In recent years, the energy storage industry has experienced rapid growth driven by the demand for energy transition, policy support, and technological innovation, ushering in unprecedented development opportunities. However, alongside this swift development, safety concerns have consistently been a focal point. With the continuous expansion of energy storage applications, incidents of lithium battery storage stations catching fire or exploding both domestically and internationally have raised alarms, such as the energy storage facility in San Diego, California, has repeatedly reignited and continued to burn for more than a week.
Monitoring the health of cells in a timely, accurate, and comprehensive manner, providing effective early warnings, and conducting proactive troubleshooting to prevent irreversible damage to energy storage systems has become an urgent issue for the industry. Hinen has always prioritized user needs, offering a full-spectrum safety protection mechanism for household storage solutions, where cell-level safety is the first step towards overall system security.
Cell Material Selection:
High-safety lithium iron phosphate (LiFePO4) material is used for cell production, significantly reducing safety risks due to its thermal stability and non-flammability.
Electrical Performance Testing:
Tests for high and low-temperature performance are conducted to ensure cell safety and stability under extreme temperature conditions.
1. Overcharge Test: Lithium batteries are subjected to a 3C overcharge test. When the voltage of the battery rises to a certain level during overcharge and stabilizes for a while, it rapidly increases until it reaches a limit, at which point the voltage drops to 0V. The cell does not catch fire, explode, or delithiate.
2. Overdischarge Test: Batteries are charged to 3.65V with a constant current and constant voltage at 1C, then discharged far below the rated voltage, cut off at 0.05C, and left to rest for 30 minutes; they are then discharged at 0.33C/1C/2C/3C constant current to 2.5V, with the 3C discharge capacity being ≥97% of the initial capacity, and the 6C discharge capacity being ≥95% of the initial capacity.
3. High-Temperature Performance: Cells are placed in a high-temperature chamber at (55±2)℃ for 4 hours, then discharged at a constant current of 1C(A) to a discharge termination voltage of 2.5V. Post-test capacity is ≥99% of the initial capacity.
4. Low-Temperature Performance: Cells are placed in a temperature chamber at (-20±2)℃ for 24 hours, then discharged at a constant current of 1C(A) to a discharge termination voltage of 2.0V. The discharge capacity at -20℃ is ≥70% of the initial capacity.
Safety and Reliability Testing:
1. Short Circuit Test: After standard charging to 100% state of charge, the battery's positive and negative terminals are externally short-circuited for 10 minutes with an external circuit resistance of less than 5mΩ. After observation for 1 hour, the cell does not catch fire or explode.
2. Puncture Test: A high-temperature steel needle with a diameter of 5mm to 8mm is used to puncture the cell at a speed of 25±2mm/s from a direction perpendicular to the cell plate, preferably close to the geometric center of the puncture face. The needle is left in the cell, and after observation for 1 hour, the cell does not catch fire or explode.
3. Compression Test: A semi-cylindrical body with a radius of 75mm and a length greater than the size of the battery being compressed is used to compress the battery at a speed of 5±1mm/s in a direction perpendicular to the cell plate. Compression is stopped when the battery voltage reaches 0V or the deformation reaches 30% or the compressive force reaches 200kN. After observation for 1 hour, the cell does not catch fire or explode.
4. Drop Test: After charging the cell to 100% state of charge, the positive and negative terminals are dropped freely from a height of 1.5m onto a concrete floor. After observation for 1 hour, the cell does not catch fire, explode, or leak.
5. Saltwater Immersion: After charging the cell to 100% state of charge, it is immersed in a 3.5% NaCl solution (mass fraction, simulating the composition of seawater at room temperature) for 2 hours. The water depth should completely submerge the individual cell. After observation for 1 hour, the cell does not catch fire, explode, or leak.
6. Temperature Cycling: After charging the cell to 100% state of charge, the battery is placed in a temperature chamber and subjected to high and low-temperature cycling five times according to the experimental conditions. After observation for 1 hour, the cell does not catch fire, explode, or leak.
Faced with the dual challenges of industry development, we must not only pursue technological innovation and breakthroughs but also adhere to the bottom line of safety. By continuously optimizing and upgrading, Hinen is committed to providing users with safer and more reliable energy storage products, jointly promoting the industry towards a healthier and more sustainable direction. Let us move forward together, opening a new chapter in energy storage while ensuring safety.
