Boron Embedded in Metal Iron Matrix as a Novel Anode Material of Excellent Performance

Abstract

Boron, the most ideal lithium‐ion battery anode material, demonstrates highest theoretical capacity up to 12 395 mA h g⁻¹ when forming Li₅B. Furthermore, it also exhibits promising features such as light weight, considerable reserves, low cost, and nontoxicity. However, boron‐based materials are not in the hotspot list because Li₅B may only exist when B is in atomically isolated/dispersed form, while the aggregate material can barely be activated to store/release Li. At this time, an ingenious design is demonstrated to activate the inert B to a high specific capacity anode material by dispersing it in a Fe matrix. The above material can be obtained after an electrochemical activation of the precursors Fe₂B/Fe and B₂O₃/Fe. The latter harvests the admirable capacity, ultrahigh tap density of 2.12 g cm⁻³, excellent cycling stability of 3180 mA h cm⁻³ at 0.1 A g⁻¹ (1500 mA h g⁻¹) after 250 cycles, and superlative rate capability of 2650 mA h cm⁻³ at 0.5 A g⁻¹, 2544 mA h cm⁻³ at 1.0 A g⁻¹, and 1696 mA h cm⁻³ at 2.0 A g⁻¹. Highly conductive matrix promoted reversible Li storage of boron‐based materials might open a new gate for advanced anode materials.