Europaisches Patentamt
J
European Patent Office
Office europeen des brevets
EUROPEAN
PATENT
0 438
741
A1
APPLICATION
© int.ci.5: H01M
(jy Application number: 90124824.5
0
Oy Publication number:
4/60, H01M 6 / 1 8
Date of filing: 19.12.90
The title of the invention has been amended
(Guidelines for Examination in the EPO, A-lll,
7.3).
© Applicant: Mine Safety Appliances Company
121 Gamma Drive
Pittsburgh Pennsylvania 15238(US)
@ Inventor: Wicelinski, Steven Paul
29 Cherry Manor Court
Reisterstown, Maryland(US)
® Priority: 03.01.90 US 460526
© Date of publication of application:
31.07.91 Bulletin 91/31
© Designated Contracting States:
CH DE FR GB IT LI
© Representative: Hoeger, Stellrecht & Partner
Uhlandstrasse 14 c
W-7000 Stuttgart 1(DE)
© Depolarizer for a lithium-iodine battery.
© Improved lithium-iodine batteries have a depolarizer of charge transfer material of polyvinylpyridine and a
divalent metal dibenzotetraazaanulene that is complexed with iodine in a ratio of 1 part by weight charge transfer
material to 14 to 50 parts iodine.
P2VP+
NidbtQQ
en
Io
rs
oo
CO
20
40
60
MILUAMP-HOURS
FIG.
I
Rank Xerox (UK) Business Services
(90/10)
EP 0 438 741 A1
IMPROVED LITHIUM-IODINE DEPOLARIZER
Field of the Invention
5
10
rs
20
The present invention relates to on improved lithium-iodine battery and, in particular, to an improved
depolarizer comprising a mixture of a divalent metal dibenzotetraazaannulene and polyvinylpyridine/b.
Background of the Invention
Lithium-halide batteries in which a lithium anode and a charge transfer polymer complexed with a
halogen to form a cathode or depolarizer are generally well known. Illustrative of these batteries are U.S.
Patent Nos. 4,148,975; 4,276,362 and 4,242,428. Batteries of this type have found wide application in
cardiac pacemakers and for powering other electronic circuits such as wrist watches and computer memory
and clock backup. Typical charge transfer complex materials include poly-2-vinylpyridine and poly-2vinylquinoline (U.S. Pat. 4,148,874).
Also, iodine doped metal complexes have been disclosed, U.S. Pat. 4,584,251, which are suitable as
cathode materials for lithium/iodine or silver/iodide cells. These metal complexes comprise a divalent metal
of nickel, iron, copper, cobalt, zinc, palladium or platinum and dibenzotetraazaannulene ("Mdbtaa").
It is an object of the present invention to provide improved battery performance over these prior art
batteries. It is a further object of the invention to provide an improved battery having higher operating
voltages during discharge and greater rate capability at lower temperatures than prior art P2VP/I2 and
Mdbtaa batteries.
Summary of the Invention
25
30
The present invention comprises a lithium anode battery having a charge transfer complex. The charge
transfer material is polyvinylpyridine (PVP) with from 1% to 50% by weight Mdbtaa. The resultant charge
transfer material is blended with iodine in a ratio of 1 part charge transfer material to 14-50 parts by weight
of iodine.
In a preferred embodiment of the invention the polymer is poly-2-vinylpyridine (P2VP) having a
molecular weight greater than 30,000. Preferably, the divalent metal is either nickel or cobalt. The Mdbtaa is
of the type disclosed in U.S. Pat. 4,584,251 and discussed in general in the following text: The cathode
material according to the U.S. patent 4,584,251 consists of an iodine-doped complex or a mixture thereof
with iodine the complex having the formula I:
(i)
35
40
R5
45
K1
50
in which M is a divalent metal atom belonging to the group consisting of Fe, Co, Ni, Cu, Zn, Pd and Pt, R1
and R2 independently of one another are a hydrogen atom or alkyl, cycloalkyl, aryl, aralkyl, alkaralkyl or
acyl each of which is unsubstituted or substituted, R3, R*, R5 and R6 independently of one another are a
hydrogen atom, alkyl, alkoxy, alkylthio and alkoxycarbonyl having 1 to 8 C atoms, aryloxy or halogen, or R3
and R* and also R5 and Rs together are <CH2>n in which n = 3, 4 or 5, -CHCH2 >mO-in which m = 1-4, or a
EP 0 438 741 A1
5
10
75
radical of the formula -CH = CH-CH = CH-.
Batteries utilizing the depolarizer of the present invention show current rate capability approximately
20% greater than similar P2VP batteries and more than 600% greater than similar Mdbtaa depolarizer
batteries. Other advantages of the invention will become apparent from a perusal of the following detailed
description of the presently preferred embodiments taken in connection with the accompanying drawings.
Brief Description of the Drawings
FIG. 1 is a grapTTshowing the discharge curves of a prior art P2VP/I2 battery, a Nidbtaa/b battery and a
battery according to the present invention under a 5 Kohm resistive load at 25° C;
FIG. 2 is a graph showing discharge curves similar to Fig. 1, except the batteries were discharged at
10° C under a 10 Kohm resistive load; and
FIG. 3 is a graph showing discharge curves of prior art P2VP and Nidbtaa depolarizer batteries and
batteries of the present invention showing the effect of various percentages of Mdbtaa mixes discharged
at 37° C under a 10 Kohm resistive load.
Presently Preferred Embodiments
The depolarizer of the present invention is a pelletized or fused mixture of iodine, polyvinylpyridine,
preferably poly-2-vinylpyridine and divalent metal dibenzotetraazaannulene. The molecular weight of polyvinylpyridine is preferably 30,000 to 400,000.
In the preferred method of manufacture, iodine and polymer is mixed with Mdbtaa in an amount
20
between about 1% and 50% by weight of the polymer. Alternatively, the metal Mdbtaa is mixed with the
polymer prior to the blending of the iodine. In the preferred embodiment, the divalent metal is nickel. The
Mdbtaa is preferably used in an amount of from 3% to 20% by weight (to polymer) to provide the most
improvement. With Mdbtaa in amounts in excess of about 50%, substantially no improvement results.
25 Similar advantages have been achieved using cobalt.
With reference to FIG. 1, a button cell was made in accordance with U.S. Pat. 4,148,975 using P2VP
having an average molecular weight of 50,000 and having a 20:1 weight ratio of iodine to polymer. As
shown in FIG. 1, this battery was identified as prior art (P2VP/I2). A similar prior art battery using Nidbtaa/b
according to U.S. Pat. 4,584,251 was prepared. A battery in accordance with the present invention was
30 prepared by adding to the prior art P2VP/I2 depolarizer material, Nidbtaa in an amount equal to 10 weight
percent of the P2VP.
All of the batteries were discharged through a constant 5 Kohm resistive load at 25 °C. As can be seen
from FIG. 1, the battery using the depolarizer of the present invention performed to a 2.0 volt cut-off better
than either of the prior art batteries.
35
Referring to FIG. 2, batteries similar to those prepared in reference to FIG. 1 were discharged under a
10 Kohm resistive load at 10° C. As can be seen from the curve of the battery of the present invention, a
significant improvement in the battery is obtained at low temperature.
In FIG. 3, discharge curves represent the discharge of prior art P2VP and Nidbtaa batteries (the same
as those of FIG. 1) through a 10 Kohm resistive load at 37° C. In comparison are discharge curves at 37° C
40 through a 10 Kohm load of batteries according to this invention with 90 parts P2VP to 10 parts by weight
Nibtaa and 50 parts P2VP to 50 parts by weight Nibtaa.
As can be seen from the curves of FIG. 3, the batteries of the present invention operated at a higher
loaded voltage than those of the prior art.
The depolarizers of the present invention provide batteries which have higher operating voltages during
45 battery discharge and operate at higher efficacy than prior art P2VP/l2*Li batteries. Moreover, the batteries
of the present invention are capable of sustaining higher current drains at lower temperatures than prior art
batteries. As shown in FIGS. 1-3, batteries of the invention demonstrate a 50 to 150 mV increase in plateau
voltage during discharge.
While presently preferred embodiments of the invention have been shown and described in particularity,
50 the invention may be otherwise embodied within the scope of the appended claims.
Claims
1.
55
A depolarizer for a lithium anode battery comprising a particulate charge transfer material of polyvinylpyridine having a molecular weight between about 30,000 to 400,000 and from 1% to 50% by weight of
said polyvinylpyridine of a divalent metal dibenzotetraazaannulene, said charge transfer material being
mixed with iodine in a ratio of about 14 to 50 parts by weight of iodine to each part of charge transfer
material.
EP 0 438 741 A1
5
2.
A depolarizer as set forth in claim 1, wherein the polyvinylpyridine is poly-2-vinylpyridine.
3.
A depolarizer as set forth in claims 1 or 2, wherein said divalent metal is nickel.
4.
A depolarizer as set forth in claims 1, 2 or 3, wherein said divalent metal dibenzotetraazaannulene is in
an amount of from 3% to 20% by weight of said polyvinylpyridine.
5.
A lithium battery comprising a lithium anode and a cathode comprising iodine and a charge transfer
material of poly-2-vinyl pyridine and 1% to 50% by weight divalent metal dibenzotetraazaannulene, said
iodine being present in an amount of 14 to 50 parts by weight to each part of charge transfer material.
6.
A lithium battery as set forth in claim 5, wherein said divalent metal is nickel.
7.
A lithium battery as set forth in claim 5, wherein said divalent metal is cobalt.
8.
A lithium battery as set forth in claims 5, 6 or 7, wherein said divalent metal tetraazaannulene is present
in an amount of from 3% to 20%.
9.
A lithium battery as set forth in claims 5, 6 or 7, wherein said poly-2-vinyl pyridine has a molecular
weight of 30,000 to 400,000
w
75
20
10. A lithium battery as set forth in claims 5, 6 or 7, wherein said charge transfer complex is either
pelletized or fused.
25
30
35
40
45
50
55
EP 0 438 741 A1
2.8
+ NidbtQQ
P2VP
(90/10)
2.0
P2VP
O
>
(PRIOR
ART)
I.O
-Nidbtaa
0.0
J
20
0
(prior
a r t )
1
60
HOURS
I
I
I
40
MILLIAMPFIG.
I
L
80
I
2.8r
P2VP
+ Nidbtaa
oo/io)
2.0
(f)
o
1.0
P2VP
0.0
0
j
i
20
(PRIOR
i
ART)
i
40
60
MILLIAMP-HOURS
FIG.
2
80
EP 0 438 741 A1
P2VP
+ Nidbtaa
(90/10)
_- — P 2 V P +
Nidbtaa (50/50)
0.4I
0
10
20
60
50
40
30
MILLIAMP-HOURS
FIG.
3
70
00
European
Patent Office
J
Application Number
EUROPEAN S E A R C H
REPORT
EP
DOCUMENTS
Category
A
D.A
CONSIDERED
TO
BE
90
12 4 8 2 4
RELEVANT
Relevant
to claim
Citation of document with Indication, where appropriate,
of relevant passages
JOURNAL OF POWER SOURCES, vol. 22, no. 1, January
1988, pages 69-76, Lausanne, CH; I. EXNAR et al.:
"Lithium-iodine batteries based on metal
dibenzo(b,i)-1 ,4,8,1 1)tetraaza(1 4)annulene-iodine charge
transfer complexes"
* Table 1 *
1,3,6,8
JOURNAL OF THE ELECTROCHEMICAL SOCIETY, vol.
136, no. 10, October 1989, pages 2811-2816, Manchester,
NH, US; C.C. STREINZ et al.: "The influence of
poly(2-vinylpyridine) molecular weight on the volume
change characteristics of Li/I2 batteries with pelletized cathodes"
*Abstract; page 281 1 column 2, lines 5-7 *
,
2,9,10
US-A-4 148 975 (A. SCHNEIDER et al.)
*Abstract; claims 1,6 *
1,2,5,10
CLASSIFICATION OFTHE
APPLICATION (Int. CI.5)
H01 M
4/60
H01 M6/18
TECHNICALFIELDS
SEARCHED(Int. CI.5)
H01 M
The present search report has been drawn up for all claims
Place of search
Date of completion of search
Examiner
The Hague
19 April 91
ANDREWS M.P.
CATEGORYOFCITEDDOCUMENTS
X: particularly relevant if taken alone
Y: particularly relevant if combined with another
document of the same catagory
A: technological background
O: non-written disclosure
P: intermediate document
T: theory or principle underlying the invention
E: earlier patent document, but published on, or after
the filing date
D: document cited in the application
L: document cited for other reasons
&: member of the same patent family, corresponding
document