Gel Polymer Electrolyte Containing 2D Silica&application In The Lithium-ion Battery

Secondary Li ion battery,as a green storage energy and supply power equipment,is widely used in portable electronic devices and electric drive transportation tools due to its strong advantages.Polymer electrolyte?PE?which replaces traditional separator/or bath solution type electrolyte can fundamentally improve Li ion battery safety property,after all,which is the most critical consideration factor for storage energy and supply power equipments.Gel polymer electrolyte,as a special existence form relating to its solid characteristics which guarantee its strength and liquid properties insuring high ionic conductivity and lithium ion transference number,becomes the hot topic in the field of separator?electrolyte?.The composite polymer electrolyte?CPE?is formed by adding fillers into PE.The outstanding filler can make CPE more excellent than PE in the aspect of electrochemical and physical performance.So the idea that we develop novel fillers occurs.Two different morphologies of silica nanoplates?PIL-FSiNP,PIL-FMSiNP?as filler were designed and synthesized in this research.The work is divided into two parts,and the specific content is as follows:1.Silica nanoplates with or without porous?NPs?using the graphene oxide as template was prepared and subsequently was chemically modified to obtain PILfunctionalized silica nanoplates?PIL-FNPs?;the morphologies of silica nanoplates were characterized by SEM and TEM;surface area and pore volume were 740.6,63.9 m2 g^-1and1.28,0.22 cm3 g^-1,respectively,for silica nanoplates with or without porous by BET test;the polymer grafting ratio of silica with or without porous was 10.0 wt.% and 30.3wt.%,respectively,by TGA test;polymer ionic liquid?PIL?was prepared by free radical polymerization of monomer and anion exchange with lithium salt;ionic liquid?IL?was prepared via two steps;the specific procedures for preparing GPE containing 15 wt.% IL was as follows in details.The research results show that filler can decrease IL activation energy and promote IL dissociation and ion movement,thereby improving theconductivity of IL,via research on the interaction between PIL-FNPs and IL in PIL-FNPs/IL dispersion;There is filler orientation effect on conductivity in the Throughplane and In-plane direction of electrolyte;The average conductivity increase times and corresponding activation energy were ⁴00%,⁸00% and 43.2,40.4 kJ mol-1 for PIL/IL/PIL-FSiNP and PIL/IL/PIL-FMSiNP electrolyte at optimized filler content of 5 wt.%,8wt.%,respectively;The differences made by PIL-FNPs exist in the way of strengthen and ionic liquid uptake of CPEs.2.Based on the previous study,the polymer electrolyte containing 20 wt.% of IL?LiTFSI?consisting of 0.5 mol kg^-1 of LiTFSI and IL mixture was analyzed via EIS,tLi+,TGA,SEM,LSV,CV and Charge-Discharge method.Test results show that thermal decomposition temperature of PIL/IL?LiTFSI?,PIL/IL?LiTFSI?/PIL-FNPs are 344 and349 0C,which fully meets the demand of practical application;conductivity increase extent of CPE containing LiTFSI salt was lower than PIL/IL/PIL-FNPs system and fillers' contribution was agreed with before;the tLi+ are 0.31,0.40,0.48 and 0.39,0.47,0.56 for PIL/IL?Li TFSI?,PIL/IL?Li TFSI?/PIL-FSiNP,PIL/IL?Li TFSI?/PIL-FMSiNP,respectively,at 40 0C and 60 0C;electrochemical decomposition potential of PIL/IL?LiTFSI?,PIL/IL?LiTFSI?/PIL-FNPs are almost 5.7,6.0 V,which was even higher than stop potential of 4.2V;after 3 cycles test,CV curves are almost overlapping for PIL/IL?Li TFSI?/PIL-FNPs CPEs and the stable SEI layer of interface between Li foil and electrolyte is formed;the first cycle discharge capacities were 96.3,109.1 and 140 mA h g^-1 at 60 0C and corresponding capacities were 41.5,77.3 and 115 mA h g^-1 after 100 cycles for cells assembled with PIL/IL?LiTFSI?,PIL/IL?Li TFSI?/PIL-FSiNP and PIL/IL?Li TFSI?/PILFMSiNP at 0.1C rate,and PIL/IL?Li TFSI?/PIL-FMSiNP electrolyte also shows good capacities and reversibility at high rate discharge.