CN1799162A - Lithium secondary cell - Google Patents

Abstract

A stable high-performance lithium secondary cell having a variable-shape case in which a cell element is contained and not bulging even though the shape of the case is variable and even if it is stored at high temperature. The lithium secondary cell comprising a cell element that includes a positive electrode, a negative electrode, and an electrolyte containing a nonaqueous solvent and a solute, and a variable-shape case containing the cell element is characterized in that DEadd(AN) is smaller than DEsol(AN) where DEsol(AN) is the difference Esol(A) - Esol(N) where Esol(N) is the enthalpy of the neutral molecular of the nonaqueous solvent determined by a predetermined calculation method and Esol(A) is the enthalpy of the anion radical produced by giving the neutral molecular one electron, and where DEadd(AN) is the difference Eadd(A) - Eadd(N) where Eadd(N) is the enthalpy of the neutral molecular of an additive [alpha] contained in the cell element determined by a predetermined calculation method and Eadd(A) is the enthalpy of the anion radical produced by giving the neutral molecular one electron.

Description

Lithium secondary battery

Technical field

The present invention relates to lithium secondary battery (in this manual, simply being called battery sometimes), in more detail, even relate to the lithium secondary battery that tight security is also arranged under high temperature is preserved.

Background technology

People are known will to have positive pole, negative pole and contain nonaqueous solvents and the electrolytical cell device of solute (cellelement) is sealed to lithium secondary battery in the shell.

The most general lithium secondary battery uses SUS metallic rigid metal shells such as (stainless steels) as shell.

In recent years, replace the lithium secondary battery of such employing metal-back, the housing material of tool shape variable that uses the laminated film that resin bed is set on the two sides of barrier layer as the lithium secondary battery of shell just by practicality.The housing material of tool shape variable is compared with metal-back, has the advantage that the freedom of design in configuration of degree of freedom height, the lithium secondary battery of shell shape design increases.In addition, when apparatus has the variable housing material of shape as the lithium secondary battery of shell, because of can making housing material lightweight, slimming, thus battery miniaturization more, lightweight, and make volume energy density and weight energy density higher.

Except shell is carried out the above-mentioned selection, the volume energy density of lithium secondary battery and the research and development of weight energy density raising are also carried out by raising with cell device self capacity.As such technology that cell device self capacity is improved, inquiring into lithium nickel composite oxide as positive active material.This is because with usually as the lithium cobalt composite oxide (LiCoO of positive active material ₂) compare, the current capacity of lithium nickel composite oxide per unit weight is big, from the angle of high capacity, is useful positive electrode.

But, adopt the lithium secondary battery of shape variable shell to compare as the lithium secondary battery in the past of shell with adopting metal-back, the mechanical strength of shell a little less than.Therefore, preserve under the hot environment and when the internal pressure of the shell of lithium secondary battery was risen, lithium secondary battery expanded.It is poor that internal pressure increases the shape stability of deterioration, poor stability and lithium secondary battery that the lithium secondary battery expansion that is produced can cause battery performance.That is, with metal-back during as shell, the rising of the internal pressure that is produced when high temperature is preserved, metal-back has enough mechanical strengths, and the internal pressure caused expansion of rising can not take place in shell.On the contrary, the material with shape variable because of its mechanical strength a little less than, so along with the rising of enclosure pressure, lithium secondary battery can expand.

The expansion of this lithium secondary battery causes the deterioration of battery performance.That is, the expansion of lithium secondary battery descends because of making electrode and electrolytical adhesiveness in the cell device in the shell of packing into, thus cause discharge capacity to descend, or make cycle characteristics variation etc.In addition, under with the situation of laminated film system shell as the shell of tool shape variable, the expansion of lithium secondary battery can make a part of junction surface of film occur leaking, and the water in air branch may leak part from this invades, and causes the battery behavior deterioration.

The expansion of this lithium secondary battery also can make lithium secondary battery in the hole.That is, with laminated film system shell during as the shape variable shell, the expansion of lithium secondary battery can cause that leaking appears in a part of junction surface of film, and electrolyte also can partly spill from this leakages sometimes.In addition, when rapid rising of above-mentioned internal pressure and increase, the danger that shell breaks in addition.

In addition, the expansion of this lithium secondary battery also causes lithium secondary battery shape stability variation, hinders the miniaturization of electric equipment.That is, owing to be placed with the more and more miniaturization of electronic equipment of lithium secondary battery in recent years, people require the space that holds battery is diminished.Thus, the internal pressure of shell rises and to cause under the situation that lithium secondary battery expands when high temperature is preserved, if will consider this expansion, must design the space that holds battery.The expansion of above-mentioned lithium secondary battery can hinder the miniaturization of electronic equipment thus.

In fact, also can be placed in the extremely hot car sometimes as mobile phone of power supply etc. with lithium secondary battery.In the case, lithium secondary battery tans by the sun under 60-85 ℃ hot environment.From then on actual conditions are seen, as the lithium secondary battery in the shell of tool shape variable that cell device is packed into, must solve the technical problem of the enclosure pressure rising that is produced when suppressing to preserve under the above-mentioned high temperature.

According to present inventor's discussion, confirm that the rising of above-mentioned internal pressure is obvious especially when using lithium nickel composite oxide as positive active material.Lithium nickel composite oxide and other lithium-transition metal composite oxide, for example the lithium cobalt composite oxide is compared with complex Li-Mn-oxide, because of the battery capacity height of its per unit weight, so be very good positive active material.But if when using lithium nickel composite oxide, the rising of above-mentioned internal pressure has than the significant trend of other lithium transition-metal oxide.Thus, actual conditions are that this problem has hindered and utilizes the practicability of lithium nickel composite oxide as the lithium secondary battery of positive active material.

In view of the above problems, the objective of the invention is the expansion of the lithium secondary battery that produced of rising of enclosure pressure when preserving, and battery performance, fail safe and the shape stability of lithium secondary battery are improved with the high temperature that the shape variable shell suppresses to become problem.

Summary of the invention

In view of above-mentioned actual conditions, deep discussion has been carried out in the expansion of the lithium secondary battery the when present inventor preserves with regard to the high temperature that becomes problem in the lithium secondary battery that suppresses employing shape variable shell.

Found that, contain additive α in the cell device by making, and the enclosure pressure expansion of caused lithium secondary battery of the rising when relation of contained nonaqueous solvents and above-mentioned additive α can suppress to preserve along with high temperature in the control electrolyte as described below, and finished the present invention.Promptly, find: with respect to the enthalpy of the neutral molecule of above-mentioned nonaqueous solvents: Esol (N) and the enthalpy of giving the above-mentioned neutral molecule anionic group that an electron institute generates: Esol's (A) is poor: Esol (A)-Esol (N), if the enthalpy of the neutral molecule of above-mentioned additive α: the Eadd (N) and the enthalpy of giving the above-mentioned neutral molecule anionic group that an electron institute generates: Eadd's (A) is poor: Eadd (A)-Eadd (N) diminishes to good.

Promptly, main points of the present invention are to contain positive pole comprising, negative pole and contain the electrolytical cell device of nonaqueous solvents and solute and hold in the lithium secondary battery of shape variable shell of above-mentioned cell device, it is characterized in that, the enthalpy of the neutral molecule of the above-mentioned nonaqueous solvents that will be obtained by the following computational methods (#) of note: Esol (N) and the enthalpy of giving the above-mentioned neutral molecule anionic group that an electron institute generates: Esol's (A) is poor: Esol (A)-Esol (N) is made as Δ Esol (AN), when above-mentioned cell device contains additive α, will be by the enthalpy of the neutral molecule of remembering the above-mentioned additive α that computational methods (#) are obtained down: Eadd (N) and the enthalpy of giving the above-mentioned neutral molecule anionic group that 1 electron institute generates: Eadd's (A) is poor: Eadd (A)-when Eadd (N) was made as Δ Eadd (AN), Δ Eadd (AN) be little than Δ Esol (AN).

Computational methods (#)

The enthalpy of neutral molecule and the enthalpy of anionic group are carried out quantum chemistry calculation by the Hartree-Fock molecular orbital method of the restriction of the non-experience that adopts 6-31G * ground state function class respectively and are tried to achieve.

Description of drawings

Fig. 1: the exploded perspective view of the battery of an embodiment of the present invention.

Fig. 2: the sectional view of the battery pith of an embodiment of the present invention.

Fig. 3: the stereogram of the cell device of the battery of demonstration an embodiment of the present invention.

Fig. 4: the stereogram of the battery of an embodiment of the present invention.

Fig. 5: the stereogram in the battery manufacture process of other execution modes of the present invention.

Fig. 6: the stereogram in the battery manufacture process of the execution mode that the present invention is other.

Fig. 7: the stereogram in the manufacture process of the battery of the execution mode that the present invention is different.

Plane graph in the manufacturing process that Fig. 8: Fig. 7 implements.

Fig. 9: the schematic isometric of unit cells element.

Figure 10: the schematic section of negative or positive electrode.

Figure 11: the schematic section of cell device.

Figure 12: (A), (B) longitudinal section of composite material one example of figure expression formation respectively housing material.

Figure 13: other routine longitudinal sections that show the composite material that constitutes housing material.

Figure 14: the stereogram in other the manufacture process of battery of execution mode of the present invention.

Figure 15: the schematic plan view of Figure 14 state.

The expanded view of the pith of Figure 16: Figure 15.

Figure 17: the sectional view that shows the injection state of insulating material.

Figure 18: the enlarged cross section figure of the blank area of cell device.

Figure 19: the figure of the relation of the expansion of lithium secondary battery when the Δ Eadd (AN) of demonstration additive α and the Δ Esol (AN) of nonaqueous solvents and high temperature are preserved.

Symbol description:

1: cell device

2,3,6,7,8: housing material

4a, 4b: joint

4A, 4F, 4G: joint fastener part

4B: packaged unit

5: insulating material

11: positive pole

11a: positive electrode material layer

12: negative pole

12b: negative electrode material layer

13: the illiquidity dielectric substrate

15a: positive electrode collector

15b: negative electrode collector

21: lead

22: positive electrode collector

23: positive electrode material layer

24: separator (dielectric substrate)

25: negative electrode material layer

26: negative electrode collector

40: metal level

41,42: synthetic resin layer

43: adhesive phase

50: injection device

51: nozzle

Embodiment

Below be elaborated with regard to lithium secondary battery of the present invention.

(1) additive α

Lithium secondary battery of the present invention is for having the positive pole of comprising, negative pole and the lithium secondary battery that contains the electrolytical cell device of nonaqueous solvents and solute and put into the shape variable shell of above-mentioned cell device, it is characterized in that, the enthalpy of the neutral molecule of the above-mentioned nonaqueous solvents that will be obtained by the following computational methods (#) of note: Esol (N) and the enthalpy of giving the above-mentioned neutral molecule anionic group that 1 electron institute generates: Esol's (A) is poor: Esol (A)-Esol (N) is made as Δ Esol (AN), when above-mentioned cell device contains additive α, will be by the following computational methods # of note) enthalpy of the neutral molecule of the above-mentioned additive α that obtained: Eadd (N) and the enthalpy of giving the above-mentioned neutral molecule anionic group that 1 electron institute generates: Eadd's (A) is poor: Eadd (A)-when Eadd (N) was made as Δ Eadd (AN), Δ Eadd (AN) was little than Δ Esol (AN).

Computational methods (#)

The enthalpy of neutral molecule and the enthalpy of anionic group are carried out quantum chemistry calculation by the Hartree-Fock molecular orbital method of the restriction of the non-experience that adopts 6-31G * ground state function class respectively and are tried to achieve.That is, neutral molecule and anionic group enthalpy is separately carried out the molecular configuration optimization by the Hartree-Fock molecular orbital method of the non-experience of the 6-31G * ground state function class of establishments such as employing Hople and is tried to achieve.But the evaluation to anionic group is to carry out with housing system (open-shell system) molecular orbital method of opening of restriction.

In the present invention, as common expression mark, the enthalpy that the enthalpy of neutral molecule is expressed as E (N), anionic group is expressed as E (A), and difference E (the A)-E (N) of the enthalpy of the enthalpy of anionic group and neutral molecule is expressed as Δ E (AN).

Below just the reason of the expansion of the lithium secondary battery by so the Δ Eadd (AN) of above-mentioned additive α can be suppressed the high temperature preservation less than the Δ Esol (AN) of above-mentioned nonaqueous solvents the time describe.

Promptly, carry out the words of preserving under the hot environment in the lithium secondary battery charged state, because of the surface of positive active material becomes catalyst, be contained in the composition that nonaqueous solvents in the electrolyte can be decomposed into gases such as carbonated, thus, this gas rises lithium secondary battery enclosure pressure, produces the expansion of the lithium secondary battery that adopts the shape variable shell.

Here the positive active material surface have catalyst action be because: for example, when positive active material is made of the lithium-transition metal composite oxide as lithium cobalt composite oxide and lithium nickel composite oxide, because of being metal oxide as cobalt/cobalt oxide or nickel oxide, the key of metallic atom and oxygen atom can polarize, the cause that the alkalescence of oxygen atom increases.In charged state, emitted in a large number especially from the positive atom lithium of positive active material, and in positive active material and the factor of negative electrical charge be in few state, become higher so be contained in the alkalescence of the oxygen atom in the positive active material.Thus, under hot environment, the position of the oxygen atom that above-mentioned alkalescence is high becomes alkaline point, makes the nonaqueous solvents in the electrolyte such as being contained in carbonate carry out decomposition reaction through necleophilic reaction, generates gases such as carbon dioxide.

Thus, as the method for the decomposition reaction that suppresses above-mentioned nonaqueous solvents, make the oxygen atom surface inactivation of the metal oxide that constitutes positive active material, the method that its alkalescence is reduced is effective.Therefore, can consider alkalescence to be reduced with the method for acid additives combination.But discussion according to the present inventor, make proton acid, Bronsted acid etc. have the acid of mobility ion to exist in the cell device in a large number even confirm, the effect of the expansion of lithium secondary battery is not only not enough when suppressing the high temperature preservation, also become the reason that cell resistance rises, cause the reduction of charge-discharge characteristic easily.That is, the expansion of the lithium secondary battery of generation when preserving for suppressing high temperature, promptly using has acid additive as the additive that is contained in the cell device, and it is all good to say, must be the additive that does not make the battery behavior variation and can fully suppress above-mentioned expansion.

Under this situation, the present inventor is thought of as the alkalescence that makes the positive active material surface and reduces, allow easily and be present in the composition of electric charge affinity of the alkalescence point on positive active material surface, particularly have precedence over the nonaqueous solvents that is contained in the electrolyte, easily and the composition of the electric charge affinity of above-mentioned alkalescence point be contained in the cell device to well.This is because if can have precedence over the decomposition reaction of nonaqueous solvents and reduce the alkalescence on positive active material surface, can suppress the decomposition reaction of nonaqueous solvents, but also the cause of the generation of gas can suppress high temperature and preserve the time.

The present inventor is on the basis of above-mentioned supposition, as have precedence over nonaqueous solvents, easily with from the composition of the electric charge affinity of the alkalescence point on positive active material surface, think that with additive α be effectively, this additive α obtains the electronics of alkalescence point easily and produces resonance than nonaqueous solvents.Such additive α must have than the easier character that turns to anionic group from neutral molecular change of nonaqueous solvents.The present inventor adopts the index of the easy degree of this variation generation of energy gap (energy gap) conduct expression from neutral molecular changeization to anionic group.Therefore think that the above-mentioned energy gap (Δ Eadd (AN)) of additive α is little of well than the above-mentioned energy gap (Δ Esol (AN)) of nonaqueous solvents.This be because, above-mentioned energy gap is little, the acceptant electronics of neutral molecule shows easily and the electron resonance of alkalescence point.

As additive α, suitable usefulness is accepted the electronics of alkalescence point on the positive active material surface and the lewis acid of easy and its resonance.And the energy gap (Δ Eadd (AN)) of this lewis acid during from neutral molecular changeization to anionic group is little better than the above-mentioned energy gap (Δ Esol (AN)) of nonaqueous solvents.

In the present invention, above-mentioned Δ Esol (AN) and above-mentioned Δ Eadd's (AN) is poor: more than 0.1eV, more than the 0.2eV, better more than 0.3eV, the spy more than the 0.7eV, is preferably in more than the 0.95eV Δ Esol (AN)-Δ Eadd (AN) fortunately more fortunately usually.If more than 0.2eV, even because of the state of electrode, the state of oxidation that constitutes the metal oxide of positive active material can be inhomogeneous, and this effect also manifests comparatively significantly.In addition, if more than 0.3eV, though anodal inner voltage distributes because of cell device easily produces, even in this case, the effect that expands when suppressing high temperature is also more obvious.On the other hand, Δ Esol (AN)-Δ Eadd (AN) is usually below 4eV, more fortunately below the 3.5eV, better below 3eV.If below 3.5eV, additive α suitably accepts electronics easily than nonaqueous solvents contained in the electrolyte, only the lewis base property point selection on positive active material surface is had an effect.

In the present invention, above-mentioned additive α is preferably the compound of the sulphur of the two keys with an above sulphur and oxygen.That is, additive α better be have sulphur and oxygen two keys and its Δ Eadd (AN) be used for the common little material of Δ Esol (AN) of electrolytical nonaqueous solvents of lithium secondary battery.With such additive α, can accept the electric charge of anodal alkalescence point and resonance is become easily, have precedence over nonaqueous solvents and make anodal surperficial inactivation, effectively prevent the expansion of shell so can suppress the decomposition reaction of nonaqueous solvents.

And be used for the performance state of compound of the present invention's above-mentioned sulphur, and better be under ambient temperature and moisture, be liquid or solid.And the ambient temperature and moisture of this moment refers to 25 ℃, the environment of 50%RH.

Compound compared with the sulphur of two keys with 1 sulphur atom and oxygen atom, the Δ Eadd (AN) of compound with sulphur of a plurality of this pair keys obtains littler value usually, exist the difference that makes with Δ Esol (AN) to become big trend, and textural also be more easily to accept electronics, comparatively stably obtain the structure that resonates.Therefore, if use the compound of the sulphur of two keys, easily make itself and anodal surface interaction, more effective expansion that prevents lithium secondary battery with a plurality of sulphur atoms and oxygen atom.In addition, the sulphur atom that forms two keys with oxygen atom with singly-bound again with the compound of the sulphur of oxygen atom combination also because of being comparatively ideal at more effective lithium secondary battery that prevents on expanding with above-mentioned identical reason.

The compound of above-mentioned sulphur is preferably the compound shown in the following formula (1).

In above-mentioned general formula (1), R ¹And R ²Independent respectively expression X ¹Or O-X ¹, X ¹The expression carbon number is the chain of 1-9 or the saturated hydrocarbyl of ring-type, chain or the unsaturated alkyl of ring-type or the aromatic hydrocarbyl of carbon number 6-9 of carbon number 1-9, but R ¹And R ²Also can be interconnected to form 5 or 6 yuan of rings of sulfur atom-containing.Here with X ¹In conjunction with the functional group of aerobic, i.e. O-X ¹As R ¹, R ², can effectively suppress the rising of enclosure pressure.

As the chain of above-mentioned carbon number 1-9 or the saturated hydrocarbyl of ring-type, for example available methyl, ethyl, n-pro-pyl, uncle's propyl group, normal-butyl, sec-butyl, cyclohexyl etc.Wherein, from the point that more can bring into play effect of the present invention, better be with methyl, ethyl.

As the chain of above-mentioned carbon number 1-9 or the unsaturated alkyl of ring-type, for example available vinyl, pi-allyl, cyclobutenyl, pentenyl etc., wherein, from more bringing into play effect of the present invention, more handy vinyl.

As the aromatic hydrocarbyl of above-mentioned carbon number 6-9, for example available, phenyl, 4-aminomethyl phenyl etc.Wherein, from more bringing into play effect of the present invention, more handy phenyl.

R ¹And R ²Carbon number add up to and to be preferably 2-7.This is because little with the substituent steric hindrance of sulphur atom combination, can effectively suppress the rising of enclosure pressure.

R ¹And R ²Can interconnect and form 5 or 6 yuan of rings of sulfur atom-containing.As such ring, for example available, 1 of divalent free radical, 4-butylidene, 1, the 5-pentylidene ,-O-(CH ₂) n-,-O-(CH ₂) m-O-etc. (n, m are respectively the integer of 2-4 usually, and n is preferably 3 or 4, and m is preferably 2 or 3).Wherein, from more bringing into play effect of the present invention, preferably the oxygen atom with the sulphur atom combination is many, steric hindrance is little-O-(CH ₂) ₃-,-O-(CH ₂) ₂-O-.

The compound of above-mentioned sulphur is preferably the compound shown in the following formula (2):

In following formula (2), R ³And R ⁴Represent X respectively independently ²Or O-X ², X ²The expression carbon number is the chain of 1-9 or the saturated hydrocarbyl of ring-type, chain or the unsaturated alkyl of ring-type or the aromatic hydrocarbyl of carbon number 6-9 of carbon number 1-9, but R ³And R ⁴Also can be interconnected to form 5 or 6 yuan of rings of sulfur atom-containing.Here with X ²Go up functional group, i.e. O-X in conjunction with aerobic ²As R ³, R ⁴Can effectively suppress the rising of enclosure pressure.

As X ², the X that has illustrated in the available and above-mentioned general formula (1) ¹Identical material.In addition, R ³And R ⁴Total carbon atom number better scope also and R ¹And R ²The better scope of total carbon number the same.In addition, at R ³And R ⁴Mutually combine and form under the situation of ring also available and R ¹And R ²Mutually combine and form group the same when encircling.

Compound as above-mentioned sulphur, for example available, dimethyl sulfoxide (DMSO), diethyl sulfoxide, diphenyl sulfoxide, tetramethylene sulfoxide, the methyl-sulfinic acid methyl esters, the ethyl sulfinic acid ethyl ester, dimethyl sulfite, sulfurous acid diethyl ester, 1,2-propylene glycol sulfite, 1,3-butanediol sulfite, the sulfurous acid diphenyl ester, glycol sulfite, the sulfurous acid vinylene, dimethyl sulfone, the diethyl sulfone, the ethyl-methyl sulfone, diphenyl sulfone, the dibenzyl sulfone, sulfolane, the 3-methyl sulfolane, 3-methyl-2,5-dihydro-thiophene 1,1-dioxide (3-methyl sulfolene), methyl mesylate, ethyl methane sulfonate, the methanesulfonic acid acetonyl ester, methanesulfonic acid tetrahydrochysene chaff ester, the ethyl sulfonic acid methyl esters, the ethyl sulfonic acid ethyl ester, the propane sulfonic acid methyl esters, methyl benzene sulfonate, 1, the 3-N-morpholinopropanesulfonic acid lactone, 1, the 4-butyl sultone, dimethyl suflfate, dithyl sulfate, sulfuric acid ethyl methyl esters, sulfuric acid methyl phenyl ester, the sulfuric acid glycol ester, sulfuric acid 1, the ammediol ester, and sulfuric acid 1, the 4-butanediol ester.To in the compound of these sulphur some, its Eadd (A) and Eadd's (N) is poor: the numeric representation of Δ Eadd (AN) is in table 1.

The eV of table 1 unit

The compound of sulphur	ΔEadd(AN)
		Dimethyl sulfoxide (DMSO)	3.23
Diethyl sulfoxide	1.49
		Diphenyl sulfoxide	1.83
Tetramethylene sulfoxide	1.70
		Dimethyl sulfite	1.85
Sulfurous acid diethyl ester	2.15
		1,2-propylene glycol sulfite	1.99
1,3-butanediol sulfite	1.86
		Glycol sulfite	2.01
Dimethyl sulfone	1.37
		The diethyl sulfone	2.58
Diphenyl sulfone	1.41
		The dibenzyl sulfone	0.45
Sulfolane	1.48
		The 3-methyl sulfolane	1.46
3-methyl-2,5-dihydro-thiophene 1,1-dioxide	0.93
		Methyl mesylate	0.25
Ethyl methane sulfonate	0.24
		Methanesulfonic acid acetyl	0.94
Methanesulfonic acid tetrahydrochysene chaff ester	-0.12
		Methyl benzene sulfonate	1.44
1, the 3-N-morpholinopropanesulfonic acid lactone	-0.17
		1, the 4-butyl sultone	0.29
Dimethyl suflfate	2.04
		Dithyl sulfate	2.07
Glycol sulfate	-0.59
		1, the ammediol sulfuric ester	3.89
1,3-butanediol sulfuric ester	-0.103

The present invention importantly, the value that is contained in the value of Δ Esol (AN) of the nonaqueous solvents in the electrolyte and the Δ Eadd (AN) in the above-mentioned table 1 is relatively.For example, the value that is contained in the Δ Esol (AN) of the nonaqueous solvents in the electrolyte is 4 o'clock, all can obtain effect of the present invention with the compound of any sulphur in the table 1.On the other hand, for example the value of Δ Esol (AN) is 2 o'clock, at the additive below 2, can obtain effect of the present invention with Δ Eadd (AN) in the table 1.

But, if during, because of the difference of the value of the value that has Δ Esol (AN) and Δ Eadd (AN) becomes big trend, so the expansion of the lithium secondary battery can more effectively suppress the high temperature preservation time with the compound of the little sulphur of the Δ Eadd (AN) in the compound of these sulphur.

From above-mentioned viewpoint, Δ Eadd (AN) is comparatively desirable at the additive α below 3: diethyl sulfoxide (1.49eV), diphenyl sulfoxide (1.83eV), tetramethylene sulfoxide (1.7eV), dimethyl sulfite (1.85eV), sulfurous acid diethyl ester (2.15eV), 1,2-propylene glycol sulfite (1.99eV), 1,3-butanediol sulfite (1.86eV), glycol sulfite (2.01eV), dimethyl sulfone (1.37eV), diethyl sulfone (2.58eV), diphenyl sulfone (1.41eV), dibenzyl sulfone (0.45eV), sulfolane (1.48eV), 3-methyl sulfolane (1.46eV), 3-methyl-2,5-dihydro-thiophene 1,1-dioxide (0.93eV), methyl mesylate (0.25eV), ethyl methane sulfonate (0.24eV), methanesulfonic acid acetyl (0.94eV), methanesulfonic acid tetrahydrochysene chaff ester (0.12eV), methyl benzene sulfonate (1.44eV), 1, the 3-N-morpholinopropanesulfonic acid lactone (0.17eV), 1,4-butyl sultone (0.29eV), dimethyl suflfate (2.04eV), dithyl sulfate (2.07eV), the sulfuric acid glycol ester (0.59eV), and 1,3-butanediol sulfuric ester is (0.103eV).

In addition, from Δ Eadd (AN) in that this puts below 2, additive α is preferably: diethyl sulfoxide (1.49eV), diphenyl sulfoxide (1.83eV), tetramethylene sulfoxide (1.7eV), dimethyl sulfite (1.85eV), 1,2-propylene glycol sulfite (1.99eV), 1,3-butanediol sulfite (1.86eV), dimethyl sulfone (1.37eV), diphenyl sulfone (1.41eV), dibenzyl sulfone (0.45eV), sulfolane (1.48eV), 3-methyl sulfolane (1.46eV), 3-methyl-2,5-dihydro-thiophene 1,1-dioxide (0.93eV), methyl mesylate (0.25eV), ethyl methane sulfonate (0.24eV), methanesulfonic acid acetyl (0.94eV), methanesulfonic acid tetrahydrochysene chaff ester (0.12eV), benzene sulphur methyl esters (1.44eV), 1, the 3-N-morpholinopropanesulfonic acid lactone (0.17eV), 1,4-butyl sultone (0.29eV), the sulfuric acid glycol ester (0.59eV), and 1,3-butanediol sulfuric ester is (0.103eV).

From Δ Eadd (AN) in that this puts below 1.5, best additive α is: diethyl sulfoxide (1.49eV), dimethyl sulfone (1.37eV), diphenyl sulfone (1.41eV), dibenzyl sulfone (0.45eV), sulfolane (1.48eV), 3-methyl sulfolane (1.46eV), 3-methyl 2,5-dihydro-thiophene 1,1-dioxide (0.93eV), methyl mesylate (0.25eV), ethyl methane sulfonate (0.24eV), methanesulfonic acid acetyl (0.94eV), methanesulfonic acid tetrahydrochysene chaff ester (0.12eV), methyl benzene sulfonate (1.44eV), 1, the 3-N-morpholinopropanesulfonic acid lactone (0.17eV), 1,4-butyl sultone (0.29eV), the sulfuric acid glycol ester (0.59eV), and 1,3-butanediol sulfuric ester is (0.103eV).

For the compound of above-mentioned sulphur, can be contained in the arbitrary portion of cell device, but, better be contained in the positive pole or in the electrolyte from being present in the angle that the positive active material surface energy prevents the expansion of shell preferably, the spy is contained in the electrolyte it.Make it be contained in the positive pole or can have precedence over the nonaqueous solvents that is contained in the electrolyte in the electrolyte, and the surface interaction of the oxygen atom of and metal oxide surperficial at positive active material, its alkalescence is descended, the expansion of the shell the when result can effectively suppress the high temperature preservation.

When making the compound of above-mentioned sulphur be contained in the electrolyte, be contained in the nonaqueous solvents in the electrolyte and the content of solute with respect to 100 weight portions, its addition usually more than 0.001 weight portion, but better contain 0.1 weight portion above, better more than 0.5 weight portion, the spy fortunately more than 1 weight portion, be preferably in more than 5 weight portions.In addition with respect to the nonaqueous solvents of 100 weight portions and the content of solute, its addition is usually below 30 weight portions, but more fortunately below 15 weight portions, better below 10 weight portions.If it is insufficient that the shell when addition when being less than this scope, prevents sometimes that high temperature from preserving expands, and addition is when surpassing this scope, and the conductivity of electrolyte can descend sometimes, and the internal resistance of battery increases.

Open the flat 8-241731 of communique number of Japan's special permission, open the flat 8-241732 of communique number of Japan's special permission, open the flat 8-321312 of communique number of Japan's special permission, open communique 2000-133305 number of Japan's special permission, No. the 2734978th, Japan's special permission, No. the 2766018th, Japan's special permission and Japan's special permission disclose the compound that is similar to the compound of the sulphur among the additive therefor α among the present invention respectively No. 2804591.

But the rising of the enclosure pressure of the lithium secondary battery when Δ Eadd (AN) relation up to specification that these documents do not have record and hint to utilize to be made the Δ Esol (AN) of the nonaqueous solvents that is contained in the electrolyte and to be contained in the additive α in the cell device can suppress the high temperature preservation.

(2) nonaqueous solvents

The electrolyte that is used for lithium secondary battery of the present invention contains nonaqueous solvents and solute (in this manual, sometimes solute and nonaqueous solvents combination being called electrolyte or nonaqueous electrolytic solution).

Be used for nonaqueous solvents of the present invention Δ Esol (AN) greater than the Δ Eadd (AN) of the additive α that had before illustrated must be arranged.As such nonaqueous solvents, cyclic carbonates such as available for example ethylene carbonate, propylene carbonate, vinylene carbonate; Non-annularity carbonates such as dimethyl carbonate, diethyl carbonate, ethyl carbonate methyl esters; Furans such as oxolane, 2-methyltetrahydrofuran; Glyme classes such as glycol dimethyl ether; Lactone such as gamma-butyrolacton; Nitriles such as acetonitrile; Deng the mixture more than a kind or 2 kinds.Wherein, be preferably the mixed solution more than a kind or 2 kinds that is selected from cyclic carbonates, non-annularity carbonates and the lactone.

Esol (A) that the nonaqueous solvents of some above-mentioned concrete examples is obtained through the computational methods that before illustrated and Esol's (N) is poor: the numeric representation of Δ Esol (AN) is in table 2.

The eV of table 2 unit

	Nonaqueous solvents	ΔEsol(AN)
			Cyclic carbonates	Ethylene carbonate (EC)	2.37
Propylene carbonate (PC)	2.39
		Vinylene carbonate (VC)		2.00
The non-annularity carbonates	Dimethyl carbonate (DMC)				2.64
		Diethyl carbonate (DEC)	2.56
	Ethyl carbonate methyl esters (EMC)			2.56
		Lactone	Gamma-butyrolacton (GBL)		2.73

As mentioned above, the present invention importantly: the comparison of the value of the Δ Esol (AN) that is contained in the nonaqueous solvents in the electrolyte in the above-mentioned table 2 and the value of the Δ Eadd (AN) that is contained in the additive α in the cell device.For example, when using propylene carbonate, can significantly bring into play effect of the present invention with additive α with the following Δ Eadd (AN) of 2.39eV as nonaqueous solvents.

With a plurality of solvents during as nonaqueous solvents, contained with respect to the solvent of nonaqueous solvents integral body (100 volume %) more than the 20 volume % in, the value of the value of the Δ Esol (AN) of the solvent that Δ Esol (AN) value is minimum and the Δ Eadd (AN) of additive α is relatively.This be because, in the present invention, additive α must have precedence over the whole solvent that constitutes nonaqueous solvents, accept the positive active material surface alkalescence point electronics and make the cause of its resonance.For example, as nonaqueous solvents, during with the mixed in equal amounts solvent of ethylene carbonate and propylene carbonate, the value that is used for the value Δ Esol (AN) relatively of the Δ Eadd (AN) of additive α is the 2.37eV of ethylene carbonate; And for example by vinylene carbonate: ethylene carbonate: in the nonaqueous solvents of propylene carbonate=form at 10: 45: 45, the value of used Δ Esol (AN) is the 2.37eV of ethylene carbonate.

The angle of the expansion of the shell when more effective inhibition high temperature is preserved in the present invention, better contains high boiling solvent in nonaqueous solvents.High boiling solvent be meant boiling point usually more than 150 ℃, more fortunately more than 180 ℃, better more than 200 ℃, and usually below 300 ℃, more fortunately below 270 ℃, better solvent in the scope below 250 ℃.Fail safe when the solvent that has an above-mentioned scope boiling point by use can guarantee more that the high temperature of battery is preserved.As such solvent, available for example ethylene carbonate (243 ℃ of boiling points), propylene carbonate (240 ℃ of boiling points) and gamma-butyrolacton (204 ℃ of boiling points) etc.These high boiling solvents can be used separately, also a plurality of uses can be and used.In addition, also can and low boiling point solvent (in the present invention, referring to that boiling point is at the solvent below 150 ℃) and use.But " boiling point is X ℃ " even be meant under pressure 1atm and be heated to X ℃ from room temperature, vapour pressure also is no more than 1atm.

(3) miscellaneous part of lithium secondary battery

Lithium secondary battery of the present invention have comprise positive pole, negative pole and contain nonaqueous solvents and the electrolytical cell device of solute and put into above-mentioned cell device the variable shell of shape arranged.

(3-1) anodal negative pole

(A) positive active material

The positive pole of lithium secondary battery of the present invention normally forms the structure of positive electrode material layer on collector body, contain usually in above-mentioned positive electrode material layer and can inhale the positive active material that storage discharges Li.

As being used for anodal positive active material, various inorganic compounds such as the composite oxides of available transition metal oxide, lithium and transition metal, transient metal sulfide.Here as transition metal, available Fe, Co, Ni, Mn etc.Specifically, MnO, V ₂O ₅, V ₆O ₁₃, TiO ₂Composite oxide power, TiS Deng lithiums such as transition metal oxide powder, lithium nickel composite oxide, lithium cobalt composite oxide, complex Li-Mn-oxide and transition metal ₂, FeS, MoS ₂In transient metal sulfide powder etc.These compounds improve for making its characteristic, also can partly carry out element substitution.Organic compounds such as also available in addition polyaniline, polypyrrole, poly-nitrence, disulfide compound, polysulfide compounds, N-fluorine pyridiniujm.Also these inorganic compounds, organic compound can be mixed and use.The particle diameter of these positive active materials is generally 1-30 μ m, 1-10 μ m more fortunately.Particle diameter is excessive too small, all has battery behavior downward trends such as speed characteristic, cycle characteristics.

In above-mentioned positive active material, from obtaining the viewpoint of high performance lithium secondary battery, lithium-transition metal composite oxides such as the more handy lithium cobalt composite oxide of positive active material, lithium nickel composite oxide, complex Li-Mn-oxide.

In the present invention, the spy is contained lithium nickel composite oxide in the positive active material fortunately.But because of the current capacity of lithium nickel composite oxide per unit weight big, adopt the battery of this material not only to improve capacity, and the lithium secondary battery of high temperature in preserving easily expand, so the relation by above-mentioned nonaqueous solvents of control and above-mentioned additive α is with remarkable performance effect of the present invention.

Lithium nickel composite oxide is for containing the oxide of lithium and nickel at least.As lithium nickel composite oxide, better with for example having α-NaFeO ₂Layer structures such as structure, as LiNiO ₂The same lithium nickel composite oxide.As concrete composition, available for example LiNiO ₂, LiNi ₂O ₄Deng.At this moment, lithium nickel composite oxide also can be the composite oxides with the part of the element substitution beyond Ni Ni position occupied.Position with other element substitutions part Ni can make the stability of crystal structure strengthen, and when repeating to discharge and recharge, because of the Ni element of a part moves to the reduction that the Li position can suppress the capacity that taken place, so cycle characteristics also strengthens.In addition, (Differential Scanning Calorimetry: the heating initial temperature differential scanning calorimetry) moves on to high temperature side can to make DSC with the part of the element substitution beyond Ni Ni position, the thermal runaway reaction of lithium nickel composite oxide in the time of also can suppressing the battery temperature rising, the fail safe the when result is the high temperature preservation strengthens.

During the position that occupies with the Ni of the element substitution part beyond the Ni, as this element (below be designated as substitutional element), available for example Al, Ti, V, Cr, Mn, Fe, Co, Li, Cu, Zn, Mg, Ga, Zr etc.Can certainly be with the position of other element substitutions Ni more than 2 kinds.More handy Al, Cr, Fe, Co, Li, Mg, Ga, Mn etc. better use Al, Co.Ni element with Co, an Al displacement part can increase the effect of improving cycle characteristics, fail safe.

During with substitutional element displacement Ni position, its ratio usually 2.5 moles of Ni element more than the %, 5 moles more than the % more fortunately, usually 50 moles of Ni element below the %, 30 moles below the % more fortunately.If the displacement ratio is too small, it is insufficient to improve effect such as cycle characteristics sometimes, if excessive, when making battery sometimes, capacity can reduce.

In above-mentioned composition, also on a small quantity anoxic, have indefinite ratio property.In addition, also available sulphur or halogen are replaced the position of a part of oxygen.

In the present invention, lithium nickel composite oxide is preferably compound shown in the following formula (3), not displacement or with the compound of Co and Al displacement Ni position,

Li _aNi _xCo _yAl _zO ₂ (3)

In the general formula (3), the number that a changes for the difference with charging and discharging state in the battery usually more than 0, more than 0.3, in addition, is generally the number in 1.1 following scopes more fortunately.And x for usually more than 0.5, more fortunately more than 0.7, in addition usually below 1, the number in the scope below 0.9 more fortunately.Y for usually more than 0, more fortunately more than 0.1, opposite usually below 0.5, the number in the scope below 0.3 more fortunately.If y is at this more than scope, capacity reduces, and on the other hand at this below scope, then effect is not enough.Z be usually 0 or more, on the other hand common below 0.1, the number in the 0.05 following scope more fortunately.If surpass this scope, capacity reduces; If below the scope, effect is not enough at this.And the relation of above-mentioned x, y, the satisfied 0.9≤x+y+z of z≤1.1 is generally 1.0.The composition of above-mentioned general formula (3) expression can improve the effect increase of cycle characteristics and fail safe as mentioned above with the position that Co replaces a part of Ni, but can realize that with the position of a part of Ni of Al displacement cycle characteristics and fail safe further improve again.

The specific area that is used for lithium nickel composite oxide of the present invention is usually at 0.01m ²/ g is above, 0.1m more fortunately ²More than/the g, better at 0.5m ²More than/the g, in addition usually at 10m ²/ g is following, 5m more fortunately ²Below/the g, better at 2m ²Below/the g.Specific area is too small, and speed characteristic reduces, and causes that capacity reduces; Excessive, cause the reaction of undesirable and electrolyte etc., cycle characteristics is reduced.Carry out the mensuration of specific area by the BET method.

Be used for the present invention lithium nickel composite oxide the quadratic average particle diameter usually more than the 0.1 μ m, more fortunately more than the 0.2 μ m, better more than the 0.3 μ m, be preferably in more than the 0.5 μ m.In addition usually below the 300 μ m, more fortunately below the 100 μ m, better below the 50 μ m, be preferably in below the 20 μ m.If the quadratic average particle diameter is too small, battery circulation deterioration increases, and produces safety issue sometimes; Excessive, inside battery resistance increases, and is difficult to realize power output sometimes.

As positive active material, can use lithium nickel composite oxide separately, also can share with other lithium-transition metal composite oxide.As such lithium-transition metal composite oxide, available lithium cobalt composite oxide.The lithium cobalt composite oxide is the oxide that contains lithium and cobalt at least.The lithium cobalt composite oxide is smooth because of discharge curve, is the useful positive electrode of speed characteristic excellence.As the lithium cobalt composite oxide, the available LiCoO that for example has layer structure ₂Deng.In addition, the lithium cobalt composite oxide also can be the composite oxides with element substitution part Co position occupied beyond the Co.With other element substitution Co the position sometimes the cycle characteristics speed characteristic of battery strengthen.Substitutional element when usually replacing a part of Co position occupied as the unit beyond the Co, available Al, Ti, V, Cr, Mn, Fe, Li, Ni, Cu, Zn, Mg, Ga, Zr, Sn, Sb, Ge etc., more handy Al, Cr, Fe, Li, Ni, Mg, Ga, Zr, Sn, Sb, Ge better use Al, Mg, Zr, Sn.In addition, also available other yuan more than 2 kinds are usually replaced the position of Co.

With the position of substitutional element displacement Co the time, the ratio of this element is generally 0.03 mole of Co element more than the %, and 0.05 mole more than the % more fortunately, usually 30 moles of Co element below the %, better at 20 moles below the %.If the displacement ratio is very few, the situation of crystal structural stability deficiency can appear improving; If capacity during as battery can reduce too much.

The lithium cobalt composite oxide is used LiCoO usually as the preceding basic composition of charging ₂Expression, but also represent the position of other element substitutions of aforesaid usefulness part Co.In addition, also anoxic on a small quantity in the above-mentioned composition formula, tool is indefinite than property or with the position of the oxygen of a sulphur or a halogen displacement part.In addition, in above-mentioned composition formula, can make the lithium amount superfluous or not enough.

The specific area of lithium cobalt composite oxide is usually at 0.01m ²/ g is above, 0.1m more fortunately ²More than/the g, better at 0.4m ²More than/the g, in addition usually at 10m ²/ g is following, 5m more fortunately ²Below/the g, better at 2m ²Below/the g.If specific area is too small, speed characteristic reduces, and causes that capacity descends; And excessive, can cause the reaction of undesirable and electrolyte etc., cycle characteristics is reduced.Press BET method measurement the specific area.

The quadratic average particle diameter of lithium cobalt composite oxide usually more than the 0.1 μ m, more fortunately more than the 0.2 μ m, better more than the 0.3 μ m, be preferably in more than the 0.5 μ m, in addition usually below the 300 μ m, more fortunately below the 100 μ m, better below the 50 μ m, be preferably in below the 20 μ m.If the quadratic average particle diameter is too small, the circulation deterioration of battery increases, and also has the problem of fail safe; If excessive, it is big that inside battery resistance becomes, and is difficult to realize power output.

(B) organic acid and/or organic acid lithium salts

In the present invention, positive pole better contains organic acid and/or organic acid lithium salts.In positive pole, contain organic acid and/or organic acid lithium salts, and in cell device, contain above-mentioned additive α can be more effective the rising of inhibition high temperature enclosure pressure when preserving.

For above-mentioned organic acid, there is not special restriction, available for example acetate, propionic acid, stearic acid, glyoxalic acid, pyruvic acid, acetoacetate, levulic acid, phenylacetic acid, benzoylamino propionic acid, benzoic acid, oxalic acid, malonic acid, butanedioic acid, glutaric acid, adipic acid, maleic acid, phthalic acid, trimellitic acid, polyacrylic acid, polymethylacrylic acid, tricarballylic acid, benzene tricarbonic acid etc.In addition, the organic acid lithium salts there is not special restriction yet, available for example above-mentioned organic acid lithium salts.

In above-mentioned organic acid, comparatively ideal is organic acid more than 2 yuan.Can effectively suppress the rising of enclosure pressure like this.As the organic acid more than 2 yuan, for example available organic 2 yuan of acid and organic 3 yuan of acid.As 2 yuan of organic acids, available for example aliphat saturated dicarboxylic acid, aliphat unsaturated dicarboxylic, aromatic dicarboxylic acid etc.As the particular compound of aliphat saturated dicarboxylic acid, for example available oxalic acid, malonic acid, butanedioic acid, glutaric acid etc.As the particular compound of aliphat unsaturated dicarboxylic, available maleic acid etc. for example.As the particular compound of aromatic dicarboxylic acid, available phthalic acid etc. for example.As organic 3 yuan of acid, for example available tricarballylic acid, benzene tricarbonic acid etc.

Above-mentioned organic acid lithium salts also better is the above organic acid lithium salts of divalent, for example available above-mentioned 2 yuan, 3 yuan organic acid lithium salts.

As the organic acid that is used for the present invention, more handy oxalic acid, butanedioic acid are better used oxalic acid.These organic acids are little because of molecule, and the effect that suppresses the internal pressure rising is big.The organic acid lithium salts also because of and the same reason of above-mentioned organic acid, the lithium salts of more handy oxalic acid, butanedioic acid is better used the lithium salts of oxalic acid.These organic acids and/or organic acid lithium salts and additive α are used in combination, and the enclosure pressure when can more effective inhibition high temperature preserving rises.

Among the present invention the content of used organic acid and/or organic acid lithium salts with respect to from after deduct the weight of above-mentioned organic acid and/or organic acid lithium salts weight the whole weight of positive electrode material layer chatted, usually more than 0.1 weight portion, more fortunately more than 0.2 weight portion, better more than 0.3 weight portion, in addition usually below 1 weight portion, more fortunately below 0.8 weight portion, better below 0.6 weight portion.When if addition is less than this scope, may when preserve, high temperature can not fully suppress enclosure pressure and rise.In addition, if when surpassing this scope, the positive active material surface is covered by the non-permeability film of superfluous lithium ion, and battery charging/discharging characteristic can be adversely affected.

With respect to the above-mentioned organic acid of additive α and/or the content of organic acid lithium salts, be additive α with respect to 100 weight portions, usually more than 1 weight portion, more fortunately more than 5 weight portions, better more than 10 weight portions; In addition usually below 150 weight portions, more fortunately below 130 weight portions, better below 120 weight portions.

The effect that enclosure pressure rises when making additive α be contained in inhibition high temperature in the cell device to preserve is greater than making organic acid and/or organic acid lithium salts be contained in effect in the positive pole.But from the battery behavior equal angles, under the situation that the content of additive α is restricted in the cell device, if above-mentioned organic acid and/or organic acid lithium salts are contained in the positive pole with above-mentioned scope, can keep battery behavior and effectively suppress high temperature the rising of the enclosure pressure when preserving.

The method that above-mentioned organic acid and/or organic acid lithium salts are contained in the positive pole is as described below.As such method, for example be: organic acid and/or organic acid lithium salts are dissolved in the appropriate solvent, after in this solution, making positive active material moistening, remove and desolvate, can obtain containing the positive active material of above-mentioned organic acid etc., this positive active material is contained in the positive pole, and the result can make above-mentioned organic acid etc. be present in the positive pole.

Moreover, be coated on the collector body with coating and with it with the positive pole manufacturing that the anodal material of formation is contained in the solvent, when drying made positive pole, if organic acid and/or organic acid lithium salts are contained in this positive pole manufacturing with in coating, the result can make above-mentioned organic acid etc. be present in the positive pole.As above-mentioned organic acid etc. being contained in anodal the manufacturing with the method in the coating, be exemplified as: after being dissolved in organic acid and/or organic acid lithium salts in the above-mentioned coating solvent for use (for example N-methyl pyrrolidone), through in this solution, making the moistening operation of positive active material, next will constitute anodal other materials and be contained in this solution, through the method for the operation of coatingization.This method is desolvated so needn't remove after moistening operation because of the solvent of shared above-mentioned moistening operation and above-mentioned coating chemical industry preface, is comparatively ideal to boosting productivity.As the method that productivity ratio is improved more, available other materials with organic acid and/or organic acid lithium salts and formation positive pole once adds in the solvent, mixes, and carries out the method that the coatingization of coating is used in anodal manufacturing.Above-mentioned adding can directly add organic acid and/or organic acid lithium salts in the above-mentioned solvent, also can in advance organic acid and/or organic acid lithium salts be dissolved in anodal the manufacturing with in the used solvent of coating, adds to this solution again.When being solid-state, the latter's method is effective at organic acid and/or organic acid lithium salts.

Japan special permission is open disclose for communique 2001-35495 number with the used organic acid of the present invention like organic acid.But the document does not have record and hint to make the rising of the enclosure pressure in the lithium secondary battery of the Δ Eadd (AN) of the Δ Esol (AN) of the nonaqueous solvents that is contained in the electrolyte and additive α relation up to specification when suppressing the high temperature preservation.

(C) negative electrode active material

The negative pole that is used for lithium secondary battery of the present invention forms negative electrode material layer usually on collector body, and in above-mentioned negative electrode material layer, contains usually and can inhale the negative electrode active material that storage discharges Li.

As negative electrode active material, available carbon class active material.As carbon class active material, available for example graphite and coal class coke, petroleum-type coke, coal class pitch carbide, petroleum-type pitch carbide or these pitches are carried out the carbide such as carbide, needle coke, pitch coke, phenolic resins and avicel cellulose etc. after the oxidation processes and these carbide are carried out the graphited material with carbon element of part, furnace black, acetylene black, pitch-based carbon fiber etc.Moreover these carbon class active materials can utilize with metal or its salt, the mixture of oxide, the form of covering.As the negative electrode active material except that above-mentioned carbon class active material, the oxide or the sulfate of available silicon, tin, zinc, manganese, iron, nickel etc.; Lithium alloys such as lithium metal and Li-Al, Li-Bi-Cd, Li-Sn-Cd; The lithium transition-metal nitride; Metal such as silicon, tin etc.The particle diameter of these negative electrode active materials is generally 1-50 μ m, 5-30 μ m more fortunately.No matter be excessive or too small, the trend that all exists battery behaviors such as starting efficiency, speed characteristic, cycle characteristics to reduce.Also the negative electrode active material more than 2 kinds that is selected from above-mentioned can be share.

(D) be contained in other materials in positive pole, the negative pole

In positive electrode material layer and negative electrode material layer, can also contain and remove adhesive in addition such as above-mentioned positive active material, negative electrode active material (in this manual, sometimes positive active material and negative electrode active material being generically and collectively referred to as active material).With respect to the active material of 100 weight portions, the content of adhesive usually more than 0.01 weight portion, more fortunately more than 0.1 weight portion, better more than 1 weight portion; In addition usually below 50 weight portions, more fortunately below 30 weight portions, better below 15 weight portions.If the amount of adhesive is very few, be difficult to form firm positive pole.If the amount of adhesive is too much, energy density and cycle characteristics may reduce.

As adhesive, available for example polyethylene, polypropylene, poly--1, paraffinic polymer such as 1-dimethyl ethene; Unsaturated base polymer such as polybutadiene, polyisoprene; Polymer with ring of polystyrene, polymethylstyrene, polyvinylpyridine, poly-N-vinyl pyrrolidones etc.; Acryloyl group derivative polymers such as polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, polymethyl acrylate, polyethyl acrylate, polyacrylic acid, polymethylacrylic acid, polyacrylamide; Polyvinyl fluoride, poly-partially-fluorine-type resins such as vinylidene fluoride, polytetrafluoroethylene; Polyacrylonitrile, poly-inclined to one side dicyano ethene etc. contain the polymer of CN base; Polyvinyl alcohol based polymer such as polyvinyl acetate, polyvinyl alcohol; Halogen-containing polymer such as polyvinyl chloride, polyvinylidene chloride; Various resins such as electric conductive polymer such as polyaniline.In addition, also can use with forms such as the mixture of above-mentioned polymer etc., modification body, derivative, random copolymer, alternate copolymer, graft copolymer, block copolymers.In addition, also can use the inorganic compound of silicate and glass and so on.In the present invention, better use polyvinyl fluoride, poly-partially-fluorine-type resins such as vinylidene fluoride, polytetrafluoroethylene.

The weight average molecular weight of adhesive usually more than 1000, more fortunately more than 10000, better more than 20000, simultaneously usually below 5000000, more fortunately below 1000000, better below 300000.Cross when hanging down, mechanical strength of electrodes may reduce.When too high, the positive pole manufacturing is coated on the collector body with coating (or negative pole manufacturing coating) and the viscosity of above-mentioned coating when making anodal (or negative pole) uprises, may be difficult to form positive electrode material layer (or negative electrode material layer).

In positive electrode material layer and negative electrode material layer, can also contain additive that electric conducting material, reinforcing agent etc. have various functions, powder, filler etc. as required.As electric conducting material,, do not have restriction especially, but use carbon dust and various metal whisker, thin foils etc. such as acetylene black, carbon black, graphite usually as long as sneak into the material that just can give conductivity in the above-mentioned active material in right amount.As reinforcing agent, available various inorganic, organic spherical, fibrous fillers etc.

As the material of the collector body that is used for positive pole and negative pole, metals such as common available aluminium, copper, nickel, tin, stainless steel, the alloy of these metals etc.At this moment, use the collector body of aluminium usually, use the collector body of copper usually as negative pole as positive pole.The shape of collector body there is not special restriction, for example available tabular, netted.The thickness of collector body is generally 1-50 μ m, 1-30 μ m more fortunately.As too thin, mechanical strength dies down, and as blocked up, it is big that battery becomes, and taking up space in battery becomes big, and the energy density of battery diminishes.

The thickness of positive pole and negative pole is usually respectively more than the 1 μ m, more fortunately more than the 10 μ m; Usually below the 500 μ m, more fortunately below the 200 μ m.The too thick too thin battery performance downward trends such as capacity and speed characteristic that all exist.

Manufacture method to anodal (or negative pole) does not have special restriction, positive pole (or negative pole) manufacturing that for example active material and used as required adhesive and electric conducting material etc. is contained in (for example N-methyl pyrrolidone) in the solvent is coated on the collector body with coating, drying and the method that makes.In addition, for example, without solvent, with active material and as required and the adhesive of usefulness and electric conducting material etc. mixing after, press to be attached on the collector body and the method that makes.In the present invention, adopt the former method, promptly make comparatively ideal of positive pole with the anodal method made from coating.If adopt the former method, organic acid and/or organic acid lithium salts evenly are present in the positive pole easily.In addition, make organic acid and/or organic acid lithium salts be present in the positive pole method as mentioned above.

(3-2) electrolyte

Electrolyte contains the nonaqueous electrolytic solution that comprises nonaqueous solvents and solute.About nonaqueous solvents, as described in (2).

As solute, available any known in the past lithium salts.For example, LiClO ₄, LiAsF ₆, LiPF ₆, LiBF ₄, LiB (C ₆H ₅) ₄, CH ₃SO ₃Li, CF ₃SO ₃Li, LiN (SO ₂CF ₃) ₂, LiN (SO ₂C ₂F ₅) ₂, LiC (SO ₂CF ₃) ₃, LiSbF ₆, LiSCN etc., the available lithium salts more than at least a kind wherein.Wherein, from making obvious results angle of the present invention, special handy LiClO ₄, LiPF ₆These solutes are generally 0.5-2.5mol/l with respect to the content of nonaqueous electrolytic solution.

Can also contain additive except that above-mentioned solute, nonaqueous solvents in the nonaqueous electrolytic solution to guarantee fail safe and battery behavior (for example cycle characteristics).

In the present invention, electrolyte not only contains nonaqueous solvents and solute, also contains polymer, and is comparatively desirable.Contain polymer and improve, prevent the leakage of liquid, so the fail safe when further improving high temperature and preserving because of non-currentization of electrolyte being made protect fluidity.On the other hand, the rising of enclosure pressure when preserving lithium secondary battery owing to high temperature, the polymer that is contained in the electrolyte may come off from electrode surface.Coming off of this polymer increases inside battery resistance greatly.Therefore, when being contained in polymer in the electrolyte, the necessity of the rising of the enclosure pressure when by additive α is contained in inhibition high temperature being preserved becomes high especially.

As the polymer that is contained in the electrolyte, as long as can to a certain degree guarantee electrolytical guarantor's fluidity, any polymer gets final product, and this is not had special restriction.For example the acrylic polymer of available polymethyl methacrylate and so on, have alkylene oxide unit the alkylene oxides macromolecule, poly-partially-vinylidene fluoride and the fluorine family macromolecule etc. of vinylidene fluoride-hexafluoropropylene copolymer and so on partially.From fully guaranteeing electrolytical guarantor's fluidity, wherein better be in the molecule that is used in by the atomic building of chain bonding, have and forming the macromolecule (being referred to as in this manual, " bridging property polymer ") of crosslinked bonding (crosslinked bonding) arbitrarily between 2 atoms.

As the material of the basic framework of bridging property polymer, for example available polyester, polyamide, Merlon, polyimides etc. are through material that polycondensation generated; The material that polyurethane, polyureas etc. form through addition polymerization; Acrylic polymers such as polymethyl methacrylate or polyvinyl family macromolecules such as polyvinyl acetate, polyvinyl chloride etc. are through material that addition polymerization generated etc.

In the present invention, because of better being carries out polymerization after above-mentioned macromolecule being contained be immersed in the separator (see below in detail and chat), so do not generate the macromolecule that addition polymerization generated of accessory substance when better use is carried out polymerization control and polymerization easily.As such polymer, available acrylic polymer.From battery behaviors such as battery capacity and speed characteristic, mechanical strengths, acrylic polymer is comparatively ideal material.

As acrylic polymer, the spy is well the macromolecule that gets with the monomer polymerization that acryloyl group will be arranged.Mono acrylic ester classes such as for example available methyl acrylate, ethyl acrylate, butyl acrylate, acrylamide, acrylic acid 2-ethoxy ethyl ester, diethylene glycol ether acrylate, polyethylene glycol alkyl ether acrylate, polypropylene glycol alkyl ether acrylate, 2 cyanoethyl acrylate; 1,2-butanediol diacrylate, 1,3 butyleneglycol diacrylate, 1,4 butanediol diacrylate, neopentylglycol diacrylate, 1, alkanediol diacrylate classes such as 6-hexanediyl ester; Polyethyleneglycol diacrylate classes such as glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate; Polypropyleneglycol diacrylate classes such as propylene glycol diacrylate, propylene glycol diacrylate, tripropylene glycol diacrylate, four propylene glycol diacrylates; Bisphenol F ethoxylate diacrylate, Bisphenol F ethoxylate dimethylacrylate, bisphenol A ethoxy thing diacrylate, trimethylolpropane triacrylate, trimethylolpropane ethoxylate triacrylate, trimethylolpropane propoxylate triacrylate, isocyanuric acid ethoxylate triacrylate, the glycerol ethoxylate triacrylate, glycerine propoxylate triacrylate, the pentaerythritol ethoxylate tetraacrylate, two trimethylolpropane ethoxylate tetraacrylate, dipentaerythritol ethoxylate six acrylate etc.

Wherein, from the conductivity of lithium ions angle, special handy many acrylic ester high molecular types that the ethylene glycol unit is arranged.

In the present invention, the co-polymer of available above-mentioned monomer component and other monomer component is as acrylic polymer.That is, above-mentioned monomer component and the monomer with other structures except that above-mentioned monomer are coexisted and polymerization.When the monomer coexistence that makes the group with unsaturated double-bonds such as containing methacryl, vinyl, pi-allyl, electrolytical intensity and guarantor's fluidity may strengthen especially.As such monomer, compounds such as available methyl methacrylate, Methacrylamide, butadiene, acrylonitrile, styrene, vinyl acetate, vinyl chloride.

Whole monomers when using acrylic polymer, the rate that exists with monomer of acryloyl group does not have special restriction, but usually more than the 50 weight %, more fortunately more than the 70 weight %, the spy is fortunately more than the 80 weight %.Above-mentionedly there be high comparatively favourable of rate in fast from polymerization speed, as to improve electrolytical productivity ratio angle.

The bridging property polymer has cross-bond.Cross-bond can make by crosslinking agent and carry out cross-linking reaction between macromolecule and form.In addition, the bridging property polymer can be formed as high molecular raw material manufacturing by the monomer (being called " polyfunctional monomer ") that use has a plurality of reflecting points.The more handy latter's method.

When making the bridging property polymer with the latter's method, as raw material, except that with the polyfunctional monomer, also can share have 1 reflecting point monomer (hereinafter referred to as " monofunctional monomer ") as raw material.When polyfunctional monomer and monofunctional monomer are share, the functional group's of polyfunctional monomer equivalent proportion usually more than 10%, more fortunately more than 15%, better more than 20%.

The method of best manufacturing bridging property polymer will be for having the polyfunctional monomer polymerization of a plurality of acryloyl groups or as required and have a method of the monofunctional monomer copolymerization of 1 acryloyl group.

With respect to electrolytical whole weight, the content that is contained in the polymer in the electrolyte usually below the 80 weight %, more fortunately below the 50 weight %, better below 20 weight %.If polymer content is too much, then exist concentration reduction that ionic conductivity is reduced because of nonaqueous electrolytic solution, thus battery behavior downward trends such as speed characteristic.On the contrary, if the low excessively words of ratio of polymer, not only be difficult to the formation gel and the retentivity of nonaqueous solvents is reduced, cause that it flows and leak of liquid, but also may not guarantee the fail safe of battery, so with respect to electrolyte, the content of polymer usually more than the 0.1 weight %, more fortunately more than the 1 weight %, better more than the 2 weight %, be preferably in more than the 5 weight %.

With respect to the ratio of the polymer of nonaqueous solvents, though can suitably select according to the size of polymer molecular weight, usually more than the 0.1 weight %, more fortunately more than the 1 weight %; Usually below the 50 weight %, more fortunately below the 30 weight %.If polymer ratio is low excessively, then exist to be difficult to form gel, the retentivity of nonaqueous electrolytic solution reduces, and produces that nonaqueous electrolytic solution flows and the trend of the problem of leak of liquid.Opposite polymer ratio is excessive, and it is too high that viscosity becomes, and in addition, there is the lowering of concentration of nonaqueous electrolytic solution in operating difficulties and ionic conductivity is reduced, battery behavior downward trends such as speed characteristic.

In the present invention, allowing monomer as polymer raw material be contained under the state in the electrolyte, with this electrolyte is filled in the space of separator (chatting in detail), it is comparatively desirable after this to make above-mentioned monomer polymerization form the method for polymer.

As these monomer methods of polymerization, gimmicks such as available heat, ultraviolet ray, electron beam for example, but in the present invention,, make monomer polymerization comparatively desirable with heating or ultraviolet irradiation from the angle of easy manufacturing.When carrying out polymerization, for effectively promoting reaction also can to add the polymerization initiator of thermal response in advance in contained electrolyte with heat.As used thermal polymerization, available azobis isobutyronitrile, 2, azo compounds such as the two isobutyric acid dimethyl esters of 2 '-azo; Benzoyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide-peroxide such as 2 ethyl hexanoic acid ester etc.From reactivity, polarity, fail safe equal angles, its independent use also can be able to be share.In addition,, in the whole functional group of monomer, allow the functional group more than 30% react usually, but better make the functional group's reaction more than 40%, better make the functional group's reaction more than 50% for obtaining polymer.

Be to improve the ionic conductivity of lithium ion, above-mentioned electrolyte is contained be immersed in positive pole, negative pole and be configured in the separator between anodal negative pole better.

Separator is usually in order to prevent that the short circuit between anodal negative pole from using.Separator is made of porous membrane usually.As the material that is used for separator, TPO such as available polyethylene or polypropylene for example; Replace the TPO that part or all hydrogen atom of these TPO forms with fluorine atom; The porous membrane of resin such as polyacrylonitrile, aromatic polyamides.From to electrolytical chemical stability, to the stability of the voltage that applied, the polyolefin after more handy polyolefin or the fluorine displacement, specifically, polyethylene, polypropylene; Replace part or all the formed material of hydrogen atom in these polyolefin with fluorine atom.Wherein, polyolefin such as special handy polyethylene, polypropylene; Polytetrafluoroethylene (PTFE) and partially poly--vinylidene fluoride, polyolefin such as the most handy polyethylene, polypropylene.But, also available their copolymer or mixture.

As the number-average molecular weight of the resin of the raw material of separator usually more than 10,000, more fortunately more than 100,000, and usually below 1,000 ten thousand, more fortunately below 3,000,000.Molecular weight is too small, and its mechanical strength is not enough, exists electrode easily to produce the trend of short circuit.In addition, if molecular weight is excessive, electrolyte is difficult to contain in the space that is immersed in porous membrane, and the productivity ratio of battery is reduced, moreover also has also downward trend of battery performance such as speed characteristic.In addition, molecular weight is excessive, with also very difficult system films such as the methods of chatting after stretching behind the mixed plasticizer.

As mentioned above, separator is generally porous membrane.As porous membrane, though available for example porousness stretched PTFE film, nonwoven fabrics etc. in the present invention, are preferably the stretched film that is formed by stretching.The porousness stretched film is even than nonwoven fabrics because of the film internal resistance, so can suppress separating out of local lithium, promptly suppresses to become the separating out of skeleton of inter-electrode short-circuit inducement.

The stretching of porousness stretched film no matter be single shaft or biaxial stretch-formed can, but more handy biaxial stretch-formed.So-calledly biaxial stretch-formedly be meant that the vertical and horizontal mechanical strength of film is more approaching, so more easy to operate on battery is made.

The void content of separator usually more than 30%, more fortunately more than 35%, usually below 80%, more fortunately below 75%, better below 72%.Void porosity is too small, and it is big that membrane resistance becomes, the speed characteristic variation.When using under two-forty especially, capacity reduces.On the contrary, voidage is excessive, and the mechanical strength of film reduces, and its result is when changing the shape of cell device, produces short circuit and becomes easy.In the present invention, voidage is big more, and the electrolytical guarantor's fluidity effect that can use the bridging property polymer to produce is strong more, so the fail safe that high temperature is preserved strengthens.

The average pore size that is present in the space in the separator usually below the 0.2 μ m, more fortunately below the 0.18 μ m, better below 0.15 μ m; Usually more than the 0.01 μ m, more fortunately more than the 0.07 μ m.The aperture is excessive, easily produces short circuit; On the contrary, the aperture is too small, and it is big that membrane resistance becomes, and battery performances such as speed characteristic have the trend of reduction.In the present invention, average pore size is big more, and the electrolytical guarantor's fluidity effect that can use the bridging property polymer to produce is big more, and the fail safe that high temperature is preserved is high more.

The thickness of separator is usually more than the 5 μ m, more fortunately more than the 7 μ m; Usually below the 50 μ m, more fortunately below the 28 μ m, better below the 25 μ m, be preferably in below the 20 μ m.If thickness is too small, can easily produce self-discharge because of slight (mild) short circuit phenomenon; And thickness is blocked up, and not only battery behavior such as speed characteristic is not enough, and volume energy density has the trend of reduction.In the present invention, the thickness of separator is little and when using the bridging property polymer, can effectively prevent self-discharge.

The proof voltage that separator has is usually more than the 0.3kV, more fortunately more than the 0.5kV.Here in the middle of " proof voltage with X kV " refers to separator is sandwiched in and when applying voltage more than the X kV, the electric current more than no 100mA between electrode flows through.If proof voltage is low excessively, when battery increases because of certain reason part resistance when charging, its as a result temperature can raise unusually.Moreover, there is the trend that prevents that effectively self-discharge from becoming difficult.From the easy degree that practicality obtains, proof voltage usually below the 1000kV, more fortunately below the 100kV, better below 10kV.

For more effective perverse perforation intensity of pin (the pinpenetration strength) when preventing that short circuit is local and exerting pressure to separator usually more than the 200gf, more fortunately more than the 230gf, better more than 300gf.But pin wears that to connect intensity excessive be unpractical, thus usually below the 2000gf, more fortunately below the 1500gf, better below 1000gf.

In addition, better the distortion that is produced during the stretching separator on a certain direction in order to the power of 0.1kg/cm is at the separator below 1%, its result is when more effectively preventing short circuit, when battery is made, carry in the operation and lamination operation of separator, also easily keep the accuracy of separator position etc., qualification rate is improved.But it is difficult in fact will to obtain the too little separator of above-mentioned distortion, so usually more than 0.01%, more fortunately more than 0.1%.

To the separator of 1 direction in 100 ℃ percent thermal shrinkage usually below 10%, more fortunately below 9%, better below 7%.Here " to the percent thermal shrinkage of 1 direction " refers to draw direction in stretched film and the percent thermal shrinkage on the vertical direction thereof respectively.Percent thermal shrinkage is excessive, the heating when making battery and under hot environment the easier electrode tip that makes such as maintenance be short-circuited.In addition, when using biaxially-stretched film,, better be to make the percent thermal shrinkage of two draw directions comparatively approaching because of the easiness on manufacturing and designing as stretched film.At this moment, the difference of the percent thermal shrinkage of two draw directions usually in 7%, but more fortunately 5% with interior, better in 4.5%.

The surface tension of separator usually more than the 40dyne/cm, more fortunately more than the 46dyne/cm, the spy is fortunately more than the 48dyne/cm.Its result easily makes electrolyte fully contain in the space that is immersed in porous membrane, boosts productivity, and can realize the raising of speed characteristic.Having capillary like this film for it is become, better is to carry out surface modification treatment such as Corona discharge Treatment, plasma treatment, fluorine gas processing to separator usually.But because of being difficult to obtain the very high film of surface tension, so surface tension is usually below the 60dyne/cm, more fortunately below the 58dyne/cm.

Separator can make as described below.To be blended in number-average molecular weight as the plasticizer of uneven dispersant and be about 10,000-1,000 ten thousand, in 100,000-3,000,000 the resin, mixing back film forming is a sheet more fortunately.After this again through making desirable separator toward the operation that in length and breadth any direction or two directions stretch with the operation of solvent extraction plasticizer with specified multiple.

(3-3) cell device and put into the shell of cell device

Lithium secondary battery of the present invention is put into shell with cell device.Cell device is that fundamental forms with the element cell element usually, and this element cell element is by constituting as the positive pole of main component and negative pole and electrolyte with active material.This element cell element formed elongated size and roll form cell device, maybe will be configured as flat this element cell element and carry out laminated multi-layer and form cell device.Promptly, form as cell device, for example can have: with flat element cell element carry out flat layer die mould that laminated multi-layer forms, the element cell element that forms the elongated size is rolled into flat tabular and rolls type, in addition, the element cell element that forms the elongated size is rolled into cylinder cylindraceous rolls type.In the present invention, from the angle of productivity ratio and Miniaturizable, the form of cell device is preferably tabular and rolls type or flat layer die mould.With the cell device of tabular volume type and flat layer die mould the time, the shell of putting into these cell devices also is tabular, but such tabular shell is when high temperature, and the spy easily produces at thickness direction expands, so adopt the effect spy of above-mentioned additive α good.

When cell device adopts tabular to roll the form of type, the element cell element roll number usually more than 2, more fortunately more than 3, better more than 4; Usually below 20, more fortunately below 15, better below 10.If the volume number is few, the capacity of entire cell tails off, and is opposite if the volume number is too much, is unfavorable for the miniaturization of battery.

When if cell device adopts the flat layer die mould, the number of plies of element cell element usually more than 5 layers, more fortunately more than 8 layers, better more than 10 layers; Usually below 50 layers, more fortunately below 30 layers, better below 25 layers.The number of plies is few, and the capacity of entire cell tails off, and the opposite number of plies is too much, and is from the miniaturization of battery, unfavorable.

Below, with the lithium secondary battery of the cell device of putting into the flat layer die mould with the shape variable body seal as an example, the contrast accompanying drawing describes the concrete shape of lithium secondary battery of the present invention.But these only are an example wherein, and the present invention is not subjected to the restriction of these execution modes.

Fig. 1 is the exploded perspective view of the battery of an embodiment of the present invention, and Fig. 2 is the sectional view of the major part of this battery, and Fig. 3 is the summary stereogram of cell device, and Fig. 4 is the stereogram of battery.

This battery is for after putting into the recess of housing material 3 with cell device 1, near insulating material 5 such as injection ring epoxy resins and the acrylic resin portion of terminal (joint 4a, 4b) of cell device 1, after this, housing material 2 is covered on housing material 3, with vacuum seal with the neighboring part 2a of housing material 2,3, the battery that 3a is bonded.

As shown in Figure 1, housing material 2 is a tabular.Housing material 3 is for having the uncovered tray shape of holding portion 3b and neighboring part 3a.This holding portion 3b is as the recess of square box shape, outwards protrudes flange and forms and neighboring part 3a is 4 limits from this holding portion 3b.

As shown in Figure 3, cell device 1 carries out lamination with a plurality of element cell elements and forms on thickness direction.From this element cell element joint 4a or 4b are drawn.To prick (that is, overlapping) and positive wire 21 joints from each joint 4a that positive pole is drawn, form the positive terminal part.Also will prick and cathode conductor 21 engages and forms the negative terminal part from each joint 4b that negative pole is drawn.

Cell device 1 is put into the holding portion 3b of housing material 3, near insulating material 5 fill nipple 4a, 4b, cover near positive terminal part and the negative terminal part cell device side with insulating material after, cover housing material 2.The 1 pair of lead 21 that extends out from cell device 1 mating surface between neighboring part 2a, the 3a on 1 limit by housing material 2,3 is respectively drawn outward.After this, the decompression (being preferably vacuum) atmosphere under with gimmicks such as heat pressure adhesive or ultrasonic bonding with neighboring part 2a, the 3a on 4 limits of housing material 2,3 between seal bond, cell device 1 is sealing in the housing material 2,3.After this, for cure process such as heating, near the terminal part, insulating material 5 is fully by firm attachment with insulating material 5.Because of before the complete firm attachment, housing material is sealed, so when adhering to, the shape of battery is no change almost.Near terminal part (joint 4a, 4b), insulating material 5 is filled, even internal pressure rises when high temperature is preserved, the internal pressure that also can effectively prevent housing material (shell) the coming off of caused cell device of rising also effectively prevents short circuit.

By with bonding joint fastener part (bonded portions) 4A, 4F, the 4G of forming between neighboring part 2a, 3a.This joint fastener part 4A, 4F, 4G are outwards given prominence to from the packaged unit 4B (packingportion) that encases cell device 1.Therefore, with this joint fastener part 4A, 4F, 4G crooked so that its extend along packaged unit 4B.

Also be fit to the following method: the side (being fixed) that these joint fasteners partly is bonded in packaged unit 4B with jointing material or adhesive tape (not having diagram) etc.The internal pressure of the housing material (shell) when Gou Zao battery can prevent effectively that high temperature from preserving like this coming off of caused cell device of rising, or the side intensity of battery, rigidity are strengthened.Certainly can prevent also that the joint fastener part that is bent breaks away from from packaged unit.In addition, because of intensity, the rigidity height of battery side, so, also can prevent the disengaging of active material even when being subjected to impacting in the side.

As above-mentioned insulating material 5, more handy synthetic resin, though illustration epoxy resin, acrylic resin, silicon tree ketone fat etc., wherein short because of the firm time of epoxy resin or acrylic resin, be fit to epoxy resin or acrylic resin.Particularly acrylic resin is less because of the possibility that it influences the battery performance variation, so best.With insulating material unhardened, have under the mobile state near the feeding terminal part, again after sclerosis, can be fully with near the good bond terminal part.

In Fig. 1, though respectively insulating material is supplied with positive terminal part and negative terminal part, the fail safe when preserving in order to improve high temperature can cover insulating material from positive terminal portion and assign on the side of negative terminal entire cell element partly.

In Fig. 1, though housing material 2,3 is what separate, in the present invention, as shown in Figure 5, housing material 2,3 also can join together.In Fig. 5, one side the linking to each other of one side of housing material 3 and housing material 2, housing material 2 becomes the lid shape to housing material 3 flexible connections.From one side that this housing material 2,3 is connected, form the recess of holding portion 3b, do not form the joint fastener part on this limit, all the other are the structure same with the joint fastener part in addition.

Even under the situation of Fig. 5, cell device 1 put into holding portion 3b after, also insulating material is injected into cell device joint 4a, 4b near.

In Fig. 1, Fig. 5, housing material 3 and flat housing material 2 have all been shown with holding portion 3b, but in the present invention, as shown in Figure 6, also available housing material 6,7 encases cell device 1, and this housing material 6,7 has holding portion 6b, the 7b of tray shape and neighboring part 6a, the 7a that stretches out from 4 limits of this holding portion 6b, 7b respectively.In Fig. 6,, can as above-mentioned Fig. 1 chorista also though housing material 6,7 joins together.

In the structure of Fig. 1, Fig. 5 and Fig. 6, the holding portion of cell device is owing to be preformed, so can more compactly cell device be put into wherein, itself is also easy and pack into.

In the above description, though cell device is packed into behind the holding portion, near insulating material injection end subdivision, but this moment, have insulating material to adhere to inflow between the mating surface of peripheral part or cell device and housing material outside, the joint that may hinder the neighboring part maybe can not be made the cell shapes of design.Therefore, near the holding portion of after insulating material being supplied with the terminal part of cell device cell device being packed into can be avoided above-mentioned problem.Special under the situation of Fig. 6, even after cell device is packed into, supply with insulating material, insulating material can not be offered on the first half of cell device substantially, this manufacture method is more satisfactory.But in the method,, place it in the housing material and carry out, so must note operation during fabrication because of the not tractable cell device of having supplied with the state of insulating material of carrying.Consider from this point, we can say that the former method is more satisfactory.

In the present invention, also can will as shown in Figure 71 flat sheet housing material 8 be converted into 2 foldings along center edge 8a, form the 1st 8A and the 2nd 8B 2, cell device 1 is placed between the 1st 8A and the 2nd 8b, as shown in Figure 8, can engage the neighboring part 8b of the 1st 8A and the 2nd 8B, cell device 1 is enclosed.In addition, also can be with the following method: making cylindricly with the two ends of membranaceous housing material are bonding, packs into behind the cell device in inside, again with the bonding method up and down of tube.

Equally in these cases, with insulating material attached to joint 4a, the 4b of cell device 1 near before or after, the 1st 8A and the 2nd 8B of housing material 8 overlapped to enclose cell device 1.Crooked and the method for joint fastener partial fixing is comparatively desirable along packaged unit.

During near the capped end subdivision cell device side, configuration and interfixes this separator edge convex camber than the separator of anodal and negative maximum between special positive pole fortunately and negative pole.

That is, in cell device, for example as shown in figure 18, separator 13 is bloated slightly in anodal 11 and negative pole 12, form edge convex camber 13a and prevent anodal 11 and the short circuit of negative pole 12.With insulating material this edge convex camber 13a is interfixed, because cell device limits by laminating direction, so the rise disengaging of caused cell device of the internal pressure of housing material (shell) can prevent effectively that high temperature from preserving the time.In addition, the whole side that can run through cell device provides insulating material, and is more satisfactory.

The method of injecting insulating material better is: the nozzle 51 with the injection device 50 of insulating material inserts in the housing materials 3 as shown in figure 17, insulating material is injected into the side end face of cell device 1.

At this moment, as Figure 14, Figure 15, shown in Figure 16, better insulating material is injected into R2, R3, R4, the R5 many places of the both sides of two R1 of corner, the R6 of side end face of configuration joint 4a or 4b and joint 4a, 4b root.The insulating material that is injected into will comprise that through effect such as capillarity whole one side of positive terminal part and negative terminal cell device side partly soaks into.These injection device 50 configuration a plurality of (6) nozzles can once inject insulating material to a plurality of positions.

As shown in figure 16, when insulating material is injected into the root of joint 4a, 4b both sides, the decanting point center of nozzle 51 (inject) more fortunately from the 2mm of joint 4a or 4b with interior place.When insulating material being injected into the root of joint 4a, 4b both sides like this, this insulating material is good bond edge convex camber 13a not only, also can obtain as above-mentioned structure shown in Figure 5: with insulating material and at least a portion that covers in positive terminal part and the negative terminal part.

In above structure,, better be root bending from packaged unit though can make the joint fastener part that membranaceous housing material is bonded along the packaged unit bending that encases cell device.At this moment, joint fastener part can be in the root bending of packaged unit once, also repeatedly bending.When bending repeatedly, better the front edge with the joint fastener part is clipped in this joint fastener part and packaged unit centre bending.Like this, can make the front edge and the isolation of joint fastener part, can prevent that moisture and air etc. from invading from front edge.

As can be used for the adhesive of fixed engagement sheet part on packaged unit, epoxy available class adhesive, acrylic adhesives, polyurethane binding, hot melt class adhesive or synthetic rubber class adhesive etc., even but under the low environment of dew point short from firm time and when being used in the manufacturing of non-water class battery, also the angle of sclerosis is seen more handy hot melt class adhesive easily.

Below the suitable structure in the element cell element is described.

Fig. 9 shows an example of the element cell element that is suitable for this lithium secondary battery element.This element cell element is that electrolytical separator 24 of the positive pole, the impregnation that are made of positive electrode collector 22 and positive electrode material layer 23 and the negative pole lamination that is made of negative electrode material layer 25 and negative electrode collector 26 are formed.For suppressing separating out of lithium skeleton, negative pole compares positive maximum.In addition, for preventing short circuit, separator 24 is than positive pole and negative maximum.Make the separator can be as mentioned above, the edge convex camber of the separator of element cell element is interfixed greater than both positive and negative polarity.

The method that a plurality of these element cell element layers are pressed into cell device is: when carrying out this lamination, to be in alternately that positive pole is put layer and negative pole put down layer normotopia (Fig. 9) the element cell element and be in opposite location, promptly anodally put down layer and negative pole is put the element cell element of the antiposition (not shown) of layer and carried out lamination and form.That is, make along the adjacent element cell element of laminating direction and carry out lamination and make with mutually (that is, anodal and positive pole and negative pole and negative pole) relative.

Extend positive terminal 4a from the positive electrode collector 22 of this element cell element, extend anode connector 4b from negative electrode collector 26.

Need not be as shown in Figure 9, between positive electrode collector and negative electrode collector lamination the element cell element of positive electrode material layer, separator and negative electrode material layer, also can make following element cell element as shown in figure 10: with positive electrode collector 15a or negative electrode collector 15b as core, at its upper strata, two sides positive pressure utmost point material layer 11a or negative electrode material layer 12a, make positive pole 11 and negative pole 12, the electrolytical separator 13 that accompanied impregnation, as shown in figure 11 alternately should positive pole 11 and negative pole 12 laminations make the element cell element.At this moment, the combination of the 1 pair of positive pole 11 and negative pole 12 (strictly speaking from the center of anodal 11 collector body 15a thickness direction to the center of the thickness direction of the collector body 15b of negative pole 12) is equivalent to an element cell element.

The flat shape of electrode can be arbitrary shape, can be made into quadrangle, circle, polygon etc.

As Fig. 9, shown in Figure 10, on collector body 22,26 or 15a, 15b, be connected with joint 4a, 4b that lead engages usefulness usually.When electrode is quadrangle, usually as shown in Figure 3 near electrode one side formation protrude in the joint 4a of positive electrode collector, in addition, the joint 4b of negative electrode collector forms near opposite side.

A plurality of element cell element layers are pressed in to make on the cell high-capacityization be effectively, at this moment, extended joint 4a and joint 4b are bonded in respectively on the thickness direction usually from the element cell element respectively, to form the terminal part of anodal and negative pole.Consequently can obtain jumbo cell device 1.

On joint 4a, 4b, engaging as shown in Figure 2 has laminar metal lead 21.Consequently the positive pole with lead 21 and cell device is connected with negative electricity.Utilize the welding of spot welding constant resistance, ultrasonic bonding or laser welding to carry out the joint between joint 4a, between 4b and the joint of joint 4a, 4b and lead 21.

At least a kind of 21 in above-mentioned positive wire and the cathode conductor better is to use annealed metal, better uses annealed metal entirely.Consequently can make all excellent battery of intensity and resistance to bend(ing).

As the metal species that is used for lead, common available aluminium or copper, nickel or SUS etc.As positive wire, material is an aluminium preferably.In addition, as cathode conductor, material is a copper preferably.

The thickness of lead 21 is usually more than 1 μ m, more fortunately more than the 10 μ m, better more than 20 μ m, better more than 40 μ m.Cross thinly, the not enough trend of mechanical strength of leads such as hot strength is arranged.In addition, the thickness of lead usually below the 1000 μ m, more fortunately below the 500 μ m, better below 100 μ m.Blocked up, have the trend of crooked poor durability, moreover also useful shell is difficult to the trend with the cell device sealing.Chat after the use annealed metal as the advantage of lead along with conductor thickness is thick more, remarkable more.

The width of lead is usually more than the 1mm, below the 20mm, the spy fortunately above, the 10mm of 1mm following about.Lead exposed parts length is usually about more than the 1mm, below the 50mm.

In the lithium secondary battery in the present invention, the shell that holds cell device has shape variable.The shape variable shell is not only easily made the battery of different shape, but also has the thin and advantage that gently volume of battery energy density and weight energy density are improved of shell self, but because of comparing with metal-back, its rigidity is not enough, and shell can expand when high temperature was preserved.Therefore, with the shape variable shell time, in cell device, contain above-mentioned additive α, can bring into play comparatively significant effect.

The shape variable shell refers to has flexible shell.Specifically, refer to have flexibility, the shell of flexibility etc.More particularly, refer to the shell that can flexibly crooked, easily the tabular shell be changed to shapes such as L font or S font with staff.

As the material of shape variable shell, metals such as the iron of available aluminium, nickel plating, copper, synthetic resin etc.The more handy laminated film that is provided with barrier layer and resin bed all is provided with the laminated film of resin bed on the two sides of special handy barrier layer.Such laminated film has beyond the high gas barrier, also has high shape variable and thinness.Consequently can make the lightweight of housing material filming, cell integrated capacity is improved.

As the material of the barrier layer that is used for laminated film, metal oxides such as alloys such as metals such as available aluminium, iron, copper, nickel, titanium, aluminium, gold, stainless steel or hastelloy, silica or aluminium oxide.Be preferably the aluminium of the excellent in workability of light weight.

As the resin that is used for resin bed, various synthetic resin such as available heat thermoplastic plastic, thermoplastic elastomer class, thermosetting resin, plastic alloy.In these resins, also can be mixed with packing materials such as filler.

As the structure of concrete laminated film, the available film that shown in Figure 12 (A), barrier layer 40 and resin bed 41 laminations is formed.In addition; better laminated film is: shown in Figure 12 (B); configuration synthetic resin layer 41 is so that it has the function as outside protective layer on the lateral surface of barrier layer 40; on medial surface, dispose synthetic resin layer 42 simultaneously; have function to prevent electrolytical corrosion and contacting of barrier layer and cell device etc., and it is laminated to the three-layer structure body as the inboard protective layer of protection barrier layer.

At this moment, the resin that is used for outside protective layer is preferably the resin of chemical resistance such as polyethylene, polypropylene, improved polyalkene, ionomer, amorphous polyolefin, PETG, polyamide and mechanical strength excellence.

As inboard protective layer, available chemical-resistant synthetic resin, for example available polyethylene, polypropylene, improved polyalkene, ionomer, vinyl-vinyl acetate copolymer etc.

In addition, laminated film can also be at as shown in figure 13 barrier layer 40 and form between the protective layer used synthetic resin layer 41, barrier layer 40 and form between the synthetic resin layer 42 that anticorrosion layer uses bonding material layer 43 is set respectively, more satisfactory.Moreover, be bonding housing material, also can on the inner face of composite material, the adhesive layer that is made of resins such as the polyethylene that can weld, polypropylene be set.Can form shell with these metals, synthetic resin or composite material.The manufacturing process of shell is: meltbility around the membranous body can and formed, and also can be by vacuum forming, reduce pressure shaping, die forming etc. with plates stretch forming.In addition, also can be by injection moulding with forming synthetic resin.When using injection moulding, usually with formation barrier layers such as sputters.

Holding portion for configuration recess on the housing material that is used for the shape variable shell can carry out stretch process to it.From the angle of easy processing, more handy film material is as housing material.

The thickness of shape variable shell usually more than the 0.01 μ m, more fortunately more than the 0.02 μ m, better more than 0.05 μ m; Usually below the 1mm, more fortunately below the 0.5mm, better below the 0.3mm, more fortunately below the 0.2mm, better below 0.15mm.Though thin more, battery more can the miniaturization lightweight, too thin, the caused danger of breaking of rising of enclosure pressure increased when not only high temperature was preserved, and can not give enough rigidity and sealing is reduced.

With cell device pack into the whole thickness of lithium secondary battery behind the shell usually below the 5mm, more fortunately below the 4.5mm, better below 4mm.For slim like this lithium secondary battery, effect of the present invention is big especially.But battery is too thin, has capacity too small, and is difficult to problems such as manufacturing, thus usually more than the 0.5mm, more fortunately more than the 1mm, better more than 2mm.

But it is first-class to be assemblied in equipment for the ease of battery, cell device is sealed in be configured as required form in the shape variable shell after, also can as required a plurality of these lithium secondary batteries be reinstalled in the external packing shell that has rigidity.

(4) purposes of lithium secondary battery

The electric equipment that lithium secondary battery of the present invention is used as power supply is: laptop computer, Writing type PC (tablet personal computer), portable data assistance (Personal Digital Assistants, PDA), electronic game machine, mobile phone, the cordless telephone handset, pager, portable terminal, portable facsimile printer, portable copier, portable printer, the stereophone broadcast receiver, home theater, LCD TV, portable dust collector, portable CD, minidisk (mini disk), electric shaver, wireless set, electronic memo, calculator, storage card, portable recorder, broadcast receiver, stand-by power supply, engine, ligthing paraphernalia, toy, game machine, load governor, clock, strobotron, camera and medicine equipment (pacemaker, hearing aids, massager etc.) etc.

Embodiment

Below, utilize embodiment that the present invention is described in more detail, but the present invention is not subjected to any restriction of following embodiment, as long as in the scope that does not change main points of the present invention, can suitably change and implement.In addition, the part in the composition is a weight portion.

A. the kind of the compound of sulphur and have or not the influence of interpolation.

(reference example 1)

As described below, make the lithium secondary battery that contains dimethyl sulfoxide (DMSO) in the electrolyte.

(anodal manufacturing)

With following composition preparation positive electrode coating.With lithium nickel composite oxide (LiNi _0.82Co _0.15Al _0.03O ₂) to make specific area be 0.38m for synthetic back, pulverizing, grade separation ²The composite oxides of/g.In addition, lithium cobalt composite oxide (LiCoO ₂) the employing specific area is 0.50m ²The composite oxides of/g.

The composition of positive electrode coating:

Lithium cobalt composite oxide (LiCoO ₂) 27 weight portions

LiNi _0.82Co _0.15Al _0.03O ₂63 weight portions

Acetylene black 5 weight portions

Partially poly--vinylidene fluoride 5 weight portions

N-N-methyl-2-2-pyrrolidone N-80 weight portions

With planetary-type mixer type mixing roll mixing 2 hours of above-mentioned raw materials is made positive electrode coating.Next, above-mentioned positive electrode coating is coated on the aluminium collector body substrate that thickness is 15 μ m by extrusion coating, dry and make and utilize adhesive that active material is bonded in multiple aperture plasma membrane on the collector body.Use roll press (calender) to carry out compacting then, make electrode slice.After this, electrode is made in the electrode slice cut-out, as positive pole.The weight of positive active material is 10mg/cm ²

(manufacturing of negative pole)

With following composition preparation negative pole coating.

The composition of negative pole coating:

Graphite (particle diameter is 15 μ m) 90 weight portions

Poly-inclined to one side vinylidene fluoride 10 weight portions

N-N-methyl-2-2-pyrrolidone N-100 weight portions

With planetary-type mixer type mixing roll mixing 2 hours of above-mentioned raw materials is made negative pole coating.Next, above-mentioned negative pole coating is coated on the copper collector substrate that thickness is 20 μ m by extrusion coating, dry and make and utilize adhesive that active material is bonded in multiple aperture plasma membrane on the collector body.Use roll press (calender) to carry out compacting then, make electrode slice.After this, electrode is made in the electrode slice cut-out, as negative pole.

(ratio of anodal negative electrode material layer)

In the manufacturing example of the anodal negative pole of above-mentioned manufacturing, the thickness of adjusting positive electrode material layer and negative electrode material layer is so that (anodal charging capacity)/(charging capacity of negative pole)=0.93.And with Li as to the utmost point with battery charge when the 1.5V-3mV, the charging capacity of negative pole is based on the capacity (mAh/g) of per unit negative pole weight.

(electrolyte forms the manufacturing of the coating of usefulness)

Mix and stir following composition, the coating that dielectric substrate forms usefulness is made in dissolving.

Electrolyte forms the composition with coating

Electrolyte 925 weight portions

The mixed liquor of ethylene carbonate and propylene carbonate (volume ratio: ethylene carbonate: propylene carbonate=1: 1) contain the LiPF of 1M concentration ₆

Tetraethylene glycol diacrylate 44 weight portions

Poly(ethylene oxide) triacrylate 22 weight portions

Dimethyl sulfoxide (DMSO) 9.3 weight portions (※)

Polymerization initiator 2 weight portions

Additive (succinyl oxide) 9 weight portions

※ contains dimethyl sulfoxide (DMSO) with the ratio with respect to 1.0 weight portions of electrolyte.

(manufacturing of lithium secondary battery)

The coating that electrolyte is formed usefulness is coated on the above-mentioned positive pole and negative pole that has prepared, in addition, prepare to be soaked with the high-molecular porous plasma membrane (separator) that dielectric substrate forms the coating of usefulness again, after being clipped in this film between positive pole and the negative pole, in 90 ℃ of heating 10 minutes, make electrolyte form tetraethylene glycol diacrylate and the polymerization of poly(ethylene oxide) triacrylate in the coating of usefulness, like this, make and comprise and contain active material and adhesive and be formed on positive pole on the collector body, negative pole and the electrolytical flat element cell element of illiquidity is arranged between positive pole and negative pole.

The lead of projected current is connected on the terminal part of positive electrode collector, negative electrode collector of said units cell device.Use 0.34mA/cm ²It is 4.2V that electric current charges to cell voltage with the cell device of such gained.After this, above-mentioned cell device is packed in the shell of the bag shape that laminated film doubling that aluminium film two sides has resin bed to cover forms, the laminated film sealing is made flat lithium secondary battery with vacuum seal.

(expansion test 1 of lithium secondary battery when high temperature is preserved)

The expansion test of lithium secondary battery was when high temperature was preserved: with lithium secondary battery in 90 ℃ preserve 4 hours after, the expansion situation of range estimation laminated film, with " nothing ", " little ", " in ", " greatly " 4 grades carry out relative evaluation.Evaluation result sees Table 3.

(mensuration of battery initial capacity)

The initial capacity of lithium secondary battery will be for will charge to the sample 0.34mA/cm that cell voltage is 4.2V ²The discharge capacity of current discharge when cell voltage is 3.0V.

Here, with the discharge capacity of the lithium secondary battery gained of reference example 1 as 100, and the discharge capacity of the secondary lithium batteries said method gained of other embodiment, comparative example is represented that with the relative value with respect to above-mentioned 100 discharge capacity its evaluation result sees Table 3.

(embodiment 1)

Form with in the composition of coating at the electrolyte of reference example 1, except replace dimethyl sulfoxide (DMSO) with tetramethylene sulfoxide, all the other all with the reference example 1 the same lithium secondary battery that makes.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 3.

(embodiment 2)

Form with in the composition of coating at the electrolyte of reference example 1, except replace dimethyl sulfoxide (DMSO) with dimethyl sulfite, all the other all with the reference example 1 the same lithium secondary battery that makes.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 3.

(embodiment 3)

Form with in the composition of coating at the electrolyte of reference example 1, except replace dimethyl sulfoxide (DMSO) with glycol sulfite, all the other all with the reference example 1 the same lithium secondary battery that makes.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 3.

(embodiment 4)

Form with in the composition of coating at the electrolyte of reference example 1, except replace dimethyl sulfoxide (DMSO) with dimethyl sulfone, all the other all with the reference example 1 the same lithium secondary battery that makes.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 3.

(embodiment 5)

Form with in the composition of coating at the electrolyte of reference example 1, except replace dimethyl sulfoxide (DMSO) with sulfolane, all the other all with the reference example 1 the same lithium secondary battery that makes.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 3.

(embodiment 6)

Form with in the composition of coating at the electrolyte of reference example 1, except replace dimethyl sulfoxide (DMSO) with methyl mesylate, all the other all with the reference example 1 the same lithium secondary battery that makes.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 3.

(embodiment 7)

Form with in the composition of coating at the electrolyte of reference example 1, except with 1, beyond the 3-N-morpholinopropanesulfonic acid lactone replacement dimethyl sulfoxide (DMSO), all the other all with the reference example 1 the same lithium secondary battery that makes.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 3.

(embodiment 8)

Form with in the composition of coating at the electrolyte of reference example 1, except replace dimethyl sulfoxide (DMSO) with dithyl sulfate, all the other all with the reference example 1 the same lithium secondary battery that makes.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 3.

(embodiment 9)

Form with in the composition of coating at the electrolyte of reference example 1, except replace dimethyl sulfoxide (DMSO) with the sulfuric acid glycol ester, all the other all with the reference example 1 the same lithium secondary battery that makes.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 3.

(comparative example 1)

Form with in the composition of coating at the electrolyte of reference example 1, except not adding dimethyl sulfoxide (DMSO), all the other all with the reference example 1 the same lithium secondary battery that makes.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 3.

(comparative example 2)

Form with in the composition of coating at the electrolyte of reference example 1, except replace dimethyl sulfoxide (DMSO) with diphenylsulfide, all the other all with the reference example 1 the same lithium secondary battery that makes.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 3.

(comparative example 3)

Form with in the composition of coating at the electrolyte of reference example 1, except replacing dimethyl sulfoxide (DMSO) with diphenylsulfide, and its addition is beyond 47 weight portions, all the other all with the reference example 1 the same lithium secondary battery that makes.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 3.

Table 3

	Additive (compound of sulphur)	Addition (with respect to the addition of electrolyte)	The expansion (remarks 1) of the lithium secondary battery when high temperature is preserved	Initial cells capacity (relative value)
					Reference example 1	Dimethyl sulfoxide (DMSO)	1.0 weight portion	In	100
Embodiment 1	Tetramethylene sulfoxide	1.0 weight portion	In	101
					Embodiment 2	Dimethyl sulfite	1.0 weight portion	Little	101
Embodiment 3	Glycol sulfite	1.0 weight portion	In	101
					Embodiment 4	Dimethyl sulfone	1.0 weight portion	Little	102
Embodiment 5	Sulfolane	1.0 weight portion	Little	101
					Embodiment 6	Methyl mesylate	1.0 weight portion	Little	102
Embodiment 7	1, the 3-N-morpholinopropanesulfonic acid lactone	1.0 weight portion	In	101
					Embodiment 8	Dithyl sulfate	1.0 weight portion	In	100
Embodiment 9	The sulfuric acid glycol ester	1.0 weight portion	Do not have	101
					Comparative example 1	Do not have	-	Greatly	100
Comparative example 2	Diphenylsulfide	1.0 weight portion	Greatly	101
					Comparative example 3	Diphenylsulfide	5.0 weight portion	Greatly	100

(remarks 1): the evaluation result when being illustrated in " expansion test 1 of lithium secondary battery when high temperature is preserved ".With the naked eye see, with the expansion situation be divided into " greatly ", " in ", " little ", " nothing ".

As known from Table 3:

At first as can be known from the result of reference example 1, embodiment 1-9 and comparative example 1, if in electrolyte not during the compound of sulfur-bearing, being expanded to of lithium secondary battery when high temperature is preserved " greatly ", and the expansion of the lithium secondary battery of the compound that in electrolyte, contains the sulphur of two keys that 1 above sulphur and oxygen are arranged high temperature can be preserved the time be controlled at " in ", " little ", " nothing ".That is, in such lithium secondary battery, the compound of sulphur with two keys of 1 above sulphur and oxygen can be used as additive α.

The second, from the result of comparative example 2,3 as can be known, even sulfur-bearing in the molecule, but do not form the compound of two keys of sulphur and oxygen, the expansion of the lithium secondary battery in the time of can not suppressing the high temperature preservation.That is, in such lithium secondary battery, diphenylsulfide does not belong to additive α.

The 3rd, respectively the result of reference example 1 and embodiment 4 and the result of embodiment 1 and embodiment 5 are compared as can be known, the double key number of intramolecular sulphur and oxygen when 1 becomes 2, the expansion of the lithium secondary battery in the time of can reducing high temperature more and preserve.

The 4th, the result with result, embodiment 5 and the embodiment 9 of reference example 1 and embodiment 2 compares as can be known respectively, by making oxygen again and the sulfide linkage that is formed with two keys of sulphur and the oxygen expansion of closing the lithium secondary battery can reduce the high temperature preservation more the time.

The 5th, from the measurement result of the initial cells capacity of reference example 1, embodiment 2-9 and comparative example 1-3 as can be known, contain tool more than 1 sulphur and the compound of the sulphur of two keys of oxygen in lithium secondary battery, not poor as the fundamental characteristics of lithium secondary battery.

" expansion test 2 of lithium secondary battery when high temperature is preserved "

For determining that reference example 1, embodiment 1-9, comparative example 1 various lithium secondary batteries prevent the limit capacity of the expansion effect of lithium secondary battery under the high temperature preservation when containing additive α in cell device, prepare 2 (n=2) or 3 (n=3) above-mentioned every kind of lithium secondary battery respectively, and these lithium secondary batteries were preserved 24 hours down in 90 ℃.

Following evaluation is carried out in the expansion of the lithium secondary battery after high temperature preserved: promptly, in the housing material laminated film of lithium secondary battery, after the part of observing expansion ticked, break lithium secondary battery.The laminated film of breaking the back gained is divided into marked part and does not have marked part.Then, from the laminated film weight of the part of observing expansion total weight, try to achieve weight ratio with respect to the dilation of laminated film total weight divided by laminated film.The density of laminated film is considered as necessarily, this weight ratio can be decided to be the area ratio of expression with respect to the area of the dilation of whole laminated film area.

Be displayed in Table 4 the value of area ratio of the above-mentioned dilation of the value of Δ Esol (AN) (comparative example 1) of the Δ Eadd (AN) (reference example 1, embodiment 1-9) of additive α and nonaqueous solvents and lithium secondary battery.The curve chart of relation that in Figure 19, has shown the area ratio of the value of Δ Esol (AN) (comparative example 1) of the Δ Eadd (AN) (reference example 1, embodiment 1-9) of additive α and nonaqueous solvents and above-mentioned dilation.In addition, in table 4 and Figure 19, Δ Esol (AN) has been used for the ethylene carbonate (Δ Esol (AN)=2.37) of solvent and the less ethylene carbonate of Δ Esol (AN) value of propylene carbonate (Δ Esol (AN)=2.39).

Table 4

			Expansion area relative value (n=2 or 3)
									ΔEsol(AN)、 ΔEadd(AN)/eV	1	2	3	Mean value
Reference example 1	Dimethyl sulfoxide (DMSO)	3.230	0.253	0.263	0.249	0.255
							Embodiment 2	Tetramethylene sulfoxide	1.699	0.252	0.253	0.251	0.252
Embodiment 3	Dimethyl sulfite	1.854	0.266	0.243	-	0.255
							Embodiment 4	Glycol sulfite	2.012	0.260	0.271	0.250	0.261
Embodiment 5	Dimethyl sulfone	1.365	0.145	0.121	0.158	0.141
							Embodiment 6	Sulfolane	1.482	0.207	0.172	0.226	0.201
Embodiment 7	Methyl mesylate	0.249	0.092	0.089	0.092	0.091
							Embodiment 8	Third sultone	-0.172	0.076	0.056	0.081	0.071
Embodiment 9	Dimethyl suflfate	2.038	0.237	0.239	0.226	0.234
							Embodiment 10	The sulfuric acid glycol ester	-0.585	0.107	0.122	0.083	0.104
Comparative example 1	Ethylene carbonate (EC)	2.370	0.182	0.255	0.174	0.204

In Figure 19, use respectively *, △, zero symbol mark and draw the n=1,2,3 of the expansion area relative value in the table 4, shown the linear approximation straight line of the mean value of each expansion area relative value.

The linear approximation straight line of the mean value of the n=1-3 from Figure 19 as can be known, promptly, with the value of the Δ Esol (AN) of the ethylene carbonate (EC) that is used for nonaqueous solvents as benchmark, when making the additive that has less than Δ Eadd (AN) value of this fiducial value be contained in the electrolyte, the area relative value of dilation diminish (expansion diminishes).And when making the additive that has greater than the value of this Δ Esol (AN) be contained in the electrolyte, dilation area relative value becomes big (expand and become big).Specifically, the Δ Eadd (AN) of dimethyl sulfoxide (DMSO) is 3.23eV, is that 2.37eV is big than the Δ Esol (AN) of EC.For this reason, under 90 ℃, 24 hours too harsh high temperature preservation condition the expansion of lithium secondary battery (reference example 1) greater than the expansion of the lithium secondary battery that does not contain additive (comparative example 1).

In above-mentioned " expansion test 1 of lithium secondary battery when high temperature is preserved " (below's be sometimes referred to as " expansion test 1 ") measurement result, the expansion evaluation result of lithium secondary battery when high temperature is preserved that contains dimethyl sulfoxide (DMSO) be " in " (reference table 3).That is, the expansion evaluation result the when high temperature that contains the lithium secondary battery of dimethyl sulfoxide (DMSO) is preserved, expansion test 1 and " expansion test 2 of lithium secondary battery during the high temperature preservation " (below be sometimes referred to as " expansion test 2 ") are different.The reason that forms this result is that it is different that the high temperature of expansion test 1 is preserved the high temperature preservation experimental condition of experimental condition and expansion test 2.That is, for the high temperature preservation condition (90 ℃, 4 hours) of expansion test 1, the high temperature preservation condition of expansion test 2 (90 ℃, 24 hours) very severe.This means by the high temperature of expansion test 2 and preserve the limit capacity that to determine additive.Two keys that sulphur and oxygen are arranged because of dimethyl sulfoxide (DMSO), in the expansion test 1 of the index that is enough to have or not practicality (practical usefulness) as judgement, the expansion of the battery in the time of can suppressing the high temperature preservation, and battery has or not in the expansion test 2 of limit evaluation means of expansion when judging that high temperature is preserved, and expansion has but taken place lithium secondary battery.This result means, even in the compound of the sulphur of regulation, the value that also will utilize the Δ Esol (AN) of the value of Δ Eadd (AN) and nonaqueous solvents is the expansion of the battery of the compound of the sulphur of particular kind of relationship when suppressing the high temperature preservation conscientiously.And, also we can say the limit capacity that can determine additive by expansion test 2, in the present invention, the meaning of the relation of the value of the value of the Δ Esol (AN) of adjustment nonaqueous solvents and the Δ Eadd (AN) of additive is clearer and more definite.

B. to the discussion of the addition of the compound of sulphur

(embodiment 10)

Form with in the composition of coating at the electrolyte of embodiment 4, except the addition with dimethyl sulfone becomes 4.7 weight portions, all the other all with the embodiment 4 the same lithium secondary batteries that make.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 5.

(embodiment 11)

Form with in the composition of coating at the electrolyte of embodiment 4, except the addition with dimethyl sulfone becomes 47 weight portions, all the other all with the embodiment 4 the same lithium secondary batteries that make.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 5.

(embodiment 12)

Form with in the composition of coating at the electrolyte of embodiment 4, except the addition with dimethyl sulfone becomes 94 weight portions, all the other all with the embodiment 4 the same lithium secondary batteries that make.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 5.

Table 5

	Additive (compound of sulphur)	Addition (with respect to the addition of electrolyte)	The expansion (remarks 2) of the lithium secondary battery when high temperature is preserved	Initial cells capacity (relative value)
					Embodiment 10	Dimethyl sulfone	0.5 weight portion	In	100
Embodiment 4	Dimethyl sulfone	1.0 weight portion	Little	102
					Embodiment 11	Dimethyl sulfone	5.0 weight portion	Do not have	101
Embodiment 12	Dimethyl sulfone	10.0 weight portion	Do not have	100

(remarks 2): the evaluation result of expression " expansion test 1 of lithium secondary battery when high temperature is preserved ".With the naked eye see, with the expansion situation be divided into " greatly ", " in ", " little ", " nothing ".

In table 4, also put down in writing of the influence of the data of embodiment 4 with the addition of detailed discussion dimethyl sulfone additive.

As can be known from the results of Table 4, in such lithium secondary battery, the compound dimethyl sulfone of sulphur that has two keys of 1 above sulphur and oxygen in the molecule has the function of additive α.When particularly containing with respect to the dimethyl sulfone more than 5.0 weight portions of electrolyte, the expansion the when high temperature that can suppress lithium secondary battery is fully preserved.In addition, from the measurement result of initial cells capacity as can be known, if addition is even increase the addition of dimethyl sulfone, not poor as the fundamental characteristics of lithium secondary battery at least when 10 weight portions are following yet.

C. the influence of positive active material

(comparative example 4)

In reference example 1, except without lithium nickel composite oxide (LiNi _0.82Co _0.15Al _0.03O ₂), and use lithium cobalt composite oxide (LiCoO separately ₂) (in the composition of positive electrode coating, add making lithium cobalt composite oxide (LiCoO as positive active material ₂) be 90 weight portions) and do not add beyond the dimethyl sulfoxide (DMSO), all the other all with the reference example 1 the same lithium secondary battery that makes.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 6.

Table 6

	Positive active material	The expansion (remarks 3) of the lithium secondary battery when high temperature is preserved	Initial cells capacity (relative value)
				Comparative example 1	LiCoO 2 LiNi 0.82Co 0.15Al 0.03O 2	Greatly	100
Comparative example 4	LiCoO 2	Do not have	82

(remarks 3): the evaluation result of expression " expansion test 1 of lithium secondary battery when high temperature is preserved ".With the naked eye see, with the expansion situation be divided into " greatly ", " in ", " little ", " nothing ".

In table 6, also put down in writing of the influence of the data of comparative example 1 with the kind of detailed discussion positive active material.

As can be known from the results of Table 6, in the lithium secondary battery of comparative example 1,4, use lithium cobalt composite oxide (LiCoO separately ₂) as positive active material,, with the naked eye see the expansion when also not finding the high temperature preservation even do not contain additive α.That is, more obvious for the expansion issues that battery capacity is become in positive active material, contain lithium nickel composite oxide greatly the shape variable shell when high temperature is preserved.

The reason that is expanded to " nothing " of the lithium secondary battery the when high temperature in the comparative example 4 is preserved is considered to: the 1st, and the lithium secondary battery in the comparative example 4 adopts polymer dielectric and high boiling solvent and becomes for high temperature preserves more stable composition; In addition, the 2nd, be to be 4 hours the high temperature holding time, short cause.90 ℃, 4 hours high temperature preservation condition in the expansion test 1, if consider the words of the practicality of lithium secondary battery, be enough conditions, but as expansion test 2, it is not the limit high temperature preservation condition that lithium secondary battery has or not expansion when judging the high temperature preservation, so the lithium secondary battery of comparative example 4 is carrying out expansion test 2, when lithium secondary battery has or not the limit of expansion to estimate when carrying out the high temperature preservation, can envision lithium secondary battery and can occur expanding.Therefore, even in the lithium secondary battery of comparative example 4, if additive α is contained in the cell device, and when adjusting nonaqueous solvents and additive α and being specific the relation, even under harsher high temperature preservation condition, also can suppress the expansion of lithium secondary battery conscientiously.

D. the influence of the specific area of positive active material

(embodiment 13)

Except in embodiment 11, being 0.60m with specific area ²Lithium nickel composite oxide (the LiNi of/g _0.82Co _0.15Al _0.03O ₂) in addition, all the other all with the embodiment 11 the same lithium secondary batteries that make.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 7.

(embodiment 14)

Except in embodiment 11, being 0.74m with specific area ²Lithium nickel composite oxide (the LiNi of/g _0.82Co _0.15Al _0.03O ₂) in addition, all the other all with the embodiment 11 the same lithium secondary batteries that make.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 7.

(embodiment 15)

Except in embodiment 11, being 0.92m with specific area ²Lithium nickel composite oxide (the LiNi of/g _0.82Co _0.15Al _0.03O ₂) in addition, all the other all with the embodiment 11 the same lithium secondary batteries that make.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 7.

(comparative example 5)

Except in reference example 1, being 0.60m with specific area ²Lithium nickel composite oxide (the LiNi of/g _0.82Co _0.15Al _0.03O ₂) and do not add beyond the dimethyl sulfoxide (DMSO), all the other all with the reference example 1 the same lithium secondary battery that makes.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 7.

Table 7

	The compound of the sulphur that is added	Specific area (the m of lithium nickel composite oxide 2/g)	The expansion (remarks 4) of the lithium secondary battery when high temperature is preserved	Initial cells capacity (relative value)
					Embodiment 11	Dimethyl sulfone	0.38	Do not have	101
Embodiment 13	Dimethyl sulfone	0.60	Little	101
					Embodiment 14	Dimethyl sulfone	0.74	In	102
Embodiment 15	Dimethyl sulfone	0.92	In	102
					Comparative example 1	Do not have	0.38	Greatly	100
Comparative example 5	Do not have	0.60	Greatly	101

(remarks 4): the evaluation result when being illustrated in " expansion test 1 of lithium secondary battery when high temperature is preserved ".With the naked eye see, with the expansion situation be divided into " greatly ", " in ", " little ", " nothing ".

As can be known from the results of Table 7, even make the specific area of lithium nickel composite oxide be changed to 0.38-0.92m ²/ g, as being expanded to of the lithium secondary battery when containing the compound of sulphur that dimethyl sulfone etc. contains two keys of 1 above sulphur and oxygen high temperature being preserved " in "-" nothing ".This result has shown that in such lithium secondary battery dimethyl sulfone has served as additive α of the present invention.On the other hand, if do not contain under the situation of dimethyl sulfone, even specific area is 0.38m ²/ g or 0.60m ²During/g, above-mentioned being expanded to " greatly ".

E. be added on organic acid and or the influence of organic acid lithium salts in the positive pole

(embodiment 16)

Except in reference example 1, by beyond the following manufacturing method for anode manufacturing, all the other are all the same with reference example 1, make lithium secondary battery.That is, make with coating so that oxalic acid is contained in the positive pole so that the preparation of following composition is anodal.

The anodal composition made from coating:

Lithium cobalt composite oxide (LiCoO ₂) 27 weight portions

LiNi _0.82Co _0.15Al _0.03O ₂63 weight portions

Acetylene black 5 weight portions

Poly-inclined to one side vinylidene fluoride 5 weight portions

Oxalic acid 0.4 weight portion

N-methyl-2-pyridine alkane ketone 80 weight portions

With planetary-type mixer type mixing roll mixing 2 hours of above-mentioned raw materials is made positive electrode coating.Next, above-mentioned positive electrode coating is coated on the aluminium collector body substrate that thickness is 15 μ m by extrusion coating, dry and make with adhesive active material is bonded in positive electrode material layer on the collector body.Use roll press (calender) to carry out compacting then, make electrode slice.After this, electrode is made in the electrode slice cut-out, as positive pole.The weight of positive active material is 10mg/cm ²

Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 8.

(embodiment 17)

In the composition except the coating that forms usefulness at the electrolyte of embodiment 16, replace beyond the dimethyl sulfoxide (DMSO) with tetramethylene sulfoxide, all the other all with the embodiment 16 the same lithium secondary batteries that make.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 8.

(embodiment 18)

In the composition except the coating that forms usefulness at the electrolyte of embodiment 16, replace beyond the dimethyl sulfoxide (DMSO) with dimethyl sulfite, all the other all with the embodiment 16 the same lithium secondary batteries that make.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 8.

(embodiment 19)

In the composition except the coating that forms usefulness at the electrolyte of embodiment 16, replace beyond the dimethyl sulfoxide (DMSO) with glycol sulfite, all the other all with the embodiment 16 the same lithium secondary batteries that make.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 8.

(embodiment 20)

In the composition except the coating that forms usefulness at the electrolyte of embodiment 16, replace beyond the dimethyl sulfoxide (DMSO) with dimethyl sulfone, all the other all with the embodiment 16 the same lithium secondary batteries that make.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 8.

(embodiment 21)

In the composition except the coating that forms usefulness at the electrolyte of embodiment 16, replace beyond the dimethyl sulfoxide (DMSO) with sulfolane, all the other all with the embodiment 16 the same lithium secondary batteries that make.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 8.

(embodiment 22)

In the composition except the coating that forms usefulness at the electrolyte of embodiment 16, replace beyond the dimethyl sulfoxide (DMSO) with methyl mesylate, all the other all with the embodiment 16 the same lithium secondary batteries that make.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 8.

(embodiment 23)

In the composition except the coating that forms usefulness at the electrolyte of embodiment 16, with 1, beyond the 3-N-morpholinopropanesulfonic acid lactone replacement dimethyl sulfoxide (DMSO), all the other all with the embodiment 16 the same lithium secondary batteries that make.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 8.

(embodiment 24)

In the composition except the coating that forms usefulness at the electrolyte of embodiment 16, replace beyond the dimethyl sulfoxide (DMSO) with dithyl sulfate, all the other all with the embodiment 16 the same lithium secondary batteries that make.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 8.

(embodiment 25)

In the composition except the coating that forms usefulness at the electrolyte of embodiment 16, replace beyond the dimethyl sulfoxide (DMSO) with the sulfuric acid glycol ester, all the other all with the embodiment 16 the same lithium secondary batteries that make.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 8.

(comparative example 6)

In the composition except the coating that forms usefulness at the electrolyte of embodiment 16, do not add beyond the dimethyl sulfoxide (DMSO), all the other all with the embodiment 16 the same lithium secondary batteries that make.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 8.

Table 8

	Additive (compound of sulphur)	Addition (with respect to the addition of electrolyte)	The expansion (remarks 5) of the lithium secondary battery when high temperature is preserved	Initial cells capacity (relative value)
					Embodiment 16	Dimethyl sulfoxide (DMSO)	1.0 weight portion	In	100
Embodiment 17	Tetramethylene sulfoxide	1.0 weight portion	In	101
					Embodiment 18	Dimethyl sulfite	1.0 weight portion	Little	101
Embodiment 19	Glycol sulfite	1.0 weight portion	In	101
					Embodiment 20	Dimethyl sulfone	1.0 weight portion	Little	102
Embodiment 21	Sulfolane	1.0 weight portion	Little	101
					Embodiment 22	Methyl mesylate	1.0 weight portion	Little	102
Embodiment 23	1, the 3-N-morpholinopropanesulfonic acid lactone	1.0 weight portion	In	101
					Embodiment 24	Dithyl sulfate	1.0 weight portion	In	100
Embodiment 25	The sulfuric acid glycol ester	1.0 weight portion	Do not have	101
					Comparative example 6	Do not have	-	Greatly	100

(remarks 5): the evaluation result when being illustrated in " expansion test 1 of lithium secondary battery when high temperature is preserved ".With the naked eye see, with the expansion situation be divided into " greatly ", " in ", " little ", " nothing ".

Oxalic acid amount one timing in making positive pole, as can be known from the results of Table 8:

At first, from the result of embodiment 16-25 and comparative example 6 as can be known, in electrolyte not during the compound of sulfur-bearing, being expanded to of the lithium secondary battery when high temperature is preserved " greatly "; The expansion of the lithium secondary battery when on the other hand, the compound that contains the sulphur of the two keys with 1 above sulphur and oxygen in electrolyte can suppress high temperature and preserves " in ", " little ", " nothing ".The expansion of the lithium secondary battery when in other words, only in positive pole, containing oxalic acid and can not fully suppress high temperature and preserve.

The second, from the comparative result of the comparison of embodiment 16 and embodiment 20 and embodiment 17 and embodiment 21 as can be known, the sulphur that molecule contains and the double key number of oxygen are from 1 expansion that becomes 2 lithium secondary batteries can reduce high temperature more and preserve the time.

The 3rd, from the comparison of embodiment 16 and embodiment 18 and the comparative result of embodiment 21 and embodiment 25, the expansion of the lithium secondary battery when again sulphur combination can further reduction high temperature of oxygen and the two keys that are formed with sulphur and oxygen being preserved.

The 4th, from the measurement result of the initial cells capacity of embodiment 16-25 and comparative example 6 as can be known,, not poor as the fundamental characteristics of lithium secondary battery even allow the compound of sulphur of two keys be included in the lithium secondary battery with 1 above sulphur and oxygen yet.

(embodiment 26)

Except in embodiment 22, the oxalic acid content in the positive pole is become beyond 0.3 weight portion, all the other all with the embodiment 22 the same lithium secondary batteries that make.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 9.

(embodiment 27)

Except in embodiment 22, the oxalic acid content in the positive pole is become beyond 0.6 weight portion, all the other all with the embodiment 22 the same lithium secondary batteries that make.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 9.

(embodiment 28)

Except in embodiment 22, the oxalic acid content in the positive pole is become beyond 1.0 weight portions, all the other all with the embodiment 22 the same lithium secondary batteries that make.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 9.

(embodiment 29)

Except in embodiment 22, make methyl mesylate content become 4.7 weight portions and the oxalic acid content in the positive pole become beyond 0.6 weight portion, all the other all with the embodiment 22 the same lithium secondary batteries that make.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 9.

(embodiment 30)

Except in embodiment 22, make methyl mesylate content become 47 weight portions and the oxalic acid content in the positive pole become beyond 0.6 weight portion, all the other all with the embodiment 22 the same lithium secondary batteries that make.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 9.

Table 9

	The addition of the compound of sulphur (with respect to the addition of electrolyte)	The addition of oxalic acid	The expansion (remarks 6) of the lithium secondary battery when high temperature is preserved	Initial cells capacity (relative value)
					Embodiment 26	1.0 weight portion	0.3 weight portion	In	103
Embodiment 22	1.0 weight portion	0.4 weight portion	Little	102
					Embodiment 27	1.0 weight portion	0.6 weight portion	Do not have	100
Embodiment 28	1.0 weight portion	1.0 weight portion	Do not have	95
					Embodiment 29	0.5 weight portion	0.6 weight portion	Little	101
Embodiment 30	5.0 weight portion	0.6 weight portion	Do not have	102

(remarks 6): the evaluation result when being illustrated in " expansion test 1 of lithium secondary battery when high temperature is preserved ".With the naked eye see, with the expansion situation be divided into " greatly ", " in ", " little ", " nothing ".

The data of embodiment 22 in table 9, have also been put down in writing so that inquire into the addition of compound additive α of sulphur in detail and the relation of the addition of oxalic acid.

We can say that from the result of table 9 addition of the compound that is added on the sulphur the electrolyte is as described below with the relation of the addition that is added on the oxalic acid in the positive pole.At first, from the comparative result of embodiment 26,22,27 and 28 as can be known, the content one that makes sulphur compound in the electrolyte regularly allows the expansion of the lithium secondary battery of oxalic acid addition when 0.3 weight portion is increased to 1.0 weight portions high temperature is preserved in the positive pole, from " " drop to " nothing ".On the other hand, from the comparative result of embodiment 29,27 and 30 as can be known, oxalic acid in making positive pole keeps 0.6 weight portion and the addition of the sulphur compound in the electrolyte is become 1.0 weight portions when above, the expansion of the lithium secondary battery in the time of almost can suppressing high temperature fully and preserve.In addition, result from embodiment 26,22,27, when the sulphur compound in the electrolyte is decided to be 1.0 weight portions, even the oxalic acid in the positive pole is become the 0.3-0.6 weight portion, perhaps from the result of embodiment 29,27,30, when the oxalic acid in the positive pole is decided to be 0.6 weight portion,, not poor as the fundamental characteristics of lithium secondary battery even when the sulphur compound in the electrolyte become the 0.5-5.0 weight portion yet.In addition, sulphur compound is that the oxalic acid in 1.0 weight portions, the positive pole is that the lithium secondary battery (embodiment 28) of 1.0 weight portions and the lithium secondary battery of other embodiment are compared, initial cells capacity step-down, but the expansion of the lithium secondary battery in the time of almost can suppressing the high temperature preservation fully, so as lithium secondary battery, its overall balance is better.

(comparative example 7)

Except in embodiment 16, do not add dimethyl sulfoxide (DMSO) and the oxalic acid content in the positive pole become beyond 0.8 weight portion, all the other all with the embodiment 16 the same lithium secondary batteries that make.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 10.

(comparative example 8)

Except in embodiment 16, do not add dimethyl sulfoxide (DMSO) and the oxalic acid content in the positive pole become beyond 1.0 weight portions, all the other all with the embodiment 16 the same lithium secondary batteries that make.Lithium secondary battery to such gained carries out " expansion test 1 of lithium secondary battery when high temperature is preserved " and reaches " mensuration of battery initial capacity ", and its evaluation result sees Table 10.

Table 10

	Sulphur compound	The addition of oxalic acid	The expansion (remarks 7) of the lithium secondary battery when high temperature is preserved	Initial cells capacity (relative value)
					Comparative example 1	Do not have and add	Do not have and add	Greatly	103
Comparative example 6	Do not have and add	0.4 weight portion	Greatly	100
					Comparative example 7	Do not have and add	0.8 weight portion	In	96
Comparative example 8	Do not have and add	1.0 weight portion	Little	93

(remarks 7): the evaluation result when being illustrated in " expansion test 1 of lithium secondary battery when high temperature is preserved ".With the naked eye see, with the expansion situation be divided into " greatly ", " in ", " little ", " nothing ".

The data of also having put down in writing comparative example 1 and comparative example 6 in table 10 are so that the relation of the addition of detailed discussion and oxalic acid.

Result from table 10, sulfur-containing compound and when being increased to the oxalic acid content in the positive pole till 0.4 weight portion not in the electrolyte, do not find the expansion of the lithium secondary battery when can suppress high temperature preserves, but, if when above-mentioned content is increased to 0.8 weight portion, 1.0 weight portions, above-mentioned expansion can be suppressed to " in ", " little ".Can envision from this result, if increase when being contained in the content of the oxalic acid in the positive pole again, the expansion of the lithium secondary battery in the time of almost can suppressing the high temperature preservation fully.But if be conceived to the initial capacity of battery, the increase of oxalic acid content is relevant with the reduction of initial capacity.Therefore, in such lithium secondary battery, the expansion of the lithium secondary battery when preserving in order to suppress high temperature also can obtain the lithium secondary battery of high power capacity, just must contain oxalic acid in positive pole and contain additive α in electrolyte.

The possibility of using on the industry

According to the present invention, the value that is contained in the Δ Esol (AN) of the nonaqueous solvents in the electrolyte by control can not damaged the security of initial capacity, speed characteristic, cycle characteristics, the lithium secondary battery of preservation characteristics excellence with the relation of the value of the Δ Eadd (AN) that is contained in the additive α in the cell device. Caused problem when the shell that can prevent from especially holding cell device is the shape variable shell, be the expansion of lithium secondary battery lithium secondary battery when High temperature storage, also excellent lithium secondary battery of excellent in safety, initial cells capacity in the time of can making High temperature storage.

Though adopt specific conformation that the present invention is had been described in detail, only otherwise depart from the intent of the present invention and scope can be carried out various variations and distortion, know this point as the technical staff.

According to Japan's special permission application (2001-171851 is applied in Japan's special permission) of being applied for June 7 calendar year 2001, Japan's special permission application (2001-179748 is applied in Japan's special permission) that applied for June 14 calendar year 2001 and Japan's special permission application (2001-192635 is applied in Japan's special permission) of being applied for June 26 calendar year 2001, their integral body is cited the application respectively.

Claims (20)

1. lithium secondary battery, it comprises having positive pole, negative pole and contain nonaqueous solvents and the electrolytical cell device of solute and hold the shape variable shell of above-mentioned cell device, it is characterized in that, the enthalpy of the neutral molecule of the above-mentioned nonaqueous solvents that will be obtained by following computational methods (#): Esol (N) and the enthalpy of giving the above-mentioned neutral molecule anionic group that 1 electron institute generates: Esol's (A) is poor: Esol (A)-Esol (N) is made as Δ Esol (AN), contain additive α at above-mentioned cell device, the enthalpy of the neutral molecule of the above-mentioned additive α that will be obtained by following computational methods (#): Eadd (N) and the enthalpy of giving the above-mentioned neutral molecule anionic group that 1 electron institute generates: Eadd's (A) is poor: Eadd (A)-when Eadd (N) is made as Δ Eadd (AN), Δ Eadd (AN) is littler than Δ Esol (AN)

Computational methods (#):

The enthalpy of neutral molecule and the enthalpy of anionic group are carried out quantum chemistry calculation by the Hartree-Fock molecular orbital method of the restriction of the non-experience that adopts 6-31G * ground state function class respectively and are tried to achieve.

2. lithium secondary battery according to claim 1 is characterized in that, above-mentioned Δ Esol (AN) and Δ Eadd's (AN) is poor: Δ Esol (AN)-Δ Eadd (AN) is more than the 0.1eV, below the 4eV.

3. lithium secondary battery according to claim 1 and 2 is characterized in that, above-mentioned additive α is a lewis acid.

4. according to each described lithium secondary battery among the claim 1-3, it is characterized in that above-mentioned additive α is the compound of sulphur with two keys of 1 above sulphur and oxygen.

5. lithium secondary battery according to claim 4 is characterized in that, the compound of above-mentioned sulphur is by formula (1) expression,

R in the formula (1) ¹And R ²Independent respectively expression X ¹Or 0-X ¹, X ¹The expression carbon number is the chain of 1-9 or the saturated hydrocarbyl of ring-type, chain or the unsaturated alkyl of ring-type or the aromatic hydrocarbyl of carbon number 6-9 of carbon number 1-9, R ¹And R ²Also can be interconnected to form 5 or 6 yuan of rings of sulfur atom-containing.

6. lithium secondary battery according to claim 4 is characterized in that, the compound of above-mentioned sulphur is by formula (2) expression,

R in the formula (2) ³And R ⁴Independent respectively expression X ²Or O-X ², X ²The expression carbon number is the chain of 1-9 or the saturated hydrocarbyl of ring-type, chain or the unsaturated alkyl of ring-type or the aromatic hydrocarbyl of carbon number 6-9 of carbon number 1-9, R ³And R ⁴Also can be interconnected to form 5 or 6 yuan of rings of sulfur atom-containing.

7. according to each described lithium secondary battery among the claim 4-6, it is characterized in that, the compound of above-mentioned sulphur is for being selected from diethyl sulfoxide, diphenyl sulfoxide, tetramethylene sulfoxide, methyl mesylate, the ethyl sulfonic acid ethyl ester, dimethyl sulfite, sulfurous acid diethyl ester, 1,2-propylene glycol sulfite, 1,3-butanediol sulfite, the sulfurous acid diphenyl ester, glycol sulfite, the sulfurous acid vinylene, dimethyl sulfone, the diethyl sulfone, the ethyl-methyl sulfone, diphenyl sulfone, the dibenzyl sulfone, sulfolane, the 3-methyl sulfolane, 3-methyl-2,5-dihydro-thiophene 1, the 1-dioxide, methyl mesylate, ethyl methane sulfonate, methanesulfonic acid acetyl, methanesulfonic acid tetrahydrochysene chaff ester, the ethyl sulfonic acid methyl esters, the ethyl sulfonic acid ethyl ester, the propane sulfonic acid methyl esters, methyl benzene sulfonate, 1, the 3-N-morpholinopropanesulfonic acid lactone, 1, the 4-butyl sultone, dimethyl suflfate, dithyl sulfate, sulfuric acid ethyl methyl esters, sulfuric acid methyl phenyl ester, the sulfuric acid glycol ester, sulfuric acid 1, the ammediol ester, and sulfuric acid 1, the compound of at least a sulphur in the 4-butanediol ester.

8. according to each described lithium secondary battery among the claim 4-7, it is characterized in that the compound of above-mentioned sulphur is contained in the electrolyte.

9. according to each described lithium secondary battery among the claim 4-8, it is characterized in that with respect to the total amount of solute and nonaqueous solvents, the content of the compound of above-mentioned sulphur is more than 0.001 weight portion, below 30 weight portions.

10. according to each described lithium secondary battery among the claim 1-9, it is characterized in that above-mentioned positive pole contains lithium nickel composite oxide.

11. lithium secondary battery according to claim 10 is characterized in that, above-mentioned lithium nickel composite oxide is by formula (3) expression,

Li _aNi _xCo _yAl _zO ₂ (3)

In the formula, a, x, y, z satisfy respectively: 0≤a≤1.1,0.5≤x≤1,0≤y≤0.5,0≤z≤0.1,0.9≤x+y+z≤1.1.

12., it is characterized in that the specific area of lithium nickel composite oxide is at 0.01-10m according to claim 10 or 11 described lithium secondary batteries ²In the scope of/g.

13., it is characterized in that above-mentioned positive pole contains organic acid and/or organic acid lithium salts according to each described lithium secondary battery among the claim 1-12.

14. lithium secondary battery according to claim 13 is characterized in that, above-mentioned organic acid is the organic acid more than 2 yuan.

15. lithium secondary battery according to claim 13 is characterized in that, above-mentioned organic acid lithium salts is the organic acid lithium salts more than 2 yuan.

16., it is characterized in that positive pole has the positive electrode material layer that is formed on the collector body according to each described lithium secondary battery among the claim 13-15; With respect to the weight that deducts the weight of above-mentioned organic acid and/or organic acid lithium salts from above-mentioned positive electrode material layer total weight, the content of above-mentioned organic acid and/or organic acid lithium salts is more than the 0.1 weight %, below the 1 weight %.

17., it is characterized in that above-mentioned electrolyte also contains polymer according to each described lithium secondary battery among the claim 1-16.

18. lithium secondary battery according to claim 17 is characterized in that, above-mentioned polymer is the bridging property polymer.

19. lithium secondary battery according to claim 18 is characterized in that, above-mentioned bridging property polymer is formed by acrylic polymer.

20., it is characterized in that above-mentioned shape variable shell is made of the laminated film that disposes gas barrier and resin bed according to each described lithium secondary battery among the claim 1-19.

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