Research On High-efficiency Formation And Charging Method For Commercial Application Mobil Phone Lithium-ion Batteries

Lithium ion batteries possess high voltage, high energy density, less environmental pollution, widely employing in small electronic products. Lithium ion batteries need activation process and charging process which usually take a long time. If the cycle stability, cycle life, Coulombs efficiency and safety performance are guaranteed, reduce the activation time will improve the productive process of the lithium ion batteries for factory. Here we studies the different current rate, segmented activation process, precharge processes after activation process for lithium ion batteries.By using Li Co O2, Li3FePO4 as the cathode material, graphite and MCMB as anode materials for the testing cells, studying the cycle of 1-2, 3-4, 1-4 by constant current with different rate to gain the impacts of the segmented activation process, precharge processes after activation process for lithium ion batteries. Studies have shown that the cycle performance kept invariable except individual rate performance tests.Li Co O2 / graphite was studied in different current rate, segmented activation process, precharge processes after activation process for commercial lithium ion batteries. And the above three groups of the batteries cycled 300 times in 0.2 C rate. The retention of the discharge capacity was over 90%. The group which experiences precharge processes after activation process maintained the highest retention can achieve over 96%. The group which experiences different rate achieve retention rate can reach 94%. The group which experiences segmented activation process lowest retention capacity, for about 90%.Electrochemical impedance spectrum was used to test the cells of the three groups. The resultshowed the the impedance changed little, which revealed that the internal impedance was uninfluenced. By X-ray diffraction(XRD) analysis, measured three batteries after 300 cycles in the test, the crystalline structure of the lithium ion batteries anode materials are not changed. Fourier transform infrared spectroscopy(FTIR) tested three sets of batteries in 300 after the cycle test, the chemical composition of the lithium ion batteries anode materials has no obvious change. The SEM photographs of the cells showed that after the cycle test, the anode and the cathode materials were both changed.