Due to the low intrinsic conductivity of LiFePO4, the morphology and size of the material itself, as well as the influence of conductive agents and binders, are easily manifested. Discussing the two contradictory factors of size and carbon coating , it is found that the impedance of LiFePO4 electrode is only related to the average particle size. The anti-site defect inside LiFePO4 (Fe occupies Li site) will have a certain impact on the performance of the battery: because the transport of lithium ions in LiFePO4 is one-dimensional, this defect will hinder the transport of lithium ions; due to the introduction of high valence states This defect also causes the instability of the LiFePO4 structure due to the additional electrostatic repulsion.

The large-sized LiFePO4 cannot fully delithiate at the end of the charge; the nanostructured LiFePO4 can reduce the anti-site defects, but can cause self-discharge due to its high surface energy. At present, the most commonly used binder is PVDF, which may react at high temperature, dissolve in non-aqueous electrolyte, and is not flexible enough, which has a certain impact on the capacity loss and shortened cycle life of LiFePO4. In addition, the current collector, diaphragm, electrolyte composition, production process, human factors, external vibration and shock will affect the performance of the battery to varying degrees.

In the normal use of the battery, the loss of active lithium ions is the main reason for the failure of LiFePO4 power batteries. Therefore, for LiFePO4 power batteries (graphite anodes), the quality and stability of the SEI film are the keys to improving the battery cycle life. The formation process of SEI film (including changes in its morphology and thickness), the action mechanism of film-forming additives, and the diffusion mechanism of lithium ions in the SEI film are increasingly being studied by various experimental and theoretical methods. It is understood that this also provides favorable conditions for improving the service life of LiFePO4 power batteries.

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