How normal is the internal resistance of lithium iron phosphate battery?

The internal resistance of lithium iron phosphate battery in Pacific automobile network is generally less than 80 milliohms. According to the internal resistance and capacity of normal series batteries, the internal resistance difference is generally1~ 2mohm, and the capacity difference is controlled at 10mAh. The voltage difference in parallel connection should not exceed 10mV, and there should be no problem after parallel equalization.

What is the internal resistance of lithium iron phosphate battery? What are the factors that affect the internal resistance of lithium batteries? What is the internal resistance of lithium iron phosphate battery after browsing 20 19-07-29 18734 times? What are the factors that affect the internal resistance of lithium batteries? With the use of lithium iron phosphate battery, the performance of the battery is declining, mainly manifested in capacity attenuation, internal resistance increase, power decline and so on. The change of battery internal resistance is influenced by various working conditions, such as temperature and discharge depth. Resistance is the resistance through which current flows when the lithium battery is working. Generally, the internal resistance of lithium batteries is divided into ohmic resistance and polarization resistance.

The internal resistance of lithium iron phosphate battery mainly includes ohmic resistance and polarization resistance. At constant temperature, the ohmic resistance is basically stable, while the polarization resistance will change with the factors affecting the polarization level. The internal resistance, static internal resistance and working internal resistance of lithium iron phosphate battery are often different, and the internal resistance also changes at different temperatures in different environments.

Lithium iron phosphate battery refers to a lithium ion battery with lithium ferrous phosphate as cathode material. The cathode materials of lithium ion batteries mainly include lithium cobaltate, lithium manganate, lithium nickelate, ternary materials and lithium ferrous phosphate. Among them, lithium cobalt oxide is the cathode material used by most lithium ion batteries at present. The internal resistance of battery refers to the resistance of current flowing through the battery when the battery is working, including ohmic resistance and polarization resistance, which includes electrochemical polarization resistance and concentration polarization resistance.

Ordinary 18650 lithium batteries, such as Samsung 18650 lithium batteries, generally have an internal resistance of less than 80 milliohms, but the actual one is less than 65 milliohms. Power 18650 lithium battery has small internal resistance due to its large discharge current. For example, the internal resistance of Samsung 18650-2200-5C power supply is less than 35 milliohms.

Common 18650 batteries are divided into lithium-ion batteries and lithium iron phosphate batteries. The nominal voltage of lithium ion battery is 3.7v, the charging cutoff voltage is 4.2v, the nominal voltage of lithium iron phosphate battery is 3.2V, the charging cutoff voltage is 3.6v, and the capacity is usually 1200mAh-3000mAh, and the common capacity is 2200mAh-2600mAh.

1, temperature The internal resistance of lithium iron phosphate battery, as a main parameter to measure the difficulty of ion and electron conduction in the battery, directly determines the dynamic characteristics of the battery, thus having an important impact on the dynamic performance of electric vehicles. The actual operating environment temperature range of electric vehicles is wide, and the internal resistance of batteries is different under different temperatures and working conditions. Master the internal relationship between battery internal resistance and temperature, SOC and charge-discharge rate. With the increase of temperature, the ohmic resistance and polarization resistance of lithium iron phosphate battery decrease during charging and discharging. The change rate of ohmic resistance is higher than polarization resistance at different temperatures, and the change rate of ohmic resistance at low temperature is higher than that at high temperature.

2. The influence of diaphragm on ionic impedance The main factors influencing the ionic impedance of diaphragm are electrolyte distribution, diaphragm area, thickness, pore size, porosity and tortuosity coefficient. For ceramic diaphragm, it is also necessary to prevent ceramic particles from blocking the pores of the diaphragm, which is not conducive to the passage of ions.

(Photo/Text/Photo: Pacific Auto Network Q&A called Beast)