Enhanced Dynamic Phase Stability and Suppressed Mn Dissolution in Low-Tortuosity Spinel LMO Electrode

Abstract

Microspinel LiMn 2 O 4 (LMO) is a widely used cathode material in power lithium-ion batteries. However, inevitable Mn dissolution and dynamic phase instability will cause the degradation of microspinel LMO during cycling. Here, a low-tortuosity LMO (LMO-LT) electrode is fabricated by an ice-templating method, which exhibits enhanced dynamic phase stability, alleviated Mn dissolution, and rare particle microcracks during cycling. It is shown that the low-tortuosity electrode enables fast lithium-ion diffusion and thus small concentration polarization, leading to uniform electrochemical reaction within microregions of the LMO-LT electrode. Furthermore, the fast lithium-ion transport kinetics and even mesoscopic scale reactions of the LMO-LT electrode effectively alleviate irreversible phase transition and Mn dissolution as well as suppress crack generation in LMO particles. As a result, the full cell [negative-to-positive capacity ratio (N/P) = 1.1] with thick LMO-LT cathode (13 mg cm −2 ) and Li 4 Ti 5 O 12 anode sustains 80.0% capacity over 200 cycles. The LMO-LT electrode further delivers 78.9% capacity of that at 0.1 C at the high rate of 5 C. This work provides an important strategy to enhance dynamic phase stability and suppress Mn dissolution at the mesoscopic scale, promoting the development of high-performance LMO electrodes.