Lithium-ion batteries are a common item in our daily lives, but they are also prone to various malfunctions, such as low battery capacity, high internal resistance, excessive thickness, abnormal battery formation, battery explosion, short circuit, and open circuit. So, what are the causes of these malfunctions?
Causes of low capacity in lithium-ion batteries: Insufficient material; significant difference in material content on both sides of the electrode; electrode breakage; insufficient electrolyte; low electrolyte conductivity; improper matching of positive and negative electrodes; low separator porosity; aging adhesive leading to material detachment; excessively thick core, resulting in incomplete charging during capacity testing; low specific capacity of positive and negative electrode materials.
Causes of high internal resistance in lithium-ion batteries: poor soldering between the negative electrode and the tab; poor soldering between the positive electrode and the tab; poor soldering between the positive tab and the cap; poor soldering between the negative tab and the shell; high internal resistance in the contact between the rivet and the pressure plate; lack of conductive agent in the positive electrode; absence of lithium salt in the electrolyte; previous short circuit of the battery; low porosity of the separator paper.
Causes of low voltage in lithium-ion batteries: side reactions (electrolyte decomposition; impurities in the positive electrode; presence of water); incomplete formation (S film not forming safely); leakage in the customer's circuit board (referring to the battery cell returned after customer processing); improper spot welding by the customer (for the battery cell after customer processing); burrs; micro-short circuit; dendrites on the negative electrode.
Causes of excessive thickness failure: air leakage in welds; electrolyte decomposition; insufficient drying of moisture; poor sealing of cap; shell wall too thick; shell too thick; core too thick (too much material attached; electrode not compacted; diaphragm too thick).
Causes of abnormal lithium-ion battery formation: poor formation (incomplete or dense S film); excessively high baking temperature → adhesive aging → material stripping; low specific capacity of negative electrode; excessive positive electrode material and insufficient negative electrode material material; air leakage in the cap or weld; electrolyte decomposition and reduced conductivity.
Causes of lithium-ion battery explosions: faulty capacity testing cabinet (causing overcharging); poor diaphragm closure effect; internal short circuit.
What are some common malfunctions of lithium-ion batteries?
Battery internal resistance: Improper welding of the positive and negative electrodes during the soldering process, or excessive internal resistance in the contact between the rivets and the pressure plate, can all affect the internal resistance of a lithium-ion battery. Insufficiently small pores in the separator can also affect the battery's internal resistance.
Battery voltage; during the production process of lithium-ion batteries, impurities in the positive electrode and dendrites in the negative electrode can both reduce the battery voltage. Incomplete formation of the SEI film during the formation process can also lead to excessively low battery voltage.
Abnormal temperature; if the lithium-ion battery experiences abnormal temperature during charging or discharging, such as overheating, the cause may be a minor short circuit inside the battery.
