Theoretical And Experimental Study On Laser Cleaning Of Cathode From Lithium-ion Batteries

Li-ion battery has become the dominant power source for electric vehicles due to its large energy density, small self-discharge, high voltage and other advantages. A large number of waste Li-ion batteries have been produced during the rapid development of electric automobile which can not only result in pollution, but also lead to serious waste of resource and energy. Thus, how to solve the problem of waste automobile batteries, prolong the service life of waste automobile batteries and reduce the secondary pollution to soil has become the urgent matter right now. However, the current recycling and utilizing technology of waste Li-ion batteries has higher cost and lower efficiency. The rise of re manufacturing technology brings a new direction for processing waste Li-ion batteries, which has an important significance to the research on environmental and effective re manufacturing technology for waste batteries. In fact, the existing re manufacturing technology of waste Li-ion batteries is still on laboratory research stage, which has poor operational safety, difficulty in controlling the quality of re manufactured product, higher cost and other problems. In order to solve these problems, an highly effective and environmental re manufacturing technology for waste batteries-pulsed laser cleaning, is proposed in this paper.First, the ablation mechanism and principle of vibration mechanism during the process of laser cleaning the electrode of waste electronic automobile Lithium iron phosphate batteries are introduced, then a theoretical model of double layer thermal elastic vibration during the cleaning process is established as well, which further deduce the temperature and displacement distribution equation during the laser cleaning and get the formula of detachment stress of SEI layer on the surface of electrode under the impact of pulsed laser.Additionally, disassemble waste Li-ion batteries. Pulsed laser with different energy value is utilized to clean the electrode, then the surface topography and element composition of cleaned electrode are analyzed through modern approaches of detection and characterization, such as, scanning electron microscope, fourier transform infrared spectrometer and X-ray photoelectron spectroscopy analysis. The experimental results show that the pulse energy is set to 0.16mJ can obtain relatively good cleaning effect under the current experimental conditions.The recovery of porosity on the surface of the electrode was analyzed by using Probe Image Processor Scanning software. The results showed that the gap between the electrodes on the surface of the electrode was increased after laser cleaning. And the recovery rate of re manufacturing battery capacity is calculated to be 98% based on the analysis of SEI layer thickness removed from the cross section of cleaned electrode. In addition, the charging and discharging cycle test of button battery composed of re manufacturing electrode sheet shows that the battery after the re manufacture charging and discharging efficiency is better than that of the discarded battery. the electrochemical performance of re manufactured battery is verified.The test indicates that, the environmental and effective re manufacturing technology for waste battery laser cleaning with lower cost and simple operation is feasible.