| The development of the battery originated in the 19th century and has a history of more than two hundred years.With the deterioration of the living environment and the scarcity of the earth’s resources,batteries with high safety,less pollution and lightness can meet the development theme of the modern era.Lithium-ion batteries,which are one of the new energy sources,have received widespread attention,so the global industrial sector is rapidly taking the lead.In this thesis,the PVA/PEO-SiO2 microporous polymer electrolyte of fluorinated borate lithium was studied and its electrochemical performance was tested.Selective synthesis of 30%PVA/PEO-3%SiO2 diaphragm and catechol-lithium oxalate boron salt(LBDOB),3-fluorocatechol-lithium oxalate boron salt(FLBDOB),which have been studied by lab member.And the formation of target products from the perspective of microscopic,functional group,crystallinity and thermal degradation temperature by SEM,IR,XRD and TG four characterization techniques[1-3].Accompanied by 1:1:1 EC(ethylene carbonate)/PC(propylene carbonate)/DME(ethylene glycol dimethyl ether)catechol-lithium oxalate boron salt,3-fluorocatechol-lithium oxalate boron salt,the 30%PVA/PEO-3%SiO2 diaphragm was immersed and taken out to obtain a microporous polymer electrolyte.Electrochemical properties of microporous polymer electrolytes from two aspects of ionic conductivity and voltage limit by AC impedance method and Linear scanning voltammetry.The ionic conductivity of the microporous polymer electrolytes was compared with the electrolytic solution of LiPF6 and LiClO4 lithium salts,they are 6.42×10-3 S·cm-1,5.06×10-3 S·cm-1,4.36－10-3 S·cm-14.89×10-3 S·m-1,and the size is LiPF6>LiClO4>FLBDOB>LBDOB.The charging voltage limits of the microporous polymer electrolytes of catechol-lithium oxalate boronate,3-fluorocatechol-lithium oxalate boron salt are 3.6 V and 4.3 V,respectively.Data analysis and fnishing,obtained with 30%PVA/PEO-3%SiO2 diaphragm and catechol-lithium oxalate boron salt,3-fluorocatechol-lithium oxalate boron salt based on the system microporous polymer electrolytes can be used to assemble batteries.Finally,the CR2032 button battery was assembled in the glove box,and the relationship between the rate,capacity and the number of cycles of the battery was tested.At the same rate,the battery charge and discharge platforms of LiPF6,3-fluorocatechol-lithium oxalate boron salt microporous polymer electrolyte are 3.5 V and 3.6 V,3.3 V and 3.2 V,respectively,the specific capacity is 179.931 mAh·g-1,174.763 mAh·g-1,the difference between the two is small.when the battery with 3-fluorocatechol-lithium oxalate boron salt as the electrolyte is set at different rates of 0.1 C,0.2 C,0.5 C,1.0 C,there is a stable charging and discharging platform,about 3.6 V and 3.2 V,and the speci’fic capacity is 1 74.067 mAh·g-1,164.06 mAh·g-1,148.345 mAh·g-1 and 125.563 mAh·g-1,respectively.The battery can have a good capacity under the voltage.After the first cycle,the capacity of the battery is close to perfect When the cycle is 50 times,the capacity is maintained near 167 mAh·g-1,which is about 89%of the theoretical capacity.The efficiency of charging and discharging is not much different from that of the first cycle,which is about 90%.Detection of assembled lithium-ion batteries in four ways,a battery of a microporous polymer electrolyte based on a 3-fluorocatechol-lithium oxalate boron salt can be used to achieve desired properties. |
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