A New Strategy to Effectively Suppress the Initial Capacity Fading of Iron Oxides by Reacting with LiBH4

Abstract

In this work, a new facile and scalable strategy to effectively suppress the initial capacity fading of iron oxides is demonstrated by reacting with lithium borohydride (LiBH4) to form a B‐containing nanocomposite. Multielement, multiphase B‐containing iron oxide nanocomposites are successfully prepared by ball‐milling Fe2O3 with LiBH4, followed by a thermochemical reaction at 25–350 °C. The resulting products exhibit a remarkably superior electrochemical performance as anode materials for Li‐ion batteries (LIBs), including a high reversible capacity, good rate capability, and long cycling durability. When cycling is conducted at 100 mA g−1, the sample prepared from Fe2O3–0.2LiBH4 delivers an initial discharge capacity of 1387 mAh g−1. After 200 cycles, the reversible capacity remains at 1148 mAh g−1, which is significantly higher than that of pristine Fe2O3 (525 mAh g−1) and Fe3O4 (552 mAh g−1). At 2000 mA g−1, a reversible capacity as high as 660 mAh g−1 is obtained for the B‐containing nanocomposite. The remarkably improved electrochemical lithium storage performance can mainly be attributed to the enhanced surface reactivity, increased Li+ ion diffusivity, stabilized solid‐electrolyte interphase (SEI) film, and depressed particle pulverization and fracture, as measured by a series of compositional, structural, and electrochemical techniques.