Interface-Engineering-Induced Electric Field Effect and Atomic Disorder in Cobalt Selenide for High-Rate and Large-Capacity Lithium Storage

Atomic interface engineering can endow electrode materials with fascinating properties by tailoring their physicochemical behaviors, which will unlock great potential for achieving high-performance lithium storage. Herein, a newfangled concept of presenting an interfacial electric field and atomic disorder in Co _0.85 Se by interface engineering is demonstrated for realizing its high-rate and large-capacity lithium storage. Transmission electron microscopy confirms the formation of abundant atomic interfaces between Co _0.85 Se and N-doped carbon (NC), and meanwhile, X-ray absorption near-edge structure tests disclose the negative charge shifts from Co _0.85 Se to NC as well as the existence of disordered Co/Se atoms and/or dangling bonds in the interface region. On one hand, the lopsided charge distribution around the atomic interface can induce an interfacial electric field, which will afford a foreign Coulomb force to facilitate the Li ⁺ transmission, thus greatly improving high-rate capability. On the other hand, the disordered Co/Se atoms and/or dangling bonds in the interface region could act as the extra active sites to hold the lithium for increasing the specific capacity. Benefiting from this multiscale coordination regulation, Co _0.85 Se/NC displays high discharge specific capacity (1139 mA h g ^-1 at 0.1 A g ^-1 ), large initial Coulombic efficiency (87.9%), and excellent rate performance. This work presents a new perspective for an in-depth understanding of the atomic interface-performance relationship of Co _0.85 Se/NC, and meanwhile, this concept can be used for guiding the design of other energy-related electrode materials.