Lithium Polymer Battery - Risks and Limitations

Risks and Limitations

• All Li-Ion cells expand at high levels of state of charge (SOC); if uncontained, this may result in delamination, and reduction of reliability and cycle life; the case of cylindrical cells provides that containment, while pouch cells, by themselves, are not contained. Therefore, to achieve the rated performance, a battery composed of pouch cells must include a strong external casing to retain its shape.
• Overcharging a Li-poly battery can cause an explosion or fire.
• During discharge on load, the load has to be removed as soon as the voltage drops below approximately 3.0 V per cell (used in a series combination), or else the batterywill subsequently no longer accept a full charge and may experience problems holding voltage under load. Li-poly batteries can be protected by circuitry that prevents over-charge and deep-discharge.
• Compared to the lithium-ion battery, Li-poly has a greater life cycle degradation rate.
• Lithium polymer-specific chargers are required in order to avoid fire and explosion.
• Explosions can also occur if the battery is short-circuited, as tremendous current passes through the cell in an instant. Radio-control enthusiasts take special precautions to ensure their battery leads are properly connected and insulated. Furthermore fires can occur if the cell or pack is punctured.
• While charging the lithium polymer batteries, the individual cells in the pack should be charged evenly. For this purpose, the cells are to be charged with special chargers. This entails special care while charging the batteries in addition to incurring expenses on procuring the chargers specific to lithium polymer batteries.