One-Step In Situ Preparation of Polymeric Selenium Sulfide Composite as Cathode Material for Enhanced Sodium/Potassium Storage.

Abstract

Alkali metal-sulfur/selenium batteries have attracted numerous attentions because they offer promising high energy density. However, the shuttle effect of the polysulfide dissolutions, poor electrical conductivity and relatively large volume variations extremely hinder their potential applications. Herein, a novel organic carbon/selenium sulfide (OC/SeS2) composite has been prepared by one-step in situ method through heating the mixture of commercial polyacrylonitrile (PAN) with selenium sulfide powder in vacuum. The carbonized PAN matrix with N-doped carbon ring structure could effectively confine the SeS2 in form of small molecules and regulate its electronic structure. The superior sodium/potassium storage performance of OC/SeS2 composite electrodes stems from its rational chemical structure design, including high electrical conductivity of the N-doped organic carbon network and chemical binding with SeS2 molecules. As a result, the OC/SeS2 cathode delivers a reversible capacity of 416 mAh g-1 after 700 cycles for sodium-ion batteries and 216 mAh g-1 after 500 cycles for potassium-ions batteries at 0.5 A g-1, respectively. These findings could open a new window to develop selenium sulfide cathode for metal-sulfur/selenium batteries.