High voltage LIB cathodes enabled by salt-reinforced liquid electrolytes

• We report a novel Li/Li1.2Ni0.15Co0.1Mn0.55O2 secondary battery that uses LiF-salt reinforced electrolytes.
• The Li/Li1.2Ni0.15Co0.1Mn0.55O2 battery exhibits stable cycling over 500 cycles with Columbic efficiencies approaching 100%.
• The presence of LiF in EC:DEC–LiPF6 electrolytes markedly increases the high-voltage stability of the electrolyte.
• The addition of LiF to EC:DEC–LiPF6 electrolytes dramatically increases the stability of Li electrodeposition.
• XPS analysis of the cathode shows that LiF reduces Mn loss during extended battery cycling.

We report on electrochemical properties of Li/Li1.2Ni0.15Co0.1Mn0.55O2 secondary batteries in electrolytes designed to stabilize electrodeposition of lithium. Ethylene carbonate (EC): dimethyl carbonate (DMC) containing a LiPF6/LiF salt blend stabilizes lithium electrodeposition and enables Li/Li1.2Ni0.15Co0.1Mn0.55O2 batteries with a high discharge capacity of 270 mAh·g− 1 at 0.05 mA cm− 2. Cells containing the LiF-reinforced electrolytes also exhibit excellent capacity retention over 500 cycles with Columbic efficiencies approaching 100%. Post-mortem SEM analysis of the lithium anode shows more compact deposition in the presence of the LiF salt additive, while XPS depth profile analysis of cathodes show a more uniform distribution of Mn over the first 180 nm from the electrode/electrolyte interface. The results imply that LiF reinforced electrolytes simultaneously facilitate stable lithium electrodeposition and reduce Mn dissolution.