Study On The Process And Uniformity Of Environment Friendly LiFePO₄Ithium-ion Batteries

Energy plays a big role on human development. China and the whole world havethe goal of sustainable development. In order to achieve that goal, the pursuiting ofclean and renewable energy resources has become a worldwide theme of the21stcentury. People are researching solar, wind, hydropower, geothermal energy, tidalenergy and other renewable energy. Some of them have been skilled controlled byhuman. But we need to store energy in excess and ues it in the case of shortfall, whichis “load shifting”, in order to ensure the people’s normal life and work. People payattention and research on the lithium-ion battery, as the storage of clean energy.In this thesis, the lithium-ion battery development and research status arecomprehensively reviewed, and we systematically expounded the preparation processof the eco-friendly water-based lithium-ion battery, the ball-milling process ofLiFePO4battery, and the improvement of the consistency of lithium-ion battery formspecific factors with sorting method. A dynamic charging method of lithium-ionbattery and its importance have also been proposed.Through four sets of comparative test, by observing the surface morphology ofbattery electrodes using scanning electron microscopy and testing electrochemicalperformance of the battery, we found that the ball-milling process can be greatlyimproved the dispersity of the active material and conductive agent in battery slurry,and help increase the rate and low temperature performance of the battery. Ratios of2C rate discharge capacity on0.5C rate discharge capacity of two materials wererespectively improved from96.69%,90.94%to100.61%,91.85%. Ratios of5Cdischarge capacity on0.5C rate discharge capacity of two materials were respectivelyimproved from96.14%,75.75%to99.56%,80.31%. The discharge platform voltageof2C increased from3.02V,3.01V to3.07V,3.03V, and the discharge platformvoltage of5C increased from2.77V,2.67V to2.85V,2.72V. For low temperatureperformance, the ratio of0.5C discharge capacity at0℃on0.5C discharge capacity atroom temperature were improved from85.80%,67.59%to88.90%,74.18%. Theplatform voltage increased from3.00V,3.02V to3.01V,3.05V. The reason is that themilling process is mainly playing a big role on improving the performance of thedispersity of conductive agent-SP in battery slurry. Therefore, the active substancecan be dispersed more uniformly so that the conductive agent to reduce aggregating to connect active substance under ideal conditions to improve the ion and electricalconductivity and migration ability. Thereby, it reduced the polarization of batterycharge and discharge and improved the rate and low temperature performance ofbatteries.Summarized lithium-ion batteries consistency key influencing factors of controlparameters on the LiFePO4lithium-ion battery production process from the dispersionof mixing slurry, coating process, the calender process, the infiltration process, theelectrolyte injection and electrolyte-retaining process.Proposed a suitable separation method from capacity, AC resistance, DCresistance, open circuit voltage as well as battery discharge curve characteristicparameters.From the internal structure of the active substance at different voltages wit hdifferent structure, we put forward an open method of dynamic battery charging whichcan be used to various chemical systems, and explained its importance.