Electrochemical Behavior Of Tin-carbon Composite Materials And Development Of Power Battery Thermal Management System

Tin?Sn?is one of the most preferred materials for negative electrode materials of lithium ion batteries.Sn has a high theoretical capacity(993 mAh g^-1)and has excellent electrical conductivity.However,the practical application of Sn as LIBs anode suffers from a severe pulverization caused by a large volume change during the Li⁺alloying and dealloying processes.Sn has a low melting point,leading to a heavy aggregation of Sn particles during the carbonization process.Highly dispersed Sn nanoparticles are difficult to prepare.The large particles are easily pulverized during the reaction,leading to a sharp decline in capacity.In response to such problems,this article effectively suppresses the problems of agglomeration during the preparation and battery capacity decay upon cycling process through two methods.First,a simple template method was used to prepare the Sn nanoparticle encapsulated in the carbon tube?Sn@aCT?.Nano-sized Sn can effectively avoid volume expansion during lithiation.The conductive network of aCT forms a supporting frame.This composite material shows excellent electrochemical performance as a negative electrode for LIBs.Through transmission electron microscopy,it was verified that the morphology of each stage in the preparation process conformed to the predetermined structural assumption.Electrochemical analysis show that the high capacity of Sn nanoparticles and the high stability of aCT are combined,showing the capacity retention capacity under long cycle.It is providing a specific capacity of 870 mAh g^-1 at a current density of 0.1 A g^-1 after 350cycles.Compared with the electrochemical performance of the intermediate structure?SnO₂@aCT?,the capacity loss caused by the early irreversible lithiation reaction is avoided.In order to compare the effect of the size of Sn particles and the role of carbon tubes,carbon-coated Sn nanoparticles yolk shell?Sn@C-YS?was prepared.The diffusion coefficients of the three electrodes are measured.The excellent ion transport ability of Sn and aCT network is confirmed.Large particles of Sn in Sn@C-YS form more SEI after contact with the electrolyte.Therefore,we have optimized the structure of Sn@C-YS.A thin layer of Sn sulfide is formed on the surface by vulcanization.The electrochemical analysis shown that the S-Sn@C electrode has a low initial charge and discharge capacity,but the output capacity is relatively stable and the capacity is stable at about 750 mAh g^-1.The S-Sn@C electrode has a stable circulation ability,due to the low SEI formed by the sulfides on the surface,the irreversible consumption of active materials is slowed down.The phenomenon of pulverization of active materials has been alleviated in cycles.In order to study the cooling performance of the battery pack thermal management system.The liquid-cooled battery pack thermal management system to be established with a company.The liquid-cooled systems have different thermal management efficiencies under different operating conditions.The optimal thermal management plan was worked out for obtain a better cooling efficiency.