Li_1.3Al_0.3Ti_1.7(PO₄)₃ Behaving as a Fast Ionic Conductor and Bridge to Boost the Electrochemical Performance of Li₄Ti₅O₁₂

Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) is a Li-ion conductive solid electrolyte with high ionic conductivity; meanwhile, it also possesses relatively high electronic conductivity compared to those of the other fast ionic conductors. In this work, LATP was composited with Li₄Ti₅O₁₂ (LTO) at a mass ratio of 0.026 and calcined at 700 °C for 5 h. The composite delivers reversible capacities of 164.8, 156.3, 152.4, 146.5, 130.5, and 158.6 mAh g^–1 at the current densities of 100, 200, 400, 800, 1600, and 100 mA g^–1, respectively, as well as a capacity of 112 mAh g^–1 after cycling at 500 mA g^–1 for 1200 cycles. The appreciable performance is attributable to the three-dimensional Li-ion diffusion channels in LATP to facilitate Li-ion migration, and the local charge imbalance resulted from the substitution of Al³⁺ for Ti⁴⁺ to promote charge transfer in LTO, thus the LATP-composited LTO exhibits enhanced ionic and electronic conductivities, as well as the markedly boosted electrochemical performance

Combined Modification of Dual-Phase Li₄Ti₅O₁₂–TiO₂ by Lithium Zirconates to Optimize Rate Capabilities and Cyclability

The low electrical conductivity and ordinary lithium-ion transfer capability of Li₄Ti₅O₁₂ restrict its application to some degree. In this work, dual-phase Li₄Ti₅O₁₂–TiO₂ (LTOT) was modified by composite zirconates of Li₂ZrO₃, Li₆Zr₂O₇ (LZO) to boost the rate capabilities and cyclability. When the homogeneous mixture of LiNO₃, Zr­(NO₃)₄·5H₂O and LTOT was roasted at 700 °C for 5 h, the obtained composite achieved a superior reversible capacity of 183.2 mAh g^–1 to the pure Li₄Ti₅O₁₂ after cycling at 100 mA g^–1 for 100 times due to the existence of a scrap of TiO₂. Meanwhile, when the composite was cycled by consecutively doubling the current density between 100 and 1600 mA g^–1, the corresponding reversible capacities are 183.2, 179.1, 176.5, 173.3, and 169.3 mAh g^–1, signifying the prominent rate capabilities. Even undergoing 1400 charge/discharge cycles at 500 mA g^–1, a reversible capacity of 144.7 mAh g^–1 was still attained, denoting splendid cyclability. From a series of comparative experiments and systematic characterizations, the formation of LZO meliorated both the Li⁺ migration kinetics and electrical conductivity on account of the concomitant superficial Zr⁴⁺ doping, responsible for the comprehensive elevation of the electrochemical performance