smaller primary sizes (<100 nm), large specific surface areas (12–15 m2 g−1), proper pore (∼4 nm) enhanced electrical conduction between particles. In addition, submicrospherical morphology allows tap densities (1.41–1.71 g cm−3). As result desirable exhibit improved electrochemical performances. optimized sample, with an ideally graded sphere-size distribution ranging from 100 to 600 nm, shows largest density 1.71 cm−3, high first cycle Coulombic efficiency 95.0% 4.5 potential. At 10 C, its capacity 119 mA h g−1 retention 95.9% over cycles.