Atmospheric pressure plasma treatment for Separator Materials
Publication Date: 2014-Jul-29
The IP.com Prior Art Database
The present publication deals with methods to improve the properties of separator materials used in Lithium Ion battery, methods involving atmospheric pressure plasma (APP).
A Battery separator is a porous sheet placed between the anode and the cathode in a liquid or solid electrolyte. The function is to prevent physical contact of the electrodes, while serving as an electrolyte reservoir to enable free ionic transport.
The properties of the separator material strongly influence the overall cell performance, although the separator does not “actively” participate in the battery operation. The mere presence of the separator component within a cell adversely affects the overall cell performance, as it adds electrical resistance and occupies limited space.
One of the most serious issues of this field of separators is the intrinsically poor compatibility with liquid electrolytes, including ethylene carbonate(EC) and dimethyl carbonate (DMC), due to the hydrophobic surface character and low surface energies.
Separator wetting speed can be correlated with electrolyte filling time in real cells. Absorbing and retaining a significant amount of electrolyte is required for ion transportation when the cell is in operation
To improve properties of separators, several methods have been reported in the literature, including those reported in the following documents :
- US-7998623 uses wettability improving agents but the influence of them for long term battery usage is not mentioned.
- J.Y Kim in Electrochim Acta 54 – 2009 uses low-pressure plasma to coat the surface of the separator with poly acrylonitrile, however it may decrease the porosity.
- WO/0034384 uses ion beams to modify the surface condition, however the treatments are done in vacuum condition which makes the process complicated...