Capacitive lithium storage of lithiated mesoporous titania

Abstract

Titania with intrinsic safety (without lithium deposition) has met the safety requirement for high-power batteries, however, its poor rate capability due to sluggish ion diffusion coefficients remains as a challenge. Here mesoporous structure titania with a fast ion-conducting surface layer through lithiation can achieve capacitive lithium storage: 220 mA h g−1 at 1 C, 114 mA h g−1 at 50 C, 93 mA h g−1 at 100 C. The improvement in rate performance can be attributed to two factors: The resulting lithiated titania shows over 5 orders of magnitude improvement of conductivity (from 0.001 to 198.20 μS cm−1) induced by the presence of bulk Ti3+, enabling an ultra-fast conduction path for electrons; The lithiated surface layer is favorable to faster lithium ion transport, addressing the limited lithium diffusion between the electrolyte and the active electrode materials. This new route may offer a general approach towards lithium batteries with capacitor-like rate performance.