Hard Carbon and Li4Ti5O12-Based Physically Mixed Anodes for Superior Li-Battery Performance with Significantly Reduced Li Content: A Case of Synergistic Materials Cooperation

Abstract

Li4Ti5O12 (LTO) and hard carbon (HC) are commonly used anodes in the Li-ion batteries. LTO has an operating voltage of 1.55 V and exhibits high-rate performance but with limited capacity. HC has high specific capacity but extremely low operating voltage. Herein, we show that a simple physical mixture of the two enhances the half-cell as well as full-cell performance through a synergistic cooperation between the materials. Specifically, the LTO-HC mixed anodes exhibit impressive performance even at high C-rates. This results from a quick internalization of Li ions by LTO followed by their distribution to HC regions via the high density of the winding internal interfaces between the two. The full cells of the LTO-HC mixed anodes with LiCoO2 (LCO) evince an enhanced operating voltage window and a well-defined plateau. Because of a reduced irreversible capacity loss in the LCO/mixed anode full cells, the overall specific capacity is better than the LCO/pristine anode full cells. Also, with the LTO-HC 20-80 anode (Li content reduced by 80%), the full cell exhibits an impressive performance when compared to pristine anodes without pre-lithiation. The LCO/mixed anode full cells have excellent cycling stability up to 500 cycles at a current density of 100 mA g(-1).