Fabrication Of Silicon Anode For Li-ion Battery Based On Laser Melt Injection

Lithium-ion Battery has the advantages of high energy density,no memory effect,high capacity performance,and has replaced the traditional secondary battery of Ni-Cr,Ni-MH,lead acid and so on since its advent.Lithium-ion battery consists of cathode,electrolyte,polymer diaphragm and anode.At present,most commercial lithium-ion batteries use graphite anode,its theoretical capacity is only 372 mA·h/g,can not meet the growing demand.The silicon anode theory capacity is 4200 mA·h/g,it is the ideal anode material to replace graphite.At present,the conductive agent,binder and silicon particles are mixed and coated directly on the surface of the current collector to realize the structuring of the silicon anode.However,the huge volume expansion of silicon alloys upon lithiation results in electrical contact loss and pulverization of the material,the capacity rapid decay.At the same time,the addition of conductive agent and binder reduces the load of silicon particles and hinders the practical application of silicon electrodes.In this study,a laser melt injection method was used to scan the surface of the metal nickel with a high-power fiber laser to form a molten pool.At the same time,silicon particles were injected into the molten pool.As the molten layer rapidly solidified,the unmelted silicon particles remained on the surface of the nickel metal.,to achieve the production of silicon anode.Through ANSYS simulation,The time-varying law of the temperature field and the nodes in the depth of the melt pool,the width of the weld pool and the laser scanning direction are obtained at the laser remelting process.Through study of laser power,scanning speed,defocus amount and other process parameters,the optimized penetration depth of the injection layer is 0.37 mm and the melt width is 2.58 mm.The tail length of the molten pool can reach 1.42 mm under laser irradiation.The injection of conventional 75 ?m particle size silicon particles was verified to be suitable for laser injection.By designing a gas atomizing and vibrating powder delivering device,silicon particles with a particle size of 5 ?m was delivered,and laser melting was performed to obtain a silicon particle deposited on the surface of a nickel substrate.The results show that the metallurgical combination of silicon particle and metal nickel substrate can be realized by laser melt injection,which provides a new method for the manufacture of silicon anode of lithium ion battery.