Study On Composite Material Of Vehicle Solid State Power Battery

At present,the safety is the most difficult challenge we facing in the liquid batteries.Since the liquid electrolyte is a flammable organic substance,explosion or fire may occur in the case of vibration or impact,which poses a great threat to personal safety.Therefore,solid-state batteries and solid electrolytes are now likely to replace current liquid batteries and electrolytes as a more reliable and safer alternative.In order to compete with liquid batteries,solid electrolytes are required to have higher ionic conductivity,and solid-state batteries have good performance.Solid-state batteries have good cycle performance and rate performance to meet normal needs.This paper mainly studies the development background,current situation and existing problems of solid-state lithium batteries,and attempt to find out the appropriate solutions.The positive electrode material adopts the lithium manganate prepared by the traditional high-temperature solid phase method.Through physical characterization and electrochemical performance test,it is found that the particle size is uniform,the grain boundary line is more obvious,and it is concluded that the structure belongs to the Fd-3m spatial structure.In the electrochemical performance test,the specific capacity of the first discharge in the charge-discharge test was 114.9mAh·g^-1,the coulombic efficiency reached 96.7%,and the specific capacity at 1C ratio was 71.3 mAh·g^-1,accounting for 62.1%of the specific capacity of the first discharge.After 50 charging and discharging cycles,the discharge specific capacity decays to 105.9 mAh·g^-1,which is up to 6.8%.It has a very good cycling performance.The lithium ion fast conductor Li_1.5Al_0.5Ge_1.5（PO₄）₃ was prepared as an inorganic filler,PEO composite solid electrolyte film was obtained by solution casting method with different mass ratios of Li_1.5Al_0.5Ge_1.5（PO₄）₃ and PEO.Linear scanning proved that its decomposition voltage is above 5.0V.The AC impedance test was carried out on different proportions of the composite electrolyte membrane.The composite electrolyte membrane LAGP-60 has the highest conductivity and can reach2.16×10^-4 S·cm^-4 at 55℃,which meets the requirements for electrolytes.Cyclic voltammetry of the composite electrolyte membrane LAGP-60 showed that the stable electrochemical window of the PEO-based solid electrolyte membrane LAGP-60 to metallic lithium can reach 8V,which is suitable for the commercial lithium ion cathode material.Exploring the impact of the assembly process on the performance of the solid state lithium battery assembled into different structures,the test temperature is 55℃.The results show that the initial discharge specific capacity of the two assembly structures a and b can reach 83.8 mAh·g^-1 and 79.9 mAh·g^-1,and the coulombic efficiency can reach 77.0%and 81.6%.It can be seen that although the a structure has a higher charge specific capacity than the b structure,its coulomb efficiency is lower than that of the b structure.The a-structure solid-state battery has a rapid decay in specific capacity under large-rate discharge,with a specific discharge capacity of 81.4mAh·g^-1 at 0.1 C,a specific discharge capacity of only 4.0 mAh·g^-1 at 1 C,and a solid-state battery of 0.1 C for b structure.The specific discharge capacity is 76.9mAh·g^-1,which is 36.7 mAh·g^-1 at 1C rate.After 1C rate discharge,it is tested at0.1C rate.The specific capacity of a and b structures can be restored to 31.2 mAh·g^-1and 50.6 mAh·g^-1.The specific capacity of the a structure and the b structure after the cycle of 50 times is 17.2 mAh·g^-1 and 43.5 mAh·g^-1,which indicates that the solid state assembly of the b structure is more suitable for the LMO-PEO solid battery material studied in this paper.