Unveiling Interstitial Anionic Electron-Driven Ultrahigh K-Ion Storage Capacity in a Novel Two-Dimensional Electride Exemplified by Sc<sub>3</sub>Si<sub>2</sub>
Yuanzheng Chen, Haifei Qin, Jun Zhou, Tong Yang, Bai Sun, Yuxiang Ni, Hongyan Wang, Simon A. T. Redfern, Maosheng Miao, Hai‐Qing Lin, Yuan Ping Feng
Abstract
Two-dimensional (2D) electrides, characterized by excess interstitial anionic electron (IAE) in a crystalline 2D material, offer promising opportunities for the development of electrode materials, in particular in rechargeable metal-ion batteries applications. Although a few such potential electride materials have been reported, they generally show low metal-ion storage capacity, and the effect of IAE on the ion storage performance remains elusive so far. Here we report a novel 2D electride, [Sc3Si2]1+·1e–, with fascinating IAE-driven high alkali metal-ion storage capacity. In particular, its K-ion specific capacity can reach up to 1497 mA h g–1, higher than any previously reported 2D materials-based anodes in K-ion batteries (PIBs). The IAE in the [Sc3Si2]1+·1e– crystal accounts for such high capacity behavior, which can drift away and balance the charge on the metal-cation, playing a crucial role in stabilizing the metal-ion adsorption and enhancing multilayer-ions adsorption. This proposed IAE-driven storage mechanism provides an unprecedented avenue for the future design of high storage capacity electrode materials.