Alumina-flame retardant separators toward safe high voltage Li-Ion batteries

In this work, we reported the easy incorporation of high amount of flame retardants in Li-ion batteries without affecting the electrochemical performance through grafting on alumina surface. The strategy consisted to firstly graft halogen- and phosphorus-based molecules on Al2O3 surface and then to incorporate the modified ceramics in the porosity of a thermally stable cellulose separator. The final composite separator was analyzed by thermogravimetric and flame test analyses. The results revealed that the use of flame retardant ceramics in the cellulose matrix was an effective method to increase the thermal stability of the separator and slow down and even avoid its combustion. The electrochemical performance of NMC/graphite Li-ion batteries assembled with the various cellulose separators were similar and even slightly better than those obtained for the cell made with a Celgard separator.