Reasons for the high internal resistance of polymer lithium batteries.
Perhaps you have also seen the situation where the internal resistance of polymer lithium batteries is too high. What is the specific reason? The polymer lithium battery factory has summarized and analyzed it for you, hoping it can be useful to you.
Due to the complex production process of lithium-ion batteries, with up to 100 large and small steps, there are also many factors that affect the internal resistance of lithium-ion batteries.
In fact, most of them are affected by the process and operation, so the same materials and models often appear. Due to different manufacturing processes, the internal resistance of batteries produced by each manufacturer varies greatly. Even if the same manufacturer, material, process, material, and batch produce batteries with the same internal resistance, there are also significant differences.
The main factors affecting the internal resistance of liquid lithium-ion batteries are as follows:
In terms of craftsmanship
(1) The positive electrode ingredient has too little conductive agent (poor conductivity between materials due to the poor conductivity of lithium cobalt itself).
(2) There are too many binders for positive electrode ingredients (binders are usually polymer materials with strong insulation properties).
(3) Too much negative electrode ingredient binder (binders are usually polymer materials with strong insulation properties).
(4) The ingredients are unevenly dispersed.
(5) The adhesive solvent is incomplete during ingredient preparation.
(6) The design of the coating and drawing surface density is too high.
(7) The compaction density is too high, and the roller compaction is too dense.
(8) The positive electrode ear is not welded firmly, resulting in virtual welding.
(9) Poor welding or riveting of the negative ear, resulting in virtual welding and detachment.
(10) The winding is not tight and the core is loose.
(11) The positive electrode ear is not firmly welded to the shell.
(12) The negative electrode ear and pole are not welded firmly.
(13) The baking temperature of the battery is too high, causing the diaphragm to shrink.
(14) Insufficient injection volume
(15) The storage time after injection is too short, and the electrolyte is not fully immersed
(16) Not fully activated during formation.
(17) Too much electrolyte leakage during the formation process.
(18) The moisture control during the production process is not strict, resulting in battery expansion.
(19) The battery charging voltage is set too high, causing overcharging.
(20) The battery storage environment is unreasonable.
In terms of materials
(21) The resistance of the positive electrode material is high.
(22) Influence of diaphragm material (diaphragm thickness, low porosity, small pore size)
(23) The influence of electrolyte materials. (Low conductivity, high viscosity)
(24) The influence of positive electrode PVDF material. (Large in quantity or molecular weight)
(25) The influence of positive electrode conductive material. (Poor conductivity, high resistance)
(26) Influence of positive and negative electrode ear materials (thin thickness, poor conductivity, poor material purity)
(27) Copper foil and aluminum foil materials have poor conductivity or surface oxides.
(28) The internal resistance of the riveting contact of the cover plate pole is relatively high.
(29) The negative electrode material has a high resistance.
other aspects
(30) Deviation of internal resistance testing instrument.
(31) Human operation.
(32) Environment.
