Use of hydroquinone to precondition manganese dioxide for use in rechargeable electrochemical cells

A method of forming a rechargeable alkaline electrochemical cell containing a cathode having manganese dioxide as its active ingredient comprising the steps of:

• forming a solution of hydroquinone that is essentially free of dissolved oxygen;
• forming a slurry including unreduced manganese dioxide suspended in a solution having a pH greater than or equal to 5, said slurry being essentially free of dissolved oxygen;
• adding said solution of hydroquinone to said slurry without allowing a significant amount of oxygen to enter said slurry, said solution of hydroquinone having a concentration of hydroquinone and being added to said slurry in an amount such that the ratio of the total weight of hydroquinone contacted with said unreduced manganese dioxide to the total weight of said unreduced manganese dioxide is from about 0.3:10 to about 2:10;
• blending said solution of hydroquinone with said slurry such that said manganese dioxide is partially reduced in a substantially uniform manner to convert a portion of said manganese dioxide to MnOOH;
• after allowing the hydroquinone to partially reduce said unreduced manganese dioxide to a uniform partially reduced manganese dioxide product generally represented by the formula MnO.sub.x wherein x is between 1.80 and 1.92, separating the partially reduced manganese dioxide product from said slurry such that said partially reduced manganese dioxide product is substantially hydroquinone-free;
• forming a cathode using said hydroquinone-free partially reduced manganese dioxide product;
• and
• combining said cathode with an anode and an electrolyte to form the cell.