The Gillette Company

Shuming Zeng

Tae-Won Lee

Stuart Michael Davis

James Joseph Cervera

Gary A Miller

Christopher P Haines

Alexander A Leef

Terry Copeland

Paul Albert Christian

George M Cintra

Alexander Boris Shelekhin

Philip D Trainer

Ou Mao

Kenneth R Taylor

A cathode having a groove extending about 10 to about 450 microns into a surface of the cathode. The cathode can also be roughened.

Battery cathode

A primary alkaline battery includes a cathode having manganese dioxide and carbon particles, an anode, a separator and an alkaline electrolyte. The carbon particles include expanded graphite particles and non-expanded graphite particles. The expanded graphite particles have a kerosene absorption greater than about 2.7 milliliters per gram.

Battery

The invention provides an improved method for preparing homogeneous intermixtures of particulate manganese dioxide and conductive carbon for use in cathodes for electrochemical cells, in particular alkaline primary cells. Homogeneous intermixtures can be prepared by mechanically activating an essentially dry admixture of particulate electrolytic manganese dioxide and a natural graphite, an expanded graphite or combinations thereof with inert, rigid milling media by the agitation process of the invention. Improved cell discharge performance at both low and high rates of discharge can be achieved for extremely low levels of highly expanded graphite, typically between about 1 and 5 wt %.

Battery cathode and method of manufacture therefor

An alkaline electrochemical cell having a cathode comprising manganese dioxide and conductive graphitized mesophase pitch-based carbon fibers having an increased BET surface area of between about 10 and 60 m /g, desirably between about 10 and 50 m /g, preferably between about 30 and 50 m /g by heat treatment between 800 and 1200&deg; C. with potassium hydroxide. The treated graphitized mesophase pitch-based carbon fibers can comprise between about 1 and 100 percent by weight of the total graphite material in the cathode, typically between about 5 and 50 percent by weight of the total graphite. The total graphite in the cathode desirably comprises between about 4 and 10 percent by weight of the cathode. The graphite can be the mixtures of the graphitized mesophase pitch-based carbon fibers with flaky crystalline graphites including expanded graphites. The graphitized mesophase pitch-based carbon fibers have a mean average diameter typically between about 1 and 10 micron. The use of said carbon fibers in the cathode increases cathode conductivity and results in improved cell performance.

Alkaline cell with improved cathode

An alkaline cell having an anode comprising zinc and a cathode comprising manganese dioxide wherein the cathode is located annularly along the inside surface of the cell housing and has a plurality of indentations on the inside of its surface facing the cell interior. Each indentation has a wall defining a channel with an opening thereto running preferably in the direction of the cell's length. The channel and opening facing the cell interior filled with anode material. The cell can have an anode current collector, typically of metal, with at least a portion of its surface extending into the cathode indentation channel. The anode current collector can have a portion of its surface extending from a point within the anode and into the cathode indentation channel through said opening. The cell can include a cathode current collector comprising a sheet of conductive material such as a sheet of metal or graphite placed within the cathode, particularly within thick regions of the cathode. The cathode current collector can be used. in conduction with a conventional single nail anode current collector or in combination with the extended surface anode current collectors of the invention. Such alkaline cells exhibit improved performance, particularly under high power application.

Cathode indentations in alkaline cell

Growing community of inventors

Brookfield, CT, United States of America

Shuming Zeng