Study On Modification Of PVDF-HFP Membrane In Lithium-ion Battery

With the large-scale application of electronic equipment,lithium-ion batteries are becoming more and more important as the main energy storage device.As an important part of lithium ion batteries,separators have a decisive influence on battery performance.How to solve the problems of poor thermal stability and low puncture strength of commercial polyolefin separator materials is the hotspot of lithium-ion battery research.This paper studies and improves the PVDF-HFP separators with strong thermal stability and high mechanical strength,and has obtained high performance separator with high rate performance,strong cycle stability and long service life.The research content includes the following aspects:First,make a brief overview of the working principle,classification and development of lithium-ion batteries;introduces the role of separators for lithium-ion batteries and the main characteristics of commercial polyolefin separators.The main research direction of this paper is to prepare composite modified membrane based on PVDF-HFP polymer.Next,the mechanical strength and electrochemical properties of common commercial separators and PVDF-HFP polymer separators were compared.It is concluded that the performance of PVDF-HFP polymer membrane is excellent and stable,and the next experimental research direction is to modify and optimize on the basis of PVDF-HFP polymer membrane to achieve higher mechanical strength.The graphene oxide?GO?is added to the PVDF-HFP polymer separator to control the crystallinity of the separator,thereby improving the performance of the battery.The experiment found that the addition of GO with a mass fraction of 1%can effectively reduce the crystallinity of the composite membrane and increase the liquid absorption.It can also improve the thermal stability and mechanical strength of the membrane.Using modified composite PVDF-HFP/GO separator,the battery can achieve a discharge capacity of 100.21 mAh g^-1 at a rate of 10 C and a discharge capacity of 161.17 mAh g^-1 at a rate of 0.5 C,and the capacity attenuation after 200 cycles is only 5%.In this paper,the composite separator prepared by adding GO to PVDF-HFP polymer has excellent electrochemical performance and safety performance,and has a certain reference role for the research of lithium ion battery separators.