Polymer lithium-ion batteries are generally used in portable devices (such as mobile phones and laptops), applications with high safety requirements (such as medical devices and drones), and special-shaped devices (such as devices as thin as a credit card and flexible electronic products).
1. Definition and characteristics of polymer lithium-ion batteries
Electrolyte form
Polymer lithium-ion batteries use solid or colloidal polymer materials (such as gel polymers) as electrolytes, replacing the liquid electrolytes in traditional liquid lithium-ion batteries. Some types also have polymers (such as PVDF) coated on the separator to enhance adhesion (semi-polymer) or form a gel network (fully polymer), reducing the amount of liquid electrolyte used and improving safety.
Structural design
Using aluminum-plastic flexible packaging film (composed of PP, Al, and nylon layers) as the outer shell, these are called soft-pack batteries. Compared to the metal shell of liquid batteries, they are lighter, thinner, and more flexible. Their thickness can be less than 0.5mm, and they can be customized into any shape (such as trapezoids, ultra-thin cards, etc.) to meet the needs of special equipment.
performance advantages
Safety: Because the electrolyte is not easily leaked and the outer casing can expand to release pressure, even in the event of a malfunction, it usually only bulges rather than explodes.
Energy density: 10%-30% higher than traditional liquid batteries, and 20%-40% lighter (no metal casing).
Cycle life: Over 500 cycles under normal use, with low self-discharge rate and no memory effect.
2. Comparison with other lithium-ion batteries: Polymer lithium-ion batteries vs. liquid lithium-ion batteries. Electrolytes: Solid/gel polymer electrolytes, some containing a small amount of liquid components. Liquid electrolyte (flammable). Safety: Less prone to explosion; failures often manifest as bulging. Safety: Relatively poor. Shape and thickness: Can be ultra-thin (<1mm), customizable to any shape. Generally, thicker, fixed shape. Weight and capacity: 10%-15% higher capacity and 20%-40% lighter for the same volume. Capacity and weight are limited by the metal casing. Voltage and combination: Single cell can achieve higher voltage (multi-layer structure). Requires multiple cells connected in series to achieve high voltage. Cost: Higher manufacturing cost (technically complex). Lower cost, mature process. 3. Summary
Polymer lithium-ion batteries, through electrolyte and structural innovations, significantly outperform traditional liquid batteries in safety, thinness, and energy density, but are more expensive. Their technological characteristics make them ideal for high-end electronics and emerging fields such as flexible devices, while liquid batteries still maintain a cost advantage in the low-to-mid-range consumer battery market.
