Ionic Liquid-Modified Silicon Nanoparticles Composite Gel Polymer Electrolyte for High-Performance Lithium Batteries

Graphical Modified with ionic liquid : The ionic liquid-modified SiO 2 nanoparticles composite polymer electrolytes (GPE@DMSN-IL) possess high ionic conductivity and large Li + transference number, which make the Li/GPE@DMSN-IL/LiFePO 4 batteries deliver high rate capacity and outstanding cycle performance, showing ability for using in high-performance lithium batteries. The excessive nano-fillers in gel polymer electrolytes (GPEs) would trend to agglomeration, which will have adverse effect on the electrochemical performance. Modifying the surface properties of nano-fillers will be an effective way for resolving the problem. In this paper, an ionic liquid (IL), (1-(trimethoxysilylpropyl)-3-butylimidazole bis(trifluoromethylsulfonyl)imide, [CPIM]TFSI) is grafted onto the surface of dendritic mesoporous silica nanoparticles (DMSN), and IL-modified DMSN (DMSN-IL) is prepared. The prepared DMSN and DMSN-IL are respectively introduced into a poly(vinylidene fluoride) (PVDF)-based gel polymer electrolyte (GPE@IL) to form composite polymer electrolytes (GPE@DMSN and GPE@DMSN-IL), and their physicochemical characteristics and electrochemical performances are investigated. Due to the surface modification, GPE@DMSN-IL obtains high ionic conductivity of 1.69×10 −3 S cm −1 at 30 °C and large Li + transference number (0.40). Furthermore, the improved mechanical strength and interface stability enable the Li/GPE@DMSN-IL/LiFePO 4 cell to achieve high rate capacity and outstanding cycle performance at high current density, showing ability for using in high-performance lithium batteries.