| abstract |
The present invention relates to lithium-ion accumulators with coated separators. The porous polymer sheet or membrane is provided with a thin coating of the non-conductive ceramic composition and conforms to the entire surface of the membrane, including the pore surfaces. The coated membrane is very suitable, for example, as an internal cell separator in lithium-ion batteries. The coating improves the mechanical properties and thermal stability of the separator and retains the electrolyte during battery operation. Coatings can be formed by a two-step vapor phase process in which atoms of one or more metals such as aluminum, calcium, magnesium, titanium, silicon and/or zirconium are deposited in a conformal layer on the workpiece surface. The metal atoms can then react with ammonia, carbon dioxide and/or water to form their respective non-conductive nitrides, carbides and/or oxides on the surface. This two-step process is repeated as necessary to obtain the desired thickness of coating of ceramic material. |