The main difference between the non-woven diaphragm and the current traditional diaphragm

First of all, in terms of materials, both PP/PE and non-woven fabrics (here refers to PET non-woven fabrics) use polymer materials with different glass transition temperatures. In simple terms, the glass transition temperature of PP/PE is below normal temperature, and as the temperature rises, the material of the film will become softer and softer (strictly speaking, it is the temperature at which the molecules are accelerated locally).

For example, when the internal temperature of the battery is about 60°C for charging and discharging, the electrode will repeatedly expand and contract, and the PP/PE separator will gradually decrease in porosity under the influence of repeated shrinkage stress.

However, in the case of using PET non-woven fabric, its glass transition temperature is above 80 ℃, and it will not become soft as the temperature rises, but also maintain a stable porosity. , making the battery cycle life longer.

In fact, the same phenomenon has been verified in the use of NiMH batteries.

When the high-rate nickel-metal hydride battery is working, when the internal temperature of the battery exceeds 100 ℃, use a general diaphragm or a general nylon diaphragm, and under the condition of 200A discharge of the D-type battery, only the After several charge-discharge cycles, the separator will quickly deteriorate.

If a special nylon separator with a high glass transition temperature is used, the life of the battery will be greatly improved. Sanyo Electric has published the results of this research.

In the future, many facts will be continuously verified in experiments, just like the non-woven separator made of glass fiber can also be used in lithium-ion batteries, and PP/PE Microporous membranes were initially considered to be large in pore size and porosity, but at that time, lithium-ion batteries were mainly used in cameras and mobile phones. certain advantages.