Common lithium-ion battery malfunctions and their causes. With the rapid development of technology, the application and uses of lithium-ion batteries are self-evident. However, lithium-ion battery accidents are still frequent in our daily lives, constantly troubling us. As the power source for new energy vehicles, the malfunction of power lithium-ion batteries is a significant cause of safety issues. Below, we will explain common lithium-ion battery malfunctions and their causes.
Common lithium-ion battery malfunctions
●Uneven charging causes low voltage: During the charging process after battery testing, uneven charging of the cells can occur due to inconsistent contact resistance or charging current in the testing cabinet. The voltage difference is small during short-term storage, but significant during long-term storage. This low voltage does not indicate a quality problem and can be resolved by recharging. Voltage is measured after storing the battery for more than 24 hours following charging during production.
● 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 within the battery.
●Short battery pack cycle life: The battery pack ends its life within the promised service life. This is because of poor consistency of the battery pack or particularly poor performance of individual series-connected cells, which makes the battery pack unable to be fully charged during charging and unable to be fully discharged during discharging.
● The battery pack may suddenly stop working during use: This could be because the lithium-ion battery has been completely discharged and reached the minimum voltage limit of the protection board or controller, causing the protection board or controller to stop working; or the continuous operating current is too large, exceeding the design protection current of the protection board or the continuous current of the controller, causing the protection board or controller to stop working. Both of these can cause the battery pack to suddenly stop working.
● Battery cells bulge due to air or liquid leakage with a pungent odor; screws turn black; cells soften; deposits harden; overheating; electrode detachment. Other signs include overcharging, over-discharging, and overload.
The common faults and causes of lithium-ion batteries are as follows:
1. Low battery capacity
Causes: a. Insufficient material; b. Significant difference in material content on both sides of the electrode; c. Electrode breakage; d. Insufficient electrolyte; e. Low electrolyte conductivity; f. Improper matching of positive and negative electrodes; g. Low diaphragm porosity; h. Adhesive aging → material detachment; i. Excessively thick core (not dried or electrolyte not penetrated); j. Incomplete charging during capacity testing; k. Low specific capacity of positive and negative electrode materials.
2. High internal resistance of the battery
Causes: a. Poor soldering between the negative electrode and the tab; b. Poor soldering between the positive electrode and the tab; c. Poor soldering between the positive tab and the cap; d. Poor soldering between the negative tab and the casing; e. High internal resistance between the rivet and the pressure plate; f. No conductive agent added to the positive electrode; g. No lithium salt in the electrolyte; h. The battery has been short-circuited before; i. Low porosity of the separator paper.
3. Low battery voltage
Reason for occurrence:
a. Side reactions (electrolyte decomposition; impurities in the positive electrode; presence of water); b. Incomplete formation (SEI film not formed safely); c. Leakage on the customer's circuit board (referring to the battery cell returned after processing by the customer); d. Customer did not spot weld according to requirements (battery cell after processing by the customer); e. Burrs; f. Micro-short circuit; g. Dendrites appear on the negative electrode.
4. The reasons for the occurrence of excessive thickness are as follows:
a. Weld leakage; b. Electrolyte decomposition; c. Incomplete drying of moisture; d. Poor sealing of the cap; e. Shell wall too thick; f. Shell too thick; g. Core too thick (too much material attached; electrode not compacted; diaphragm too thick).
5. Abnormal battery formation
a. Incomplete or incomplete SEI film formation; b. Baking temperature too high → adhesive aging → material detachment; c. Low specific capacity of negative electrode; d. Excessive positive electrode material attachment but insufficient negative electrode material attachment; e. Leaking cap or weld; f. Electrolyte decomposition, reduced conductivity.
6. Battery explosion
a. The capacity divider is faulty (causing overcharging); b. The diaphragm has poor closure effect; c. There is an internal short circuit.
7. Battery short circuit
a. Dust; b. Tear during packaging; c. Scratches (divider paper too small or not properly padded); d. Uneven winding; e. Not properly packaged; f. Holes in the divider; g. Burrs
8. Battery open circuit.
a) The tab and rivet are not properly welded, or the effective weld area is small;
