WO2014157533A1 - Nonaqueous secondary battery and electrolyte solution for nonaqueous secondary batteries - Google Patents

Abstract

A nonaqueous secondary battery which comprises a positive electrode, a negative electrode and a nonaqueous electrolyte solution, and wherein: the negative electrode has a normal operating potential of 1.2 V or more with respect to lithium metal; and the nonaqueous electrolyte solution contains an electrolyte, an organic solvent and a compound represented by formula (I) or an onium salt that has an aryl group or a heterocyclic group in a partial structure. (In the formula, each of X¹ and X² represents a specific substituent; L¹ represents -O-, -S-, -NR^a-, -CO-, -CR^bR^c- or a combination thereof; each of R^a-R^c independently represents a hydrogen atom or a substituent; and R^a-R^c and X¹ may combine together to form a ring.)

Description

Non-aqueous secondary battery and electrolyte for non-aqueous secondary battery

The present invention relates to a non-aqueous secondary battery and an electrolyte for a non-aqueous secondary battery.

Lithium secondary batteries are widely used as power sources for portable electronic devices such as mobile phones and notebook computers. Along with the expansion of applications centering on such portable use, lighter and smaller products with higher energy density and higher capacity have been developed. On the other hand, in terms of reliability, there was an overcharge phenomenon as a problem inherent to lithium secondary batteries. In this case, even if the secondary battery has reached a fully charged state, if the charging is further continued, the electrodes are short-circuited to cause a problem. In particular, a lithium secondary battery using an organic electrolyte solution has been desired to be sufficiently handled from the viewpoint of ensuring safety in use.

Measures are usually taken on the electrical equipment side where the battery is installed. Specifically, a charge control circuit is incorporated, and the supply of electricity is cut off when full charge is reached. However, even though it is extremely rare, the above circuit cannot cope with it, and it is assumed that an overcharged state is reached. Even in such a case, if the non-aqueous electrolyte is improved and overcharge can be suppressed, the reliability can be further improved.

For the purpose of suppressing or preventing such overcharge, several additives to be added to the non-aqueous electrolyte have been proposed. Among them, a representative example is biphenyl disclosed in Patent Document 1. As a result, it acts on the electrode during overcharging to increase the electrical resistance in the system and suppress the progress of the malfunction. Apart from this, there is one that stops excessive progress of defects by detecting gas generated during overcharge with a pressure-sensitive valve and releasing internal gas. Cyclohexylbenzene has been proposed as a gas releasing agent applied to the electrolyte of a battery having this pressure-sensitive mechanism (see Patent Document 2).

Japanese Patent Laid-Open No. 07-302614 Japanese Patent No. 3113652

The present inventor considers that in the non-aqueous secondary battery having a pressure-sensitive mechanism, in order to prevent the overcharge more effectively, it is considered that the addition of the cyclohexylbenzene is not sufficient, and a more effective additive. Explored. At this time, it is also developed that it is suitable for negative electrodes that operate at a high potential using lithium titanate (LTO), etc., which have recently been widely used, or a high potential positive electrode if necessary, and exhibits high performance. Was the goal.

Accordingly, the present invention provides a non-aqueous secondary battery that can simultaneously satisfy high overcharge prevention properties based on gas generation from a non-aqueous electrolyte, battery performance deterioration suppression properties, and low-temperature characteristics, and a method for using the same. It aims at providing the electrolyte solution for non-aqueous secondary batteries.

The above problem has been solved by the following means.
[1] A non-aqueous secondary battery having a positive electrode, a negative electrode, and a non-aqueous electrolyte,
The negative electrode has a normal operating potential of 1.2 V or more for lithium metal,
The nonaqueous electrolytic solution is a nonaqueous secondary battery including an electrolyte, an organic solvent, and an onium salt having a compound represented by the following formula (I), an aryl group, or a heterocyclic group in a partial structure.

(X ^1, X ² represents a substituent, at least one of with aryl-containing group or L ¹ is a group which forms a heterocyclic group. Both may be the same or different from each other. The X ^1, X ² is may form a ring structure bonded to fused with each other. Alternatively, X ¹ is omitted, X ² and L ¹ and there is a good .X ¹ also form a ring with L ¹ combined with optionally form a ring .L ¹ is ^{-O -, - S -, -} NR a -, - CO -, - CR b R c -, or a combination thereof ^.R a ~ R ^c each independently represents ^a hydrogen atom or a substituent, and R ^a to R ^c may combine with X ¹ to form a ring.)
[2] The nonaqueous secondary battery according to [1], wherein the compound represented by the formula (I) has an aryl group or heterocyclic group having at least one alkyl group in a partial structure.
[3] The nonaqueous secondary battery according to [1] or [2], wherein L ¹ is —O—, — (CO) O—, —NR ^a —, or a combination thereof.
[4] L ¹ is * -O-**, *-(CR ^b R ^c ) _m3 -**, *-(CO) O-**, * -O (CO) O-**, * -NR The non-removal according to any one of [1] to [3], which is ^a -**, * -NR ^a (CO) O-**, or * -NR ^a -NR ^a (CO) O-**. Water secondary battery.
(R ^a to R ^c are as defined in formula (I). M3 is an integer of 1 to 6. * is a bond on the CO side, and ** is a bond on the X ¹ side.)
[5] The nonaqueous two-component solvent according to any one of [1] to [4], wherein X ¹ and X ² are an alkyl group and a substituent having a partial structure selected from the following formulas (X1) to (X12): Next battery.

(R ^X1 represents a substituent. N11 represents an integer of 0 to 4. n12 represents an integer of 0 to 5. n13 represents an integer of 0 to 11. n14 represents an integer of 0 to 8. n15 Represents an integer of 0 to 4. n16 represents an integer of 0 to 10. L ² represents an alkylene group that may contain an aryl group, * represents a bond, Formulas (X1), (X5), (X11) for shows, including NR ^a is a site contained in ^{L 1} of formula (I).)
[6] In the compound represented by the formula (I), when X ¹ and X ² form a ring, or when X ² and L ¹ combine to form a ring, the compound represented by the formula (I) In the compound [1] to [5], when X ¹ and X ² form a ring, the compound is a compound represented by any one of the following formulas (C1) to (C6): The non-aqueous secondary battery as described.

(R ^C1 represents a substituent. M1 represents an integer of 0 to 4. m2 represents an integer of 0 to 2.)
[7] The nonaqueous secondary battery according to [1], wherein the onium salt is a compound represented by any one of the following formulas (II) to (VII).

(R ¹ to R ²⁷ are a hydrogen atom, an alkyl group, an alkoxy group, an alkoxycarbonyl group, an aryl group, or a heterocyclic group. R ¹ to R ²⁷ are bonded to each other or bonded to each other to form a ring structure. Z ⁻ represents an anion.
[8] The nonaqueous secondary battery according to [7], wherein R ¹ to R ²⁷ are selected from an alkyl group or the following (R1) to (R10).

(R ³¹ represents a substituent. L ³ and L ⁴ each independently represent an alkylene group that may contain an aryl group. N3 represents an integer of 0 to 10. n4 represents an integer of 0 to 11. n5 represents an integer of 0 to 9. n6 represents an integer of 0 to 5. n7 represents an integer of 0 to 4. * represents a bond.)
[9] The nonaqueous secondary battery according to any one of [1] to [8], wherein the working potential of the negative electrode is 1.4 V to 2 V with respect to lithium metal.
[10] The nonaqueous secondary battery according to any one of [1] to [9], wherein the negative electrode is lithium titanate (LTO).
[11] The nonaqueous secondary battery according to any one of [1] to [10], wherein the positive electrode active material is a transition metal oxide capable of inserting and releasing alkali metal ions.
[12] The nonaqueous solution according to any one of [1] to [11], wherein the active material contained in the positive electrode contains a transition metal oxide represented by any of the following formulas (MA) to (MC): Next battery.
Li _a M ¹ O _b (MA)
Li _c M ² ₂ O _d (MB)
Li _e M ³ (PO ₄ ) _f ... (MC)
(In the formula, M ¹ and M ² each independently represent one or more elements selected from Co, Ni, Fe, Mn, Cu, and V. M ³ independently represents V, Ti. , Cr, Mn, Fe, Co, Ni, and Cu represent one or more elements selected from the group consisting of M ¹ to M ³ , a part of which is the first (Ia) of the periodic table other than lithium. ) Group element, Group 2 (IIa) element, Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, and B may be substituted. a represents 0 to 1.2, b represents 1 to 3, c represents 0 to 2, d represents 3 to 5, e represents 0 to 2, and f represents 1 to 5. )
[13] The active material of the positive electrode is lithium cobaltate, lithium manganate, lithium nickelate, lithium nickel manganese cobaltate, lithium manganese nickelate, lithium nickel cobaltaluminate, or lithium iron phosphate [1] to [1] [12] The nonaqueous secondary battery according to any one of [12].
[14] The nonaqueous secondary battery according to any one of [1] to [13], wherein the normal charge positive electrode potential of the battery is 4.25 V (Li / Li ⁺ reference) or more.
[15] An electrolyte solution for a non-aqueous secondary battery comprising an electrolyte, an organic solvent, and an onium salt having a compound represented by the following formula (I) or an aryl group or heterocyclic group in a partial structure.

(X ¹ and X ² each represents a substituent, and at least one of them is an aryl group-containing group or a group that forms a heterocyclic group with L ^1. Both may be the same or different. X ¹ and X ² may form a ring structure bonded to fused with each other. Alternatively, X ¹ is omitted, X ² and L ¹ and there is a good .X ¹ also form a ring with L ¹ combined with optionally form a ring .L ¹ is ^{-O -, - S -, -} NR a -, - CO -, - CR b R c -, or a combination thereof ^.R a ~ R ^c each independently represents ^a hydrogen atom or a substituent, and R ^a to R ^c may combine with X ¹ to form a ring.)
[16] The electrolyte solution for a non-aqueous secondary battery according to [15], wherein the onium salt is a compound represented by any of the following formulas (II) to (VII).

(R ¹ to R ²⁷ are a hydrogen atom, an alkyl group, an alkoxy group, an alkoxycarbonyl group, an aryl group, or a heterocyclic group. R ¹ to R ²⁷ are bonded to each other or bonded to each other to form a ring structure. Z ⁻ represents an anion.
[17] A non-aqueous secondary battery having a positive electrode, a negative electrode, and a non-aqueous electrolyte,
The negative electrode normally has a working potential of 1.2 V or more for lithium metal, and the non-aqueous electrolyte is a non-aqueous secondary battery containing an electrolyte and a specific organic compound having a reduction initiation potential of less than 1.2 V.
[18] The nonaqueous secondary battery according to [17], wherein the specific organic compound generates an effective amount of gas when overcharged.

According to the non-aqueous secondary battery electrolyte and non-aqueous secondary battery of the present invention, the high overcharge prevention property based on the gas generation from the non-aqueous electrolyte solution, the battery performance deterioration suppression property, and the low-temperature characteristics. You can be satisfied at the same time. Moreover, even if it is the conditions using a negative electrode of a high potential if necessary, it can be suitably adapted to this and exhibit its high performance.
The above and other features and advantages of the present invention will become more apparent from the following description and accompanying drawings.

It is sectional drawing which shows typically the mechanism of the lithium secondary battery which concerns on preferable embodiment of this invention. It is sectional drawing which shows the specific structure of the lithium secondary battery which concerns on preferable embodiment of this invention. It is a fragmentary sectional side view which shows the battery cover body with a pressure-sensitive mechanism which concerns on preferable embodiment of this invention. It is sectional drawing which shows typically the structure of CR2032-type coin battery.

The electrolyte solution for a non-aqueous secondary battery of the present invention contains an electrolyte and the following specific organic compound in an organic solvent. The specific organic compound preferably has a reduction initiation potential of less than 1.2 V, and more preferably generates an effective amount of gas during overcharge. The reason why the above-mentioned excellent effect is obtained by using this specific organic compound is understood as follows including estimation.
In a lithium secondary battery, the potential of the positive electrode suddenly rises during overcharge and the potential of the negative electrode also changes. In particular, when a high potential negative electrode is used, the potential drops sharply. Such changes may be more pronounced on the negative electrode than on the positive electrode. It is understood that the specific organic compound responds sensitively to such a change in potential of the negative electrode and generates gas while decomposing part of the molecular structure. At this time, if the compound of formula (I) is taken as an example, the carbonyl group undergoes reduction, and the decarboxylation reaction proceeds using the generated anion radical as a reaction starting point to generate anion species and radical species. On the other hand, it is considered that the anions and radicals are further oxidized and released as gases. That is, it is expected that the reaction proceeds in a chain manner from one molecule and gas is effectively generated. Carbon dioxide is a stable and non-flammable gas and has high reliability. However, this mechanism of action includes estimation, and the present invention is not construed as being limited thereto. Hereinafter, the present invention will be described in detail.

<Specific organic compounds>
1st Embodiment which concerns on the specific organic compound used for this invention is a compound shown by following formula (I).

· ^X 1, ^{X 2}
X ¹ and X ² are substituents, and at least one of them is an aryl group-containing group or a group that forms a heterocyclic group with L ¹ . Both may be the same or different. X ¹ and X ² may be bonded to each other or condensed to form a ring structure. Alternatively, X ¹ may be omitted, and X ² and L ¹ may be bonded to form a ring. X ¹ and L ¹ may combine to form a ring.
The aryl group preferably has 6 to 22 carbon atoms, more preferably 6 to 14 carbon atoms, and particularly preferably 6 to 10 carbon atoms. Specific examples include a phenyl group, a naphthyl group, an anthracenyl group, a phenanthryl group, and the like, and among them, a phenyl group is preferable. The aryl group may further have the following substituent R ^X1 as an optional substituent.
The heterocyclic group formed by X ¹ and L ¹ preferably has 1 to 12 carbon atoms, more preferably 2 to 8 carbon atoms, and particularly preferably 2 to 5 carbon atoms. The number of atoms constituting the ring is preferably a 3-membered to 6-membered ring. Specifically, N-pyrrolidyl group, N-oxopyrrolidyl group, N-imidazolidyl group, N-oxoimidazolidyl group, N-pyrazolidyl group, N-oxopyrazolidyl group, N-piperidyl group, N-oxo Piperidyl group, N-morpholyl group, N-phenoxazinyl group, N-phenothiazinyl group, N-imidazolidyl group, N-pyrazolyl group, N-piperidinone group, N-pyrrolyl group (N- is L ¹ or O at the N position) It means that it is couple | bonded with.). The heterocyclic group may further have the following substituent R ^X1 as an optional substituent.

When X ¹ and X ² are substituents other than the aryl group-containing group and the group that forms a heterocyclic group, examples thereof include examples of the substituent R ^X1 described later (excluding the group corresponding to the above). .
Specifically, an alkyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms) or an alkoxy group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms) To 3 are particularly preferred), an acyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms), an acyloxy group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms). 1 to 3 are particularly preferred), a sulfonyl group-containing group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 and particularly preferably 1 to 3), and a carbonyl group-containing group (preferably having 2 to 12 carbon atoms) 2-6 are more preferred, 2-4 are particularly preferred), alkenyl groups (preferably having 2-8 carbon atoms, more preferred 2-4), amino groups (preferably having 0-6 carbon atoms, more preferably 0-3). Preferred), Phosphino (Preferably 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms), phosphinyl group (preferably 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms), A halogen atom is mentioned.
Hereinafter, the example in which the ^{X 1} and ^{L 1} is to form a hetero ring (I-1), examples which ^{X 1} is omitted and ^{X 2} and ^{L 1} to form a ring with (I-2) I will show you. The ring α containing L ¹ is a heterocyclic ring, and examples of the heterocyclic group listed above can be given. In formula I-1, X ¹ is shown in an abbreviated form. It means that X ² and L ¹ of ring β are connected by a single bond.

X ¹ and X ² are preferably structures selected from the following formulas (X1) to (X12). However, the formula (X1), is shown including NR ^a is a site contained in ^{L 1} of (X5), for (X11), the formula (I).

・ R ^X1
In the formula, R ^X1 represents a substituent. Examples of the substituent include the examples of the optional substituent T described later. Among them, an alkyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms), an alkoxy group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, and 1 to 3 carbon atoms). Particularly preferred), an acyl group (preferably 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms), an acyloxy group (preferably 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, 1 to 6 carbon atoms). 3 is particularly preferred), a sulfonyl group-containing group (preferably 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms), a carbonyl group-containing group (preferably 2 to 12 carbon atoms, preferably 2 to 6 carbon atoms). Is more preferable, 2 to 4 are particularly preferable), an alkenyl group (preferably having 2 to 8 carbon atoms, more preferably 2 to 4), an amino group (preferably having 0 to 6 carbon atoms, and more preferably 0 to 3), Phosphino group ( A prime number of 1 to 12, preferably 1 to 6, more preferably 1 to 3, and a phosphinyl group (preferably 1 to 12, preferably 1 to 6, more preferably 1 to 3), a halogen atom Is preferred.
When there are a plurality of R ^{X1 s} , they may be different from each other, and they may be bonded or condensed to form a ring.

N11 represents an integer of 0-4. n12 represents an integer of 0 to 5. n13 represents an integer of 0 to 11. n14 represents an integer of 0 to 8. n15 represents an integer of 0 to 4. n16 represents an integer of 0 to 10.

・ L ²
L ² represents an alkylene group that may contain an aryl group. Specifically, — (R ^e R ^f C) _n — is preferable, and n is preferably 1 to 6. R ^e and R ^f are each independently a hydrogen atom, an alkyl group (preferably 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms), an aryl group (preferably 6 to 22 carbon atoms, 6 to 14, more preferably phenyl or naphthyl), or an aralkyl group (preferably having a carbon number of 7 to 23, more preferably 7 to 15, particularly preferably a benzyl group). R ^e and R ^f may be bonded to each other or condensed to form a ring structure.
When R ^e and R ^f are an alkyl group, an aryl group, or an aralkyl group, they may further have a group represented by R ^X1 .

* Represents a bond, and is bonded to L ¹ or O in the formula (I).

・ L ¹
L ¹ is —O—, —S—, —NR ^a —, —CO—, —CR ^b R ^c —, or a combination thereof. R ^a to R ^c each independently represents a hydrogen atom or a substituent. When R ^a to R ^c are substituents, examples of the substituent T described later are given. R ^a to R ^c are, among others, a hydrogen atom, an alkyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms), an aryl group (preferably having 6 to 10 carbon atoms), aralkyl A group (preferably having 7 to 11 carbon atoms) or —CO—O—R ^d is preferred. Among the alkyl groups, a methyl group, an ethyl group, and a propyl group are preferable. R ^d is a substituent, and specific examples thereof include the substituent T described later. Among them, an alkyl group (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, and particularly preferably 1 to 3 carbon atoms), aryl A group (preferably having 6 to 22 carbon atoms, more preferably 6 to 14 carbon atoms, and particularly preferably phenyl or naphthyl) is preferred. R ^a to R ^c may further have a group represented by R ^X1 .
Among these, L ¹ is preferably —O—, — (CO) O—, —NR ^a —, or a combination thereof. That is, the compound represented by the formula (I) is preferably a carbonate compound, an oxalate compound, or an amide compound. Further, L ¹ represents * -O-**, *-(CR ^b R ^c ) _m3 -**, *-(CO) O-**, * -O (CO) O-**, * -NR. It is preferably ^a -**, * -NR ^a (CO) O-**, or * -NR ^a -NR ^a (CO) O-**. * Is a bond on the CO side. ** represents a bond ^{X 1} side. R ^a to R ^c are as defined above. m3 is an integer of 1-6. When m3 is 2 or more, the plurality of substituents defined therein may be the same as or different from each other.

R ^a to R ^c may combine with X ¹ to form a ring. Preferable ring formed includes a saturated heterocyclic group having 3 to 12 carbon atoms or a cycloalkylene group having 3 to 12 carbon atoms. These rings may further have a substituent T.

The compound represented by the formula (I) is preferably a compound having an aryl group having at least one alkyl group (preferable range is as defined above) or a heterocyclic group in a partial structure.

In the formula (I), when X ¹ and X ² form a ring, or when X ² and L ¹ combine to form a ring, it is preferably represented by the following formula (Ia).

L ¹ has the same meaning as in formula (I).
X ³ represents an alkylene group (preferably having 1 to 6 carbon atoms, more preferably 2 to 4 carbon atoms), an alkenylene group (preferably having 2 to 6 carbon atoms, more preferably 2 to 4 carbon atoms), an alkynylene group (having 2 to 6 carbon atoms). Preferably 2 to 4), an arylene group (preferably having 6 to 14 carbon atoms, more preferably 6 to 10), and an aralkylene group (preferably having 7 to 15 carbon atoms, more preferably 7 to 11). . X ³ may further have a substituent (for example, R ^X1 ). X ³ may further have a substituent R ^X1 as an optional substituent.

Further, in the formula (I), when X ¹ and X ² form a ring, or when X ² and L ¹ combine to form a ring, any one of the following formulas (C1) to (C6): It is preferable that it is a compound represented by these.

In the formula, R ^C1 represents a substituent. The preferred range is the same as R ^X1 . In the formulas (C1), (C2), (C4), and (C5), it is preferable that at least one of R ^C1 is an aryl group or a heterocyclic group. The preferred aryl group and heterocyclic group are the same as X ¹ and X ² . When there are a plurality of R ^{C1 s} , they may be different from each other, and they may be bonded or condensed to form a ring.

M1 represents an integer from 0 to 4. m2 represents an integer of 0-2. When m1 and m2 are 2 or more, a plurality of substituents defined therein may be the same as or different from each other.

Specific examples of the compound represented by the formula (1) are shown below, but the present invention is not construed as being limited thereto.

The second embodiment relating to the specific organic compound used in the present invention is an onium salt having an aryl group or a cyclic group in a partial structure. The onium salt is preferably a sulfur-containing onium salt, a sulfur-containing nitrogen onium salt, or a phosphorus-containing onium salt. In particular, the nitrogen-containing onium salt is more preferably a nitrogen-containing heteroaromatic onium salt. The aryl group and heterocyclic group have the same meanings as defined in formula (I).

The onium salt is preferably a compound represented by any of the following formulas (II) to (VII).

・ R ¹ to R ²⁷
R ¹ to R ²⁷ are each a hydrogen atom, an alkyl group (preferably 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, particularly preferably 1 to 3 carbon atoms), an alkoxy group (preferably 1 to 12 carbon atoms, preferably 1 to 6 carbon atoms). More preferably, 1 to 3 is particularly preferable), an alkoxycarbonyl group (having 2 to 12 carbon atoms, more preferably 2 to 6), an aryl group, and a heterocyclic group. The aryl group and heterocyclic group herein are preferably the same as those described for X ¹ and X ² .
R ¹ to R ²⁷ may be bonded to each other or condensed to form a ring structure. When R ¹ to R ²⁷ are alkyl groups, they are linear or branched alkyl groups (preferably having 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, and particularly preferably 1 to 3 carbon atoms), cycloalkyl groups (carbon number carbon atoms). 3 to 14 are preferable, 3 to 8 are more preferable, and 3 to 6 are particularly preferable.) An aralkyl group (preferably having 7 to 23 carbon atoms and more preferably 7 to 15 carbon atoms) is preferable. The cycloalkyl group may be condensed with an aromatic ring (benzene ring, naphthalene ring, phenanthrene ring, anthracene ring, etc.). The alkylene group of the aralkyl group preferably has 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, and particularly preferably 1 to 3 carbon atoms.

R ¹ to R ²⁷ are also preferably represented by any of the following formulas (R1) to (R10).

R ³¹ represents a substituent. R ³¹ has the same preferred range as R ^X1 . When there are a plurality of R ^{31 s} , they may be different from each other, and they may be bonded or condensed to form a ring.

L ³ and L ⁴ each independently represent a linking group having the same meaning as L ² . L ⁴ and the benzene ring or its substituent R ³¹ may be bonded or condensed to form a ring structure. L ³ and L ⁴ may be linked to a benzene ring or a cyclohexane ring to form a ring. At this time, the substituent R ³¹ may be interposed.

N3 represents an integer from 0 to 10. n4 represents an integer of 0 to 11. n5 represents an integer of 0 to 9. n6 represents an integer of 0 to 5. n7 represents an integer of 0 to 4.

* Represents a bond.

· Z ^-
Z ⁻ represents an anion. The anion may be either an inorganic anion or an organic anion. Preferred examples include hexafluorophosphate anion, tetrafluoroboron anion, hexafluoroantimony anion and the like.

The compound of the formula (III) is preferably a compound of the following formula (III-1) when two of R ⁴ to R ⁷ are bonded to form a ring structure.

R ⁴¹ and R ⁴² are each independently the same group as R ¹ to R ²⁷ (excluding a hydrogen atom), and the preferred range is also the same. n7 is an integer of 0 to 8.

The compound represented by the above formula (I) can be synthesized by a conventional method. Specifically, the carbonate compound can be synthesized by a known method using triphosgene as a raw material, and the oxalate compound can be synthesized by using oxalyl chloride as a raw material. Hydrazide compounds can be synthesized by known methods of hydrazine and corresponding acid chloride compounds, and amides by corresponding carbamate compounds and acid chlorides. References for the synthesis of the amide and hydrazine are shown below.
US Patent Application US2006 / 277693 23-24 Column Suzuki, Ichiro; Iwata, Yukari; Takeda, Kei "Tetrahedron Letters" 2008, vol. 49, # 20, p. 3238-3241

In the electrolytic solution according to the present invention, the specific organic compound is preferably contained in an amount of 0.1% by mass or more with respect to the entire nonaqueous electrolytic solution (including the electrolyte), preferably 0.5% by mass or more. It is more preferable to make it contain, it is more preferable to make it contain at 1 mass% or more, and it is preferable that it is more than 2 mass%. As an upper limit, 20 mass% or less is preferable, 10 mass% or less is more preferable, and 5 mass% or less is especially preferable. By containing the specific organic compound at the lower limit value or more, a sufficient amount of gas generation at the time of overcharge can be obtained. By setting it to the upper limit value or less, it is preferable without excessively impairing battery performance.

The specific organic compound preferably has a reduction initiation potential of less than 1.2 V, more preferably 1.0 V or less, and particularly preferably 0.8 V or less. The lower limit is preferably 0.1 V or more, more preferably 0.2 V or more, and particularly preferably 0.3 V or more. It is preferable that the specific organic compound has a reduction initiation potential in this range, so that when it is used in combination with a negative electrode having a high potential, the life characteristics are not deteriorated and the gas generation force can be maintained for a long period.

The exemplified compound may have an arbitrary substituent T.
Examples of the substituent T include the following.
An alkyl group (preferably an alkyl group having 1 to 20 carbon atoms, such as methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2-ethoxyethyl, 1-carboxymethyl, etc.), alkenyl A group (preferably an alkenyl group having 2 to 20 carbon atoms such as vinyl, allyl, oleyl and the like), an alkynyl group (preferably an alkynyl group having 2 to 20 carbon atoms such as ethynyl, butadiynyl, phenylethynyl and the like), A cycloalkyl group (preferably a cycloalkyl group having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc.), an aryl group (preferably an aryl group having 6 to 26 carbon atoms, for example, Phenyl, 1-naphthyl, 4-methoxyphenyl, -Chlorophenyl, 3-methylphenyl, etc.), heterocyclic groups (preferably heterocyclic groups of 2 to 20 carbon atoms, preferably 5- or 6-membered heterocycles having at least one oxygen atom, sulfur atom, nitrogen atom) A cyclic group is preferred, for example, 2-pyridyl, 4-pyridyl, 2-imidazolyl, 2-benzimidazolyl, 2-thiazolyl, 2-oxazolyl, etc.), an alkoxy group (preferably an alkoxy group having 1 to 20 carbon atoms, for example, Methoxy, ethoxy, isopropyloxy, benzyloxy, etc.), aryloxy groups (preferably aryloxy groups having 6 to 26 carbon atoms, such as phenoxy, 1-naphthyloxy, 3-methylphenoxy, 4-methoxyphenoxy, etc.), An alkoxycarbonyl group (preferably an alkoxycarbonyl group having 2 to 20 carbon atoms) Nyl groups such as ethoxycarbonyl, 2-ethylhexyloxycarbonyl and the like, amino groups (preferably containing an amino group having 0 to 20 carbon atoms, alkylamino group, arylamino group, such as amino, N, N-dimethyl) Amino, N, N-diethylamino, N-ethylamino, anilino, etc.), sulfamoyl groups (preferably sulfamoyl groups having 0 to 20 carbon atoms, such as N, N-dimethylsulfamoyl, N-phenylsulfamoyl, etc.) ), An acyl group (preferably an acyl group having 1 to 20 carbon atoms, such as acetyl, propionyl, butyryl, benzoyl, etc.), an acyloxy group (preferably an acyloxy group having 1 to 20 carbon atoms, such as acetyloxy, benzoyl) Oxy, etc.), a carbamoyl group (preferably a C 1-20 carbon Rubamoyl groups such as N, N-dimethylcarbamoyl and N-phenylcarbamoyl), acylamino groups (preferably acylamino groups having 1 to 20 carbon atoms such as acetylamino and benzoylamino), sulfonamide groups (preferably Is a sulfamoyl group having 0 to 20 carbon atoms, such as methanesulfonamide, benzenesulfonamide, N-methylmethanesulfonamide, N-ethylbenzenesulfonamide, etc., an alkylthio group (preferably an alkylthio group having 1 to 20 carbon atoms) For example, methylthio, ethylthio, isopropylthio, benzylthio, etc.), arylthio groups (preferably arylthio groups having 6 to 26 carbon atoms, such as phenylthio, 1-naphthylthio, 3-methylphenylthio, 4-methoxyphenylthio, etc.) An alkyl or arylsulfonyl group (preferably an alkyl or arylsulfonyl group having 1 to 20 carbon atoms, such as methylsulfonyl, ethylsulfonyl, benzenesulfonyl, etc.), hydroxyl group, cyano group, halogen atom (for example, fluorine atom, chlorine atom, Bromine atom, iodine atom, etc.), more preferably alkyl group, alkenyl group, aryl group, heterocyclic group, alkoxy group, aryloxy group, alkoxycarbonyl group, amino group, acylamino group, hydroxyl group or halogen atom Particularly preferred are an alkyl group, an alkenyl group, a heterocyclic group, an alkoxy group, an alkoxycarbonyl group, an amino group, an acylamino group or a hydroxyl group.
In addition, each of the groups listed as the substituent T may be further substituted with the substituent T described above.

When the compound or substituent / linking group contains an alkyl group / alkylene group, alkenyl group / alkenylene group, etc., these may be cyclic or chain-like, and may be linear or branched, and substituted as described above. It may be substituted or unsubstituted. Moreover, when an aryl group, a heterocyclic group, etc. are included, they may be monocyclic or condensed and may be similarly substituted or unsubstituted.

(Organic solvent)
The organic solvent used in the present invention is preferably an aprotic organic solvent, and more preferably an aprotic organic solvent having 2 to 10 carbon atoms. The organic solvent is preferably a compound having an ether group, a carbonyl group, an ester group, or a carbonate group. The said compound may have a substituent and the said substituent T is mentioned as the example. In particular, an organic solvent containing a linear carbonate group having 2 to 16 carbon atoms is preferable.

Examples of the organic solvent include ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, γ-butyrolactone, γ-valerolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2- Methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate , Methyl isobutyrate, methyl trimethylacetate, ethyl trimethylacetate, acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, N, N-dimethylformamide, N-methylpyrrolidinone, N-methyl Examples thereof include tiloxazolidinone, N, N′-dimethylimidazolidinone, nitromethane, nitroethane, sulfolane, trimethyl phosphate, dimethyl sulfoxide, and dimethyl sulfoxide phosphoric acid. These may be used alone or in combination of two or more. Among them, at least one member selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate is preferable. Particularly, a high viscosity (high dielectric constant) solvent such as ethylene carbonate or propylene carbonate (for example, ratio A combination of a dielectric constant ε ≧ 30) and a low viscosity solvent such as dimethyl carbonate, ethyl methyl carbonate, or diethyl carbonate (for example, viscosity ≦ 1 mPa · s) is more preferable. This is because the dissociation property of the electrolyte salt and the ion mobility are improved.
A preferred embodiment includes a solvent containing propylene carbonate in an amount of 5% by volume or more, more preferably 10% by volume or more, and still more preferably 15% by volume or more based on the total solvent. In a more preferred embodiment, the cyclic carbonate is contained in an amount of 20 to 80% by volume based on the total solvent, and 25 to 100% by volume of the cyclic carbonate is propylene carbonate. As a more preferred embodiment, a chain carbonate selected from dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate is contained in an amount of 20 to 80% by volume based on the total solvent, and a cyclic carbonate selected from ethylene carbonate or propylene carbonate is added in an amount of 20 to The content is 80% by volume, and 25 to 100% by volume (more preferably 40 to 100% by volume) of the cyclic carbonate is propylene carbonate. By containing a predetermined amount or more of propylene carbonate, capacity deterioration can be reduced even in a large current discharge at a low temperature.
However, the organic solvent used in the present invention is not limited to the above examples.

(Functional additives)
The electrolytic solution of the present invention preferably contains various functional additives. Examples of the function manifested by this additive include improved flame retardancy, improved cycle characteristics, and improved capacity characteristics. Examples of functional additives that are preferably applied to the electrolyte of the present invention are shown below.

<Aromatic compound (A)>
Examples of aromatic compounds include biphenyl compounds and alkyl-substituted benzene compounds. The biphenyl compound has a partial structure in which two benzene rings are bonded by a single bond, and the benzene ring may have a substituent, and preferred substituents are alkyl groups having 1 to 4 carbon atoms (for example, Methyl, ethyl, propyl, t-butyl, etc.) and aryl groups having 6 to 10 carbon atoms (eg, phenyl, naphthyl, etc.).
Specific examples of the biphenyl compound include biphenyl, o-terphenyl, m-terphenyl, p-terphenyl, 4-methylbiphenyl, 4-ethylbiphenyl, and 4-tert-butylbiphenyl.
The alkyl-substituted benzene compound is preferably a benzene compound substituted with an alkyl group having 1 to 10 carbon atoms, and specific examples include cyclohexylbenzene, t-amylbenzene, and t-butylbenzene.

<Halogen-containing compound (B)>
The halogen atom contained in the halogen-containing compound is preferably a fluorine atom, a chlorine atom, or a bromine atom, and more preferably a fluorine atom. The number of halogen atoms is preferably 1 to 6, more preferably 1 to 3. The halogen-containing compound is preferably a carbonate compound substituted with a fluorine atom, a polyether compound having a fluorine atom, or a fluorine-substituted aromatic compound.
The halogen-substituted carbonate compound may be either linear or cyclic. From the viewpoint of ion conductivity, a cyclic carbonate compound having a high coordination property of an electrolyte salt (for example, lithium ion) is preferable, and a 5-membered cyclic carbonate compound is particularly preferable. preferable.
Preferred specific examples of the halogen-substituted carbonate compound are shown below. Among these, compounds of Bex1 to Bex4 are particularly preferable, and Bex1 is particularly preferable.

<Polymerizable compound (C)>
The polymerizable compound is preferably a compound having a carbon-carbon double bond, and is selected from carbonate compounds having a double bond such as vinylene carbonate and vinyl ethylene carbonate, acrylate groups, methacrylate groups, cyanoacrylate groups, and αCF ₃ acrylate groups. A compound having a group and a compound having a styryl group are preferable, and a carbonate compound having a double bond or a compound having two or more polymerizable groups in the molecule is more preferable.

<Phosphorus-containing compound (D)>
As a phosphorus containing compound, a phosphate ester compound and a phosphazene compound are preferable. Preferable examples of the phosphate ester compound include trimethyl phosphate, triethyl phosphate, triphenyl phosphate, and tribenzyl phosphate. As the phosphorus-containing compound, a compound represented by the following formula (D2) or (D3) is also preferable.

In the formula, R ^D4 to R ^D11 each represent a monovalent substituent. Among the monovalent substituents, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an amino group, a halogen atom such as fluorine, chlorine or bromine is preferable. At least one of the substituents of R ^D4 to R ^D11 is preferably a fluorine atom, more preferably a substituent composed of an alkoxy group, an amino group, or a fluorine atom.

<Sulfur-containing compound (E)>
As the sulfur-containing compound, a compound having —SO ₂ —, —SO ₃ —, —OS (═O) O— bond is preferable, and cyclic sulfur-containing compounds such as propane sultone, propene sultone, ethylene sulfite, and sulfonic acid Esters are preferred.

As the sulfur-containing cyclic compound, compounds represented by the following formulas (E1) and (E2) are preferable.

In the formula, X ¹ and X ² each independently represent —O— or —C (Ra) (Rb) —. Here, Ra and Rb each independently represent a hydrogen atom or a substituent. The substituent is preferably an alkyl group having 1 to 8 carbon atoms, a fluorine atom, or an aryl group having 6 to 12 carbon atoms. α represents an atomic group necessary for forming a 5- to 6-membered ring. The skeleton of α may contain a sulfur atom, an oxygen atom, etc. in addition to a carbon atom. α may be substituted, and examples of the substituent include a substituent T, preferably an alkyl group, a fluorine atom, and an aryl group.

<Silicon-containing compound (F)>
As the silicon-containing compound, a compound represented by the following formula (F1) or (F2) is preferable.

R ^F1 represents an alkyl group, an alkenyl group, an acyl group, an acyloxy group, or an alkoxycarbonyl group.
R ^F2 represents an alkyl group, an alkenyl group, an alkynyl group, or an alkoxy group.
A plurality of R ^F1 and R ^{F2 in} one formula may be different or the same.

<Nitrile compound (G)>
As the nitrile compound, a compound represented by the following formula (G) is preferable.

In the formula, R ^G1 to R ^G3 each independently represent a hydrogen atom, an alkyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a cyano group, a carbamoyl group, a sulfonyl group, or a phosphonyl group. As examples of the preferable substituents, examples of the substituent T can be referred to, and among them, a compound in which any one of R ^G1 to R ^G3 has a plurality of nitrile groups containing a cyano group is preferable.

-Ng represents an integer of 1-8.

Specific examples of the compound represented by the formula (G) include acetonitrile, propionitrile, isobutyronitrile, succinonitrile, malononitrile, glutaronitrile, adiponitrile, 2-methylglutanonitrile, hexanetricarbonitrile, propane. Tetracarbonitrile and the like are preferable. Particularly preferred are succinonitrile, malononitrile, glutaronitrile, adiponitrile, 2-methylglutanonitrile, hexanetricarbonitrile, and propanetetracarbonitrile.

<Metal complex compound (H)>
As the metal complex compound, a transition metal complex or a rare earth complex is preferable. Of these, complexes represented by any of the following formulas (H-1) to (H-3) are preferred.

In the formula, X ^H and Y ^H are a methyl group, an n-butyl group, a bis (trimethylsilyl) amino group, and a thioisocyanate group, respectively, and X ^H and Y ^H are condensed to form a cyclic alkenyl group (butadiene group). (Positional metallacycle) may be formed. In the formula, ^MH represents a transition element or a rare earth element. Specifically, ^MH is preferably Fe, Ru, Cr, V, Ta, Mo, Ti, Zr, Hf, Y, La, Ce, Sw, Nd, Lu, Er, Yb, and Gd. m ^H and n ^H are integers satisfying 0 ≦ m ^H + n ^H ≦ 3. n ^H + m ^H is preferably 1 or more. When n ^H and m ^H are 2 or more, the 2 or more groups defined therein may be different from each other.

The metal complex compound is also preferably a compound having a partial structure represented by the following formula (H-4).

M ^H — (NR ^1H R ^2H ) q ^H Formula (H-4)

In the formula, ^MH represents a transition element or a rare earth element and is synonymous with formulas (H-1) to (H-3).

R ^1H and R ^2H are hydrogen, an alkyl group (preferably having a carbon number of 1 to 6), an alkenyl group (preferably having a carbon number of 2 to 6), an alkynyl group (preferably having a carbon number of 2 to 6), and an aryl group (preferably having a carbon number). Represents a heteroaryl group (preferably having a carbon number of 3 to 6), an alkylsilyl group (preferably having a carbon number of 1 to 6), or a halogen. R ^1H and R ^2H may be linked to each other. R ^1H and R ^2H may each be connected to form a ring. Preferable examples of R ^1H and R ^2H include examples of the substituent T described later. Of these, a methyl group, an ethyl group, and a trimethylsilyl group are preferable.
q ^H represents an integer of 1 to 4, preferably an integer of 2 to 4. More preferably, it is 2 or 4. When q ^H is 2 or more, where a plurality of groups as defined may be the same or different from each other.

The metal complex compound is also preferably a compound represented by any of the following formulas.

・ M ^h
The central metal ^M h is, Ti, Zr, ZrO, Hf , V, Cr, Fe, Ce is particularly preferred, Ti, Zr, Hf, V , Cr is the most preferred.

・ R ^3h , R ^5h , R ^7h to R ^10h
These represent substituents. Of these, an alkyl group, an alkoxy group, an aryl group, an alkenyl group, and a halogen atom are preferable. An alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, and 2 carbon atoms. More preferred are alkenyl groups of 6 to 6 and are preferably methyl, ethyl, propyl, isopropyl, isobutyl, t-butyl, perfluoromethyl, methoxy, phenyl, ethenyl.

・ R ^33h , R ^55h
R ^33h and R ^55h represent a hydrogen atom or a substituent of R ^3h .

・ Y ^h
Y ^h is preferably an alkyl group having 1 to 6 carbon atoms or a bis (trialkylsilyl) amino group, and more preferably a methyl group or a bis (trimethylsilyl) amino group.

^{· L h, m h, o} h
l ^h , m ^h , and o ^h represent an integer of 0 to 3, and an integer of 0 to 2 is preferable. When l ^h , m ^h , and o ^h are 2 or more, the plurality of structural portions defined therein may be the same as or different from each other.

・ L ^h
L ^h is preferably an alkylene group or an arylene group, more preferably a cycloalkylene group having 3 to 6 carbon atoms or an arylene group having 6 to 14 carbon atoms, and further preferably cyclohexylene or phenylene.

<Imide compound (I)>
As the imide compound, a sulfonimide compound having a perfluoro group is preferable from the viewpoint of oxidation resistance, and specifically, a perfluorosulfoimide lithium compound may be mentioned.
Specific examples of the imide compound include the following structures, and Cex1 and Cex2 are more preferable.

The electrolytic solution of the present invention may contain at least one selected from the above, a negative electrode film forming agent, a flame retardant, an overcharge preventing agent and the like. The content ratio of these functional additives in the nonaqueous electrolytic solution is not particularly limited, but is preferably 0.001% by mass to 10% by mass with respect to the entire nonaqueous electrolytic solution (including the electrolyte). By adding these compounds, it is possible to suppress rupture / ignition of the battery at the time of abnormality due to overcharge, and to improve the capacity maintenance characteristic and cycle characteristic after high-temperature storage.

(Electrolytes)
The electrolyte used in the electrolytic solution of the present invention is a salt of a metal ion belonging to Group 1 or Group 2 of the periodic table. The material is appropriately selected depending on the intended use of the electrolytic solution. For example, lithium salt, potassium salt, sodium salt, calcium salt, magnesium salt and the like can be mentioned. When used in a secondary battery or the like, lithium salt is preferable from the viewpoint of output. When the electrolytic solution of the present invention is used as an electrolyte of a non-aqueous electrolytic solution for a lithium secondary battery, a lithium salt may be selected as a metal ion salt. The lithium salt is not particularly limited as long as it is a lithium salt usually used for an electrolyte of a non-aqueous electrolyte solution for a lithium secondary battery. For example, those described below are preferable.

(L-1) Inorganic lithium salts: inorganic fluoride salts such as LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiSbF ₆ ; perhalogenates such as LiClO ₄ , LiBrO ₄ , LiIO ₄ ; inorganic chloride salts such as LiAlCl ₄ etc.

(L-2) Fluorine-containing organic lithium salt: perfluoroalkane sulfonate such as LiCF ₃ SO ₃ ; LiN (CF ₃ SO ₂ ) ₂ , LiN (CF ₃ CF ₂ SO ₂ ) ₂ , LiN (FSO ₂ ) ₂ , Perfluoroalkanesulfonylimide salts such as LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ); perfluoroalkanesulfonylmethide salts such as LiC (CF ₃ SO ₂ ) ₃ ; Li [PF ₅ (CF ₂ CF ₂ CF ₃ )], Li [PF ₄ (CF ₂ CF ₂ CF ₃ ) ₂ ], Li [PF ₃ (CF ₂ CF ₂ CF ₃ ) ₃ ], Li [PF ₅ (CF ₂ CF ₂ CF ₂ CF _{3 )], Li [PF 4 (} CF 2 CF 2 CF 2 CF 3) 2], Li [PF 3 (CF 2 CF 2 CF 2 CF 3) 3] fluoroalkyl fluoride such as potash Acid salts, and the like.

(L-3) Oxalatoborate salt: lithium bis (oxalato) borate, lithium difluorooxalatoborate and the like.
Among these, LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiSbF ₆ , LiClO ₄ , Li (Rf ¹ SO ₃ ), LiN (Rf ¹ SO ₂ ) ₂ , LiN (FSO ₂ ) ₂ , and LiN (Rf ¹ SO ₂ ) (Rf ² SO ₂ ), preferably LiPF ₆ , LiBF ₄ , LiN (Rf ¹ SO ₂ ) ₂ , LiN (FSO ₂ ) ₂ , and LiN (Rf ¹ SO ₂ ) (Rf ² SO ₂ ) More preferred are imide salts. Here, Rf ¹ and Rf ² each represent a perfluoroalkyl group.
In addition, the electrolyte used for electrolyte solution may be used individually by 1 type, or may combine 2 or more types arbitrarily.
The content of the electrolyte (metal ions belonging to Group 1 or Group 2 of the periodic table or a metal salt thereof) in the electrolytic solution is added in an amount that provides a preferable salt concentration described below in the method for preparing the electrolytic solution. The salt concentration is appropriately selected depending on the intended use of the electrolytic solution, but is generally 10% to 50% by mass, more preferably 15% to 30% by mass, based on the total mass of the electrolytic solution. In addition, when evaluating as an ion density | concentration, what is necessary is just to calculate by salt conversion with the metal applied suitably.

[Method for preparing electrolytic solution]
The electrolyte solution for a non-aqueous secondary battery of the present invention is prepared by a conventional method by dissolving each of the above components in the non-aqueous electrolyte solvent, including an example in which a lithium salt is used as a metal ion salt.

In the present invention, “non-water” means that water is not substantially contained, and a trace amount of water may be contained as long as the effects of the invention are not hindered. In view of obtaining good characteristics, the water content is preferably 200 ppm (mass basis) or less, more preferably 100 ppm or less, and even more preferably 20 ppm or less. Although there is no lower limit in particular, it is practical that it is 1 ppm or more considering inevitable mixing. The viscosity of the electrolytic solution of the present invention is not particularly limited, but it is preferably 10 to 0.1 mPa · s, more preferably 5 to 0.5 mPa · s at 25 ° C.
In the present invention, the viscosity of the electrolytic solution is based on the value measured by the following measuring method unless otherwise specified.

<Measurement method of viscosity>
The viscosity is a value measured by the following method. 1 mL of a sample is put into a rheometer (CLS 500) and measured using a Steel Cone (both manufactured by TA Instruments) having a diameter of 4 cm / 2 °. The sample is kept warm in advance until the temperature becomes constant at the measurement start temperature, and the measurement starts thereafter. The measurement temperature is 25 ° C.

[Secondary battery]
In this invention, it is preferable to set it as the non-aqueous secondary battery containing the said non-aqueous electrolyte. As a preferred embodiment, a lithium ion secondary battery will be described with reference to FIG. 1 schematically showing the mechanism. The lithium ion secondary battery 10 of this embodiment includes the electrolyte solution 5 for a non-aqueous secondary battery of the present invention and a positive electrode C capable of inserting and releasing lithium ions (a positive electrode current collector 1 and a positive electrode active material layer 2). And a negative electrode A (negative electrode current collector 3, negative electrode active material layer 4) capable of inserting and releasing lithium ions or dissolving and depositing lithium ions. In addition to these essential members, considering the purpose of use of the battery, the shape of the potential, etc., a separator 9 disposed between the positive electrode and the negative electrode, a current collecting terminal (not shown), an outer case, etc. (Not shown). If necessary, a protective element may be attached to at least one of the inside of the battery and the outside of the battery. By adopting such a structure, lithium ion transfer a and b occurs in the electrolytic solution 5, charging α and discharging β can be performed, and operation or power storage is performed via the operation mechanism 6 via the circuit wiring 7. It can be performed. Hereinafter, the configuration of the lithium secondary battery which is a preferred embodiment of the present invention will be described in more detail.

(Battery shape)
The battery shape to which the lithium secondary battery of the present embodiment is applied is not particularly limited, and examples thereof include a bottomed cylindrical shape, a bottomed square shape, a thin shape, a sheet shape, and a paper shape. Any of these may be used. Further, it may be of a different shape such as a horseshoe shape or a comb shape considering the shape of the system or device to be incorporated. Among them, from the viewpoint of efficiently releasing the heat inside the battery to the outside, a square shape such as a bottomed square shape or a thin shape having at least one surface that is relatively flat and has a large area is preferable.

In the case of a battery having a bottomed cylindrical shape, since the outer surface area with respect to the power generating element to be filled becomes small, it is preferable to design so that Joule heat generated by the internal resistance at the time of charging or discharging efficiently escapes to the outside. Moreover, it is preferable to design so that the filling ratio of the substance having high thermal conductivity is increased and the temperature distribution inside is reduced. FIG. 2 is an example of a bottomed cylindrical lithium secondary battery 100. This battery is a bottomed cylindrical lithium secondary battery 100 in which a positive electrode sheet 14 and a negative electrode sheet 16 overlapped with a separator 12 are wound and accommodated in an outer can 18.

In the bottomed square shape, the ratio of the area S of the largest surface (the product of the width and height of the outer dimensions excluding the terminal portion, unit cm ² ) to the thickness T (unit cm) of the battery outer shape The 2S / T value is preferably 100 or more, and more preferably 200 or more. By increasing the maximum surface, it is possible to improve characteristics such as cycle performance and high-temperature storage even for high-power and large-capacity batteries, and increase the heat dissipation efficiency during abnormal heat generation. It is possible to suppress the state of “rupture”.

(Members constituting the battery)
The lithium secondary battery according to the present embodiment is configured to include the electrolytic solution 5, the positive electrode and negative electrode electrode mixtures C and A, and the separator basic member 9, based on FIG. 1. Hereinafter, each of these members will be described.

(Electrode mixture)
The electrode mixture is obtained by applying a dispersion of an active material and a conductive agent, a binder, a filler, etc. on a current collector (electrode substrate). In a lithium battery, the active material is a positive electrode active material. It is preferable to use a negative electrode mixture in which the positive electrode mixture and the active material are a negative electrode active material. Next, each component in the dispersion (electrode composition) constituting the electrode mixture will be described.

-Positive electrode active material It is preferable to use a transition metal oxide for the positive electrode active material, and in particular, it has a transition element M ^a (one or more elements selected from Co, Ni, Fe, Mn, Cu, V). Is preferred. Further, mixed element M ^b (elements of the first (Ia) group of the metal periodic table other than lithium, elements of the second (IIa) group, Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si , P, B, etc.) may be mixed. Examples of the transition metal oxide include specific transition metal oxides including those represented by any of the following formulas (MA) to (MC), or other transition metal oxides such as V ₂ O ₅ and MnO _2. Is mentioned. As the positive electrode active material, a particulate positive electrode active material may be used. Specifically, a transition metal oxide capable of reversibly inserting and releasing lithium ions can be used, but the specific transition metal oxide is preferably used.

The transition metal oxides, oxides containing the transition element M ^a is preferably exemplified. At this time, a mixed element M ^b (preferably Al) or the like may be mixed. The mixing amount is preferably 0 to 30 mol% with respect to the amount of the transition metal. That the molar ratio of li / ^{M a} was synthesized were mixed so that 0.3 to 2.2, more preferably.

[Transition metal oxide represented by formula (MA) (layered rock salt structure)]
As the lithium-containing transition metal oxide, those represented by the following formula are preferable.
Li _a M ¹ O _b (MA)

Wherein, ^{M 1} is the same meaning as defined above Ma. a represents 0 to 1.2, preferably 0.1 to 1.15, and more preferably 0.6 to 1.1. b represents 1 to 3 and is preferably 2. A part of M ¹ may be substituted with the mixed element M ^b . The transition metal oxide represented by the formula (MA) typically has a layered rock salt structure.

The transition metal oxide is more preferably one represented by the following formulas.
_{(MA-1) Li g CoO} k
_{(MA-2) Li g NiO} k
_{(MA-3) Li g MnO} k
_{(MA-4) Li g Co} j Ni 1-j O k
_{(MA-5) Li g Ni} j Mn 1-j O k
_{(MA-6) Li g Co} j Ni i Al 1-j-i O k
_{(MA-7) Li g Co} j Ni i Mn 1-j-i O k

Here, g has the same meaning as a. j represents 0.1 to 0.9. i represents 0 to 1; However, 1-ji is 0 or more. k has the same meaning as b. Specific examples of the transition metal compound include LiCoO ₂ (lithium cobaltate [LCO]), LiNi ₂ O ₂ (lithium nickelate) LiNi _0.85 Co _0.01 Al _0.05 O ₂ (nickel cobalt aluminum acid Lithium [NCA]), LiNi _0.33 Co _0.33 Mn _0.33 O ₂ (lithium nickel manganese cobaltate [NMC]), LiNi _0.5 Mn _0.5 O ₂ (lithium manganese nickelate).

The transition metal oxide represented by the formula (MA) partially overlaps, but when represented by changing the notation, those represented by the following are also preferable examples.
_{(I) Li g Ni x Mn} y Co z O 2 (x> 0.2, y> 0.2, z ≧ 0, x + y + z = 1)
Representative:
_{Li g Ni 1/3 Mn 1/3 Co 1/3} O 2
Li _g Ni _1/2 Mn _1/2 O _{2
(Ii) Li g Ni x Co} y Al z O 2 (x> 0.7, y>0.1,0.1>z> 0.05, x + y + z = 1)
Representative:
_{Li g Ni 0.8 Co 0.15 Al 0.05} O 2

[Transition metal oxide represented by formula (MB) (spinel structure)]
Among the lithium-containing transition metal oxides, those represented by the following formula (MB) are also preferable.
Li _c M ² ₂ O _d (MB)

Wherein, ^{M 2} are as defined above Ma. c represents 0 to 2, preferably 0.1 to 1.15, and more preferably 0.6 to 1.5. d represents 3 to 5 and is preferably 4.

The transition metal oxide represented by the formula (MB) is more preferably one represented by the following formulas.
_{(MB-1) Li m Mn} 2 O n
_{(MB-2) Li m Mn} p Al 2-p O n
_{(MB-3) Li m Mn} p Ni 2-p O n

m is synonymous with c. n is synonymous with d. p represents 0-2. Specific examples of the transition metal compound are LiMn ₂ O ₄ and LiMn _1.5 Ni _0.5 O ₄ .

Preferred examples of the transition metal oxide represented by the formula (MB) include those represented by the following.
(A) LiCoMnO ₄
(B) Li ₂ FeMn ₃ O ₈
(C) Li ₂ CuMn ₃ O ₈
(D) Li ₂ CrMn ₃ O ₈
(E) Li ₂ NiMn ₃ O ₈
Of these, an electrode containing Ni is more preferable from the viewpoint of high capacity and high output.

[Transition metal oxide represented by formula (MC)]
As the lithium-containing transition metal oxide, it is also preferable to use a lithium-containing transition metal phosphor oxide, and among them, one represented by the following formula (MC) is also preferable.
Li _e M ³ (PO ₄ ) _f ... (MC)

In the formula, e represents 0 to 2, preferably 0.1 to 1.15, and more preferably 0.5 to 1.5. f represents 1 to 5, and preferably 0.5 to 2.

The M ³ represents one or more elements selected from V, Ti, Cr, Mn, Fe, Co, Ni, and Cu. Wherein ^{M 3} represents, in addition to the mixing element ^{M b} above, Ti, Cr, Zn, Zr, may be substituted by other metals such as Nb. Specific examples include, for example, olivine-type iron phosphates such as LiFePO ₄ and Li ₃ Fe ₂ (PO ₄ ) ₃ , iron pyrophosphates such as LiFeP ₂ O ₇ , cobalt phosphates such as LiCoPO ₄ , and Li _3. Monoclinic Nasicon type vanadium phosphate salts such as V ₂ (PO ₄ ) ₃ (lithium vanadium phosphate) can be mentioned.
The a, c, g, m, and e values representing the composition of Li are values that change due to charge and discharge, and are typically evaluated as values in a stable state when Li is contained. In the above formulas (a) to (e), the composition of Li is shown as a specific value, but this also varies depending on the operation of the battery.

In the present invention, the positive electrode active material is preferably a material that can maintain normal use at a positive electrode potential (Li / Li ⁺ standard) of 3.5 V or higher, more preferably 3.8 V or higher, and more preferably 4 V or higher. More preferably, it is more preferably 4.25V or more, and further preferably 4.3V or more. Although there is no upper limit in particular, it is practical that it is 5V or less. By setting it as the above range, cycle characteristics and high rate discharge characteristics can be improved.
Here, being able to maintain normal use means that even when charging is performed at that voltage, the electrode material does not deteriorate and cannot be used, and this potential is also referred to as a normal usable potential. The electrode active material charge / discharge potential may be specified from the peak. The peak of the potential can be specified by preparing a tripolar cell composed of a working electrode, a reference electrode, and a counter electrode, and performing electrochemical measurement (cyclic voltammetry). The configuration of the tripolar cell and the measurement conditions for electrochemical measurement are as follows.

<Configuration of tripolar cell>
-Working electrode: Active material electrode prepared on platinum electrode by sol-gel method or sputtering method-Reference electrode: Lithium-Counter electrode: Lithium-Dilution media: EC / EMC = 1/2 LiPF ₆ 1M, manufactured by Kishida Chemical Co., Ltd. <Measurement Conditions>
・ Scanning speed: 1mV / s
・ Measurement temperature: 25 ℃

The positive electrode potential during charging / discharging (Li / Li ⁺ reference) is (positive electrode potential) = (negative electrode potential) + (battery voltage). When lithium titanate is used as the negative electrode, the negative electrode potential is 1.55V. When graphite is used as the negative electrode, the negative electrode potential is 0.
1V. The battery voltage is observed during charging and the positive electrode potential is calculated.

In the nonaqueous secondary battery of the present invention, the average particle size of the positive electrode active material used is not particularly limited, but is preferably 0.1 μm to 50 μm. The specific surface area is not particularly limited, but is preferably 0.01 m ² / g to 50 m ² / g by the BET method. Further, the pH of the supernatant when 5 g of the positive electrode active material is dissolved in 100 ml of distilled water is preferably 7 or more and 12 or less.

A well-known pulverizer or classifier is used to make the positive electrode active substance have a predetermined particle size. For example, a mortar, a ball mill, a vibration ball mill, a vibration mill, a satellite ball mill, a planetary ball mill, a swirling air flow type jet mill, a sieve, or the like is used. The positive electrode active material obtained by the firing method may be used after being washed with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.

The blending amount of the positive electrode active material is not particularly limited, but is preferably 60 to 98% by mass, and 70 to 95% by mass in 100% by mass of the solid component in the dispersion (mixture) for constituting the active material layer. % Is more preferable.

Negative electrode active material As the negative electrode active material, a material having a normal operating potential of 1.2 V (preferably 1.4 to 2 V) or more with respect to lithium metal is used. The operating potential is a value measured by the measurement method described for the positive electrode active material, that is, electrochemical measurement (cyclic voltammetry) using the triode cell. Specifically, it is preferable to use a material containing a carbon atom (C), a silicon atom (Si), or a titanium atom (Ti) that can insert and release ions of metals belonging to the first group or the second group. . Examples include carbonaceous materials, metal oxides such as silicon oxide, metal composite oxides, lithium alloys such as lithium alone and lithium aluminum alloys, and metals such as Si that can form alloys with lithium. These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and ratios. Of these, carbonaceous materials or lithium composite oxides are preferably used from the viewpoint of reliability. Further, the metal composite oxide is not particularly limited as long as it can occlude and release lithium, but it preferably contains titanium and / or lithium as a constituent component from the viewpoint of high current density charge / discharge characteristics. .

The carbonaceous material used as the negative electrode active material is a material substantially made of carbon. Examples thereof include carbonaceous materials obtained by baking various synthetic resins such as artificial pitches such as petroleum pitch, natural graphite, and vapor-grown graphite, and PAN-based resins and furfuryl alcohol resins. Furthermore, various carbon fibers such as PAN-based carbon fiber, cellulose-based carbon fiber, pitch-based carbon fiber, vapor-grown carbon fiber, dehydrated PVA-based carbon fiber, lignin carbon fiber, glassy carbon fiber, activated carbon fiber, mesophase micro Examples thereof include spheres, graphite whiskers, and flat graphite.

These carbonaceous materials can be divided into non-graphitizable carbon materials and graphite-based carbon materials depending on the degree of graphitization. Further, the carbonaceous material preferably has a face spacing, density, and crystallite size described in JP-A-62-222066, JP-A-2-6856, and 3-45473. The carbonaceous material does not have to be a single material, and a mixture of natural graphite and artificial graphite described in JP-A-5-90844, graphite having a coating layer described in JP-A-6-4516, or the like is used. You can also.

In the nonaqueous secondary battery of the present invention, the average particle size of the negative electrode active material used is preferably 0.1 μm to 60 μm. To obtain a predetermined particle size, a well-known pulverizer or classifier is used. For example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a swirling air flow type jet mill or a sieve is preferably used. When pulverizing, wet pulverization in the presence of water or an organic solvent such as methanol can be performed as necessary. In order to obtain a desired particle size, classification is preferably performed. The classification method is not particularly limited, and a sieve, an air classifier, or the like can be used as necessary. Classification can be used both dry and wet.

The chemical formula of the compound obtained by the firing method can be calculated from an inductively coupled plasma (ICP) emission spectroscopic analysis method as a measurement method and a mass difference between powders before and after firing as a simple method.

In the present invention, the effect of using a specific negative electrode active material such as LTO for the negative electrode of the battery is estimated as follows. That is, in the conventional battery using a specific electrode (tin), the charge / discharge efficiency deteriorates due to Li generated by the reduction reaction or metal interaction, but this point is considered to be improved. On the other hand, as a mechanism of gas generation from a specific organic compound, a hydrogen elimination reaction by an intramolecular cyclization reaction can be considered. It is understood that the compound of the present invention has an unsaturated bond via a linking group in the molecule and promotes this intramolecular cyclization. In this respect, the negative electrode using tin is considered to have reduced its effect because the additive having an active unsaturated site reacts and disappears due to generation of lithium dendrite.

The electrolyte solution of the present invention is preferably combined with a high potential negative electrode (preferably lithium-titanium oxide, a potential of 1.55 V vs. Li metal) and a low potential negative electrode (preferably a carbon material, potential of about 0.1 V vs. Li). Excellent properties are exhibited in any combination with (metal).

The negative electrode active material used in the non-aqueous secondary battery of the present invention preferably contains lithium titanate. More specifically, Li ₄ Ti ₅ O ₁₂ is preferable in that the volume fluctuation at the time of occlusion and release of lithium ions is small, so that deterioration of the electrode is suppressed and the life of the lithium ion secondary battery can be improved. By combining a specific negative electrode and a specific electrolyte, the stability of the secondary battery is improved even under various usage conditions.

-Conductive material As the conductive material, any electronic conductive material that does not cause a chemical change in the configured secondary battery may be used, and any known conductive material may be used. Usually, natural graphite (scale-like graphite, scale-like graphite, earth-like graphite, etc.), artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber and metal powder (copper, nickel, aluminum, silver (Japanese Patent Laid-Open No. Sho 63-63)) 10148,554), etc.), metal fibers or polyphenylene derivatives (described in JP-A-59-20971) can be contained as one kind or a mixture thereof. Among these, the combined use of graphite and acetylene black is particularly preferable. The addition amount of the conductive agent is preferably 1 to 50% by mass, and more preferably 2 to 30% by mass. In the case of carbon or graphite, 2 to 15% by mass is particularly preferable.

-Binders Examples of binders include polysaccharides, thermoplastic resins, and polymers having rubber elasticity. Among them, for example, starch, carboxymethyl cellulose, cellulose, diacetyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose. Water-soluble, such as sodium alginate, polyacrylic acid, sodium polyacrylate, polyvinylphenol, polyvinyl methyl ether, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylonitrile, polyacrylamide, polyhydroxy (meth) acrylate, styrene-maleic acid copolymer Polymer, polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, vinyl Redene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, polyvinyl acetal resin, methyl methacrylate, 2-ethylhexyl acrylate, etc. ) (Meth) acrylic ester copolymer containing acrylic ester, (meth) acrylic ester-acrylonitrile copolymer, polyvinyl ester copolymer containing vinyl ester such as vinyl acetate, styrene-butadiene copolymer , Acrylonitrile-butadiene copolymer, polybutadiene, neoprene rubber, fluoro rubber, polyethylene oxide, polyester polyurethane resin, polyether polyurethane resin, polycarbonate Polyurethane resins, polyester resins, phenolic resins, emulsion (latex) or a suspension such as an epoxy resin is preferable, a latex of polyacrylate, carboxymethyl cellulose, polytetrafluoroethylene, polyvinylidene fluoride is more preferable.

Binders can be used alone or in combination of two or more. When the amount of the binder added is small, the holding power and cohesive force of the electrode mixture are weakened. If the amount is too large, the electrode volume increases and the capacity per electrode unit volume or unit mass decreases. For this reason, the addition amount of the binder is preferably 1 to 30% by mass, and more preferably 2 to 10% by mass.

-Filler The electrode compound material may contain the filler. As the material for forming the filler, any fibrous material that does not cause a chemical change in the secondary battery of the present invention can be used. Usually, fibrous fillers made of materials such as olefin polymers such as polypropylene and polyethylene, glass, and carbon are used. The addition amount of the filler is not particularly limited, but is preferably 0 to 30% by mass in the dispersion.

-Current collector As the positive / negative electrode current collector, an electron conductor that does not cause a chemical change in the nonaqueous electrolyte secondary battery of the present invention is used. As the current collector of the positive electrode, in addition to aluminum, stainless steel, nickel, titanium, etc., the surface of aluminum or stainless steel is preferably treated with carbon, nickel, titanium, or silver. Among them, aluminum and aluminum alloys are preferable. More preferred.

As the negative electrode current collector, aluminum, copper, stainless steel, nickel and titanium are preferable, and aluminum, copper and copper alloy are more preferable.

As the shape of the current collector, a film sheet shape is usually used, but a net, a punched material, a lath body, a porous body, a foamed body, a molded body of a fiber group, and the like can also be used. The thickness of the current collector is not particularly limited, but is preferably 1 μm to 500 μm. Moreover, it is also preferable that the current collector surface is roughened by surface treatment.
An electrode mixture of the lithium secondary battery is formed by a member appropriately selected from these materials.

(Separator)
The separator used in the non-aqueous secondary battery of the present invention is particularly a material that has mechanical strength for electrically insulating the positive electrode and the negative electrode, ion permeability, and oxidation / reduction resistance at the contact surface between the positive electrode and the negative electrode. There is no limit. As such a material, a porous polymer material, an inorganic material, an organic-inorganic hybrid material, glass fiber, or the like is used. These separators preferably have a shutdown function for ensuring reliability, that is, a function of closing a gap at 80 ° C. or higher to increase resistance and interrupting current, and a closing temperature is 90 ° C. or higher and 180 ° C. or lower. It is preferable.

The shape of the holes of the separator is usually circular or elliptical, and the size is 0.05 μm to 30 μm, preferably 0.1 μm to 20 μm. Furthermore, it may be a rod-like or irregular-shaped hole as in the case of making by a stretching method or a phase separation method. The ratio of these gaps, that is, the porosity, is 20% to 90%, preferably 35% to 80%.

The polymer material may be a single material such as a cellulose nonwoven fabric, polyethylene, or polypropylene, or may be a material using two or more composite materials. What laminated | stacked the 2 or more types of microporous film which changed the hole diameter, the porosity, the obstruction | occlusion temperature of a hole, etc. is preferable.

As the inorganic substance, oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates such as barium sulfate and calcium sulfate are used, and those having a particle shape or fiber shape are used. As the form, a thin film shape such as a non-woven fabric, a woven fabric, or a microporous film is used. As the thin film shape, those having a pore diameter of 0.01 μm to 1 μm and a thickness of 5 μm to 50 μm are preferably used. In addition to the independent thin film shape, a separator formed by forming a composite porous layer containing the inorganic particles on the surface layer of the positive electrode and / or the negative electrode using a resin binder can be used. For example, alumina particles having a 90% particle diameter of less than 1 μm are formed on both surfaces of the positive electrode as a porous layer using a fluororesin binder.

(Production of non-aqueous secondary battery)
As described above, the shape of the nonaqueous secondary battery of the present invention can be applied to any shape such as a sheet shape, a square shape, and a cylinder shape. A positive electrode active material or a mixture of negative electrode active materials is mainly used after being applied (coated), dried and compressed on a current collector.

Hereinafter, with reference to FIG. 2, a configuration and a manufacturing method thereof will be described using the bottomed cylindrical lithium secondary battery 100 as an example. In a battery having a bottomed cylindrical shape, since the outer surface area with respect to the power generating element to be filled becomes small, it is preferable to design so that Joule heat generated by the internal resistance at the time of charging and discharging efficiently escapes to the outside. Moreover, it is preferable to design so that the filling ratio of the substance having high thermal conductivity is increased and the temperature distribution inside is reduced. FIG. 2 shows an example of a bottomed cylindrical lithium secondary battery 100. This battery is a bottomed cylindrical lithium secondary battery 100 in which a positive electrode sheet 14 and a negative electrode sheet 16 overlapped with a separator 12 are wound and accommodated in an outer can 18. In addition, in the figure, 20 is an insulating plate, 22 is a sealing plate, 24 is a positive electrode current collector, 26 is a gasket, 28 is a pressure sensitive valve body, and 30 is a current interruption element. In addition, although the illustration in the enlarged circle has changed hatching in consideration of visibility, each member corresponds to the whole drawing by reference numerals.

First, a negative electrode active material is mixed with a binder or filler used as desired in an organic solvent to prepare a slurry or paste negative electrode mixture. The obtained negative electrode mixture is uniformly applied over the entire surface of both surfaces of the metal core as a current collector, and then the organic solvent is removed to form a negative electrode mixture layer. Further, the laminate of the current collector and the negative electrode composite material layer is rolled with a roll press or the like to prepare a predetermined thickness to obtain a negative electrode sheet (electrode sheet). At this time, the coating method of each agent, the drying of the coated material, and the method of forming the positive and negative electrodes may be in accordance with conventional methods.

In the present embodiment, a cylindrical battery is taken as an example, but the present invention is not limited to this, for example, after the positive and negative electrode sheets produced by the above method are overlapped via a separator, After processing into a sheet battery as it is, or inserting it into a rectangular can after being folded and electrically connecting the can and the sheet, injecting an electrolyte and sealing the opening using a sealing plate A square battery may be formed.

In any of the embodiments, the safety valve can be used as a sealing plate for sealing the opening. In addition to the safety valve, the sealing member may be provided with various conventionally known safety elements. For example, a fuse, bimetal, PTC element, or the like is preferably used as the overcurrent prevention element.

Further, in addition to the safety valve, as a countermeasure against an increase in the internal pressure of the battery can, a method of cutting the battery can, a method of cracking the gasket, a method of cracking the sealing plate, or a method of cutting the lead plate can be used. Further, the charger may be provided with a protection circuit incorporating measures against overcharge and overdischarge, or may be connected independently.

For the can and lead plate, a metal or alloy having electrical conductivity can be used. For example, metals such as iron, nickel, titanium, chromium, molybdenum, copper, and aluminum, or alloys thereof are preferably used.

A known method (eg, direct current or alternating current electric welding, laser welding, ultrasonic welding) can be used as a welding method for the cap, can, sheet, and lead plate. As the sealing agent for sealing, a conventionally known compound or mixture such as asphalt can be used.

(Pressure sensitive mechanism)
The non-aqueous secondary battery according to the present invention preferably has a pressure-sensitive mechanism (a mechanism that cuts off current when a predetermined pressure or higher is reached). Although the pressure-sensitive mechanism uses a pressure-sensitive valve as described above, various devices such as a device that detects a pressure change by a pressure-sensitive sensor and interrupts energization can be employed. FIG. 3 is a partial cross-sectional side view showing another example of the pressure-sensitive valve.
As shown in FIG. 3, the current interrupting sealing body 50 is composed of a stainless steel positive electrode cap 51 formed in an inverted dish shape (cap shape) and a stainless steel bottom plate 54 formed in a dish shape. The The positive electrode cap 51 includes a convex portion 52 that bulges toward the outside of the battery, and a flat flange portion 53 that forms the bottom side of the convex portion 52, and a plurality of gas vents are formed at the corners of the convex portion 52. A hole 52a is provided. On the other hand, the bottom plate 54 includes a concave portion 55 that bulges toward the inside of the battery, and a flat flange portion 56 that constitutes the bottom side portion of the concave portion 55. A gas vent hole 55 a is provided at the corner of the recess 55.
Housed in the positive electrode cap 51 and the bottom plate 54 is a power lead-out plate 57 that deforms when the gas pressure inside the battery rises and exceeds a predetermined pressure. The power lead-out plate 57 includes a concave portion 57a and a flange portion 57b, and is formed of, for example, an aluminum foil having a thickness of 0.2 mm and a surface unevenness of 0.005 mm. The lowest portion of the recess 57 a is disposed in contact with the upper surface of the recess 55 of the bottom plate 54, and the flange portion 57 b is sandwiched between the flange portion 53 of the positive electrode cap 51 and the flange portion 56 of the bottom plate 54. . The positive electrode cap 51 and the bottom plate 54 are sealed in a liquid-tight manner by a sealing body insulating gasket 59 made of polypropylene (PP).
A PTC (Positive Temperature Coefficient) thermistor element 58 is disposed at a part of the upper portion of the flange portion 57b. When an overcurrent flows in the battery and an abnormal heat generation phenomenon occurs, the resistance value of the PTC thermistor element 58 increases. Increase to reduce overcurrent. Then, when the gas pressure inside the battery rises and exceeds a predetermined pressure, the recess 57a of the power lead-out plate 57 is deformed, so that the contact between the power lead-out plate 57 and the concave portion 55 of the bottom plate 54 is cut off and an overcurrent or short circuit occurs. The current is interrupted.
By using the electrolyte for a non-aqueous secondary battery according to the present invention, in the secondary battery having the pressure-sensitive mechanism, more gas is instantly generated at the time of overcharging, and accurate and quick interruption of current is possible. And

It is preferable that the specific organic compound of the present invention does not generate gas during normal charging but generates an effective amount of gas during overcharging. Here, “to generate an effective amount of gas at the time of overcharging” means that the results of the gas generation amount test and the charge life test at the time of overcharging in the examples described later are equivalent to the examples.

[Applications of non-aqueous secondary batteries]

Secondary batteries called lithium batteries are secondary batteries that use the insertion and extraction of lithium for charge / discharge reactions (lithium ion secondary batteries), and secondary batteries that use precipitation and dissolution of lithium (lithium metal secondary batteries). ). In the present invention, application as a lithium ion secondary battery is preferable.
Since the nonaqueous secondary battery of the present invention can produce a secondary battery with good cycle performance, it is applied to various applications. Although there is no particular limitation on the application mode, for example, when installed in an electronic device, a notebook computer, a pen input personal computer, a mobile personal computer, an electronic book player, a mobile phone, a cordless phone, a pager, a handy terminal, a mobile fax machine, a mobile phone Copy, portable printer, headphone stereo, video movie, LCD TV, handy cleaner, portable CD, minidisc, electric shaver, transceiver, electronic notebook, calculator, memory card, portable tape recorder, radio, backup power supply, memory card, etc. It is done. Other consumer products include automobiles, electric vehicles, motors, lighting equipment, toys, game equipment, road conditioners, watches, strobes, cameras, medical equipment (such as pacemakers, hearing aids, and shoulder grinders). Furthermore, it can be used for various military use and space use. Moreover, it can also combine with a solar cell.

In particular, it is preferable to be applied to applications requiring high capacity and high rate discharge characteristics from the viewpoint of exhibiting the advantages of reliability and high rate discharge characteristics during overcharge. For example, in power storage facilities and the like that are expected to increase in capacity in the future, high reliability is indispensable and further compatibility of battery performance is required. In addition, electric vehicles are equipped with high-capacity rechargeable batteries and are expected to be charged daily at home, and even higher reliability is required for overcharging (NEDO Technology Development Organization, Fuel Cell / Hydrogen Technology Development Department, Energy Storage Technology Development Office “NEDO Next-Generation Automotive Storage Battery Technology Development Roadmap 2008” (June 2009)). In addition, when starting and accelerating, it is necessary to discharge at a high rate, and it is important that the high-rate discharge capacity does not deteriorate even after repeated charging and discharging. According to the present invention, it is possible to exhibit the excellent effect correspondingly to such a usage pattern.

Hereinafter, the present invention will be described in more detail, but the present invention is not construed as being limited thereto.

(Example 1)
(Preparation of electrolyte)
LiPF ₆ was added so that it might become 1 mol / L (12.7 mass%) with respect to the solution which mixed ethylene carbonate (EC) and ethyl methyl carbonate (EMC) by the volume ratio 1: 2, and becomes electrolyte solution used as a reference | standard Was made. On the other hand, it mixed with the additive and addition amount of the following table 1, and prepared the non-aqueous electrolyte.

(Production of 2032 type coin battery)
The positive electrode is made of NMC: LiNi _0.33 Co _0.33 Mn _0.33 O ₂ 85% by mass, conductive auxiliary agent: carbon black 7.5% by mass, binder: PVDF 7.5% by mass, and the negative electrode is LTO: 94% by mass of lithium titanate, conductive assistant: 3% by mass of carbon black, binder: 3% by mass of PVDF The separator is glass filter paper (manufactured by ADVANTEC: GA-55, thickness: 0.21 mm). Using the positive and negative electrodes and separators described above, 2032 type coin batteries (diameter: 20 mm, height: 3.2 mm, top cover, bottom cover: SUS 250 μm, FIG. 4) were prepared for each test electrolyte. The battery characteristic items were evaluated.

<Gas generation during overcharge>
Using a 2032 battery manufactured in the above procedure, in a 45 ° C constant temperature bath, after charging at 1 C constant current until the battery voltage reached 4.95 V at 1.8 mA, the battery voltage became 1.2 V at 0.4 mA. A 0.2C discharge was performed until the battery volume was measured. The measurement was performed using a precision hydrometer set (precision balance: AUW120D, specific gravity measurement kit: SMK-401) manufactured by Shimadzu Corporation. The ratio of the increase in battery volume after the overcharge test to the volume during battery production was defined as the amount of gas generated during overcharge.

Gas generation during overcharge = (battery volume after overcharge test-battery volume during creation) / battery volume during creation x 100

This gas generation amount is less than 1 C
1 to less than 2 B
2 or more and less than 3 A
3 or more AA
As evaluated.

<4.3V capacity maintenance rate>
Using the 2032 battery produced by the above method, 1C constant current charging was performed in a constant temperature bath at 60 ° C. until the electrode potential reached 4.5 V (voltage 2.95 V) at 4.0 mA. This constant voltage charging was continued until the current value reached 0.12 mA (however, the upper limit of the charging time was 2 hours). Next, 1C constant current discharge was performed at 4.0 mA until the electrode potential reached 2.75 V (voltage 1.2 V), and one cycle was obtained. This was repeated until 300 cycles were reached, and the discharge capacity (mAh) after 300 cycles was measured. From this result, the discharge capacity retention rate was calculated by the following formula.
Discharge capacity maintenance rate (%) =
(Discharge capacity after 300 cycles / discharge capacity after 1 cycle) × 100

70% or more A
60% or more and less than 70% B
50% or more and less than 60% C

<4.3V low temperature characteristics>
The temperature of the cycle characteristic test was changed from 60 ° C to 5 ° C. In the same manner as above, the discharge capacity between the first cycles was measured, and the low temperature capacity retention rate was calculated by the following formula.
Low temperature capacity retention rate (%) =
(5 ° C. discharge capacity / 60 ° C. discharge capacity) × 100

70% or more A
60% or more and less than 70% B
50% or more and less than 60% C

The results are shown in Table 1 below.

Test No. : Comparative examples starting with C * 1 Compound addition amount: Content (% by mass) with respect to the total amount of electrolyte (including electrolyte)
* 2 Solvent addition amount: Content (% by volume) with respect to the total amount of solvent

From the above results, by using the specific organic compound according to the present invention, the high overcharge prevention property based on the generation of gas from the non-aqueous electrolyte, the battery performance deterioration suppression property (cycle property), and the low temperature property are satisfied at the same time. I can see that

While this invention has been described in conjunction with its embodiments, we do not intend to limit our invention in any detail of the description unless otherwise specified and are contrary to the spirit and scope of the invention as set forth in the appended claims. I think it should be interpreted widely.
This application claims priority based on Japanese Patent Application No. 2013-070495, filed in Japan on March 28, 2013, which is hereby incorporated herein by reference. Capture as part.

C positive electrode (positive electrode composite)
1 Positive electrode conductive material (current collector)
2 Positive electrode active material layer A Positive electrode (positive electrode mixture)
3 Negative electrode conductive material (current collector)
4 Negative electrode active material layer 5 Nonaqueous electrolyte 6 Operating means 7 Wiring 9 Separator 10 Lithium ion secondary battery 12 Separator 14 Positive electrode sheet 16 Negative electrode sheet 18 Exterior can 20 also serving as negative electrode Insulating plate 22 Sealing plate 24 Positive electrode current collector 26 Gasket 28 Pressure-sensitive valve body 30 Current interrupting element 100 Bottomed cylindrical lithium secondary battery 50 Current interrupting sealing body 51 Positive electrode cap 52 Convex part 52a Gas vent hole 53 Flange part 54 Bottom plate 55 Concave part 56 Flange part 57 Power outlet plate 57a Concave part 57
57b Flange part 58 PTC thermistor element 59 Insulating gasket 61 for sealing body Negative electrode terminal (upper cover)
62 Negative electrode 63 Separator (including electrolyte)
64 Gasket (sealing material)
65 Positive electrode 66 Positive electrode tube (bottom cover)

Claims (18)

1. A non-aqueous secondary battery having a positive electrode, a negative electrode, and a non-aqueous electrolyte,
   The negative electrode has a normal operating potential of 1.2 V or more for lithium metal,
   The nonaqueous electrolytic solution is a nonaqueous secondary battery including an electrolyte, an organic solvent, and an onium salt having a partial structure having a compound represented by the following formula (I), an aryl group, or a heterocyclic group.
   

   

   (X ¹ and X ² each represents a substituent, and at least one of them is an aryl group-containing group or a group that forms a heterocyclic group with L ^1. Both may be the same or different. X ¹ and X ² may form a ring structure bonded to fused with each other. Alternatively, X ¹ is omitted, X ² and L ¹ and there is a good .X ¹ also form a ring with L ¹ combined with optionally form a ring .L ¹ is ^{-O -, - S -, -} NR a -, - CO -, - CR b R c -, or a combination thereof ^.R a ~ R ^c each independently represents ^a hydrogen atom or a substituent, and R ^a to R ^c may combine with X ¹ to form a ring.)
2. The non-aqueous secondary battery according to claim 1, wherein the compound represented by the formula (I) has an aryl group or heterocyclic group having at least one alkyl group in a partial structure.
3. The non-aqueous secondary battery according to claim 1 or 2, wherein L ¹ is -O-,-(CO) O-, -NR ^a- , or a combination thereof.
4. L ¹ is * —O — **, * — (CR ^b R ^c ) _m3 — **, * — (CO) O — **, * —O (CO) O — **, * —NR ^a —. The nonaqueous secondary battery according to any one of claims 1 to 3, which is **, * -NR ^a (CO) O-**, or * -NR ^a -NR ^a (CO) O-**. .
   (R ^a to R ^c are as defined in formula (I). M3 is an integer of 1 to 6. * is a bond on the CO side, and ** is a bond on the X ¹ side.)
5. The nonaqueous secondary battery according to any one of claims 1 to 4, wherein X ¹ and X ² are an alkyl group and a substituent having a partial structure selected from the following formulas (X1) to (X12).
   

   

   (R ^X1 represents a substituent. N11 represents an integer of 0 to 4. n12 represents an integer of 0 to 5. n13 represents an integer of 0 to 11. n14 represents an integer of 0 to 8. n15 Represents an integer of 0 to 4. n16 represents an integer of 0 to 10. L ² represents an alkylene group that may contain an aryl group, * represents a bond, Formulas (X1), (X5), (X11) for shows, including NR ^a is a site contained in ^{L 1} of formula (I).)
6. In the compound represented by the formula (I), when X ¹ and X ² form a ring, or when X ² and L ¹ combine to form a ring, the compound represented by the formula (I) The compound according to any one of claims 1 to 5, wherein in the compound, when X ¹ and X ² form a ring, the compound is a compound represented by any one of the following formulas (C1) to (C6): Non-aqueous secondary battery.
   

   

   (R ^C1 represents a substituent. M1 represents an integer of 0 to 4. m2 represents an integer of 0 to 2.
7. The non-aqueous secondary battery according to claim 1, wherein the onium salt is a compound represented by any one of the following formulas (II) to (VII).
   

   

   (R ¹ to R ²⁷ are a hydrogen atom, an alkyl group, an alkoxy group, an alkoxycarbonyl group, an aryl group, or a heterocyclic group. R ¹ to R ²⁷ are bonded to each other or bonded to each other to form a ring structure. Z ⁻ represents an anion.
8. The nonaqueous secondary battery according to claim 7, wherein R ¹ to R ²⁷ are selected from an alkyl group or the following (R1) to (R10).
   

   

   (R ³¹ represents a substituent. L ³ and L ⁴ each independently represent an alkylene group that may contain an aryl group. N3 represents an integer of 0 to 10. n4 represents an integer of 0 to 11. n5 represents an integer of 0 to 9. n6 represents an integer of 0 to 5. n7 represents an integer of 0 to 4. * represents a bond.)
9. The nonaqueous secondary battery according to any one of claims 1 to 8, wherein an operating potential of the negative electrode is 1.4 V to 2 V with respect to lithium as a metal.
10. The nonaqueous secondary battery according to any one of claims 1 to 9, wherein the negative electrode is lithium titanate (LTO).
11. The non-aqueous secondary battery according to any one of claims 1 to 10, wherein the positive electrode active material is a transition metal oxide capable of inserting and releasing alkali metal ions.
12. The nonaqueous secondary battery according to any one of claims 1 to 11, wherein the active material contained in the positive electrode includes a transition metal oxide represented by any of the following formulas (MA) to (MC).
    Li _a M ¹ O _b (MA)
    Li _c M ² ₂ O _d (MB)
    Li _e M ³ (PO ₄ ) _f ... (MC)
    (In the formula, M ¹ and M ² each independently represent one or more elements selected from Co, Ni, Fe, Mn, Cu, and V. M ³ independently represents V, Ti. , Cr, Mn, Fe, Co, Ni, and Cu represent one or more elements selected from the group consisting of M ¹ to M ³ , a part of which is the first (Ia) of the periodic table other than lithium. ) Group element, Group 2 (IIa) element, Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, and B may be substituted. a represents 0 to 1.2, b represents 1 to 3, c represents 0 to 2, d represents 3 to 5, e represents 0 to 2, and f represents 1 to 5. )
13. The active material of the positive electrode is lithium cobalt oxide, lithium manganate, lithium nickelate, lithium nickel manganese cobaltate, lithium manganese nickelate, lithium nickel cobaltaluminate, or lithium iron phosphate. The non-aqueous secondary battery according to claim 1.
14. The nonaqueous secondary battery according to any one of claims 1 to 13, wherein a normal charge positive electrode potential of the battery is 4.25 V (Li / Li ⁺ reference) or more.
15. An electrolyte for a non-aqueous secondary battery comprising an electrolyte, an organic solvent, and an onium salt having a compound represented by the following formula (I) or an aryl group or heterocyclic group in a partial structure.
    

    

    (X ¹ and X ² each represents a substituent, and at least one of them is an aryl group-containing group or a group that forms a heterocyclic group with L ^1. Both may be the same or different. X ¹ and X ² may form a ring structure bonded to fused with each other. Alternatively, X ¹ is omitted, X ² and L ¹ and there is a good .X ¹ also form a ring with L ¹ combined with optionally form a ring .L ¹ is ^{-O -, - S -, -} NR a -, - CO -, - CR b R c -, or a combination thereof ^.R a ~ R ^c each independently represents ^a hydrogen atom or a substituent, and R ^a to R ^c may combine with X ¹ to form a ring.)
16. The electrolyte solution for a non-aqueous secondary battery according to claim 15, wherein the onium salt is a compound represented by any of the following formulas (II) to (VII).
    

    

    (R ¹ to R ²⁷ are a hydrogen atom, an alkyl group, an alkoxy group, an alkoxycarbonyl group, an aryl group, or a heterocyclic group. R ¹ to R ²⁷ are bonded to each other or bonded to each other to form a ring structure. Z ⁻ represents an anion.
17. A non-aqueous secondary battery having a positive electrode, a negative electrode, and a non-aqueous electrolyte,
    The negative electrode normally has an operating potential of 1.2 V or more for lithium metal, and the non-aqueous electrolyte includes an electrolyte and a specific organic compound having a reduction initiation potential of less than 1.2 V.
18. The non-aqueous secondary battery according to claim 17, wherein the specific organic compound generates an effective amount of gas when overcharged.

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