Disordered carbon coating free Li0.2375La0.5875TiO3: a superior perovskite anode material for high power long-life lithium-ion batteries

摘要

The perovskite-type oxide LixLa(2-x)/3TiO3 (LLTO) was prepared by high temperature solid-phase method as an high power and long cycling life negative electrode material for lithium-ion battery. Compared to the previously reported LLTO series anode materials, Li0.2375La0.5875TiO3 shows higher capacity and cycle stability, which delivers a reversible discharge capacity of 270 mAh g(-1) at a current density of 100 mA g(-1) and retained 258 mAh g(-1) after 1000 cycles. Moreover, excellent rate performance is also shown. It delivers a charge capacity of ca. 241.3, 186.8, 165.2, 145.2 and 246.4 mAh g(-1), respectively, at the end of each 10 cycles at the current density of 100, 500, 1000, 2000 and back to 100 mA g(-1). The molecular dynamics (MD) simulations based on a special quasi-random structures (SQS-64) super cell confirm the direct Li+ migrations between neighboring Li+/vacancies. The metallic nature of the Li0.2375La0.5875TiO3 is one of the important factors that improve the performance of the sample. Most important of all, the highly active Li+, which is ca. 10(-9) cm(2) s(-1) from Cyclic voltammetry/Electro-chemical impedance spectroscopy (CV/EIS) results and ca. 10(-7) cm(2) s(-1) from MD simulations, and the vacancies at 1a/1b sites, which facilitate the migration of two neighboring lithium ions, also greatly contribute to the high performance of the material.