Li-ion battery performance and safety performance analysis

5) Charge retention and recovery capability: fully charged and left for 28 days at room temperature, charge retention discharge time is not less than 96min (80%), charge recovery discharge time is not less than 108min (90%); (6) Storage performance ：Single cells or battery packs for storage test should be selected from those with a processing date of less than 3 months, with a capacity of 50%-60% before storage, at an ambient temperature of 40℃±5℃, and a relative humidity of 45%-75% Environmental storage for 90 days. After the expiration of the storage period, take out the battery pack, fully charge it at 0.2C and leave it for 1h, then discharge to the final voltage at a constant current of 0.5C. The above test can be repeated for 3 times, and the discharge time shall not be less than 72min (60%); (7) Cycle Life: The battery or battery pack is charged at 0.2C, and discharged at 0.5C. The test stops when the discharge capacity is lower than 72min (60%) for two consecutive times. The cycle life of the single battery is not less than 600 times, and the cycle life of the battery pack is not Less than 500 times; (8) High-temperature shelf life: should be selected from single batteries with a processing date of less than three months for high-temperature shelf life test, and 50%±5% of capacity should be charged before shelving, and then at ambient temperature Shelve for 7 days under the strip at 55℃±2℃. Take out the battery after 7 days and put it aside for 2～5h at an ambient temperature of 20℃±5℃. First discharge the battery to the final voltage at 0.5C, charge it at 0.2C after 0.5h, and then let it stand for 0.5h, then discharge it to the final voltage at a constant current of 0.5C, and use this capacity as the recovery capacity. The above steps are a one-week cycle, until the discharge time of a certain week is less than 72min (60%), the test is over. Shelf life is not less than 56 days (8-week cycle). (1) Continuous charging: The single battery is charged at a constant current of 0.2ItA. When the single battery terminal voltage reaches the charging limit voltage, it is changed to constant voltage charging and maintained for 28 days. After the test, there should be no leakage, no discouragement, and no leakage. Rupture, no fire, no explosion (equivalent to fully charged floating). (2) Overcharge: Charge the single battery with a constant current voltage source at 3C constant current. After the voltage reaches 10V, switch to constant voltage charging until the battery explodes or catches fire or the charging time is 90min or the battery surface temperature is stable (within 45min) Stop charging when the temperature difference is less than or equal to 2℃), the battery should not catch fire or explode (3C10V); charge the battery pack at a constant current of 0.5 ItA with a voltage-stabilizing source, and turn after the voltage reaches n×5V (n is the number of single cells in series) Charge with constant voltage. Stop charging until the battery pack explodes or catches fire or the charging time is 90 minutes or the surface temperature of the battery pack is stable (the temperature difference within 45 minutes is less than or equal to 2°C). The battery should not catch fire or explode. (3) Forced discharge (reverse charge): First discharge the single battery with a constant current of 0.2ItA to the termination voltage, and then reverse charge the battery with a current of 1ItA. The charging time is required to be no less than 90min, and the battery should not catch fire. Do not explode; discharge one of the single cells of the battery pack to the final voltage, and the rest are fully charged batteries, and then discharge at a constant current of 1 ItA until the battery pack voltage is 0V, stop the discharge, the battery should not catch fire or explode . (4) Short circuit detection: the single battery is externally short-circuited for 90 minutes, or the battery surface temperature is stable (temperature difference within 45 minutes ≤ 2) to stop the short circuit, the external circuit resistance should be less than 50m, the battery should not fire or explode; pack the battery The positive and negative poles are connected with copper wires less than the resistance 0.1 until the battery pack voltage is less than 0.2V or the surface temperature of the battery pack is stable (the temperature difference within 45min is less than or equal to 2°C), the battery should not fire or explode. Statement: Some pictures and pictures of articles published on this site The content comes from the Internet, if there is any infringement, please contact to delete the previous article: Detailed explanation of lithium ion battery cathode material