A safe electrolyte system is prepared from N-methyl-N-propylpiperidinium bis (trifluoromethanesulfonyl) imide (PP13TFSI), organic electrolyte (1molL−1 LiPF6/EC-DEC) and lithium bis (oxalato) borate (LiBOB). The additive of LiBOB enhances the stability of interface between electrolyte and anode. The LiBOB-containing mixed electrolytes show non-flammability and good compatibility with active materials. The performance of anode for lithium ion battery is successfully improved by LiBOB-containing mixed electrolytes, which shows 200mAhg−1 reversible capacities at 0.3C rate. The ionic conductivity and the lithium ion transference number in LiBOB-containing mixed electrolytes system also suits to application for lithium ion battery.