US5415957A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Cathode material and secondary battery using the same
Assignee: NTT Inc
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Filing: 1993-10-01
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Granted: 1995-05-16
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Expires: 2013-10-01
Abstract
Abstract 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° and 600° 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.
Inventors
- 👤 Shigeto Okada
- 👤 Hideaki Ohtsuka
- 👤 Hajime Arai
- 👤 Masasi Shibata
- 👤 Masahiro Ichimura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 15:01
CPC Classifications
H; H01; H01M; H01M4/00; H01M4/02; H01M4/36; H01M4/58; H01M4/5825; Y; Y02; Y02E; Y02E60/00; Y02E60/10
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
45 words
A secondary battery having a positive electrode comprising an anhydrous ferric sulfate having a hexagonal crystal symmetry, a negative electrode comprising an alkaline metal, and a non-aqueous electrolyte solution comprising a non-aqueous solvent and a salt of said alkaline metal dissolved in said non-aqueous solvent.
Claim 2
Dependent Claim
45 words
A secondary battery having a positive electrode comprising an anhydrous ferric sulfate having a hexagonal crystal symmetry, a negative electrode comprising an alkaline metal, and a non-aqueous electrolyte solution comprising a non-aqueous solvent and a salt of said alkaline metal dissolved in said non-aqueous solvent.
Claim 3
Dependent Claim
30 words
A secondary battery as claimed in claim 1, wherein said anhydrous ferric sulfate is obtained by heat treating an iron sulfate in a temperature range between 250° and 600° C.
Claim 4
Dependent Claim
38 words
A secondary battery as claimed in claim 2, wherein said anhydrous ferric sulfate is obtained by heating (NH 4 ) 2 Fe(SO 4 ) 2 .6H 2 O, in a temperature range between 430° and 600 ° C.
Claim 5
Dependent Claim
35 words
A secondary battery as claimed in claim 2, wherein said anhydrous ferric sulfate is obtained by heating (NH 4 )Fe(SO 4 ) 2 .12H 2 O, in a temperature range between 430° and 600° C.
Claim 6
Dependent Claim
35 words
A secondary battery as claimed in claim 2, wherein said anhydrous ferric sulfate is obtained by heating Fe 2 (SO 4 ) 3 .nH 2 O in a temperature range between 250° and 600° C.
Claim 7
Dependent Claim
14 words
A secondary battery as claimed in claim 1, wherein said alkaline metal is lithium.
Claim 8
Dependent Claim
27 words
A secondary battery as claimed in claim 1, wherein said negative electrode is selected from the group consisting of lithium, a lithium alloy and a lithium compound.
Claim 9
Dependent Claim
44 words
A secondary battery as claimed in claim 7, wherein said lithium alloy is selected from the group consisting of a lithium aluminum alloy and a Wood's metal alloy, and said lithium compound is selected from the group consisting of lithium carbonate and lithium nitrate.
Claim 10
Dependent Claim
48 words
A secondary battery as claimed in claim 1, wherein said non-aqueous solvent medium is selected from the group consisting of ethylene carbonate, 2-ethyltetrahydrofuran diethoxysilane, 2-methyltetrahydrofuran, methyl formate, dimethyl sulfoxide, propylene carbonate, acetonytrile, γ-butylolactone, dimethulformamide, 1,2-dimethoxyethane, diethyl carbonate, dimethyl carbonate, methylethyl carbonate, tetrahydrofuran, 1,3-dioxolan, 4-methyl-1,3-dioxolan and a mixture thereof.
Claim 11
Dependent Claim
23 words
A secondary battery as claimed in claim 9, wherein said non-aqueous solvent medium is an equal volumetric mixture of ethylene carbonate and 2-methyltetrahydrofuran.
Claim 12
Dependent Claim
108 words
A secondary battery as claimed in claim 6, wherein said salt of said alkaline metal is selected from the group consisting of LiAsF 6 , LiBF 4 , LiPF 6 , LiAlCl 4 , LiClO 4 , LiC(CF 3 SO 2 ) 3 , LiC(CF 3 SO 2 ) 2 , LiCF 3 SO 3 , LiC n F 2n+1 SO 3 where n is an integer greater than 1, LiC n F 2n-1 SO 3 where n is an integer greater than 1, LiCl, LiSCN, LiSbF 6 , LiCF 3 CO 2 , Li 2 B 10 Cl 10 , lithium tetraphenylborate, and lithium tetrakis- (3,5-bis-(trifluoromethyl)phenyl) borate.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-05-15 | 1998-11-14 | 1999-05-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-05-15 | 2002-11-14 | 2003-05-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-05-15 | 2006-11-14 | 2007-05-16 | $7700.00 | Window Closed / Lapsed |