Preparation And Performance Testing Of New High Voltage Resistant Separators And Acrylate Polymer Electrolytes

High-voltage lithium-ion batteries have become a major research focus.As a major part of lithium batteries,the separator plays a critical role in the development of high voltage lithium batteries.Thus,a major focus of high-voltage lithium-ion battery research should be to find new separator materials and electrolyte with wide electrochemical window,high ionic conductive and safety performance.Herein,it was demonstrated a sustainable and superior heat-resistant alginate nonwoven separator for high-voltage(5 V)lithium batteries.It was demonstrated that the resultant alginate nonwoven separator exhibited better mechanical property(37 Mpa),superior thermal stability(up to 150 °C),and higher ionic conductivity(1.4 × 10-3 S/cm)as compared to commercially available polyolefin(PP)separator.More impressively,the 5 V class LiNi0.5Mn1.5O4(LNMO)/Li cell with this alginate nonwoven separator delivered much better cycling stability(maintaining 79.6% of its initial discharge capacity)than that(69.3 %)of PP2500 separator after 200 cycles at an elevated temperature of 55 °C.In addition,the LiFePO4/Li cell assembled with such alginate nonwoven separator could still charge and discharge normally even at an elevated temperature of 150 °C.The abovementioned fascinating characteristics of alginate separator provide great probability for its application for high voltage(5 V)lithium batteries at elevated temperatures.The lattice solution was prepared by using triethylene glycol dimethacrylate(TEGDMA)as the monomer,2,2-Azobis(AIBN)as the initiator,Propylene carbonate(PC)as the plasticizer and lithium difluoro(oxalato)borate(LiDFOB)as the lithium salt.The triethylene glycol dimethacrylate(CTE)gel polymer electrolyte was fabricated by in situ polymerization.The synthesized CTE gel polymer electrolyte has an ionic conductivity of 1.64 × 10-4 S cm-1 at 25 oC.The electrochemical window was 2.5 V-4.75 V and the ion transference number was 0.62.The LCoO2(LCO)/Li battery assembled with CTE electrolyte own excellent rate performance and cycle performance at 25 °C.This is due to the higher ion conductivity and ion transport number and better interfacial stability of the electrolyte.It can be seen that CTE gel polymer electrolyte can be applied to the field of high voltage LCoO2(LCO)lithium ion battery electrolyte.The alginate separator and CTE gel polymer electrolyte proposed in this paper own excellent electrochemical performance and superior rate and cycle property in high voltage lithium-ion battery,which is of great significance to the development of high voltage lithium ion battery.