Impregnated separator for electrochemical cell and method of making same

An electrochemical cell comprising:

• a container having bottom and top ends and an upstanding wall disposed therebetween;
• a positive electrode disposed in said container;
• a negative electrode disposed in said container;
• an electrolyte solution;
• and
• a separator disposed between said positive electrode and said negative electrode, said separator comprising a single layer of a porous substrate and a polymer solution applied in the presence of a coagulating agent to coagulate and form a semi-solid material, said porous substrate comprises fibrous paper, said fibrous paper is cellulose based.

A method of forming a separator for use in an electrochemical cell for separating a positive electrode from a negative electrode, said method comprising the steps of:

• providing a porous substrate;
• applying a coagulating agent to said porous substrate;
• applying a liquid polymer solution to said porous substrate, wherein said liquid polymer impregnates said porous substrate;
• allowing said polymer solution to coagulate in the presence of said coagulating agent to form a semi-solid material;
• and
• rolling said sheet of porous substrate into a cylindrical shape.

A method of assembling an electrochemical cell, said method comprising the steps of:

• providing a container having a bottom end and a top end and upstanding walls disposed therebetween;
• disposing a positive electrode in said container;
• disposing a negative electrode in said container;
• providing a porous substrate;
• forming said porous substrate into a separator;
• applying electrolyte solution to said separator;
• applying a liquid polymer solution to said porous substrate in the presence of a coagulating agent so that said polymer solution coagulates to form a semi-solid material, wherein said step of applying a liquid polymer comprises impregnating said porous substrate with said liquid polymer;
• and
• disposing said separator between said positive electrode and said negative electrode.