Towards safer electrolytes: comparing the air stability and electrochemical properties of NaPF 6 , NaTFSI and NaB(hfip) 4 ·DME for sodium-ion batteries

Acknowledgements: SM acknowledges support from the Royal Society through an Industry Fellowship (IF2\23200112). DMCO and SM also acknowledge funding from the Faraday Institution through the Industry SPRINT programme (grant number FIRG074) and Batri Ltd for supply of hard carbon. DMCO, CPG and DSW would like to thank the Faraday Institution FIRG064 and FIRG089 for supporting this work. XPS data collection was performed at the Cardiff hub of the EPSRC National Facility for X-ray photoelectron spectroscopy, the EPSRC National Facility for XPS (“HarwellXPS”, EP/Y023587/1, EP/Y023609/1, EP/Y023536/1, EP/Y023552/1 and EP/Y023544/1).