Surface-oriented and nanoflake-stacked LiNi0.5Mn1.5O4 spinel for high-rate and long-cycle-life lithium ion batteries

Abstract

Spinel LiNi_0.5Mn_1.5O₄ has attracted extensive interest as an appealing cathode material of next generation lithium-ion batteries to meet the cost/performance requirements for electric vehicle applications and renewable electric energy storage. In this paper, we report, for the first time, a nanoflake-stacked LiNi_0.5Mn_1.5O₄ spinel with oriented growth of the (001) planes synthesized via an in situ template route. The resultant LiNi_0.5Mn_1.5O₄ cathode delivers an initial discharge capacity of 133.5 mA h g⁻¹ at 1 C with capacity retention of 86% after 500 cycles. X-ray diffraction and transmission electron microscopy results suggest that the growth of (111) facets on the surfaces of the nanoflake-stacked LiNi_0.5Mn_1.5O₄ spinel is significantly restricted, which helps to inhibit the dissolution of manganese from the lattice and ensure an excellent cycling stability. Moreover, the very thin nanoflakes and large interspaces between the nanoflakes are favorable for Li ion transportation, leading to a fast kinetics of the LiNi_0.5Mn_1.5O₄ spinel. As a result, the material demonstrates a reversible capacity of 96 mA h g⁻¹ even at 50 C rate, showing a feasible application for high-power lithium ion batteries. In particular, this study provides a synthetic strategy to fabricate insertion materials with a surface-oriented morphology and nanoflake-stacked structure for energy storage, fast-ion conductors and other applications.