Insight into the Capacity Fading Mechanism of Amorphous Se₂S₅ Confined in Micro/Mesoporous Carbon Matrix in Ether-Based Electrolytes

Abstract

In contrast to the stable cycle performance of space confined Se-based cathodes for lithium batteries in carbonate-based electrolytes, their common capacity fading in ether-based electrolytes has been paid less attention and not yet well-addressed so far. In this work, the lithiation/delithiation of amorphous Se2S5 confined in micro/mesoporous carbon (Se2S5/MPC) cathode was investigated by in situ X-ray near edge absorption spectroscopy (XANES) and theoretical calculations. The Se2S5/MPC composite was synthesized by a modified vaporization-condensation method to ensure a good encapsulation of Se2S5 into the pores of MPC host. In situ XANES results illustrated that the lithiation/delithiation reversibility of Se component was gradually decreased in ether-based electrolytes, leading to an aggravated formation of long-chain polyselenides during cycling and further capacity decay. Moreover, ab initio calculations revealed that the binding energy of polyselenides (Li2Sen) with carbon host is in an order of Li2Se6 > Li2Se4 > Li2Se. The insights into the failure mechanism of Se-based cathode gain in this work are expected to serve as a guide for future design on high performance Se-based cathodes.

Synchrotron X‐Ray and Neutron Diffraction, Total Scattering, and Small‐Angle Scattering Techniques for Rechargeable Battery Research

“…Unlike ordered materials, amorphous materials do not exhibit diffraction peaks, instead, they may produce broad SAS signals if there are domain or void structures that have different scattering lengths from the surrounding matrix. The size and shape of the domains or voids in battery may change during charging and discharging processes, which can be monitored and used to investigate reactions happening in materials . Elia et al studied the aluminum graphite batteries, and found the roughness of graphite electrodes increases after charge–discharge cycle comparing to pristine graphite electrode due to AlCl 3 intercalation, indicated by the deceased Porod law index .…”

A Self‐Repairing Cathode Material for Lithium–Selenium Batteries: Se−C Chemically Bonded Selenium–Graphene Composite

“…In this work, we propose a new chemical absorption mechanism. It is commonly found in Li‐Se batteries that Se forms chain‐like polyselenides . Thus, as a strategy to avoid the dissolution of Se, we envisaged the stabilization of polyselenide chains on the cathode material.…”

Mesoporous Carbon@Titanium Nitride Hollow Spheres as an Efficient SeS2 Host for Advanced Li–SeS2 Batteries

“…[14,15] After that, as eries of studies further demonstrated the advantages of Se x S y over Sand Se,and clearly improved the electrochemical performance of Li-Se x S y batteries. [20][21][22][23][24][25][26] However, the study of Se x S y -based materials is still in av ery early stage,a nd the ideas of recent studies are usually limited to the formation of composites of pristine carbonaceous materials with Se x S y ,s o the application potential of the Se x S y cathode has not yet been fully demonstrated. It has been found that, as for Scathodes with an ether-based electrolyte,S e x S y cathodes also suffer serious dissolution of reaction intermediate products during charging/discharging processes,w hich could not be readily controlled simply by using ordinary pure carbonaceous hosts.…”