Perhaps everyone has seen the situation of large internal resistance of polymer lithium batteries. What is the specific reason? The polymer lithium battery factory will help you summarize and analyze it. I hope that it will come in handy for you.

Due to the complicated production process of lithium-ion batteries, there are more than 100 large and small processes , and there are many factors affecting the internal resistance of lithium-ion batteries.

In fact, most of them are process and process operation effects, so the same materials often appear. The same type of battery has different internal resistances produced by each manufacturer because of different manufacturing processes. Even the same manufacturer, the same material, the same process, the same material, the same batch. There is also a big difference in the internal resistance of the battery produced.

The main factors affecting the internal resistance of liquid lithium-ion batteries are as follows:

Process aspect
( 1) The positive electrode compound has too little conductive agent (the conductivity between the material and the material is not good because the conductivity of lithium cobalt itself is very poor).
( 2) Excessive binder of the positive electrode (the binder is generally a polymer material with strong insulation properties).
( 3 ) Excessive binder of the negative electrode (the binder is generally a polymer material with strong insulation properties).
( 4 ) The ingredients are dispersed unevenly.
( 5 ) The binder solvent is not complete when the ingredients are dispensed.
( 6 ) The coating draw density is too large.
( 7 ) The compaction density is too large and the roller pressure is too strong.
( 8 ) The positive ear is not welded well and there is virtual welding.
( 9 ) The negative ear welding or riveting is not strong, and there is a virtual welding and desoldering.
( 10 ) The winding is not tight and the core is slack.
( 1 1) The positive electrode is not welded to the housing.
( 1 2) The negative pole and the pole are not welded firmly.
( 13 ) The battery baking temperature is too high and the diaphragm shrinks.
( 14 ) too little liquid injection
( 15 ) The shelf life is too short after the injection, and the electrolyte is not fully wetted.
( 16 ) Not fully activated at the time of formation.
( 17 ) The electrolyte leaks too much during the formation process.
( 18 ) The moisture control in the production process is not strict and the battery expands.
( 19 ) The battery charging voltage is set too high, causing overcharging.
( 20 ) The battery storage environment is unreasonable.

Material aspect

( 21) The positive electrode material has a large electrical resistance.
( 22) Influence of diaphragm material (thickness of diaphragm, small porosity, small aperture)
( 23) Influence of electrolyte materials. (small conductivity, high viscosity)
( 24) Effect of positive PVDF material. (large amount or large molecular weight)
( 25) Influence of positive electrode conductive material. (poor conductivity, high resistance)
( 26) Influence of positive and negative electrode materials (thickness, poor conductivity, poor material purity)
( 27) Copper foil, aluminum foil material has poor conductivity or oxide on the surface.
( 28) The internal resistance of the cover pole riveting contact is too large.
( 29) The negative electrode material has a large electrical resistance.

other aspects
( 30) Internal resistance test instrument deviation.
( 31) Man-made operations.
( 32) Environment.