Nippon Telegraph and Telephone Corporation

Hajime Arai

Shigeto Okada

Jun-ichi Yamaki

Yoji Sakurai

Hideaki Ohtsuka

Masasi Shibata

Masahiro Ichimura

A positive electrode material for use in lithium batteries contains a compound represented by the chemical formula Li.sub.x Fe.sub.2 (SO.sub.4).sub.3 (0&lt;x.ltoreq.2). This positive electrode material is made from low cost material which is available in abundant quantities. Moreover a lithium battery using this material has a large discharge energy and long cycle life.

Material for use in the positive electrodes of lithium batteries, its

A cathode material made of anhydrous ferric sulfate with a hexagonal crystal structure is presented for use in a secondary battery which generates a stable open-circuit-voltage of about 3.6 volts and offers a recharge cycling capacity of over 100 times. The cathode material is obtained by heating hydrous iron sulfate material in a temperature range between 250.degree. and 600.degree. C. to remove the water of crystallization. The secondary battery made with this cathode material provides a long-service life and a stable output voltage economically, because the starting material, iron sulfate, is abundantly available at relatively low cost.

Cathode material and secondary battery using the same

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Mito, Japan

Hajime Arai