The cause of the failure of lithium iron phosphate battery production process.lithium ion golf cart batteries Processing

　　The impurities in the electrode activity material failure to the battery failure: During the synthesis process of LifePO4, there will be a small amount of FE? O?, Fe2P, Fe, Fe4 (P2O7) 3 and other impurities. It will piercing the diaphragm and cause the internal short circuit. LIFEPO4 is exposed to the air for a long time. The moisture will deteriorate the battery and the aging mechanism of aging: the surface of the material on the surface of the material forms non -fixed -type iron phosphate. LIFEPO4 is constantly being consumed and manifested as an increase in volume; then the crystallization slowly forms LIFEPO4 (OH). In LI3PO2 in LIFEPO4, impurities are electrochemical inertia. The higher the impurities of graphite negative (mainly AL and Fe), the greater the irreversible capacity loss (the smaller the reversible capacity loss).

　　The failure of the formation method to the battery: The irreversible loss of the active lithium ion is first reflected in the lithium ion consumed during the formation of a solid electrolytes. Studies have found that increased temperatures will cause more irreversible lithium ion losses, because when the increase is increased, the proportion of inorganic components in the SEL membrane will increase. Gas will cause more defects in the SEI film. Through these defective solvents, lithium ions will be embedded in a large amount of graphite negative. When turning into it, the composition and thickness of the SEL membrane formed by small current charging is uniform, but it takes time; large current charging will cause more side reactions, resulting in increasing irreversible lithium ion loss, and the increase in negative electrode interface impedance will also increase, but the province will be provincial At the time, the use of small current constant current-large current constant flow constant voltage modes can be used, which can take into account the advantages of the two. The use of electrochemical methods further proves that the activation of the battery affects the stability of the SEI membrane. The higher the stability of the SEI membrane, the lower the self -discharge rate of the battery.

　　Water in the production environment is invalidated by the battery: In actual production, the battery will inevitably contact the air. Because the positive and negative pole materials are mostly micron or nano -level particles, and the solvent molecules in the electrolytes are large in electricity, there are large electrical negatives. Carboxyl and sub -stable carbon -carbon bonds can easily absorb water in the air. Lithium salt (especially lipf6) in water molecules and electrolyte reacts, not only the decomposition consumes electrolytes (decompose PF5), but also produces acidic substance HF. Both PF5 and HF will destroy the SEI speakers, and HF will also promote the corrosion of LIFEPO4 activated substances. Water molecules will also remove lithium -lithium graphite negative, forming a lithium hydroxide net at the bottom of the SEI membrane.

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