Controlled Synthesis of FeSe2 Nanoflakes Toward Advanced Sodium Storage Behavior Integrated with Ether-Based Electrolyte

Abstract

Sodium ion batteries based on the more sodium source reserve than that of lithium have been designed as promising alternatives to lithium ion batteries. However, several problems including unsatisfied specific capacity and serious cyclic stability must be solved before the reality. One of the effective approaches to solve the abovementioned problems is to search for suitable anode materials. In this work, we designed and prepared FeSe2 nanoflakes via a simple hydrothermal method which can be adjusted in composition by Fe precursor. As a potential anode for sodium storage, the optimized FeSe2 electrode was further evaluated in different electrolytes of NaClO4 in propylene carbonate/fluoroethylene carbonate and NaCF3SO3 in diethylene glycol dimethyl ether. The capacity was about 470[Formula: see text]mAh[Formula: see text]g[Formula: see text] and 535[Formula: see text]mAh[Formula: see text]g[Formula: see text] at 0.5[Formula: see text]A[Formula: see text]g[Formula: see text], respectively, in the voltage between 0.5[Formula: see text]V and 2.9[Formula: see text]V in the cycle of stabilization phase. Superior performance both in capacity and in stability was obtained in ether-based electrolyte, which affords the property without plugging the intermediates of transition metal dichalcogenides during charge/discharge processes.