U.S. patent application number 09/249502 was filed with the patent office on 2002-01-17 for nonaqueous electrolyte battery.
Invention is credited to FUJITA, SHIGERU, OJIMA, HIDEAKI, SEGAWA, KEN, TOMITA, TAKASHI.
Application Number | 20020006543 09/249502 |
Document ID | / |
Family ID | 12341734 |
Filed Date | 2002-01-17 |
United States Patent
Application |
20020006543 |
Kind Code |
A1 |
SEGAWA, KEN ; et
al. |
January 17, 2002 |
NONAQUEOUS ELECTROLYTE BATTERY
Abstract
A nonaqueous electrolyte battery which is capable of minimizing
damage if the battery is crushed with pressure is disclosed. The
nonaqueous electrolyte battery according to the present invention
incorporates: a spirally coil formed by, through a separator,
winding a positive electrode which incorporates an elongated
positive-electrode collector having two sides on each of which an
active material for the positive electrode has been formed and a
negative electrode which incorporates an elongated
negative-electrode collector having two sides on each of which an
active material for the negative electrode has been formed, wherein
the positive electrode has a lengthwise directional end which has
two sides each of which is provided with a
positive-electrode-collector exposed portion in which a
positive-electrode collector is exposed, the negative electrode has
a lengthwise directional end which has two sides each of which is
provided with a negative-electrode-collector exposed portion in
which a negative-electrode collector is exposed, and the
positive-electrode-collector exposed portion and the
negative-electrode-collector exposed portion cover the coil one or
more times through the separator.
Inventors: |
SEGAWA, KEN; (MIYAGI,
JP) ; FUJITA, SHIGERU; (MIYAGI, JP) ; OJIMA,
HIDEAKI; (MIYAGI, JP) ; TOMITA, TAKASHI;
(MIYAGI, JP) |
Correspondence
Address: |
SONNENSCHEIN NATH & ROSENTHAL
P.O. BOX 061080
WACKER DRIVE STATION
CHICAGO
IL
60606-1080
US
|
Family ID: |
12341734 |
Appl. No.: |
09/249502 |
Filed: |
February 12, 1999 |
Current U.S.
Class: |
429/94 ;
429/231.1; 429/231.3; 429/231.8 |
Current CPC
Class: |
H01M 10/0525 20130101;
H01M 10/613 20150401; Y02P 70/50 20151101; H01M 10/0431 20130101;
H01M 50/578 20210101; H01M 10/0587 20130101; H01M 10/4235 20130101;
H01M 10/643 20150401; H01M 50/342 20210101; Y02E 60/10 20130101;
H01M 10/654 20150401 |
Class at
Publication: |
429/94 ;
429/231.1; 429/231.3; 429/231.8 |
International
Class: |
H01M 010/36; H01M
004/48; H01M 004/52 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 13, 1998 |
JP |
P10-031820 |
Claims
What is claimed is:
1. A nonaqueous electrolyte battery comprising: a spirally coil
formed by, through a separator, winding a positive electrode which
incorporates an elongated positive-electrode collector having two
sides on each of which an active material for the positive
electrode has been formed and a negative electrode which
incorporates an elongated negative-electrode collector having two
sides on each of which an active material for the negative
electrode has been formed, wherein said positive electrode has a
lengthwise directional end which has two sides each of which is
provided with a positive-electrode-collector exposed portion in
which a positive-electrode collector is exposed, said negative
electrode has a lengthwise directional end which has two sides each
of which is provided with a negative-electrode-collector exposed
portion in which a negative-electrode collector is exposed, and
said positive-electrode-coll- ector exposed portion and said
negative-electrode-collector exposed portion cover said coil one or
more times through said separator.
2. A nonaqueous electrolyte battery according to claim 1, wherein
when an assumption is made that the length of said
positive-electrode-collector exposed portion is L.sub.1 and the
outer diameter of said coil is d, relationship L.sub.1.gtoreq..pi.d
is satisfied.
3. A nonaqueous electrolyte battery according to claim 1, wherein
when an assumption is made that the length of said
negative-electrode-collector exposed portion is L.sub.2 and the
outer diameter of said coil is d, relationship L.sub.2.gtoreq..pi.d
is satisfied.
4. A nonaqueous electrolyte battery according to claim 1, wherein
said coil has a structure that said negative electrode is disposed
outer than said positive electrode, and said
negative-electrode-collector exposed portion covers said
positive-electrode-collector exposed portion.
5. A nonaqueous electrolyte battery according to claim 1, wherein
said active material for the positive electrode is composite metal
oxide expressed by LiMO.sub.2 (where M is at least any one of Co,
Ni, Mn, Fe, Al and Ti).
6. A nonaqueous electrolyte battery according to claim 1, wherein
said active material for the negative electrode is any one of a
carbon material, a crystalline or amorphous metal oxide permitting
doping/dedoping of lithium ions.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a nonaqueous electrolyte
battery containing nonaqueous solvent as solvent of an electrolyte
thereof.
[0003] 2. Related Background Art
[0004] A lithium secondary battery containing nonaqueous
electrolyte incorporates a positive electrode which is usually
constituted by applying, to aluminum foil, metal oxide and the like
serving as an active material for the positive electrode. Moreover,
a negative electrode of the battery is constituted by crimping, to
copper foil, lithium serving as an active material for the negative
electrode. In addition, a separator constituted by a finely-porous
film made of polyethylene is disposed between the two electrodes
obtained as described above. A coil constituted by winding and
stacking the obtained structure is accommodated in a can made of
stainless steel and serving as an external electrode (for example,
an external negative electrode).
[0005] The above-mentioned lithium secondary battery has
characteristics of a large capacity, high voltage and a large
output. If the circuit or the like under abnormal conditions causes
the positive electrode and the negative electrode of the battery to
be short-circuited, the temperature of the battery is undesirably
raised. To prevent rise in the temperature of the battery, a
variety of protective means, such as a temperature fuse, an
electric current fuse and a PTC device are provided for the
battery. In addition, a safety valve for preventing rise in the
pressure in the battery is provided.
[0006] However, a variety of abnormal states are assumed to occur
as well as the short circuit of the positive electrode and the
negative electrode of the battery caused from an abnormal state of
the circuit in the battery. If the battery is crushed by external
pressure by accident, the separator between the positive electrode
and the negative electrode is broken or melted. Thus, the positive
electrode and the negative electrode are short-circuited. If the
positive electrode and the negative electrode are short-circuited,
there is apprehension that the battery is damaged by heat, smoke or
the like.
SUMMARY OF THE INVENTION
[0007] In view of the foregoing, an object of the present invention
is to provide a nonaqueous electrolyte battery which is capable of
minimizing damage thereof even if the battery is crushed by dint of
pressure.
[0008] According to one aspect of the present invention, there is
provided a nonaqueous electrolyte battery comprising: a spirally
coil formed by, through a separator, winding a positive electrode
which incorporates an elongated positive-electrode collector having
two sides on each of which an active material for the positive
electrode has been formed and a negative electrode which
incorporates an elongated negative-electrode collector having two
sides on each of which an active material for the negative
electrode has been formed, wherein the positive electrode has a
lengthwise directional end which has two sides each of which is
provided with a positive-electrode-collector exposed portion in
which a positive-electrode collector is exposed, the negative
electrode has a lengthwise directional end which has two sides each
of which is provided with a negative-electrode-collector exposed
portion in which a negative-electrode collector is exposed, and the
positive-electrode-colle- ctor exposed portion and the
negative-electrode-collector exposed portion cover the coil one or
more times through the separator.
[0009] The nonaqueous electrolyte battery according to the present
invention incorporates the coil covered with the
positive-electrode-colle- ctor exposed portion and the
negative-electrode-collector exposed portion. Therefore, even if
the battery is crushed with pressure, the
positive-electrode-collector exposed portion and the
negative-electrode-collector exposed portion are first
short-circuited. The nonaqueous electrolyte battery according to
the present invention enables heat produced by dint of short
circuit between the positive-electrode-collector exposed portion
and the negative-electrode-collector exposed portion to be
diffused. Therefore, any critical influence is exerted on the
active materials for the electrodes. As a result, damage of the
overall body of the battery can be prevented.
[0010] Other objects, features and advantages of the invention will
be evident from the following detailed description of the preferred
embodiments described in conjunction with the attached
drawings.
BRIEF DESCRIPTION OF THE DRAWING
[0011] FIG. 1 is a vertical cross sectional view showing an example
of the structure of a nonaqueous electrolyte battery according to
the present invention;
[0012] FIG. 2 is a perspective view showing an example of the
structure of a positive electrode;
[0013] FIG. 3 is a perspective view showing an example of the
structure of a negative electrode;
[0014] FIG. 4 is a lateral cross sectional view showing an example
of the structure of a coil; and
[0015] FIG. 5 is a lateral cross sectional view showing circle A
shown in FIG. 4.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] An embodiment of the present invention will now be described
with reference to the drawings.
[0017] FIG. 1 is a vertical cross sectional view showing an example
of the structure of a nonaqueous electrolyte battery according to
the present invention.
[0018] The nonaqueous electrolyte battery 1 incorporates a spirally
coil 5 constituted by, in a hermetic state, winding an elongated
positive electrode 2 and an elongated negative electrode 3 through
separators 4a and 4b. The spirally coil 5 is accommodated in a
battery can 6.
[0019] As shown in FIG. 2, the positive electrode 2 has a
positive-electrode collector 7 having two sides on each of which a
positive-electrode active material layer 8 is formed. When the
positive electrode 2 is manufactured, 91 wt % of MnO.sub.2, which
is a material for the positive electrode, 6 wt % of a conductive
material and 3 wt % of a binder are mixed with one another. Thus, a
positive electrode mix is prepared. It is preferable that the
material for the positive electrode contain Li in a sufficiently
large quantity. For example, a composite metal oxide and an
interlayer compound containing Li are suitable materials, the
composite metal oxide being composed of lithium expressed by, for
example, LiMO.sub.2 (where M is at least one type of a material
selected from Co, Ni, Mn, Fe, Al, V and Ti) and transition
metal.
[0020] The conductive material for imparting conductivity to the
positive electrode and the binder for joining the material for the
positive electrode to the positive electrode collector may be
conventional materials.
[0021] The conductive material may be graphite or carbon black,
while the binder may be made of fluororesin, such as polyvinylidene
fluoride.
[0022] Then, the positive electrode mix is dispersed in
N-methyl-2-pyrolidone so as to be slurried. The slurry
positive-electrode mix is uniformly applied to each of the two
surfaces of aluminum foil which will be formed into a
positive-electrode collector 7 and which has a thickness of, for
example 20 .mu.m, and then it is dried. Thus, a positive-electrode
active material layer 8 is formed so that the positive electrode 2
is manufactured.
[0023] The positive electrode 2 has a positive-electrode-collector
exposed portion 9 formed at a lengthwise directional end thereof.
The positive-electrode-collector exposed portion 9 has two surfaces
on each of which the positive-electrode active material layer 8 is
not formed so that the positive-electrode collector 7 is
exposed.
[0024] The end portion formed into the positive-electrode-collector
exposed portion 9 serves as an outer portion of the spirally coil 5
formed by the winding operation. The positive-electrode-collector
exposed portion 9 covers the spirally coil 5 at least one time.
Assuming that the outer diameter of the spirally coil 5 is d,
length L.sub.1 of the positive-electrode-collector exposed portion
9 is .pi.d or longer.
[0025] As shown in FIG. 3, the negative electrode 3 incorporates
the negative-electrode collector 10 which has two surfaces on each
of which a negative-electrode active material 11 is formed. The
negative electrode 3 is manufactured by bonding, for example, metal
lithium foil which serves as a negative-electrode active material
11 to copper foil which serves as the negative-electrode collector
10 and which has a thickness of, for example, 10 .mu.m. The
negative electrode 3 may be a structure obtained by applying, to
the negative-electrode collector 10, a material for a negative
electrode, which permits doping/dedoping of lithium ions, and the
binder.
[0026] The material for the negative electrode may be, for example,
a carbon material. The carbon material is exemplified by thermal
decomposition carbon, cokes (pitch cokes, needle cokes, petroleum
cokes or the like), graphite, vitreous carbon, a calcinated organic
polymer compound (a material obtained by calcinating phenol resin,
furan resin or the like), carbon fiber and active carbon. The
material for the negative electrode may be crystalline or amorphous
metal oxide which permits doping/dedoping of lithium ions, as well
as the carbon material.
[0027] The binder for joining the material for the negative
electrode to the negative-electrode collector may be a conventional
material. For example, the binder may be fluororesin, such as
polyvinylidene fluoride.
[0028] The negative electrode 3 has a negative-electrode-collector
exposed portion 12 formed at a lengthwise directional end thereof.
The negative-electrode-collector exposed portion 12 has two
surfaces on each of which the negative-electrode active material 1
is not formed so that the negative-electrode collector 10 is
exposed.
[0029] The end portion formed into the negative-electrode-collector
exposed portion 12 serves as an outer portion of the spirally coil
5 formed by the winding operation. The negative-electrode-collector
exposed portion 12 covers the spirally coil 5 at least one time.
Assuming that the outer diameter of the spirally coil 5 is d,
length L.sub.2 of the negative-electrode-collector exposed portion
12 is .pi.d or longer.
[0030] The spirally coil 5 is formed by spirally winding a member
formed by stacking, in this sequential order, the positive
electrode 2, the separator 4a, the negative electrode 3 and the
separator 4b.
[0031] Each of the separators 4a and 4b is made of an insulating
material having a relatively high specific heat. Each of the
separators 4a and 4b is constituted by a finely-porous
polypropylene film having a thickness of about 25 .mu.m.
[0032] The separator is not limited particularly. The separator may
be woven fabrics, unwoven fabrics or a finely porous film made of
synthetic resin or the like. Among the foregoing materials, a
finely-porous film made of polyolefin is a preferred material from
viewpoints of realizing a required thickness, strength of the
formed film and resistance of the film. Specifically, any one of a
polyethylene finely-porous film, a polypropylene finely-porous
film, a finely-porous film and their mixture may be employed.
[0033] FIG. 4 is a lateral cross sectional view showing an example
of the structure of the spirally coil 5. FIG. 5 is an enlarged view
showing circle A shown in FIG. 4.
[0034] The spirally coil 5 is covered with the
positive-electrode-collecto- r exposed portion 9 and the
negative-electrode-collector exposed portion 12 one or more times.
Moreover, the outermost portion of the spirally coil 5 is formed
into the separator 4b.
[0035] It is preferable that the negative electrode 3 of the
spirally coil 5 is positioned outer than the positive electrode 2.
Moreover, it is preferable that the negative-electrode-collector
exposed portion 12 covers the positive-electrode-collector exposed
portion 9. Since the negative electrode 3 is positioned outer than
the positive electrode 2, short circuit in the battery can be
prevented as described later.
[0036] The nonaqueous electrolyte battery 1 has the structure that
the spirally coil 5 is accommodated in the battery can 6, as shown
in FIG. 1.
[0037] To constitute the nonaqueous electrolyte battery 1 by
accommodating the spirally coil 5 in the battery can 6, an
insulating plate 13 is inserted into the bottom of the battery can
6 made of, for example, iron and previously plated with nickel.
Thus, the spirally coil 5 is accommodated.
[0038] To collect electric currents of the negative electrode 3, an
end of a negative-electrode lead 14 made of, for example, nickel,
is crimped to the negative electrode 3. Another end of the
negative-electrode lead 14 is welded to the battery can 6. As a
result, the battery can 6 is electrically conducted to the negative
electrode 3 so as to be formed into an external negative electrode
of the nonaqueous electrolyte battery 1. To collect electric
currents of the positive electrode 2, an end of a
positive-electrode lead 15 made of, for example, aluminum, is
joined to the positive electrode 2. Another end of the
positive-electrode lead 15 is electrically connected to a battery
cover 17 through a current-interrupting thin plate 16. The
current-interrupting thin plate 16 interrupts an electric current
to correspond to the internal pressure of the battery. As a result,
the battery cover 17 and the positive electrode 2 are electrically
conducted to each other so as to be formed into the external
positive electrode of the nonaqueous electrolyte battery 1.
[0039] The negative electrode 3 of the spirally coil 5 is
positioned outer than the positive electrode 2. Therefore, short
circuit between the battery can 6 electrically conducted to the
negative electrode 3 and the positive electrode 2 occurring in the
battery can be prevented even if the separator 4b which is the
outermost element of the spirally coil 5 is curled up. As a result,
the manufacturing yield can be improved.
[0040] Then, a nonaqueous electrolyte is injected into the battery
can 6. The nonaqueous electrolyte is prepared by dissolving
LiPF.sub.6, which is an electrolyte, in mixed solvent prepared by
mixing 50 vol % of propylene carbonate, which is organic solvent,
and 50 vol % di-methoxyehtane. The dissolving ratio with respect to
the mixed solvent is 1 mol/l.
[0041] The organic solvent, which is not limited particularly, is
exemplified by propylene carbonate, ethylene carbonate,
1,2-dimethoxyethane, 1,2-diethoxyethane, diethylcarbonate,
.gamma.-butyrolactone, tetrahydrofuran, 1,3-dioxolane,
4-methyl-1,3-dioxolane, diethylether, sulfolane, methylsulfolane,
acetonitrile and propionitrile. The foregoing material is used
solely or two or more types of the materials are used as mixed
solvent.
[0042] The electrolyte, which is not limited particularly, is
exemplified by LiClO.sub.4, LiAsF.sub.6, LiPF.sub.6, LiBF.sub.4,
LiB (C.sub.6H.sub.5).sub.4, LiCl, LiBr, LiSO.sub.3CH.sub.3 and
LiSO.sub.3CF.sub.3.
[0043] Finally, the battery can 6 is crimped through an insulating
sealing gasket 18 applied with asphalt so that the battery cover 17
is secured. As a result, the cylindrical nonaqueous electrolyte
battery 1 can be manufactured.
[0044] The nonaqueous electrolyte battery 1 has a center pin 19
which is connected to the positive-electrode lead 15 and the
negative-electrode lead 14. Moreover, a safety valve unit 20 for
removing gas in the battery if the pressure in the battery is
raised to a level higher than a predetermined level is provided for
the nonaqueous electrolyte battery 1. In addition, a PTC (Positive
Temperature Coefficient) device 21 for preventing rise in the
temperature in the battery is provided for the nonaqueous
electrolyte battery 1.
[0045] The problem of heat and smoke caused from crush of the
nonaqueous electrolyte battery with external pressure will now be
described. If the battery can is crushed with external pressure,
the separator is initially broken. Thus, the positive electrode and
the negative electrode are short-circuited in the battery, causing
heat to be produced. The heat causes reactions to take place and
thus smoke is produced.
[0046] If the nonaqueous electrolyte battery 1 encounters an
abnormal state such as crush of the battery body, the
positive-electrode-collector exposed portion 9 and the
negative-electrode-collector exposed portion 12 are, at the outer
periphery of the spirally coil 5, short-circuited initially. The
short circuit between the positive-electrode-collector exposed
portion 9 and the negative-electrode-collector exposed portion 12
occurs at a position apart from the positive-electrode active
material layer 8 and the negative-electrode active material 11.
Moreover, separators 4a and 4b each having a relatively high
specific heat are disposed around the position at which the short
circuit has taken place. Therefore, even if heat is produced owning
to the short circuit between the positive-electrode-collector
exposed portion 9 and the negative-electrode-collector exposed
portion 12, heat can be diffused. As a result, a critical influence
is not exerted on the active material layer for the electrode.
[0047] Therefore, damage, such as heat and smoke, which exerts an
effect on the overall body of the battery can satisfactorily be
prevented. As a result, a nonaqueous electrolyte battery 1
exhibiting excellent safety can be obtained.
[0048] If the length of the positive-electrode-collector exposed
portion 9 or that of the negative-electrode-collector exposed
portion 12 is shorter than .pi.d, the positive-electrode-collector
exposed portion 9 and the negative-electrode-collector exposed
portion 12 cannot cover the spirally coil 5 one or more times. A
state in which the spirally coil 5 is not covered by the
positive-electrode-collector exposed portion 9 and the
negative-electrode-collector exposed portion 12 one or more times
will now be described. If the battery is crushed at a position
which is not covered with the positive-electrode-collector exposed
portion 9 and the negative-electrode-collector exposed portion 12,
the positive-electrode-collector exposed portion 9 and the
negative-electrode-collector exposed portion 12 cannot first be
short-circuited. Therefore, damage cannot be minimized.
[0049] If the positive-electrode-collector exposed portion 9 or the
negative-electrode-collector exposed portion 12 is provided for
only one side, short circuit between the
positive-electrode-collector exposed portion 9 and the
negative-electrode-collector exposed portion 12 cannot be caused to
take place at a position sufficiently apart from the active
material for the electrode. Therefore, an adverse influence on the
active material for the electrode cannot be minimized.
[0050] Therefore, the electrode-collector exposed portions are
disposed on the two sides of the electrodes and their lengths are
made to be .pi.d or longer. Thus, the safety of the nonaqueous
electrolyte battery 1 can furthermore be improved.
[0051] Although the lithium secondary battery has been described in
the above-mentioned embodiment, the present invention is not
limited to this. The present invention may be applied to a
nonaqueous electrolyte battery as well as the lithium secondary
battery.
EXAMPLES
[0052] Nonaqueous electrolyte batteries having the above-mentioned
structure were manufactured so as to be subjected to pressure crush
tests.
Example 1
[0053] Initially, a positive electrode was manufactured.
[0054] Initially, 91 wt % of MnO.sub.2, 6 wt % of the conductive
material and 3 wt % of the binder were mixed so that a
positive-electrode mix was prepared. The conductive material was
graphite, while the binder was polyvinylidene fluoride.
[0055] Then, the positive-electrode mix was dispersed in
N-methyl-2-pyrolidone so as to be slurried. The slurry was
uniformly applied to the two sides of aluminum foil which served as
a positive electrode collector and which had a thickness of 20
.mu.m. Then, the slurry was dried, and then aluminum foil was
compressed and molded by a roll pressing machine. Thus, the
positive electrode was manufactured.
[0056] At this time, the active material layer for the positive
electrode was not formed on either of the two sides at an end of
the positive electrode. Therefore, the positive-electrode-collector
exposed portion in which the positive electrode collector was
exposed was formed. The length of the positive-electrode-collector
exposed portion was made to be .pi.d.
[0057] Then, a negative electrode was manufactured.
[0058] The negative electrode was manufactured by applying metal
lithium foil which was an active material for the negative
electrode to copper foil which was a negative-electrode collector
and which had a thickness of 10 .mu.m.
[0059] At this time, the active material layer for the negative
electrode was not formed on either of the two sides at an end of
the negative electrode. Therefore, the negative-electrode-collector
exposed portion in which the negative-electrode collector was
exposed was formed. The length of the negative-electrode-collector
exposed portion was made to be .pi.d.
[0060] The positive electrode, the separator, the negative
electrode and the separator were sequentially hermetically stacked
in this sequential order. Then, the stacked structure was spirally
wound plural times so that a coil was constituted. The separator
was made of finely-porous polypropylene film having a thickness of
25 .mu.m.
[0061] Then, an insulating plate is inserted into the bottom of a
battery can previously plated with nickel and made of iron. Then,
the above-mentioned coil was accommodated in the battery can. To
collect electric currents of the negative electrode, an end of the
negative-electrode lead was crimped to the negative electrode.
Another end of the negative-electrode lead was welded to the
battery can.
[0062] To collect electric currents of the positive electrode, an
end of a positive-electrode lead made of aluminum is joined to the
positive electrode. Another end of the positive-electrode lead was
electrically connected to the battery cover through a
current-interrupting thin plate.
[0063] Then, a nonaqueous electrolyte was injected into the battery
can. The nonaqueous electrolyte was prepared by dissolving
LiPF.sub.6 in mixed solvent prepared by mixing 50 vol % of
propylene carbonate and 50 vol % di-methoxyehtane. The dissolving
ratio with respect to the mixed solvent was 1 mol/l.
[0064] Finally, the battery can was crimped through an insulating
sealing gasket applied with asphalt so that the battery cover was
secured. As a result, a cylindrical nonaqueous electrolyte battery
having a diameter of about 18 mm and a height of about 65 mm was
manufactured.
Example 2
[0065] A process similar to that according to Example 1 was
performed except for a structure that the length of each of the
positive-electrode-collector exposed portion and the
negative-electrode-collector exposed portion was made to be 2
.pi.d. Thus, a nonaqueous electrolyte battery was manufactured.
Comparative Example 1
[0066] A process similar to that according to Example 1 was
performed except for a structure that the
positive-electrode-collector exposed portion was not provided for
the positive electrode and the negative-electrode-collector exposed
portion was not provided for the negative electrode. Thus, a
nonaqueous electrolyte battery was manufactured.
Comparative Example 2
[0067] A process similar to that according to Example 1 was
performed except for a structure that the
positive-electrode-collector exposed portion was provided for only
either side of the positive electrode. Thus, a nonaqueous
electrolyte battery was manufactured.
Comparative Example 3
[0068] A process similar to that according to Example 1 was
performed except for a structure that the
negative-electrode-collector exposed portion was not provided for
the negative electrode. Thus, a nonaqueous electrolyte battery was
manufactured.
Comparative Example 4
[0069] A process similar to that according to Example 1 was
performed except for a structure that the
positive-electrode-collector exposed portion was provided for only
either side of the negative electrode. Thus, a nonaqueous
electrolyte battery was manufactured.
Comparative Example 5
[0070] A process similar to that according to Example 1 was
performed except for a structure that the length of each of the
positive-electrode-collector exposed portion and the
negative-electrode-collector exposed portion was made to be 0.5
.pi.d. Thus, a nonaqueous electrolyte battery was manufactured.
Comparative Example 6
[0071] A process similar to that according to Example 1 was
performed except for a structure that the length of the
positive-electrode-collecto- r exposed portion was made to be 0.5
.pi.d and that of the negative-electrode-collector exposed portion
was made to be .pi.d. Thus, a nonaqueous electrolyte battery was
manufactured.
Comparative Example 7
[0072] A process similar to that according to Example 1 was
performed except for a structure that the length of the
positive-electrode-collecto- r exposed portion was made to be .pi.d
and that of the negative-electrode-collector exposed portion was
made to be 0.5 .pi.d. Thus, a nonaqueous electrolyte battery was
manufactured.
[0073] A predetermined number of the thus-manufactured nonaqueous
electrolyte batteries according to Examples 1 and 2 and Comparative
Examples 1 to 7 were prepared. Each of the nonaqueous electrolyte
batteries were charged/discharged 100 cycles in a voltage range
from 1.5 V to 3.0 V. Then, the nonaqueous electrolyte battery was
charged to 3.0 V, and then a pressure crush test was performed.
[0074] The nonaqueous electrolyte batteries according to
Comparative Examples 1 to 3 incorporated the electrodes having no
electrode-collector exposed portion, only either of the electrodes
provided with the electrode-collector exposed portion or an
electrode having the electrode-collector exposed portion provided
for either surface thereof. A portion of the foregoing nonaqueous
electrolyte batteries encountered damage, such as heat and/or
smoke, of the overall bodies of the batteries.
[0075] The nonaqueous electrolyte batteries according to Examples 1
and 2 and having the structure that the electrode-collector exposed
portion was provided for each of the two sides of the two
electrodes were free from damage, such as heat and/or smoke, of the
overall bodies of the batteries.
[0076] Therefore, the structure that the electrode-collector
exposed portions were provided for the two sides of the two
electrodes improved the safety of the nonaqueous electrolyte
battery.
[0077] In Examples 1 and 2 and Comparative Examples 1 and 5 to 7,
experiments were performed such that the length of the
positive-electrode-collector exposed portion or that of the
negative-electrode-collector exposed portion was changed.
[0078] The number of the batteries subjected to the experiments and
batteries encountered heat and/or smoke were shown in Table 1.
1 TABLE 1 Length of Length of Positive- Negative- Number of
Electrode- Electrode- Number of Batteries Collector Ex- Collector
Ex- Tested Produced posed Portion posed Portion Batteries Smoke
Example 1 .pi.d .pi.d 5 0 Example 2 2 .pi.d 2 .pi.d 5 0 Comparative
0 0 5 5 Example 1 Comparative 0.5 .pi.d 0.5 .pi.d 5 3 Example 5
Comparative 0.5 .pi.d .pi.d 5 2 Example 6 Comparative .pi.d 0.5
.pi.d 5 3 Example 7
[0079] As can be understood from Table 1, the nonaqueous
electrolyte batteries according to Comparative Examples 1 and 5 to
7 each having the structure that the length of the
electrode-collector exposed portion was shorter than .pi.d
encountered damage, such as heat and smoke, of the overall bodies
of the batteries.
[0080] On the other hand, the nonaqueous electrolyte batteries
according to Examples 1 and 2 each having the structure that the
length of the electrode-collector exposed portion is longer than
.pi.d were free from any damage of the overall bodies of the
batteries.
[0081] Therefore, when the length of the electrode-collector
exposed portion is not shorter than .pi.d, the safety of the
nonaqueous electrolyte battery can furthermore be improved.
[0082] The nonaqueous electrolyte battery according to the present
invention is structured such that short circuit takes place between
the positive-electrode-collector exposed portion and the
negative-electrode-collector exposed portion provided on the two
sides of the electrodes. Therefore, heat can be diffused. As a
result, any critical influence is not exerted on the active
materials for the positive electrode and the negative electrode.
Moreover, heat and smoke can be prevented.
[0083] The nonaqueous electrolyte battery according to the present
invention has the structure that the electrode-collector exposed
portions are provided for the two sides of the two electrodes.
Moreover, the electrode-collector exposed portion covers the coil
one or more times. Therefore, heat and smoke which are produced
when the battery has been crushed can furthermore satisfactorily be
prevented.
[0084] Therefore, damage of the battery and an adverse influence on
the environment can be minimized. As a result, a nonaqueous
electrolyte battery exhibiting excellent safety and reliability can
be provided.
[0085] Although the invention has been described in its preferred
form and structure with a certain degree of particularity, it is
understood that the present disclosure of the preferred form can be
changed in the details of construction and in the combination and
arrangement of parts without departing from the spirit and the
scope of the invention as hereinafter claimed.
* * * * *