Cycle process during the charge and discharge system

Lithium-ion batteries use process is the process of charge and discharge cycles, the magnitude of charge and discharge current, charge and discharge cut-off voltage selection and use of charge and discharge methods such as charging and discharging system of lithium-ion battery cycle life is also very important. It is usually used in solar powered portable generator. Where blindly increase the battery operating current, increase the charge cut-off voltage, reduce the discharge cut-off voltage and so will decrease the battery performance.

Different electrochemical systems of lithium-ion battery charge and discharge cut-off voltage is different. In the lithium-ion battery charging process, where more than the charge cut-off voltage that occurred overcharge.

K.Maher and other LiCoO2 battery charge cut-off voltage in turn from 4.2V set to 4.9V, and the experimental electrode materials were X-ray diffraction and Raman spectroscopy experiments showed that the graphite anode and lithium cobalt oxide anode were structural changes. By testing the different cut-off voltage of the electrode after charging different SOC entropy curve, also found that the electrode material structural changes occurred.

Lithium-ion battery overcharge, from the cathode out of the excess lithium ions will be deposited or embedded in the negative electrode, the active lithium easily with the solvent reaction, the release of heat so that the battery temperature. Positive decomposition of oxygen generated by the decomposition of the electrolyte easily and produce a lot of heat.

When the discharge voltage of the lithium battery is lower than the discharge cut-off voltage, overdischarge is formed. In the process of over-discharge, the lithium-ion from the negative pole will be excessive prolapse, the next re-embedded when the charging will be more difficult. YU Zhong-Bao and so on to the MCMB as the cathode, LiCoO2 positive for the battery over-discharge to 0V, the copper collector fluid was more serious corrosion, negative SEI film was damaged, re-formed SEI film performance is poor, the negative resistance increases, polarization enhancement. The battery discharge capacity in the cycle after the discharge, the charge and discharge efficiency is greatly reduced.

Li Yan were studied 18650 lithium-ion battery discharge at different magnification. The results show that the LifePo4 battery pack capacity decay increases almost proportionally with the increase of charge / discharge ratio. High-rate cycle of LiCoO2 / graphite lithium-ion battery capacity of a serious decline.

The main reason for the serious attenuation of the capacity is the change of the structure of the cathode material and the thickening of the negative electrode surface film, which leads to the decrease of Li + and the obstruction of the diffusion channel. In the case of large current discharge, the need for rapid ion implantation, out of the positive and negative, the reaction is very fast.

Tang Zhiyuan and so on through the experimental analysis that: because the battery discharge in large current needs in a short period of time to release a large capacity, rapid and violent electrode reaction, some lithium ions too late to de-embedded or through the anode material discharge process has ended . In addition, the battery tabs may fuse under heavy current conditions and equipment components may be damaged.

Through analysis we can see, both in the design and manufacture or use of the process, the impact of lithium-ion battery cycle life of many factors. Lithium-ion battery applications more and more widely, for example used in portable solar power generator, the demand for lithium batteries in the quantity and quality are put forward higher requirements. Cycle life of lithium-ion batteries directly affect the use of time and quality, so producers of its influencing factors of the study is very necessary. Only in the development and production process will affect the cycle life of all factors are well grasped, enterprises can in the fierce competition in the market take the initiative. Consumers should pay attention to the use of lithium-ion battery characteristics, according to the instructions prompt use of batteries.