Rod-Like LiBC Anode with High Specific Capacity in Li-Ion Batteries.

Abstract

As a well-known graphite-like material in superconductivity, lithium borocarbide (LiBC) can also be utilized as an electrode material in Li-ion batteries with a high specific capacity, which is assigned to the B-B bond produced through the aqueous reaction or the initial charge process. In this work, a rod-like LiBC sample (Ti-LiBC) is synthesized with the precursors of LiH + B + graphite in a sealed Ti tube through high-temperature sintering. Compared with the normal SUS-LiBC sintered in a sealed SUS304 tube, the Ti-LiBC possesses a lot of B-B bonds and a strong EPR signal, and it delivers a higher specific capacity (ca. 500 mAh g^-1 at a mean discharge and charge potentials of 0.85 and 1.89 V, respectively) with excellent rate and cycle performances. Actually, the Ti metal can react with the H₂ gas to produce the TiH₂ phase at a high temperature, of which the extent determines the morphology of LiBC product, and the substitution of Li metal for LiH as the precursor can also result in the rod-like structure and the high specific capacity. Therefore, a hydrogen-free atmosphere is the key to synthesizing rodlike LiBC with excellent electrochemical properties, and this strategy might be extended to other graphite-like materials.