Fibrous battery cells

A cell assembly comprising:

• a hollow, fibrous, membrane separator having an outer diameter in the range of about 100 .mu.m to about 5 mm where the length of the fiber is longer than the fiber diameter, said membrane separator comprising pores and being selected from the group consisting of microfiltration, ultrafiltration and reverse osmosis membranes;
• an inner, electrically conductive, fibrous, positive or negative electrode, including an active material, located within the hollow inner periphery of said hollow separator, where the length of the electrode is longer than the electrode diameter;
• an electrolyte disposed in said pores of the membrane separator;
• and
• an outer positive or negative electrode comprising a layer of electrically conductive material and an electrode active material in contact with said membrane separator, wherein said outer electrode comprises:
• a coating of electrode active material and electrically conductive material surrounding or impregnating said membrane separator, or
• an electrically conductive single fiber covered or in contact with a positive or negative electroactive material surrounding said membrane separator.