How to improve lithium ion battery performance? How to see how the trial is to state!

Författare: Iflowpower – Leverantör av bärbar kraftverk

The lithium ion battery with lithium iron phosphate is a high safety, the advantage of long cycle life, is the mainstream battery of the electric car. The battery will shorten its life for a long time, explore the capacity loss of the power lithium ion battery during high temperature storage procedures, which helps to understand the failure mode of lithium-ion battery, and improve battery performance. Although a large amount of literature has been studied by the lithium ion battery capacity loss, the original is attributed to the electrolyte reduction analysis, the growth thickening of SEI membrane and the polarization caused by the battery, but current research is limited to button (Hem) Less research on the failure of the commercial lithium-ion battery (full battery).

Ningde Times CATL uses its commercially based on the lithium-ion battery as a sample, explores its original originating in power, 60 ¡ã C storage capacity loss. By physical characterization and electrochemical performance evaluation, the mechanism of decomposing battery capacity from battery and pole level level is very worth exploring! 1. Test process test using CATL processed nominal capacity of 86AH lithium-ion battery.

The battery is a cathode material, graphite is an anode material, using a polyethylene (PE) diaphragm and carbonate group LiPF6 electrolyte. Select the 20 batteries close to the same batch and electrical performance to store, detect the electrical performance of the battery. 100% SOC battery 60 ¡ã C is stored in a press between 2.

50 to 3.65V, a discharge of 0.5C magnification - charging cycle.

Then continue to be stored at 60 ¡ã C for 60 ¡ã C. Such repeated, recording the capacity attenuation process of the battery. During each capacity detection, the DC internal resistance (DCR) of the battery 5C30S is detected.

Take different storage times and in a fully discharged state (100% DOD), disassemble. Use field emission scanning electron microscope to observe the polar morphology, use the specific surface specific surface area than surface decomposition. In the glove box, the electrode sheet is sealed with a translucent tape, and the electrode material material is composed using X-ray diffraction instrument.

The polar piece after the dissolution of the battery is the working electrode, the lithium sheet is the counter electrode, and is equipped into a CR2032 buckle battery, and the electrochemical properties of the yin and inferior plate. Electrochemical impedance spectrum of buckle batteries with electrochemical workstation. Elemental content of the electrode sheet using an inductive coupling plasma emitting spectrometer (ICP-OES).

2. As a result, discussion 2.1 Battery performance decomposition is charged and discharged by 0.

02C smash. In Fig. 1 (c), a lithium ion is embedded in a plurality of platforms caused by lithium ions in the battery voltage curve, indicating that 0.

02c magnification has been embedded for lithium ion. The relaxation of graphite structures in the process of leaving enough time can effectively eliminate the effects of polarization on cycles. Compared with 0.

5C magnification, it is only 0.8% (90.7% vs.

91.4%) and 1.4% (85.

8% vs.87.3%).

Therefore, the battery capacity attenuation caused by long-term high temperature storage is an irreversible capacity attenuation. In addition, FIG. 1 (a) shows that the amplitude of the capacity of the battery has increased with the storage time, which also shows that the internal polarization of the battery is not an important original caused by the indifference of the calendar storage battery capacity.

2.2 Battery capacity attenuation machine Decomposes to decompose battery capacity attenuation root sources, the high-temperature storage battery is charged to 100% SOC or discharged to 100% DOD after 1C magnification. Decompose the disassembled pole to examine the effects of high temperature storage on the structure, elemental composition and electrochemical properties of the yin and inferior active material.

2.2.1 LIFEPO4 in the deepening of the deepel deeper deletion will appear very close to the FEPO4XRD map, while the LIFEPO4XRD spectrum is very close to the Lifepo4XRD spectrum in the LIFEPO4 of the depth.

At the same time, there is a lithium phase and lithium phase in the fully discosted LiFePO4 pole, and the lithium-phase content is increased with the storage time, indicating that the number of lithium ions capable of embedding the FEPO4 lattice is redu.