Metal Selenides Anode Materials for Sodium Ion Batteries: Synthesis, Modification, and Application

The powerful and rapid development of lithium-ion batteries (LIBs) in secondary batteries field makes lithium resources in short supply, leading to rising battery costs. Under the circumstances, sodium-ion batteries (SIBs) with low cost, inexhaustible sodium reserves, and analogous work principle to LIBs, have evolved as one of the most anticipated candidates for large-scale energy storage devices. Thereinto, the applicable electrode is a core element for the smooth development of SIBs. Among various anode materials, metal selenides (MSex ) with relatively high theoretical capacity and unique structures have aroused extensive interest. Regrettably, MSex suffers from large volume expansion and unwished side reactions, which result in poor electrochemistry performance. Thus, strategies such as carbon modification, structural design, voltage control as well as electrolyte and binder optimization are adopted to alleviate these issues. In this review, the synthesis methods and main reaction mechanisms of MSex are systematically summarized. Meanwhile, the major challenges of MSex and the corresponding available strategies are proposed. Furthermore, the recent research progress on layered and nonlayered MSex for application in SIBs is presented and discussed in detail. Finally, the future development focuses of MSex in the field of rechargeable ion batteries are highlighted.