Reasons for capacity decay of lithium iron phosphate battery

Date:Jul 31, 2019

1. The internal resistance of the lithium battery, especially the inconsistent polarization internal resistance, makes the voltage change of individual batteries during charging and discharging, resulting in a drastic change of the entire battery pack.

2. The inconsistency of the voltage of the ultra-thin battery of the single cell will affect the peaking capability of the battery, so that the energy released by the overall lithium iron phosphate battery is reduced.

3. Due to the exothermic and endothermic process in the operation of ultra-thin batteries, the battery temperature will constantly change. When overheating, it will bring performance degradation and safety hazards. It turns out that the electric vehicle operation and test fires that have occurred in recent years have led to fire. Cables are caused by overheating protection and cause the battery to heat up. The battery type is not only lithium manganate, but also lithium iron phosphate battery.

4. Capacity is the most serious factor in discreteness. Inconsistent capacity mainly causes performance problems in two aspects. First, some lithium iron phosphate batteries will be in an overcharged and overdischarged state, resulting in unsafe factors such as combustion and explosion, and secondly, low. Since the capacity of the single cell is terminated early, the energy of other cells in the entire ultra-thin battery pack cannot be completely released, thereby causing the life of the entire lithium iron phosphate battery to be attenuated.

5. Oxidative decomposition and interfacial reaction of electrolyte

The properties of the electrolyte significantly affect the specific capacity, lifetime, rate charge and discharge performance, operating temperature range, and safety performance of the lithium ion battery. The electrolyte mainly includes three parts: solvent, electrolyte and additive. Decomposition of the solvent and decomposition of the electrolyte result in loss of battery capacity.

6, temperature is definitely one of the key factors affecting the life of lithium iron phosphate battery, too high temperature

Too low a temperature will cause a decrease in the active lithium ion content, thereby reducing the life of the lithium battery.

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