Enhanced thermal stability of a lithiated nano-silicon electrode by fluoroethylene carbonate and vinylene carbonate

► The thermal behavior of a nano-LixSi anode in electrolytes has been investigated. ► The thermal runaway is delayed by ∼50 °C in the presence of FEC and VC additives. ► We identified two mechanisms of LixSi protection by the additives during heating. ► FEC and VC electrochemically generate a thermally stable SEI covering the LixSi. ► A robust “secondary SEI” is formed by thermal degradation of FEC and VC.