US Patent 7811337 Ultracapacitor electrode with controlled sulfur content

Particles of active electrode material are made by blending mixing a mixture of activated carbon and binder. In selected implementations, sulfur level in the activated carbon is relatively low and the binder is inert. For example, sulfur content of the activated carbon and the resultant mixture is below 300 ppm and in other implementations, below 50 ppm. The electrode material may be attached to a current collector to obtain an electrode for use in various electrical devices, including a double layer capacitor. The electrode decreases current leakage of the capacitor.