Lithium Polymer Battery Cell 854565 3400mAh 3.7V Pouch Lipo Li-Polymer Batteries

Saftey features:

1. Overcharge Protection

   • Battery Management System (BMS): A well - designed lithium - polymer battery is often equipped with a BMS. The BMS monitors the battery's voltage during charging. When the voltage of the battery cells approaches the maximum safe charging voltage (usually around 4.2V per cell), the BMS will cut off the charging current to prevent overcharging. This is crucial because overcharging can cause the battery to overheat, swell, and in extreme cases, lead to a thermal runaway reaction that may result in a fire or explosion.

   • Pressure - Relief Mechanisms: Some lithium - polymer batteries have built - in pressure - relief valves. If the internal pressure of the battery rises due to overcharging or other abnormal conditions, these valves can open to release the pressure and prevent the battery from rupturing.

2. Over - discharge Protection

   • Voltage Cut - off: The BMS also monitors the battery's voltage during discharge. When the voltage drops to a pre - set minimum level (typically around 3.0 - 3.2V per cell), the BMS will cut off the discharge circuit. Over - discharge can damage the battery's electrodes and reduce its overall lifespan and performance. By preventing over - discharge, the safety and usability of the battery are maintained.

3. Short - Circuit Protection

   • Internal Fuse or Circuit Breaker: Many lithium - polymer batteries have an internal fuse or circuit breaker. In the event of a short - circuit, such as when the positive and negative terminals are accidentally connected directly or due to internal cell damage, the fuse will blow or the circuit breaker will trip, cutting off the current flow and preventing excessive current from passing through the battery. This helps to avoid overheating and potential safety hazards caused by a large - current short - circuit.

   • Separator Function: The separator between the cathode and anode in the battery plays a vital role in short - circuit prevention. It is a microporous material that allows lithium ions to pass through but physically separates the two electrodes. If the separator is damaged and the electrodes come into direct contact, a short - circuit can occur. High - quality separators are designed to maintain their integrity and prevent this from happening.

4. Thermal Protection

   • Temperature Sensors: Lithium - polymer batteries are often equipped with temperature sensors. These sensors work in conjunction with the BMS to monitor the battery's temperature. If the temperature rises above a certain safe level (for example, due to overcharging, over - current, or external heat sources), the BMS can take measures such as reducing the charging or discharging current or completely shutting down the battery to prevent overheating and the associated risks.

   • Thermal - Stable Materials: The choice of materials used in the battery's construction also contributes to its thermal safety. For example, the use of thermally stable electrolytes and electrode materials can help to reduce the likelihood of thermal runaway. Some lithium - iron - phosphate - based lithium - polymer batteries have better thermal stability compared to other chemistries and are less likely to experience a rapid temperature increase under abnormal conditions.

5. Chemical Stability

   • Electrolyte Composition: The electrolyte in a lithium - polymer battery is carefully formulated to have good chemical stability. A stable electrolyte is less likely to react violently with the electrode materials or decompose under normal or slightly abnormal conditions. For example, the use of lithium hexafluorophosphate (LiPF₆) - based electrolytes, along with appropriate solvents such as ethylene carbonate and dimethyl carbonate, provides a relatively stable environment for lithium - ion transport while minimizing the risk of chemical reactions that could lead to safety issues.

   • Electrode Materials: The cathode and anode materials are also selected for their chemical stability. For example, lithium - iron - phosphate cathodes have a more stable crystal structure compared to some other cathode materials and are less likely to release oxygen during abnormal conditions, which reduces the risk of combustion and explosion.

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