Study On Preparation And Application Of Carbon Fiber Composite Structure For Energy Storage

With the continuous development of modern transportation such as transportation,intelligent systems and unmanned driving,new challenges have been raised to the lightweight,safety,payload and cycle life of traditional batteries.Meanwhile,the 14 th Five-Year Plan issued by the government is committed to developing a circular economy and promoting carbon peaking and carbon neutrality.As a new type of composite material,carbon fiber has light weight,high strength and good electrical conductivity,and is widely used in military,aerospace,shipbuilding and other fields.Therefore,research interests such as structural battery,structure-function integration,and structural energy storage based on carbon fiber have emerged and quickly become a new research hotspot.Structural energy storage mainly uses the excellent mechanical properties of carbon fiber to combine the structural parts made of carbon fiber composite materials with the energy storage system.By combining the functions of composite materials and batteries,in addition to being able to withstand stress and strain,it can also store electrical energy,which can effectively reduce the mass of the system,simplify the structural design,increase the safety of the energy storage system,and improve the overall performance of the system.In this paper,based on carbon fiber composite materials,structural energy storage samples were prepared,the mechanical and electrochemical properties were tested and optimized according to finite element simulation analysis,and finally the samples were put into practical application.The main research contents include the following aspects:(1)The positive and negative materials of the energy storage cell are lithium cobalt oxide and graphite respectively,the conductive agent is conductive carbon black,as well as a binder and other additives.Firstly,mix them uniformly in a certain proportion and add a solvent to prepare positive and negative electrodes.Then,positive and negative electrode slices are prepared by coating-rollingdrying process and packaged in a vacuum glove box.And finally the electrochemical performance of the packaged cells is tested.The test results show that the reversibility of the cell is high and the cycle performance is relatively stable;under the discharge current of 0.05 A,the cell capacity is 231 m Ah,the energy density is 162 Wh/kg,and the internal resistance is 0.241 Ω.2)This paper adopts the vacuum resin infusion process to prepare the structural energy storage so as to ensure the stability of the electrochemical performance of the internal cells and prevent the cells from being damaged by the hot pressing process.The resin adopts medium and low temperature epoxy resin,and the vacuum negative pressure was controlled at-0.1 MPa,the electrochemical performance test of the prepared samples was carried out to explore the influence of the molding process on the performance of the cell.The test results show that the reversibility of the structural energy storage sample is still high,the capacitance fluctuation is within 5%,and the internal resistance change is small,indicating that the vacuum resin infusion process has little effect on the electrochemical performance of the cell.(3)In order to verify the load-bearing performance of the structural battery,compression and three-point bending tests were performed on the prepared structural battery,respectively.The test results show that the maximum compressive stress is 16.5 k N,the capacitance retention rate before crushing is94%,and the capacity after crushing is still over 80%;the maximum bending stress is 2673 N,and the capacity retention rate before the end of the test is all above 80%,the capacity retention rate after the test is only 61%.(4)In order to ensure the reliability of the later practical application,the accuracy of the test results is assisted by the finite element analysis,and the application analysis of the energy storage landscape light is done.The results show that the deformation and stress distribution of the compression and threepoint bending test are basically the same as the actual test,which proves the reliability of the test and provides the basic theoretical support for the later application of energy storage landscape lights and the optimization and improvement of the structure.