1, electrical performance:
(1) Rated capacity: 0.5C discharge, single battery discharge time is not less than 2h, battery pack discharge time is not less than 108min (95%);
(2) 1C discharge capacity: 1C discharge, single battery discharge time is not less than 57min (95%), battery pack discharge time is not less than 54min (90%);
(3) Low temperature discharge capacity: 0.5C discharge at -20℃, the discharge time of monomer or battery pack is not less than 72min (60%);
(4) High temperature discharge capacity: 0.5C discharge at 55℃, the discharge time of single battery is not less than 104min (95%), and the discharge time of battery pack is not less than 108min (90%);
(5) Charge retention and recovery ability: shelved at room temperature for 28 days at full charge, charge retention discharge time is not less than 96min (80%), charge recovery discharge time is not less than 108min (90%);
(6) Storage performance: The single
battery or battery pack for storage test should be selected from the production date of less than 3 months, the capacity of 50% to 60% before storage, and the environment temperature of 40 ° C ±5 ° C, relative humidity of 45% to 75% environment storage for 90 days. After the storage period is expired, the battery pack is taken out, fully charged at 0.2C and shelving for 1h, and constant discharge at 0.5C to the termination voltage. The above test can be repeated for 3 times, and the discharge time is not less than 72min (60%).
(7) Cycle life: the battery or battery pack is charged by 0.2C and discharged by 0.5C. When the discharge capacity is lower than 72min (60%) for two consecutive times, the test is stopped. 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 shelving life: it should be selected from the single battery with a production date of less than three months for high temperature shelving life test, and should be filled with 50%±5% capacity before shelving, and then shelved under the ambient temperature of 55 ° C ±2 ° C for 7 days. After 7 days, the battery is removed and left for 2 to 5h at an ambient temperature of 20 ° C ±5 ° C. First, the battery is discharged to the termination voltage at 0.5C, and then charged at 0.2C after 0.5h, after 0.5h, and then at 0.5C constant discharge to the termination voltage, and this capacity is used as the recovery capacity. The above steps were repeated for 1 week until the discharge time was less than 72min (60%) in a certain week, and the test was over. Shelf life is not less than 56 days (8-week cycle).
2. Safety performance
(1) Continuous charging: the single battery is charged at 0.2ItA constant current. When the end voltage of the single battery reaches the charging limit voltage, it is charged at constant voltage and kept for 28d. After the test, there should be no leakage, no deflation, no rupture, no fire, no explosion (equivalent to full floating charge).
(2) Overcharge: the single battery is charged with a constant current voltage regulator at 3C constant current, the voltage reaches 10V, and then it is charged at constant voltage, until the battery exploses or fires or the charging time is 90min or the battery surface temperature is stable (the temperature difference within 45min is less than 2℃), and the battery should not catch fire or explode (3C10V); Use a voltage regulator to charge the battery pack at a constant current of 0.5ItA. When the voltage reaches n x 5V (n is the number of single batteries in series), the battery pack is charged at a constant voltage. Stop charging until the battery pack exploses or fires, 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 2 ° C).
(3) Forced discharge (reverse charge) : the single battery is first discharged at 0.2ItA constant to the termination voltage, and then reverse charge the battery with 1ItA current, requiring that the charging time is not less than 90min, and the battery should not catch fire or explode; Discharge one cell of the battery pack to the termination voltage, and the rest are fully charged batteries, and then stop discharging with 1ItA constant discharge until the voltage of the battery pack is 0V, and the battery should not catch fire or explode.
(4) Short circuit test: the single battery is shorted externally for 90min, or the battery surface temperature is stable (temperature difference within 45min ≤2) to stop short circuit, the external line resistance should be less than 50mΩ, the battery should not fire, do not explode; Connect the positive and negative electrodes of the battery string with a copper wire with a resistance less than 0.1Ω until the battery string voltage is less than 0.2V or the surface temperature of the battery string is stable (the temperature difference within 45 minutes is less than or equal to 2 ° C). No fire or explosion occurs in the battery string
3. Mechanical properties
(1) Extrusion: the single battery is placed in the middle of two extrusion planes, and the pressure is gradually increased to 13kN. The extrusion direction of the cylindrical battery is perpendicular to the vertical axis of the cylindrical axis, and the square battery squeezes the wide and narrow sides of the battery. Each battery can only be squeezed once. The test results shall comply with 4.1.2.1. A steel rod with a diameter of 15cm is placed on the battery pack to squeeze the battery pack on the wide and narrow sides, and the battery pack is squeezed to 85% of the original size of the battery pack, and held for 5 minutes. Each battery pack is only squeezed once.
(2) Acupuncture: The single battery is placed in a steel fixture, and the steel nail of φ3mm ~ φ8mm is used to run through the direction perpendicular to the battery plate (the steel needle stays in the battery) for 90min, or the battery surface temperature is stable (the temperature difference within 45min is less than 2℃).
(3) Heavy impact: the single battery is placed on a steel plane, with a diameter of 15.8mm steel rod flat on the center of the battery, the vertical axis of the steel rod is parallel to the plane, so that the weight of 9.1kg free fall from the height of 610mm on the steel rod in the center of the battery; When the battery is cylindrical, the impact direction is perpendicular to the vertical axis of the cylindrical surface; When a single battery is square, the wide and narrow sides of the battery should be impacted, and each battery can only accept one impact.
(4) mechanical impact; The battery or battery pack is fixed to the test equipment using a rigid fixation method (the method can support all fixed surfaces of the battery or battery pack). One shock of equal value in each of the three perpendicular directions. At least one direction should be ensured to be perpendicular to the wide face of the battery or battery pack, and each shock should be carried out as follows: in the first 3ms, the minimum average acceleration is 735m/s2, and the peak acceleration should be between 1225m /s2 and 1715m /s2.
(5) Vibration: The battery or battery pack is installed directly or through the fixture installed on the shaking table surface for vibration test. The test conditions were frequency 10Hz ~ 55Hz, acceleration 29.4m /s2, frequency sweep cycles of 10 times in each direction of XYZ, and frequency sweep rate of 1oct/min.
(6) Free fall: The single battery or battery pack is freely dropped from a height (lowest height) of 600mm to a 20mm thick hard board on the cement floor, once from each of the three directions XYZ. After the free fall.
4. Environmental adaptability
(1) High temperature baking: Put the single battery into a high temperature explosion-proof box, and heat up to 130℃ at the heating rate of (5±2℃) /min, and hold heat at this temperature for 10min.
(2) High temperature storage: the single battery or battery pack is placed in the oven at 75±2 ° C for 48h, and the battery should not leak, not deflate, not break, not fire, not explode.
(3) Low air pressure: (UL standard).
