Sanyo Electric Co., Ltd.

Mitsubishi Chemical Industries Limited

Noriyuki Yoshinaga

Masahisa Fujimoto

Nobuhiro Furukawa

Koji Ueno

Toshiyuki Nohma

Koji Nishio

Masatoshi Takahashi

Tetsumi Suzuki

Tsukasa Itou

Kazuro Moriwaki

Kazuo Teraji

Kouji Negoro

Kazumi Hasegawa

Sunao Harada

Kazunari Mori

The present invention discloses a secondary cell. The secondary cell comprises a positive electrode, a negative electrode which is made of a carbon material, and non-aqueous electrolytic solution, wherein the secondary cell is characterized in that the carbon material as the material of the negative electrode is produced by carbonizing natural high polymers.

Secondary cell and the producing method thereof

Provided is a novel lithium secondary battery comprising a positive electrode comprising a compound capable of occluding and discharging lithium, a negative electrode composed mainly of a carbon material which comprises a graphite as an only or as a principal component, a separator between said positive electrode and said negative electrode; and an electrolyte solution of an electrolyte solute dissolved in a solvent comprising at least one specific cyclic compound. The lithium secondary battery has a large capacity, small self-discharge rate and excellent cycle characteristics and high charge-discharge efficiency.

Lithium secondary battery

Provided is a novel lithium secondary battery including a positive electrode including a compound capable of occluding and discharging lithium, a negative electrode composed mainly of a carbon material which includes a graphite as an only or as a principal component, a separator between the positive electrode and the negative electrode; and an electrolyte solution of an electrolyte solute dissolved in a solvent including at least one specific cyclic compound. The lithium secondary battery has a large capacity, small self-discharge rate and excellent cycle characteristics and high charge-discharge efficiency.

A secondary battery has a positive electrode principally comprising a lithium-containing complex oxide, a negative electrode principally comprising a carbon material and an organic electrolyte solution, said negative electrode utilizing a mixed binder comprising a polyamic acid and at least one polymer selected from the group consisting of a polyamide resin, polyvinylpyrrolidone and a hydroxyalkylcellulose. The battery has a long cycle life and, at the same time, hardly breaks or bursts even when the battery temperature becomes abnormally high, thereby being highly reliable.

Secondary battery utilizing a mixed binder

The present invention provides a secondary cell with an enlarged capacity, therefore enlarging a discharge capacity as well as improving charge/discharge cycle characteristics. The secondary cell has a carbon material for a negative electrode, wherein the spacing of (002) planes d.sub.002, a true density, a crystallite size in the direction of c axis Lc, a and specific surface area of the carbon material are restricted to ranges of 3.39.ANG. to 3.62.ANG., 1.70 g/cc to 2.20 g/cc, 10.ANG. to 50.ANG., and 2 m.sup.2 /g to 50 m.sup.2, respectively. The carbon material is selected from a carbon material group consisting of needle cokes, pitch cokes, and coke derived from furfuryl alcohol.

Secondary cell

A secondary battery is comprised at a positive electrode, an electrolyte and a negative electrode which intercalates lithium reversibly. The negative electrode uses a carbon compound having a crystal structure of graphite in which carbon (C) is partially replaced by both boron (B) and nitrogen (N) and has the formula BC.sub.3 N or in which (C) is partially replaced by boron (B) and has the formula BC.sub.3. In the battery, the positive electrode may be a metal chalcogen or metal oxide, such as FeS.sub.2, MoS.sub.2, TiS.sub.2, LiNiO.sub.2, LiMn.sub.2 O.sub.3, LiFeO.sub.2 LiCoO.sub.2 or MnO.sub.2. The electrolyte may be a nonaqueous electrolyte or a solid electrolyte. The non-aqueous electrolyte uses an organic solvent and a lithium salt.

Secondary battery and manufacturing method therefor

A rechargeable secondary cell having the following as main components: a positive electrode formed of a conductive polymer, a negative electrode, a separator disposed between the positive and negative electrodes, an electrolyte comprising a mixed solvent of .gamma.-butyrolactone and a cyclic carbonic ester compound or ethylene carbonate, each being expressed by the following chemical formula. ##STR1## (where R.sup.1 is a lower alkyl group having 1-3 carbon atoms and R.sup.2 is a hydrogen atom or a methyl group, R.sup.2 being a hydrogen atom, and R.sup.1 being a group other than the methyl group.)

An electrically conductive material containing no substantial amount of water and prepared by polymerizing, in the presence of an oxidizing agent, a compound having conjugated double bonds on a base material in a gas phase. The base material has spaces capable of retaining the oxidizing agent. The electrically conductive material is used for at least one electrode of a secondary battery.

Growing community of inventors

Sumoto, Japan

Noriyuki Yoshinaga