JP2017212339A - Nonaqueous lithium type power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous lithium type power storage device which is arranged while making considerations to achieve all of initial high input and output characteristics, excellent electrochemical characteristics under a low-temperature environment, and high durability at a high temperature (e.g. 40-90°C), and which shows practically superior characteristics.SOLUTION: In a nonaqueous lithium power storage device, a negative electrode active material layer includes a particular sulfur compound; the total amount of the sulfur compound is 6.0×10mol/g-2,000×10mol/g per unit mass of a negative electrode active material; a nonaqueous electrolyte solution includes at least two kinds of sultone compounds; and the total content of the sultone compounds is 0.5-15 mass% to a total mass of the nonaqueous electrolyte solution.SELECTED DRAWING: None

Description

  The present invention relates to a non-aqueous lithium storage element.

In recent years, midnight power storage systems, home-use distributed power storage systems based on solar power generation technology, power storage systems for electric vehicles, etc. have attracted attention from the viewpoint of global environment conservation and effective use of energy for resource saving. Yes.
The first requirement in these power storage systems is that the energy density of the power storage elements used is high. As a promising candidate for an energy storage device with high energy density that can meet such demands, development of lithium ion batteries has been energetically advanced.
The second requirement is high output characteristics. For example, a combination of a high-efficiency engine and a power storage system (for example, a hybrid electric vehicle) or a combination of a fuel cell and a power storage system (for example, a fuel cell electric vehicle) requires a high output discharge characteristic in the power storage system during acceleration. Has been.

At present, electric double layer capacitors, nickel metal hydride batteries, and the like have been developed as high power storage elements.
Among the electric double layer capacitors, those using activated carbon for the electrodes have an output characteristic of about 0.5 to 1 kW / L. This electric double layer capacitor has high durability (particularly, cycle characteristics and high temperature storage characteristics), and has been considered as an optimum storage element in the field where the high output is required. However, for its practical use, it is a foothold that the energy density is as low as about 1 to 5 Wh / L and the output duration is short.
On the other hand, nickel-metal hydride batteries currently used in hybrid electric vehicles realize high output equivalent to electric double layer capacitors and have an energy density of about 160 Wh / L. However, research is underway energetically to further increase the energy density and output, further improve the stability at high temperatures, and enhance the durability.

  In addition, research for higher output is also being conducted in lithium ion batteries. For example, a lithium ion battery has been developed that can obtain a high output exceeding 3 kW / L at a discharge depth (that is, a value representing what percentage of the discharge capacity of the device is discharged) 50%. However, the energy density is 100 Wh / L or less, and the high energy density, which is the greatest feature of the lithium ion battery, is intentionally suppressed. Furthermore, the durability (particularly cycle characteristics and high-temperature storage characteristics) of lithium ion batteries is inferior to electric double layer capacitors. Therefore, in order to give practical durability to the lithium ion battery, it can be used only in a range where the depth of discharge is narrower than the range of 0 to 100%. Since the capacity that can actually be used is further reduced, research for further improving the durability is being actively pursued.

  As described above, there is a strong demand for practical use of a power storage element having high output density, high energy density, and durability. However, the above-described existing power storage element has advantages and disadvantages. Therefore, a new power storage element that satisfies these technical requirements has been demanded, and development of a power storage element called a lithium ion capacitor has been actively developed as a promising candidate.

  A lithium ion capacitor is a type of energy storage device that uses a non-aqueous electrolyte containing an electrolyte containing lithium ions (that is, a non-aqueous lithium-type energy storage device). It is a power storage element that charges and discharges by a non-Faraday reaction by adsorption / desorption of ions and a Faraday reaction by occlusion / release of lithium ions in the negative electrode, similar to a lithium ion battery.

  As described above, an electric double layer capacitor that charges and discharges by a non-Faraday reaction in both the positive electrode and the negative electrode is excellent in output characteristics but has a low energy density. On the other hand, a lithium ion battery that is a secondary battery that performs charge and discharge by a Faraday reaction in both the positive electrode and the negative electrode is excellent in energy density but inferior in output characteristics. A lithium ion capacitor is a new power storage element that aims to achieve both excellent output characteristics and high energy density by performing charge and discharge by a non-Faraday reaction at the positive electrode and a Faraday reaction at the negative electrode.

  Examples of the use of the lithium ion capacitor include railways, construction machinery, automobile power storage, and the like. In these applications, since the operating environment is harsh, the capacitor used must have excellent temperature characteristics from high temperature to low temperature. In addition, the capacitor used is required not to deteriorate in electrochemical characteristics even when used for a long time in a wide temperature range from high temperature to low temperature. However, performance degradation caused by gas generation due to decomposition of the electrolytic solution at high temperatures and performance degradation caused by reduced electrical conductivity of the electrolytic solution are problematic at low temperatures. As a countermeasure technique against such problems, reductive decomposition of the nonaqueous electrolyte accompanying subsequent charging / discharging is performed by adding an additive to the nonaqueous electrolyte and forming a coating composed of the decomposition product on the surface of the negative electrode active material. There is a technique for suppressing the battery life and improving the durability of the battery. As a technique related to this, Patent Document 1 proposes a lithium ion capacitor containing two types of additives having different structures in an electrolytic solution. Patent Documents 2 and 3 propose lithium ion secondary batteries in which a certain amount of film is formed on the surface of the negative electrode active material by adding an additive. Patent Documents 4 and 5 propose lithium ion secondary batteries in which corrosion of the aluminum current collector is suppressed when an imide lithium salt is used.

JP 2014-27196 A Japanese Patent Laying-Open No. 2015-125833 Japanese Patent Application Laid-Open No. 2014-137861 JP 2014-13704 A JP 2004-165151 A

  Patent Documents 1 and 2 describe improvement in high-temperature durability, but the effect is not sufficient, and further, no effect has been confirmed for improving the initial characteristics at low temperatures. Patent Document 3 describes that charging / discharging cycle characteristics of a lithium ion secondary battery are improved by blending 1,3-propane sultone in an electrolytic solution, but results are shown for characteristic changes at high temperatures. Absent. Patent Document 4 discloses a technique for suppressing corrosion of a current collector when an imide lithium salt is added and improving good cycle characteristics. However, the results regarding the improvement in initial characteristics at low temperatures and the durability at high temperatures are shown. Is not shown. Patent Document 5 describes improvement in durability at high temperature, but the effect is not sufficient, and further, no effect has been confirmed for improving characteristics at low temperatures.

As described above, in the conventional lithium ion capacitor, only superiority or inferiority is evaluated by paying attention only to the initial characteristics or long-term durability.
In view of such a current situation, the problems to be solved by the present invention are high initial input / output characteristics, excellent electrochemical characteristics in a low temperature environment, and high durability at high temperatures (for example, 40 to 90 ° C.). In view of the above, it is an object of the present invention to provide a non-aqueous lithium storage element that exhibits practically excellent characteristics.

｛式（１）中、Ｒ^１は、炭素数１〜２４のアルキル基、炭素数１〜２４のモノ若しくはポリヒドロキシアルキル基又はそのリチウムアルコキシド、炭素数２〜２４のアルケニル基、炭素数２〜２４のモノ若しくはポリヒドロキシアルケニル基又はそのリチウムアルコキシド、炭素数３〜６のシクロアルキル基、又はアリール基であり、そしてＸ^１は、水素、リチウム、又は炭素数１〜１２のアルキル基である。｝

｛式（２）中、Ｒ^２は、炭素数１〜２４のアルキル基、炭素数１〜２４のモノ若しくはポリヒドロキシアルキル基又はそのリチウムアルコキシド、炭素数２〜２４のアルケニル基、炭素数２〜２４のモノ又はポリヒドロキシアルケニル基、炭素数３〜６のシクロアルキル基、又はアリール基であり、そしてＸ^２及びＸ^３は、各々独立に、水素、リチウム、又は炭素数１〜１２のアルキル基である。｝
のそれぞれで表されるスルホン酸誘導体、並びに下記式（３）及び（４）：

｛式（３）中、Ｒ^３は、炭素数１〜２４のアルキル基、炭素数１〜２４のモノ若しくはポリヒドロキシアルキル基又はそのリチウムアルコキシド、炭素数２〜２４のアルケニル基、炭素数２〜２４のモノ若しくはポリヒドロキシアルケニル基又はそのリチウムアルコキシド、炭素数３〜６のシクロアルキル基、又はアリール基であり、そしてＸ^４は、水素、リチウム、又は炭素数１〜１２のアルキル基である。｝

｛式（４）中、Ｒ^４は、炭素数１〜２４のアルキル基、炭素数１〜２４のモノ若しくはポリヒドロキシアルキル基又はそのリチウムアルコキシド、炭素数２〜２４のアルケニル基、炭素数２〜２４のモノ若しくはポリヒドロキシアルケニル基又はそのリチウムアルコキシド、炭素数３〜６のシクロアルキル基、又はアリール基であり、そしてＸ^５及びＸ^６は、各々独立に、水素、リチウム、又は炭素数１〜１２のアルキル基である。｝
のそれぞれで表される亜硫酸誘導体から成る群より選択される少なくとも１種の硫黄化合物を含み、かつ該スルホン酸誘導体及び該亜硫酸誘導体の総量が、該負極活物質の単位質量当たり６．０×１０^−６ｍｏｌ／ｇ〜２，０００×１０^−６ｍｏｌ／ｇであり、
そして該非水電解液中に下記式（５）〜（７）：

｛式（５）中、Ｒ^１１〜Ｒ^１６は、水素原子、ハロゲン原子、炭素数１〜１２のアルキル基、又は炭素数１〜１２のハロゲン化アルキル基を表し、互いに同一であっても異なっていてもよく；そしてｎは０〜３の整数である。｝

｛式（６）中、Ｒ^１１〜Ｒ^１４は、水素原子、ハロゲン原子、炭素数１〜１２のアルキル基、又は炭素数１〜１２のハロゲン化アルキル基を表し、互いに同一であっても異なっていてもよく；そしてｎは０〜３の整数である。｝

｛式（７）中、Ｒ^１１〜Ｒ^１６は、水素原子、ハロゲン原子、炭素数１〜１２のアルキル基、又は炭素数１〜１２のハロゲン化アルキル基を表し、互いに同一であっても異なっていてもよい。｝
のそれぞれで表されるスルトン化合物を２種以上含有し、該スルトン化合物の総含有量が、該非水電解液の総量に対して０．５質量％〜１５質量％である、
前記非水系リチウム蓄電素子。
［２］
前記式（５）で表されるスルトン化合物が、１，３−プロパンスルトン、２，４−ブタンスルトン、１，４−ブタンスルトン、１，３−ブタンスルトン又は２，４−ペンタンスルトンであり、前記式（６）で表されるスルトン化合物が、１，３−プロペンスルトン又は１，４−ブテンスルトンであり、そして前記式（７）で表されるスルトン化合物が、１，５，２，４−ジオキサジチエパン２，２，４，４−テトラオキシド（シクロジソン）である、［１］に記載の非水系リチウム蓄電素子。
［３］
前記非水系電解液が、前記非水系電解液の総量を基準として、０．３ｍｏｌ／Ｌ以上１．５ｍｏｌ／Ｌ以下の濃度でＬｉＮ（ＳＯ_２Ｆ）_２を含有する、［１］又は［２］に記載の非水系リチウム蓄電素子。
［４］
前記非水系電解液が、ＬｉＰＦ_６及びＬｉＢＦ_４のうち少なくとも１種を含有する、［１］〜［３］のいずれか１項に記載の非水系リチウム蓄電素子。
［５］
前記非水系電解液が、ＬｉＮ（ＳＯ_２Ｆ）_２及びＬｉＰＦ_６を含有し、
前記非水系電解液に含まれるＡｌ濃度が、前記非水系電解液の総量を基準として、１ｐｐｍ以上５０ｐｐｍ以下の範囲であり、かつ
前記非水系電解液に含まれるＬｉＰＯ_２Ｆ_２濃度が、前記非水系電解液の総量を基準として、１ｐｐｍ以上１００ｐｐｍ以下の範囲である、
［１］に記載の非水系リチウム蓄電素子。
［６］
前記ＬｉＮ（ＳＯ_２Ｆ）_２と前記ＬｉＰＦ_６のモル比が、９：１〜３：７である、［５］に記載の非水系リチウム蓄電素子。
［７］
前記非水系電解液が、
エチレンカーボネートと、
（ａ）ジメチルカーボネート、ジエチルカーボネート及びエチルメチルカーボネートから選択される少なくとも１種とを含む有機溶媒を含有し、そして
前記（ａ）ジメチルカーボネート、ジエチルカーボネート及びエチルメチルカーボネートから選択される少なくとも１種の体積比率が、前記有機溶媒の総量を基準として、２０％以上である、［１］〜［６］のいずれか１項に記載の非水系リチウム蓄電素子。
［８］
負極電極体、正極電極体、及びセパレータを有する電極積層体と、非水系電解液とが外装体に収容されて成る非水系リチウム蓄電素子であって、
該負極電極体が、負極集電体と、該負極集電体の片面上又は両面上に設けられた、負極活物質を含む負極活物質層とを有し、該負極活物質はリチウムイオンを吸蔵・放出できる炭素材料を含み、
該正極電極体が、正極集電体と、該正極集電体の片面上又は両面上に設けられた、正極活物質を含む正極活物質層とを有し、該正極活物質は活性炭を含み、
該非水系電解液が、該非水系電解液の総量基準で、０．５ｍｏｌ／Ｌ以上のリチウム塩を含み、
該負極活物質層が、下記式（１）及び（２）：

｛式（１）中、Ｒ^１は、炭素数１〜２４のアルキル基、炭素数１〜２４のモノ若しくはポリヒドロキシアルキル基又はそのリチウムアルコキシド、炭素数２〜２４のアルケニル基、炭素数２〜２４のモノ若しくはポリヒドロキシアルケニル基又はそのリチウムアルコキシド、炭素数３〜６のシクロアルキル基、又はアリール基であり、そしてＸ^１は、水素、リチウム、又は炭素数１〜１２のアルキル基である。｝

｛式（２）中、Ｒ^２は、炭素数１〜２４のアルキル基、炭素数１〜２４のモノ若しくはポリヒドロキシアルキル基又はそのリチウムアルコキシド、炭素数２〜２４のアルケニル基、炭素数２〜２４のモノ又はポリヒドロキシアルケニル基、炭素数３〜６のシクロアルキル基、又はアリール基であり、そしてＸ^２及びＸ^３は、各々独立に、水素、リチウム、又は炭素数１〜１２のアルキル基である。｝
のそれぞれで表されるスルホン酸誘導体、並びに下記式（３）及び（４）：

｛式（３）中、Ｒ^３は、炭素数１〜２４のアルキル基、炭素数１〜２４のモノ若しくはポリヒドロキシアルキル基又はそのリチウムアルコキシド、炭素数２〜２４のアルケニル基、炭素数２〜２４のモノ若しくはポリヒドロキシアルケニル基又はそのリチウムアルコキシド、炭素数３〜６のシクロアルキル基、又はアリール基であり、そしてＸ^４は、水素、リチウム、又は炭素数１〜１２のアルキル基である。｝

｛式（４）中、Ｒ^４は、炭素数１〜２４のアルキル基、炭素数１〜２４のモノ若しくはポリヒドロキシアルキル基又はそのリチウムアルコキシド、炭素数２〜２４のアルケニル基、炭素数２〜２４のモノ若しくはポリヒドロキシアルケニル基又はそのリチウムアルコキシド、炭素数３〜６のシクロアルキル基、又はアリール基であり、そしてＸ^５及びＸ^６は、各々独立に、水素、リチウム、又は炭素数１〜１２のアルキル基である。｝
のそれぞれで表される亜硫酸誘導体から成る群より選択される少なくとも１種の硫黄化合物を含み、かつ該スルホン酸誘導体及び該亜硫酸誘導体の総量が、該負極活物質の単位質量当たり６．０×１０^−６ｍｏｌ／ｇ〜２，０００×１０^−６ｍｏｌ／ｇであり、
該非水電解液は、下記式（５）〜（７）：

｛式（５）中、Ｒ^１１〜Ｒ^１６は、水素原子、ハロゲン原子、炭素数１〜１２のアルキル基、又は炭素数１〜１２のハロゲン化アルキル基を表し、互いに同一であっても異なっていてもよく；そしてｎは０〜３の整数である。｝

｛式（６）中、Ｒ^１１〜Ｒ^１４は、水素原子、ハロゲン原子、炭素数１〜１２のアルキル基、又は炭素数１〜１２のハロゲン化アルキル基を表し、互いに同一であっても異なっていてもよく；そしてｎは０〜３の整数である。｝

｛式（７）中、Ｒ^１１〜Ｒ^１６は、水素原子、ハロゲン原子、炭素数１〜１２のアルキル基、又は炭素数１〜１２のハロゲン化アルキル基を表し、互いに同一であっても異なっていてもよい。｝
のそれぞれで表されるスルトン化合物を少なくとも２種以上含有し、該スルトン化合物の総含有量が、該非水系電解液の総量に対して０．５質量％〜１５質量％であり、
そして該非水系リチウム蓄電素子を、セル電圧４Ｖ及び環境温度６０℃で４か月間保存した後の２５℃における内部抵抗をＲｂ（Ω）、該非水系リチウム蓄電素子の保存前の２５℃における内部抵抗をＲａ（Ω）、保存前の−３０℃における内部抵抗をＲｃ（Ω）、並びに保存前の２５℃における静電容量をＦ（Ｆ）とした時、以下の（ａ）から（ｄ）：
（ａ）ＲａとＦとの積Ｒａ・Ｆが１．９以下である；
（ｂ）Ｒｂ／Ｒａが１．８以下である；
（ｃ）該非水系リチウム蓄電素子をセル電圧４Ｖ及び環境温度６０℃で４か月間保存した時に発生するガス量が、２５℃において２６×１０^−３ｃｃ／Ｆ以下である；並びに
（ｄ）ＲｃとＦの積Ｒｃ・Ｆが２４以下である；
の全てを満たすことを特徴とする、非水系リチウム蓄電素子。 The inventors of the present invention conducted intensive research and experiments to solve the above problems. As a result, the negative electrode active material layer contains at least one sulfonic acid derivative or sulfite derivative, and further contains at least two or more sultone compounds in the non-aqueous electrolyte solution of the non-aqueous lithium storage element. It is possible to achieve both high initial input / output characteristics in a wide temperature range and high durability at high temperatures (for example, 40 to 90 ° C.). Furthermore, by using a specific electrolyte, input / output characteristics and high temperatures can be achieved. The inventors have found that the durability is remarkably improved and have completed the present invention.
That is, the present invention is as follows.
[1]
An electrode laminate including a negative electrode body, a positive electrode body, and a separator, and a non-aqueous electrolyte solution is housed in an exterior body.
The negative electrode body includes a negative electrode current collector, and a negative electrode active material layer including a negative electrode active material provided on one or both surfaces of the negative electrode current collector. The negative electrode active material contains lithium ions. Includes carbon materials that can be occluded and released,
The positive electrode body includes a positive electrode current collector and a positive electrode active material layer including a positive electrode active material provided on one or both surfaces of the positive electrode current collector, and the positive electrode active material includes activated carbon. ,
The non-aqueous electrolyte contains 0.5 mol / L or more lithium salt based on the total amount of the non-aqueous electrolyte,
The negative electrode active material layer has the following formulas (1) and (2):

{In Formula (1), R ¹ is an alkyl group having 1 to 24 carbon atoms, a mono- or polyhydroxyalkyl group having 1 to 24 carbon atoms, or a lithium alkoxide thereof, an alkenyl group having 2 to 24 carbon atoms, or 2 to 2 carbon atoms. 24 mono- or polyhydroxyalkenyl groups or lithium alkoxides thereof, cycloalkyl groups having 3 to 6 carbon atoms, or aryl groups, and X ¹ is hydrogen, lithium, or alkyl groups having 1 to 12 carbon atoms. }

{In formula (2), R ² represents an alkyl group having 1 to 24 carbon atoms, a mono- or polyhydroxyalkyl group having 1 to 24 carbon atoms or a lithium alkoxide thereof, an alkenyl group having 2 to 24 carbon atoms, and 2 to 2 carbon atoms. 24 mono- or polyhydroxyalkenyl groups, cycloalkyl groups having 3 to 6 carbon atoms, or aryl groups, and X ² and X ³ are each independently hydrogen, lithium, or an alkyl group having 1 to 12 carbon atoms. It is. }
And the following formulas (3) and (4):

{In Formula (3), R ³ represents an alkyl group having 1 to 24 carbon atoms, a mono- or polyhydroxyalkyl group having 1 to 24 carbon atoms or a lithium alkoxide thereof, an alkenyl group having 2 to 24 carbon atoms, and 2 to 2 carbon atoms. 24 mono- or polyhydroxyalkenyl groups or lithium alkoxides thereof, cycloalkyl groups having 3 to 6 carbon atoms, or aryl groups, and X ⁴ is hydrogen, lithium, or alkyl groups having 1 to 12 carbon atoms. }

{In the formula (4), R ⁴ represents an alkyl group having 1 to 24 carbon atoms, a mono- or polyhydroxyalkyl group having 1 to 24 carbon atoms or a lithium alkoxide thereof, an alkenyl group having 2 to 24 carbon atoms, or 2 to 2 carbon atoms. 24 mono- or polyhydroxyalkenyl group or a lithium alkoxide thereof, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group, and X ⁵ and X ⁶ are each independently hydrogen, lithium, or 1 to 3 carbon atoms. 12 alkyl groups. }
And at least one sulfur compound selected from the group consisting of sulfite derivatives represented by each of the above, and the total amount of the sulfonic acid derivative and the sulfite derivative is 6.0 × 10 6 per unit mass of the negative electrode active material ⁻⁶ mol / g to 2,000 × 10 ⁻⁶ mol / g,
And in the non-aqueous electrolyte, the following formulas (5) to (7):

{In Formula (5), R ^{11 to} R ¹⁶ represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, or a halogenated alkyl group having 1 to 12 carbon atoms. And n is an integer from 0 to 3. }

{In Formula (6), R ^{11 to} R ¹⁴ represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, or a halogenated alkyl group having 1 to 12 carbon atoms, and they may be the same or different from each other. And n is an integer from 0 to 3. }

{In Formula (7), R ^{11 to} R ¹⁶ represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, or a halogenated alkyl group having 1 to 12 carbon atoms, and they may be the same or different from each other. It may be. }
2 or more of sultone compounds represented by each of the above, the total content of the sultone compound is 0.5% by mass to 15% by mass with respect to the total amount of the non-aqueous electrolyte,
The non-aqueous lithium storage element.
[2]
The sultone compound represented by the formula (5) is 1,3-propane sultone, 2,4-butane sultone, 1,4-butane sultone, 1,3-butane sultone, or 2,4-pentane sultone, The sultone compound represented by 6) is 1,3-propene sultone or 1,4-butene sultone, and the sultone compound represented by the formula (7) is 1,5,2,4-dioxadi The non-aqueous lithium storage element according to [1], which is Thiepane 2,2,4,4-tetraoxide (cyclodison).
[3]
[1] or [2], wherein the non-aqueous electrolyte contains LiN (SO ₂ F) ₂ at a concentration of 0.3 mol / L to 1.5 mol / L based on the total amount of the non-aqueous electrolyte. ] The non-aqueous lithium electrical storage element of description.
[4]
The non-aqueous lithium storage element according to any one of [1] to [3], wherein the non-aqueous electrolyte contains at least one of LiPF ₆ and LiBF ₄ .
[5]
The non-aqueous electrolyte contains LiN (SO ₂ F) ₂ and LiPF ₆ ,
The Al concentration contained in the non-aqueous electrolyte is in the range of 1 ppm to 50 ppm based on the total amount of the non-aqueous electrolyte, and the LiPO ₂ F ₂ concentration contained in the non-aqueous electrolyte is the non-aqueous electrolyte. Based on the total amount of the aqueous electrolyte, it is in the range of 1 ppm to 100 ppm.
The non-aqueous lithium storage element according to [1].
[6]
The non-aqueous lithium storage element according to [5], wherein a molar ratio of the LiN (SO ₂ F) ₂ and the LiPF ₆ is 9: 1 to 3: 7.
[7]
The non-aqueous electrolyte solution is
Ethylene carbonate,
(A) an organic solvent comprising at least one selected from dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, and (a) at least one selected from dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate The non-aqueous lithium storage element according to any one of [1] to [6], wherein a volume ratio is 20% or more based on a total amount of the organic solvent.
[8]
An electrode laminate including a negative electrode body, a positive electrode body, and a separator, and a non-aqueous electrolyte solution is housed in an exterior body.
The negative electrode body includes a negative electrode current collector, and a negative electrode active material layer including a negative electrode active material provided on one or both surfaces of the negative electrode current collector. The negative electrode active material contains lithium ions. Includes carbon materials that can be occluded and released,
The positive electrode body includes a positive electrode current collector and a positive electrode active material layer including a positive electrode active material provided on one or both surfaces of the positive electrode current collector, and the positive electrode active material includes activated carbon. ,
The non-aqueous electrolyte contains 0.5 mol / L or more lithium salt based on the total amount of the non-aqueous electrolyte,
The negative electrode active material layer has the following formulas (1) and (2):

{In Formula (1), R ¹ is an alkyl group having 1 to 24 carbon atoms, a mono- or polyhydroxyalkyl group having 1 to 24 carbon atoms, or a lithium alkoxide thereof, an alkenyl group having 2 to 24 carbon atoms, or 2 to 2 carbon atoms. 24 mono- or polyhydroxyalkenyl groups or lithium alkoxides thereof, cycloalkyl groups having 3 to 6 carbon atoms, or aryl groups, and X ¹ is hydrogen, lithium, or alkyl groups having 1 to 12 carbon atoms. }

{In formula (2), R ² represents an alkyl group having 1 to 24 carbon atoms, a mono- or polyhydroxyalkyl group having 1 to 24 carbon atoms or a lithium alkoxide thereof, an alkenyl group having 2 to 24 carbon atoms, and 2 to 2 carbon atoms. 24 mono- or polyhydroxyalkenyl groups, cycloalkyl groups having 3 to 6 carbon atoms, or aryl groups, and X ² and X ³ are each independently hydrogen, lithium, or an alkyl group having 1 to 12 carbon atoms. It is. }
And the following formulas (3) and (4):

{In Formula (3), R ³ represents an alkyl group having 1 to 24 carbon atoms, a mono- or polyhydroxyalkyl group having 1 to 24 carbon atoms or a lithium alkoxide thereof, an alkenyl group having 2 to 24 carbon atoms, and 2 to 2 carbon atoms. 24 mono- or polyhydroxyalkenyl groups or lithium alkoxides thereof, cycloalkyl groups having 3 to 6 carbon atoms, or aryl groups, and X ⁴ is hydrogen, lithium, or alkyl groups having 1 to 12 carbon atoms. }

{In the formula (4), R ⁴ represents an alkyl group having 1 to 24 carbon atoms, a mono- or polyhydroxyalkyl group having 1 to 24 carbon atoms or a lithium alkoxide thereof, an alkenyl group having 2 to 24 carbon atoms, or 2 to 2 carbon atoms. 24 mono- or polyhydroxyalkenyl group or a lithium alkoxide thereof, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group, and X ⁵ and X ⁶ are each independently hydrogen, lithium, or 1 to 3 carbon atoms. 12 alkyl groups. }
And at least one sulfur compound selected from the group consisting of sulfite derivatives represented by each of the above, and the total amount of the sulfonic acid derivative and the sulfite derivative is 6.0 × 10 6 per unit mass of the negative electrode active material ⁻⁶ mol / g to 2,000 × 10 ⁻⁶ mol / g,
The nonaqueous electrolytic solution has the following formulas (5) to (7):

{In Formula (5), R ^{11 to} R ¹⁶ represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, or a halogenated alkyl group having 1 to 12 carbon atoms. And n is an integer from 0 to 3. }

{In Formula (6), R ^{11 to} R ¹⁴ represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, or a halogenated alkyl group having 1 to 12 carbon atoms, and they may be the same or different from each other. And n is an integer from 0 to 3. }

{In Formula (7), R ^{11 to} R ¹⁶ represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, or a halogenated alkyl group having 1 to 12 carbon atoms, and they may be the same or different from each other. It may be. }
At least two kinds of sultone compounds represented by each of the above, the total content of the sultone compound is 0.5% by mass to 15% by mass with respect to the total amount of the non-aqueous electrolyte solution,
The internal resistance at 25 ° C. after storage of the non-aqueous lithium storage element for 4 months at a cell voltage of 4 V and an environmental temperature of 60 ° C. is Rb (Ω), and the internal resistance at 25 ° C. before storage of the non-aqueous lithium storage element is When Ra (Ω), the internal resistance at −30 ° C. before storage is Rc (Ω), and the capacitance at 25 ° C. before storage is F (F), the following (a) to (d):
(A) The product Ra · F of Ra and F is 1.9 or less;
(B) Rb / Ra is 1.8 or less;
(C) The amount of gas generated when the non-aqueous lithium storage element is stored for 4 months at a cell voltage of 4 V and an environmental temperature of 60 ° C. is 26 × 10 ⁻³ cc / F or less at 25 ° C .; and (d) Rc And the product Rc · F of F and F is 24 or less;
A non-aqueous lithium electricity storage device characterized by satisfying all of the above.

  The non-aqueous lithium storage element according to the present invention achieves all of initial high input / output characteristics, excellent electrochemical characteristics in a low temperature environment, and high durability at high temperatures (for example, 40 to 90 ° C.). It exhibits excellent characteristics in practical use.

  Hereinafter, although an embodiment of the present invention is described in detail, the present invention is not limited to the following embodiment.

[Storage element]
The electricity storage device according to the embodiment of the present invention is
An electrode laminate having a negative electrode body, a positive electrode body, and a separator;
A non-aqueous electrolyte solution is accommodated in the exterior body.
The negative electrode body is
A negative electrode current collector;
A negative electrode active material layer provided on one side or both sides of the negative electrode current collector. The negative electrode active material layer contains a negative electrode active material containing a carbon material capable of inserting and extracting lithium ions.
The positive electrode body is
A positive electrode current collector;
A positive electrode active material layer provided on one side or both sides of the positive electrode current collector. The positive electrode active material layer contains a positive electrode active material containing activated carbon.

The non-aqueous lithium storage element in one embodiment of the present invention has an internal resistance of Rb (Ω) at 25 ° C. after storage for 4 months at a cell voltage of 4 V and an environmental temperature of 60 ° C., and storage of the non-aqueous lithium storage element. When the internal resistance at the previous 25 ° C. is Ra (Ω), the internal resistance at −30 ° C. before storage is Rc (Ω), and the capacitance at 25 ° C. before storage is F (F), the following conditions: (A)-(d):
(A) The product Ra · F of Ra and F is 1.9 or less;
(B) Rb / Ra is 1.8 or less;
(C) The amount of gas generated when the non-aqueous lithium storage element is stored for 4 months at a cell voltage of 4 V and an environmental temperature of 60 ° C. is 26 × 10 ⁻³ cc / F or less at 25 ° C .; and (d) The product Rc · F of Rc and F is 24 or less;
It is preferable that all of these are satisfied.

  Capacitance F (F) here means charging to 3.8 V by constant current and constant voltage charging with a constant voltage charging time of 1 hour at a current value of 1.5 C, and then to 1. A value calculated by F = Q / (3.8−2.2) from the capacity Q when a constant current discharge is performed at a current value of 5C.

In the present specification, the internal resistances Ra (Ω), Rb (Ω), and Rc (Ω) are values obtained by the following methods, respectively:
First, constant current charging at a predetermined environmental temperature (25 ° C. or −30 ° C.) with a current value of 1.5 C until reaching 3.8 V, and then applying a constant voltage of 3.8 V For a total of 2 hours, followed by a constant current discharge to 2.2 V at a current value of 50 C to obtain a discharge curve (time-voltage). In this discharge curve, when the voltage at the discharge time = 0 second obtained by extrapolating from the voltage values at the time of the discharge time 2 seconds and 4 seconds by linear approximation is E0, the drop voltage (ΔE) = 3. It is a value calculated by 8-E0 and R = ΔE / (50C (current value)).

  In this specification, “4 months storage at a cell voltage of 4.0 V” means that the cell corresponding to the non-aqueous lithium storage element is stored for 4 months while the cell voltage is substantially maintained at 4.0 V. Means preserved. Specifically, by applying a constant voltage of 4.0 V at a current value of 2.0 C with constant current constant voltage charging for 2 hours each time before storage and every week after the start of storage, the cell The voltage is maintained at 4.0V.

  Regarding the condition (a), Ra · F is preferably 1.9 or less, more preferably 1.8 or less, from the viewpoint of developing sufficient charge capacity and discharge capacity for a large current. More preferably, it is 1.6 or less. When Ra · F is equal to or less than the above upper limit value, a storage element having excellent input / output characteristics can be obtained. Therefore, it is preferable that a power storage system using the power storage element and a high-efficiency engine, for example, can be combined with a high load applied to the power storage element.

  Regarding condition (d), Rc · F is preferably 24 or less, more preferably 20 or less, from the viewpoint of expressing sufficient charge capacity and discharge capacity even in a low temperature environment of −30 ° C. More preferably, it is 18 or less. When Rc · F is equal to or less than the above upper limit, a power storage element having excellent output characteristics can be obtained even in a low temperature environment. Therefore, it is possible to obtain a power storage element that provides sufficient power for driving a motor when starting an engine of a car, a motorcycle, or the like in a low temperature environment.

  Regarding condition (b), Rb / Ra is 1.8 or less from the viewpoint of developing sufficient charge capacity and discharge capacity for a large current when exposed to a high temperature environment for a long time. More preferably, it is 1.6 or less, More preferably, it is 1.4 or less. If Rb / Ra is less than or equal to the above upper limit value, excellent output characteristics can be obtained stably over a long period of time, leading to a longer life of the device.

Regarding condition (c), the amount of gas generated when stored for 4 months at a cell voltage of 4.0 V and an environmental temperature of 60 ° C. was measured at 25 ° C. from the viewpoint that the generated gas would not deteriorate the characteristics of the device. The value is preferably 26 × 10 ⁻³ cc / F or less, more preferably 20 × 10 ⁻³ cc / F or less, and still more preferably 10 × 10 ⁻³ cc / F or less. If the amount of gas generated under the above conditions is less than or equal to the above upper limit value, there is no possibility that the cell expands due to gas generation even when the device is exposed to a high temperature for a long time. Therefore, a power storage element having sufficient safety and durability can be obtained.

  The power storage device provided in one embodiment of the present invention could not be provided by the prior art by showing the relatively small Ra · F, Rc · F, Rb / Ra, and the amount of gas generated as described above. Excellent device characteristics. As an example of means for achieving such small Ra · F, Rc · F, Rb / Ra, and amount of generated gas, for example, application of a specific non-aqueous electrolyte composition as described below can be cited.

[Electrolyte]
The electrolyte solution in the embodiment of the present invention is a non-aqueous electrolyte solution. This electrolytic solution contains the nonaqueous solvent mentioned later.
The nonaqueous electrolytic solution contains 0.5 mol / L or more lithium salt based on the total amount of the nonaqueous electrolytic solution. The content of the lithium salt in the non-aqueous electrolyte is preferably 0.8 mol / L or more, and more preferably 1.0 to 1.5 mol / L.

In the present embodiment, the non-aqueous electrolyte includes lithium bisfluorosulfonylimide (LiN (SO ₂ F) ₂ ), LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ as an electrolyte salt, LiN (SO ₂ CF ₃ ) (SO ₂ C ₂ F ₅ ), LiN (SO ₂ CF ₃ ) (SO ₂ C ₂ F ₄ H), LiC (SO ₂ F) ₃ , LiC (SO ₂ CF ₃ ) ₃ , Can generate at least one sulfite ion or sulfate ion selected from the group consisting of LiC (SO ₂ C ₂ F ₅ ) ₃ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiPF ₆ , and LiBF _4. It is preferable to contain a lithium salt. Of these, LiN (SO ₂ F) ₂ is preferred.

The concentration of LiN (SO ₂ F) _{2 in} the non-aqueous electrolyte according to this embodiment is preferably 0.3 mol / L or more and 1.5 mol / L or less, more preferably 0.6 mol / L or more and 1. 2 mol / L or less. If the concentration of LiN (SO ₂ F) ₂ is 0.3 mol / L or more, the ion conductivity of the electrolytic solution is increased, and an appropriate amount of at least one of sulfite ions and sulfate ions is deposited on the negative electrode electrolyte layer, Thereby, the gas generation amount resulting from decomposition | disassembly of electrolyte solution can be reduced. On the other hand, when the concentration is 1.5 mol / L or less, the electrolyte salt does not precipitate during charging and discharging, and the viscosity of the electrolytic solution does not increase even after a long period of time.

The non-aqueous electrolyte solution may contain only the above LiN (SO ₂ F) ₂ as an electrolyte salt, or may contain other electrolyte salts.
As other electrolyte salt contained in the non-aqueous electrolyte solution, it is possible to use a fluorine-containing lithium salt having a solubility of 0.5 mol / L or more in the non-aqueous electrolyte solution and other than LiN (SO ₂ F) _2. it can. Suitable lithium salts include, for example, LiPF ₆ and LiBF ₄ , and mixed salts thereof. As another electrolyte salt, it is preferable to use one or more of LiPF ₆ and LiBF ₄ from the viewpoint of developing high conductivity, and it is particularly preferable to use LiPF ₆ .

The non-aqueous solvent for the non-aqueous electrolyte solution in the present embodiment may be an organic solvent. Organic solvents are:
Ethylene carbonate,
(A) containing at least one selected from dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate, and the volume ratio of the component (a) is 20% or more based on the total amount of the organic solvent preferable.
When the volume ratio of the component (a) is 20% or more based on the total amount of the organic solvent, high conductivity can be maintained and low viscosity can be maintained. Therefore, more preferably, the volume ratio of the component (a) is 30% or more, and more preferably 35% or more, based on the total amount of the organic solvent.

The Li salt of the non-aqueous electrolyte in the present embodiment is composed of LiN (SO ₂ F) ₂ and LiPF ₆ , and the molar ratio is preferably 9: 1 to 3: 7, more preferably 9: 1. ~ 4: 6. When the ratio of LiN (SO ₂ F) ₂ to 1 mol of LiPF ₆ is smaller than 9 mol, corrosion of the positive electrode current collector due to LiN (SO ₂ F) ₂ is suppressed, which is preferable from the viewpoint of long-term durability.
Moreover, since the proportion of LiN _(SO 2 _{F) 2} is 3/7 mol greater than for 1 mole of LiPF _6, the decomposition of LiPF ₆ can be suppressed, from the viewpoint of long-term durability, preferably, also low temperature (e.g., From the viewpoint of input / output characteristics at −30 ° C.).

  The non-aqueous electrolyte for the non-aqueous lithium storage element according to this embodiment contains two or more sultone compounds represented by the following general formulas (5) to (7).

｛式（５）中、Ｒ^１１〜Ｒ^１６は、水素原子、ハロゲン原子、炭素数１〜１２のアルキル基、又は炭素数１〜１２のハロゲン化アルキル基を表し、互いに同一であっても異なっていてもよく；そしてｎは０〜３の整数である。｝

{In Formula (5), R ^{11 to} R ¹⁶ represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, or a halogenated alkyl group having 1 to 12 carbon atoms. And n is an integer from 0 to 3. }

｛式（６）中、Ｒ^１１〜Ｒ^１４は、水素原子、ハロゲン原子、炭素数１〜１２のアルキル基、又は炭素数１〜１２のハロゲン化アルキル基を表し、互いに同一であっても異なっていてもよく；そしてｎは０〜３の整数である。｝

{In Formula (6), R ^{11 to} R ¹⁴ represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, or a halogenated alkyl group having 1 to 12 carbon atoms, and they may be the same or different from each other. And n is an integer from 0 to 3. }

｛式（７）中、Ｒ^１１〜Ｒ^１６は、水素原子、ハロゲン原子、炭素数１〜１２のアルキル基、又は炭素数１〜１２のハロゲン化アルキル基を表し、互いに同一であっても異なっていてもよい。｝

{In Formula (7), R ^{11 to} R ¹⁶ represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, or a halogenated alkyl group having 1 to 12 carbon atoms, and they may be the same or different from each other. It may be. }

  In the present embodiment, the sultone compound represented by the formula (5) is 1 from the viewpoint of little adverse effect on resistance and the suppression of gas generation by suppressing decomposition of the non-aqueous electrolyte at high temperature. , 3-propane sultone, 2,4-butane sultone, 1,4-butane sultone, 1,3-butane sultone, or 2,4-pentane sultone is preferable. As the sultone compound represented by the formula (6), 1,3-butane sultone is preferable. Propene sultone or 1,4-butene sultone is preferred, and the sultone compound represented by formula (7) is preferably 1,5,2,4-dioxadithiepan 2,2,4,4-tetraoxide, Other sultone compounds include methylene bis (benzene sulfonic acid), methylene bis (phenyl methane sulfonic acid), methylene bis (ethane sulfonic acid), Chirenbisu (2,4,6, trimethyl benzene sulfonic acid), and methylenebis (2-trifluoromethylbenzene sulfonate) are preferred. In the present embodiment, the non-aqueous electrolyte solution more preferably contains other sultone compounds in addition to at least two selected from sultone compounds represented by formulas (5) to (7).

  The non-aqueous lithium storage element according to this embodiment has long-term high-temperature durability by containing two or more sultone compounds represented by general formulas (5) to (7) in the non-aqueous electrolyte solution. improves. The reason for this is not clear, but a non-aqueous electrolyte solution containing one kind of sultone compound does not produce a good film on the negative electrode, but a non-aqueous electrolyte solution containing two or more kinds of sultone compounds. In this case, it is presumed that each works in a complementary manner to produce a good film on the negative electrode.

  The total content of the sultone compound in the non-aqueous electrolyte of the non-aqueous lithium storage element in the present embodiment is 0.5% by mass to 15% by mass based on the total amount of the non-aqueous electrolyte. To do. Here, the content of the sultone compound contained in the non-aqueous electrolyte of the non-aqueous lithium storage element is determined by laminating the negative electrode body, the positive electrode body, and the separator, and inserting the laminated body with the electrode terminals connected into the exterior body Then, the nonaqueous lithium storage element is assembled by injecting a nonaqueous electrolyte and sealing the exterior body, the completed nonaqueous lithium storage element is disassembled, and the taken out nonaqueous electrolyte is, for example, NMR It can be obtained by analyzing the above. If the total content of sultone compounds in the non-aqueous electrolyte solution is 0.5 mass% or more, it is possible to suppress gas generation by suppressing decomposition of the electrolyte solution at a high temperature. On the other hand, if the total content is 15% by mass or less, a decrease in the ionic conductivity of the electrolytic solution can be suppressed, and high input / output characteristics can be maintained. In addition, since the non-aqueous electrolyte solution of the non-aqueous lithium storage element contains 0.5% by mass to 15% by mass of the sultone compound, the coating on the negative electrode is destroyed at a high temperature due to a reductive decomposition reaction of the electrolyte solvent or the like. In this case, a good film can be regenerated, which is preferable in terms of long-term durability. If the non-aqueous electrolyte solution of the non-aqueous lithium storage element does not contain 0.5% by mass or more of a sultone compound, a good film cannot be regenerated when the negative electrode film is destroyed at high temperatures. Long-term durability is not good. In addition, the content of the sultone compound present in the non-aqueous electrolyte solution of the non-aqueous lithium storage element is preferably 1% by mass or more and 10% by mass or less from the viewpoint of achieving both high input / output characteristics and durability. Preferably they are 3 mass% or more and 8 mass% or less.

In the present embodiment, the non-aqueous electrolyte preferably contains LiN (SO ₂ F) ₂ and LiPF ₆ , and the aluminum (Al) concentration contained in the non-aqueous electrolyte is determined when the cell is completed or after long-term use. (For example, after the cell voltage is stored at 4 V in an 80 ° C. environment and after two months have passed), the range is preferably in the range of 0.1 ppm to 50 ppm based on the total amount of the non-aqueous electrolyte. When LiN (SO ₂ F) ₂ is present in the non-aqueous electrolyte, the positive electrode current collector including the aluminum foil is corroded and aluminum is eluted, so that the Al concentration in the non-aqueous electrolyte is reduced to 0.1 ppm or less. It is practically difficult to suppress. On the other hand, if the Al concentration in the non-aqueous electrolyte is 50 ppm or less, it is preferable from the viewpoint of self-discharge after the high-temperature storage test, since the elution of aluminum is sufficiently suppressed.

In the present embodiment, the concentration of LiPO ₂ F ₂ contained in the non-aqueous electrolyte is determined after completion of the cell or after long-term use (for example, after storing the cell voltage at 4 V in an 80 ° C. environment and after 2 months have passed). In the above, it is preferably in the range of 1 ppm to 100 ppm, more preferably in the range of 1 ppm to 65 ppm, based on the total amount of the non-aqueous electrolyte. When LiPF ₆ is present in the non-aqueous electrolyte, it is practically difficult to suppress the concentration of LiPO ₂ F ₂ as a reaction product to 1 ppm or less. On the other hand, if the concentration of LiPO ₂ F ₂ is 100 ppm or less, gas generation during high temperature use is suppressed, which is preferable from the viewpoint of high temperature durability.

[Positive electrode body and negative electrode body]
In the non-aqueous lithium storage element according to this embodiment, the positive electrode body is
A positive electrode current collector;
A positive electrode active material layer provided on one side or both sides of the positive electrode current collector. The positive electrode active material layer contains a positive electrode active material containing activated carbon.
In the non-aqueous lithium storage element according to this embodiment, the negative electrode body is
A negative electrode current collector;
A negative electrode active material layer provided on one side or both sides of the negative electrode current collector. The negative electrode active material layer contains a negative electrode active material containing a carbon material capable of inserting and extracting lithium ions.

  In the positive and negative electrode bodies according to the present embodiment, a common configuration can be applied to components other than the positive electrode active material and the negative electrode active material. Hereinafter, after describing the positive electrode active material and the negative electrode active material in order, the common elements will be described together.

[Positive electrode active material]
The positive electrode active material includes activated carbon. As the positive electrode active material, only activated carbon may be used, or other materials as described later may be used in combination with activated carbon. The activated carbon content based on the total amount of the positive electrode active material is preferably 50% by mass or more, and more preferably 70% by mass or more. The content of the activated carbon may be 100% by mass. However, from the viewpoint of obtaining good effects by using other materials in combination, for example, the content is preferably 90% by mass or less, and 80% by mass or less. May be.

There are no particular restrictions on the type of activated carbon and its raw material in the positive electrode active material, but it is preferable to optimally control the pores of the activated carbon in order to achieve both high input / output characteristics and high energy density. Specifically, the amount of mesopores derived from pores having a diameter of 20 to 500 mm calculated by the BJH method is V1 (cc / g), and the amount of micropores derived from pores having a diameter of less than 20 mm calculated by the MP method is calculated. When V2 (cc / g)
(1) For high input / output characteristics, 0.3 <V1 ≦ 0.8 and 0.5 ≦ V2 ≦ 1.0 are satisfied, and the specific surface area measured by the BET method is 1,500 m ^2. Activated carbon (hereinafter also referred to as “activated carbon 1”) exhibiting at least / g and no greater than 3,000 m ² / g,
(2) In order to obtain a high energy density, 0.8 <V1 ≦ 2.5 and 0.8 <V2 ≦ 3.0 are satisfied, and the specific surface area measured by the BET method is 3,000 m ^2. Activated carbon (hereinafter also referred to as “activated carbon 2”) exhibiting at least / g and not more than 4,000 m ² / g is preferred.
Hereinafter, the (1) activated carbon 1 and the (2) activated carbon 2 will be described individually and sequentially.

[Activated carbon 1]
The mesopore amount V1 of the activated carbon 1 is preferably larger than 0.3 cc / g from the viewpoint of improving the input / output characteristics when the positive electrode material is incorporated in the electric storage element. On the other hand, it is preferable that it is 0.8 cc / g or less from the point which suppresses the fall of the bulk density of a positive electrode. This V1 is more preferably 0.35 cc / g or more and 0.7 cc / g or less, and further preferably 0.4 cc / g or more and 0.6 cc / g or less.
The micropore amount V2 of the activated carbon 1 is preferably 0.5 cc / g or more in order to increase the specific surface area of the activated carbon and increase the capacity. On the other hand, V2 is preferably 1.0 cc / g or less from the viewpoint of suppressing the bulk of the activated carbon, increasing the density as an electrode, and increasing the capacity per unit volume. This V2 is more preferably 0.6 cc / g or more and 1.0 cc / g or less, and further preferably 0.8 cc / g or more and 1.0 cc / g or less.

  The ratio of the mesopore volume V1 to the micropore volume V2 (V1 / V2) is preferably in the range of 0.3 ≦ V1 / V2 ≦ 0.9. V1 / V2 is preferably 0.3 or more from the viewpoint of increasing the ratio of the mesopore amount to the micropore amount to such an extent that a decrease in output characteristics can be suppressed while obtaining a high capacity. On the other hand, V1 / V2 is preferably 0.9 or less from the viewpoint of increasing the ratio of the micropore amount to the mesopore amount to such an extent that a decrease in capacity can be suppressed while obtaining high output characteristics. A more preferable range of V1 / V2 is 0.4 ≦ V1 / V2 ≦ 0.7, and a further preferable range of V1 / V2 is 0.55 ≦ V1 / V2 ≦ 0.7.

  In this specification, the amount of micropores and the amount of mesopores are values determined by the following methods, respectively. The sample is vacuum-dried overnight at 500 ° C., and adsorption / desorption isotherms are measured using nitrogen as an adsorbate. Using the isotherm on the desorption side at this time, the micropore volume is calculated by the MP method, and the mesopore volume is calculated by the BJH method.

The MP method uses a “t-plot method” (BC Lippens, JH de Boer, J. Catalysis, 4319 (1965)), and uses a micropore volume, a micropore area, and a micropore. Is a method for obtaining the distribution of R. S. It is a method devised by Mikhail, Brunauer, Bodor (RS Mikhal, S. Brunauer, EE Bodor, J. Colloid Interface Sci., 26, 45 (1968)).
The BJH method is a calculation method generally used for analysis of mesopores, and was proposed by Barrett, Joyner, Halenda et al. (EP Barrett, LG Joyner and P. Halenda, J. Am. Chem. Soc., 73, 373 (1951)).

The average pore diameter of the activated carbon 1 is preferably 17 mm or more, more preferably 18 mm or more, and most preferably 20 mm or more from the viewpoint of maximizing the output of the obtained electricity storage device. On the other hand, the average pore diameter of the activated carbon 1 is preferably 25 mm or less from the viewpoint of maximizing the capacity of the obtained electricity storage element. The average pore diameter described in the present specification refers to the total pore volume per mass of the sample obtained by measuring each equilibrium adsorption amount of nitrogen gas at each liquid pressure at a liquid nitrogen temperature, and the BET specific surface area. It is obtained by dividing by.
BET specific surface area of the activated carbon 1 is preferably from 1,500 m ² / g or more 3,000 m ² / g, more preferably not more than 1,500 m ² / g or more 2,500 m ² / g. When the BET specific surface area is 1,500 m ² / g or more, a good energy density is easily obtained. On the other hand, when the BET specific surface area is 3,000 m ² / g or less, the strength of the electrode is maintained. Since there is no need to add a large amount of binder, the performance per electrode volume tends to be high.

The activated carbon 1 having the above-described features can be obtained using, for example, the raw materials and processing methods described below.
In the embodiment of the present invention, the carbon source used as a raw material of the activated carbon 1 is not particularly limited, and for example, plant systems such as wood, wood flour, coconut shell, by-products during pulp production, bagasse, and molasses. Raw materials: Fossil materials such as peat, lignite, lignite, bituminous coal, anthracite, petroleum distillation residue components, petroleum pitch, coke, coal tar; phenol resin, vinyl chloride resin, vinyl acetate resin, melamine resin, urea resin, resorcinol resin, Various synthetic resins such as celluloid, epoxy resin, polyurethane resin, polyester resin, and polyamide resin; synthetic rubbers such as polybutylene, polybutadiene, and polychloroprene; other synthetic wood, synthetic pulp, and their carbides. Among these raw materials, plant-based raw materials such as coconut shells and wood flour and their carbides are preferable from the viewpoint of mass production and cost, and coconut shells are particularly preferable.

As a carbonization and activation method for making these raw materials into the activated carbon 1, known methods such as a fixed bed method, a moving bed method, a fluidized bed method, a slurry method, and a rotary kiln method can be employed.
As a carbonization method of these raw materials, for example, inert gas such as nitrogen, carbon dioxide, helium, argon, xenon, neon, carbon monoxide, combustion exhaust gas, or other gas mainly composed of these inert gases and And a method of firing at about 400 to 700 ° C. (preferably 450 to 600 ° C.) for about 30 minutes to 10 hours.

As a method for activating the carbide obtained by the carbonization method, for example, a gas activation method in which firing is performed using an activation gas such as water vapor, carbon dioxide, and oxygen is preferably used. Among these, a method using water vapor or carbon dioxide as the activation gas is preferable.
In this activation method, the carbide is supplied for 3 to 12 hours (preferably 5 to 11) while supplying the activation gas at a rate of 0.5 to 3.0 kg / h (preferably 0.7 to 2.0 kg / h). It is preferable to activate by heating up to a predetermined reached temperature (for example, 800 to 1,000 ° C.) over a period of time, more preferably 6 to 10 hours.
Furthermore, prior to the activation treatment of the carbide, the carbide may be activated in advance. In this primary activation, the carbon material can be gas activated by firing at a temperature of less than 900 ° C. using an activation gas such as water vapor, carbon dioxide, or oxygen.
By appropriately combining the firing temperature and firing time in the carbonization method, the activation gas supply amount and the heating rate and the maximum activation temperature in the activation method, the activated carbon 1 having the above characteristics that can be used in the present embodiment. Can be manufactured.
The average particle diameter of the activated carbon 1 is preferably 1 to 20 μm. Throughout this specification, “average particle size” means that when the particle size distribution is measured using a particle size distribution measuring device, the cumulative curve is 50% when the cumulative curve is obtained with the total volume as 100%. The particle diameter (that is, 50% diameter (Median diameter)). This average particle diameter can be measured with a commercially available laser diffraction particle size distribution analyzer.

  When the average particle size is 1 μm or more, the capacity per electrode volume tends to increase because the density of the active material layer is high. A small average particle diameter may lead to a drawback of low durability, but such a defect is unlikely to occur if the average particle diameter is 1 μm or more. On the other hand, when the average particle size is 20 μm or less, it tends to be easily adapted to high-speed charge / discharge. The average particle diameter is more preferably 2 to 15 μm, still more preferably 3 to 10 μm.

[Activated carbon 2]
The mesopore amount V1 of the activated carbon 2 is preferably a value larger than 0.8 cc / g from the viewpoint of increasing the output characteristics when the positive electrode material is incorporated in the energy storage device. From the viewpoint of suppressing a decrease in the capacity of the power storage element, it is preferably 2.5 cc / g or less. V1 is more preferably from 1.00 cc / g to 2.0 cc / g, and still more preferably from 1.2 cc / g to 1.8 cc / g.

On the other hand, the micropore volume V2 of the activated carbon 2 is preferably larger than 0.8 cc / g in order to increase the specific surface area of the activated carbon and increase the capacity. V2 is preferably 3.0 cc / g or less from the viewpoint of increasing the density of the activated carbon as an electrode and increasing the capacity per unit volume. V2 is more preferably greater than 1.0 cc / g and not greater than 2.5 cc / g, and still more preferably not less than 1.5 cc / g and not greater than 2.5 cc / g.
The method for measuring the micropore amount and the mesopore amount in the activated carbon 2 can depend on the method described above with respect to the activated carbon 1.

The activated carbon 2 having the mesopore volume V1 and the micropore volume V2 described above has a BET specific surface area larger than the activated carbon used for the conventional electric double layer capacitor or lithium ion capacitor. The specific BET specific surface area value of the activated carbon 2 is preferably 3,000 m ² / g or more and 4,000 m ² / g or less, more preferably 3,200 m ² / g or more and 3,800 m ² / g or less. It is more preferable. When the BET specific surface area is 3,000 m ² / g or more, a good energy density is easily obtained. On the other hand, when the BET specific surface area is 4,000 m ² / g or less, there is no need to add a large amount of binder in order to maintain the strength of the electrode, so that the performance per electrode volume tends to be high.

The activated carbon 2 having the above-described characteristics can be obtained using, for example, the raw materials and processing methods described below.
The carbon source used as a raw material for the activated carbon 2 is not particularly limited as long as it is a carbon source that is usually used as a raw material for activated carbon. For example, plant-based materials such as wood, wood powder, and coconut shells; fossil-based materials such as petroleum pitch and coke; Examples include synthetic resins. Among these raw materials, phenol resin and furan resin are particularly preferable because they are suitable for producing activated carbon 2 having a high specific surface area.

  Examples of the method for carbonizing these raw materials or the heating method during the activation treatment include known methods such as a fixed bed method, a moving bed method, a fluidized bed method, a slurry method, and a rotary kiln method. The atmosphere at the time of heating is an inert gas such as nitrogen, carbon dioxide, helium, or argon, or a gas mixed with other gases containing these inert gases as a main component. The carbonization temperature is generally about 400 to 700 ° C., and the method of firing for about 0.5 to 10 hours is common.

As the activation method of the carbide after the carbonization treatment, for example, a gas activation method in which firing is performed using an activation gas such as water vapor, carbon dioxide, oxygen, or an alkali metal activation method in which heat treatment is performed after mixing with an alkali metal compound is possible. However, an alkali metal activation method is preferable for producing activated carbon having a large specific surface area.
In this activation method, a carbide and an alkali metal compound such as KOH or NaOH are mixed at a mass ratio of carbide: alkali metal compound of 1: 1 or more (the amount of the alkali metal compound is equal to or more than the amount of the carbide). A large amount), followed by heating in an inert gas atmosphere at a temperature of 600 to 900 ° C. for 0.5 to 5 hours, and then washing and removing the alkali metal compound with acid and water, followed by drying. I do.

In order to increase the amount of micropores and not increase the amount of mesopores, it is preferable to mix with KOH with a larger amount of carbides during activation. In order to increase the amount of any hole, it is preferable to use a large amount of KOH. In order to mainly increase the amount of mesopores, water vapor activation may be performed after alkali activation treatment.
The average particle diameter of the activated carbon 2 is preferably 1 μm or more and 30 μm or less. More preferably, they are 2 micrometers or more and 20 micrometers or less.

[Composition of positive electrode active material]
Each of the activated carbons 1 and 2 may be one type of activated carbon, or a mixture of two or more types of activated carbon, and each characteristic value described above may be shown as the entire mixture.
Said activated carbon 1 and 2 may select and use any one of these, and may mix and use both.
The positive electrode active material is a material other than activated carbon 1 and 2 (for example, activated carbon not having the specific V1 and / or V2, or a material other than activated carbon (for example, a composite oxide of lithium and a transition metal)). May be included. In the illustrated embodiment, the content of the activated carbon 1, the content of the activated carbon 2, or the total content of the activated carbons 1 and 2 is preferably more than 50% by mass of the total positive electrode active material, and more preferably 70% by mass or more. 90% by mass or more is more preferable, and 100% by mass is most preferable.

[Negative electrode active material]
A negative electrode active material contains the carbon material which can occlude / release lithium ion. As the negative electrode active material, only this carbon material may be used, or in addition to this carbon material, other materials that occlude and release lithium ions can be used in combination. Examples of the other material include lithium titanium composite oxide and conductive polymer. In the illustrated embodiment, the content of the carbon material capable of occluding and releasing lithium ions is preferably 50% by mass or more, more preferably 70% by mass or more based on the total amount of the negative electrode active material. Although it can be 100% by mass, it is preferably 90% by mass or less, and may be 80% by mass or less, for example, from the viewpoint of obtaining the effect of the combined use of other materials.

Examples of the carbon material that can occlude and release lithium ions include hard carbon, graphitizable carbon, and composite porous carbon material.
More preferable examples of the negative electrode active material are composite porous materials 1 and 2 and a porous carbon material 3 formed by depositing a carbon material on the surface of activated carbon, which will be described later. These are advantageous in terms of resistance of the negative electrode. The composite porous materials 1 and 2 and the porous carbon material 3 may each be used alone or in combination of two or more thereof. As the carbon material in the negative electrode active material, only one or more selected from the composite porous materials 1 and 2 and the porous carbon material 3 may be used, or the composite porous materials 1 and 2 and the porous material may be used. In addition to one or more selected from the carbon material 3, other carbon materials may be used in combination.

  Hereinafter, the composite porous materials 1 and 2 described above, the porous carbon material 3, and other carbon materials will be sequentially described.

[Composite porous material 1]
The composite porous material 1 is a composite porous material defined by the following mesopore volume Vm1 and micropore volume Vm2.
The composite porous material 1 has a mesopore amount derived from pores having a diameter of 20 to 500 mm calculated by the BJH method as Vm1 (cc / g), and micropores derived from pores having a diameter of less than 20 mm calculated by the MP method. When the amount is Vm2 (cc / g), the material satisfies 0.010 ≦ Vm1 ≦ 0.250, 0.001 ≦ Vm2 ≦ 0.200, and 1.5 ≦ Vm1 / Vm2 ≦ 20.0.
The composite porous material can be obtained, for example, by heat-treating activated carbon and a carbon material precursor in the coexistence state.

  There is no restriction | limiting in particular as activated carbon used as a raw material of said composite porous material 1 as long as the composite porous material 1 obtained exhibits a desired characteristic. For example, commercially available products obtained from various raw materials such as petroleum-based, coal-based, plant-based, and polymer-based materials can be used. In particular, it is preferable to use activated carbon powder having an average particle diameter of 1 μm or more and 15 μm or less. The average particle size is more preferably 2 μm or more and 10 μm or less.

  The carbon material precursor used as the raw material of the composite porous material 1 is an organic material that can deposit the carbon material on activated carbon by heat treatment. The carbon material precursor may be a solid, a liquid, or a substance that can be dissolved in a solvent. Examples of such a carbon material precursor include pitch, mesocarbon microbeads, coke, synthetic resin (for example, phenol resin) and the like. Among these carbon material precursors, it is preferable from the viewpoint of production cost to use an inexpensive pitch. Pitch is roughly divided into petroleum pitch and coal pitch. Examples of petroleum pitches include crude oil distillation residue, fluid catalytic cracking residue (decant oil, etc.), bottom oil derived from thermal crackers, ethylene tar obtained during naphtha cracking, and the like.

  When the pitch is used, the composite porous material heat-treats the pitch in the presence of activated carbon, and causes the volatile component or pyrolysis component of the pitch to thermally react on the surface of the activated carbon to deposit the carbon material on the activated carbon. Thereby, the composite porous material 1 is obtained. In this case, at a temperature of about 200 to 500 ° C., the deposition of pitch volatile components or pyrolysis components into the activated carbon pores proceeds, and at 400 ° C. or higher, the reaction in which the deposited components become carbon materials proceeds. . The peak temperature (maximum temperature reached) during the heat treatment is appropriately determined depending on the characteristics of the composite porous material 1 to be obtained, the thermal reaction pattern, the thermal reaction atmosphere, and the like. This temperature is preferably 400 ° C. or higher, more preferably 450 ° C. to 1,000 ° C., and still more preferably about 500 to 800 ° C. The time for maintaining the peak temperature during the heat treatment may be 30 minutes to 10 hours, preferably 1 hour to 7 hours, and more preferably 2 hours to 5 hours. For example, when the heat treatment is performed for 2 hours to 5 hours at a peak temperature of about 500 to 800 ° C., the carbon material deposited on the activated carbon surface is considered to be a polycyclic aromatic hydrocarbon.

The softening point of the pitch used as the carbon material precursor is preferably 30 ° C. or higher and 250 ° C. or lower, and more preferably 60 ° C. or higher and 130 ° C. or lower. If the softening point of the pitch is 30 ° C. or higher, the handling property is not hindered and it is possible to prepare with high accuracy. If this value is 250 ° C. or lower, a relatively large amount of low molecular compounds are present, and it is possible to deposit even relatively fine pores in the activated carbon.
Specific methods for producing the above composite porous material include, for example:
A method in which activated carbon is heat-treated in an inert atmosphere containing hydrocarbon gas volatilized from a carbon material precursor, and the carbon material is deposited in a gas phase;
A method in which activated carbon and a carbon material precursor are premixed and heat-treated;
A method in which a carbon material precursor dissolved in a solvent is applied to activated carbon and dried, followed by heat treatment;
Etc.

The composite porous material 1 is obtained by depositing a carbon material on the surface of activated carbon. Here, the pore distribution after the carbon material is deposited inside the pores of the activated carbon is important. The pore distribution can be defined by the amount of mesopores and the amount of micropores. In the present embodiment, the ratio of mesopore volume / micropore volume is particularly important as well as the absolute values of mesopore volume and micropore volume.
In one embodiment of the present invention, the amount of mesopores derived from pores having a diameter of 20 mm or more and 500 mm or less calculated by the BJH method in the composite porous material 1 is less than 20 mm in diameter calculated by Vm1 (cc / g) and MP method. When the amount of micropores derived from the pores is Vm2 (cc / g), 0.010 ≦ Vm1 ≦ 0.250, 0.001 ≦ Vm2 ≦ 0.200, and 1.5 ≦ Vm1 / Vm2 ≦ 20 0.0 is preferred.

  The mesopore amount Vm1 is more preferably 0.010 ≦ Vm1 ≦ 0.225, and further preferably 0.010 ≦ Vm1 ≦ 0.200. About micropore amount Vm2, 0.001 <= Vm2 <= 0.150 is more preferable, and 0.001 <= Vm2 <= 0.100 is still more preferable. The ratio of mesopore amount / micropore amount is more preferably 1.5 ≦ Vm1 / Vm2 ≦ 15.0, and further preferably 1.5 ≦ Vm1 / Vm2 ≦ 10.0. If the mesopore volume Vm1 is less than or equal to the upper limit (Vm1 ≦ 0.250), high charge / discharge efficiency with respect to lithium ions can be maintained, and the mesopore volume Vm1 and the micropore volume Vm2 are equal to or greater than the lower limit (0.010 ≦ Vm1, 0. If 001 ≦ Vm2), high output characteristics can be obtained.

In mesopores having a large pore diameter, ion conductivity is higher than in micropores. Therefore, the mesopore amount is necessary to obtain high output characteristics. On the other hand, impurities such as moisture, which are considered to adversely affect the durability of the electricity storage element, are difficult to desorb in the micropores having a small pore diameter. For this reason, it is considered necessary to control the amount of micropores in order to obtain high durability. Therefore, it is important to control the ratio between the mesopore amount and the micropore amount. When this value is equal to or greater than the lower limit (1.5 ≦ Vm1 / Vm2) (the carbon material adheres more to the micropores than the mesopores of the activated carbon, and the composite porous material after deposition has a larger mesopore volume, When the amount of pores is small), high energy density and high output characteristics and high durability (cycle characteristics, float characteristics, etc.) are compatible. When the ratio between the mesopore amount and the micropore amount is not more than the upper limit (Vm1 / Vm2 ≦ 20.0), high output characteristics can be obtained.
In the present invention, the method for measuring the mesopore volume Vm1 and the micropore volume Vm2 is the same as the method for measuring activated carbon in the positive electrode active material described above.

In one embodiment of the present invention, as described above, the mesopore / micropore ratio after the carbon material is deposited on the surface of the activated carbon is important. In order to obtain a composite porous material having a pore distribution range defined in the present invention, the pore distribution of activated carbon used as a raw material is important.
In the activated carbon used for forming the composite porous material as the negative electrode active material, the mesopore amount derived from the pores having a diameter of 20 to 500 mm calculated by the BJH method is V1 (cc / g), the diameter calculated by the MP method. When the amount of micropores derived from pores less than 20 mm is V2 (cc / g), 0.050 ≦ V1 ≦ 0.500, 0.005 ≦ V2 ≦ 1.000, and 0.2 ≦ V1 / It is preferable that V2 ≦ 20.0.
About mesopore amount V1, 0.050 <= V1 <= 0.350 is more preferable, and 0.100 <= V1 <= 0.300 is still more preferable. The micropore amount V2 is more preferably 0.005 ≦ V2 ≦ 0.850, and further preferably 0.100 ≦ V2 ≦ 0.800. The ratio of mesopore amount / micropore amount is more preferably 0.22 ≦ V1 / V2 ≦ 15.0, and further preferably 0.25 ≦ V1 / V2 ≦ 10.0. In order to obtain the pore structure of the composite porous material 1 of the present embodiment when the mesopore volume V1 of the activated carbon is 0.500 or less and the micropore volume V2 is 1.000 or less. Since it is sufficient to deposit an appropriate amount of carbon material, the pore structure tends to be easily controlled. For the same reason, when the mesopore volume V1 of the activated carbon is 0.050 or more and the micropore volume V2 is 0.005 or more, V1 / V2 is 0.2 or more and V1 / V2 is 20 Even if it is 0.0 or less, the pore structure of the composite porous material 1 of the present embodiment can be easily obtained from the pore distribution of the activated carbon.

The average particle size of the composite porous material 1 in the present embodiment is preferably 1 μm or more and 10 μm or less. About a lower limit, More preferably, it is 2 micrometers or more, More preferably, it is 2.5 micrometers or more. About an upper limit, More preferably, it is 6 micrometers or less, More preferably, it is 4 micrometers or less. If the average particle size is 1 μm or more and 10 μm or less, good durability is maintained.
In the composite porous material 1, the hydrogen atom / carbon atom ratio (hereinafter also referred to as “H / C”) is preferably 0.05 or more and 0.35 or less, and 0.05 or more. More preferably, it is 0.15 or less. When H / C is 0.35 or less, the structure (typically polycyclic aromatic conjugated structure) of the carbon material deposited on the activated carbon surface is sufficiently developed, so the capacity (energy density) ) And charging / discharging efficiency is high. On the other hand, when H / C is 0.05 or more, since carbonization does not proceed excessively, a good energy density can be obtained. H / C is measured by an elemental analyzer.

The composite porous material 1 preferably has an amorphous structure derived from the activated carbon as a raw material and a crystal structure mainly derived from the deposited carbon material. A structure with low crystallinity is preferable for exhibiting high output characteristics, and a structure with high crystallinity is preferable for maintaining reversibility in charge and discharge. From such a viewpoint, as the composite porous material 1,
The (002) plane spacing d ₀₀₂ measured by the X-ray wide angle diffraction method is 3.60 mm or more and 4.00 mm or less, and the crystallite size Lc in the c-axis direction obtained from the half width of this peak is 8. Preferred is from 0 to 20.0 cm;
It is more preferable that d ₀₀₂ is 3.60 to 3.75 and the crystallite size Lc in the c-axis direction obtained from the half width of this peak is 11.0 to 16.0.

[Composite porous material 2]
The composite porous material 2 is a composite porous material in which a carbon material is deposited on the surface of activated carbon, and the mass ratio of the carbon material to the activated carbon is 10% or more and 60% or less. This mass ratio is preferably 15% or more and 55% or less, more preferably 18% or more and 50% or less, and particularly preferably 20% or more and 47% or less. If the mass ratio of the carbon material is 10% or more, the micropores possessed by the activated carbon can be appropriately filled with the carbon material, and the charge / discharge efficiency of lithium ions is improved, so that the durability is not impaired. . When the mass ratio of the carbonaceous material is 60% or less, the specific surface area can be increased by appropriately maintaining the pores of the activated carbon. Therefore, the doping amount of lithium ions can be increased. As a result, high output density and high durability can be maintained even if the negative electrode is thinned.

The specific surface area measured by the BET method on the composite porous material ^2, 350m ² / ^g~1,500m 2 / g are ^preferred, 400m ² / ^g~1,100m 2 / g is more preferable. When this specific surface area is 350 m ² / g or more, it can be said that the composite porous material 2 appropriately retains pores. Therefore, as a result of increasing the doping amount of lithium ions, the negative electrode can be made thin. On the other hand, when the specific surface area is 1,500 m ² / g or less, it can be said that the micropores possessed by the activated carbon are appropriately filled. Therefore, since the charge / discharge efficiency of lithium ions is improved, the durability is not impaired.
The composite porous material 2 can be obtained, for example, by performing a heat treatment in a state where activated carbon and a carbon material precursor coexist. The specific examples of the activated carbon and the carbon material precursor and the heat treatment method for producing the composite porous material 2 are the same as those described above for the composite porous material 1, and therefore the description thereof will not be repeated here.
However, the softening point of the pitch used for obtaining the composite porous material 2 is preferably 30 ° C. or higher and 100 ° C. or lower, and more preferably 35 ° C. or higher and 85 ° C. or lower. If the softening point of the pitch is 30 ° C. or higher, the handling property is not hindered, and it is possible to prepare with high accuracy. Since many low molecular weight compounds are present in the pitch having a softening point of 100 ° C. or less, it is possible to deposit fine pores in the activated carbon by using the pitch.

The composite porous material 2 is obtained by depositing a carbon material on the surface of activated carbon. Here, the pore distribution after the carbon material is deposited inside the pores of the activated carbon is important. This pore distribution can be defined by the amount of mesopores and the amount of micropores. The composite porous material 2 has a mesopore amount derived from pores having a diameter of 20 to 500 mm calculated by the BJH method as Vm1 (cc / g), and a micropore derived from pores having a diameter of less than 20 mm calculated by the MP method. When the amount is Vm2 (cc / g), it is preferable that the Vm1 and Vm2 satisfy any one of the following three relationships:
(1) 0.010 ≦ Vm1 ≦ 0.300 and 0.010 ≦ Vm2 ≦ 0.200
(2) 0.010 ≦ Vm1 ≦ 0.200 and 0.200 ≦ Vm2 ≦ 0.400
(3) 0.010 ≦ Vm1 ≦ 0.100 and 0.400 ≦ Vm2 ≦ 0.650
As for (1), 0.050 ≦ Vm1 ≦ 0.300 and 0.010 ≦ Vm2 ≦ 0.200 are more preferable.

When the mesopore amount Vm1 is not more than the upper limit (Vm1 ≦ 0.300), the specific surface area of the composite porous material can be increased, and the doping amount of lithium ions can be increased. In addition to this, since the bulk density of the negative electrode can be further increased, the negative electrode can be made thin. When the micropore amount Vm2 is not more than the upper limit (Vm1 ≦ 0.650), high charge / discharge efficiency with respect to lithium ions can be maintained. On the other hand, if the mesopore volume Vm1 and the micropore volume Vm2 are equal to or higher than the lower limit (0.010 ≦ Vm1, 0.010 ≦ Vm2), high output characteristics can be obtained.
In the present embodiment, the method for measuring the mesopore amount Vm1 and the micropore amount Vm2 is the same as the method for measuring activated carbon in the positive electrode active material described above.
The average particle size, the hydrogen atom / carbon atom number ratio (H / C), and the crystal structure of the composite porous material 2 in the present embodiment have been described above for the composite porous material 1, respectively. It is used as it is.

  In the composite porous material 2, the average pore diameter is preferably 28 mm or more, more preferably 30 mm or more from the viewpoint of achieving high output characteristics. On the other hand, from the point of obtaining a high energy density, it is preferably 65 mm or less, more preferably 60 mm or less. In the present embodiment, the average pore diameter is obtained by dividing the total pore volume per mass obtained by measuring each equilibrium adsorption amount of nitrogen gas at each relative pressure under liquid nitrogen temperature by the BET specific surface area. Value.

[Porous carbon material 3]
The porous carbon material 3 has Vm1 (cc / g) as the amount of mesopores derived from pores having a diameter of 20 to 500 mm calculated by the BJH method, and micropores derived from pores having a diameter of less than 20 mm calculated by the MP method. When the amount is Vm2 (cc / g), it can be defined by the mesopore amount and the micropore amount, and those satisfying 21 ≦ Vm1 / Vm2 ≦ 100 and 0.20 <Vm1 ≦ 0.65 are preferable.

  When the porous carbon material having the pore structure as described above is used as the negative electrode material, the input / output characteristics of the power storage element are enhanced, and the input / output characteristics at a low temperature are remarkably improved. The reason for this is not limited by this theory, but because the amount of mesopores is much larger than the amount of micropores, the diffusion resistance of solvated lithium ions in the negative electrode material becomes extremely small. It is thought that the insertion / extraction of lithium ions into / from the metal becomes extremely smooth.

  Therefore, the ratio of the mesopore volume Vm1 to the micropore volume Vm2 is 21 ≦ Vm1 / Vm2 ≦ 100, more preferably 35 ≦ Vm1 / Vm2 ≦ 85, and still more preferably 45 ≦ Vm1 / Vm2 ≦ 65. The mesopore amount Vm1 is 0.20 <Vm1 ≦ 0.65, more preferably 0.30 <Vm1 ≦ 0.50, and still more preferably 0.35 <Vm1 ≦ 0.40. If 21 ≦ Vm1 / Vm2, high input / output characteristics can be exhibited. If Vm1 / Vm2 ≦ 100, the specific gravity is maintained at a certain level and the characteristics per volume are maintained, or the negative electrode active The physical strength of the material layer can be maintained. Similarly, if 0.20 <Vm1, high input / output characteristics can be exhibited. If Vm1 ≦ 0.65, the specific gravity is maintained at a certain level and the characteristics per volume are maintained. Alternatively, the physical strength of the negative electrode active material layer can be maintained.

  The primary particle diameter of the porous carbon material 3 is 1 μm or more and 20 μm or less, more preferably 2.5 μm or more and 12 μm or less, and further preferably 3.5 μm or more and 8 μm or less. If it is 1 μm or more, it can have mesopores that can contribute to high input / output characteristics even within the particles, and the insertion and removal of lithium ions into and from the negative electrode material becomes smooth, and the electron conduction between the negative electrode material particles is high. Therefore, the input / output characteristics can be improved. Further, the density of the negative electrode active material layer can be maintained, and the characteristics per volume can be maintained. Furthermore, cycle durability can also be improved. On the other hand, when the thickness is 20 μm or less, since the amount of occlusion / desorption of lithium ions inside the particles is relatively small, high input / output characteristics can be expressed. As used herein, the primary particle size refers to a particle whose primary particle is not agglomerated, when the cumulative curve is determined by measuring the particle size distribution using a particle size distribution measuring device with the total volume being 100%. The particle diameter at the point where the ratio is 50% is defined as 50% diameter, which means the 50% diameter (Median diameter). When primary particles aggregate and there is a possibility that secondary particle aggregates may be measured by the above method, 100 particles selected arbitrarily by observing with a scanning electron microscope (SEM) or a transmission electron microscope (TEM) It shall mean the arithmetic mean value of the particle diameter.

  The porous carbon material 3 is preferably formed from a non-graphitizable carbon material. When the material of the carbon portion of the porous carbon material is a non-graphitizable carbon material, the irreversible capacity when lithium ions are occluded / desorbed is reduced, and the charge / discharge efficiency is improved. In addition, self-discharge and leakage current can be suppressed, and a negative electrode material having excellent cycle durability can be provided.

[Other carbon materials]
Examples of other carbon materials contained in the negative electrode active material include amorphous carbonaceous materials such as graphite, graphitizable carbon materials (soft carbon), non-graphitizable carbon materials (hard carbon), and polyacene-based materials; carbon Examples thereof include nanotubes, fullerenes, carbon nanophones, fibrous carbonaceous materials, and the like that do not fall under any of the composite porous materials 1 and 2 and the porous carbon material 3 described above.
When the negative electrode active material contains other carbon materials, the use ratio of the other carbon materials is preferably 50% by mass or less, and preferably 20% by mass or less with respect to the total of the carbon materials. More preferred.

[Other components of negative electrode active material layer]
In addition to the negative electrode active material, for example, a conductive filler, a binder, and the like can be added to the negative electrode active material layer as necessary.
The type of conductive filler is not particularly limited, and examples thereof include acetylene black, ketjen black, and vapor grown carbon fiber. For example, the addition amount of the conductive filler is preferably 0 to 30% by mass with respect to the negative electrode active material.
Although it does not restrict | limit especially as a binder, For example, PVdF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), a styrene-butadiene copolymer etc. can be used. The amount of the binder added is preferably, for example, in the range of 3 to 20% by mass with respect to the negative electrode active material.

[Negative electrode active material layer]
Hereinafter, the negative electrode active material layer according to the present invention will be described.
The negative electrode active material layer according to the present invention comprises a sulfonic acid derivative represented by each of the following formulas (1) and (2) and a sulfite derivative represented by each of the following formulas (3) and (4). comprising at least one sulfur compound is more selective, and the total amount of the sulfonic acid derivative and nitrous acid derivatives, 6.0 × ¹⁰ -6 per unit weight of the negative electrode active material mol / g~2,000 × 10 ^{- 6} mol / g.

｛式（１）中、Ｒ^１は、炭素数１〜２４のアルキル基、炭素数１〜２４のモノ若しくはポリヒドロキシアルキル基又はそのリチウムアルコキシド、炭素数２〜２４のアルケニル基、炭素数２〜２４のモノ若しくはポリヒドロキシアルケニル基又はそのリチウムアルコキシド、炭素数３〜６のシクロアルキル基、又はアリール基であり、そしてＸ^１は、水素、リチウム、又は炭素数１〜１２のアルキル基である。｝

{In Formula (1), R ¹ is an alkyl group having 1 to 24 carbon atoms, a mono- or polyhydroxyalkyl group having 1 to 24 carbon atoms, or a lithium alkoxide thereof, an alkenyl group having 2 to 24 carbon atoms, or 2 to 2 carbon atoms. 24 mono- or polyhydroxyalkenyl groups or lithium alkoxides thereof, cycloalkyl groups having 3 to 6 carbon atoms, or aryl groups, and X ¹ is hydrogen, lithium, or alkyl groups having 1 to 12 carbon atoms. }

｛式（２）中、Ｒ^２は、炭素数１〜２４のアルキル基、炭素数１〜２４のモノ若しくはポリヒドロキシアルキル基又はそのリチウムアルコキシド、炭素数２〜２４のアルケニル基、炭素数２〜２４のモノ又はポリヒドロキシアルケニル基、炭素数３〜６のシクロアルキル基、又はアリール基であり、そしてＸ^２及びＸ^３は、各々独立に、水素、リチウム、又は炭素数１〜１２のアルキル基である。｝

{In formula (2), R ² represents an alkyl group having 1 to 24 carbon atoms, a mono- or polyhydroxyalkyl group having 1 to 24 carbon atoms or a lithium alkoxide thereof, an alkenyl group having 2 to 24 carbon atoms, and 2 to 2 carbon atoms. 24 mono- or polyhydroxyalkenyl groups, cycloalkyl groups having 3 to 6 carbon atoms, or aryl groups, and X ² and X ³ are each independently hydrogen, lithium, or an alkyl group having 1 to 12 carbon atoms. It is. }

｛式（３）中、Ｒ^３は、炭素数１〜２４のアルキル基、炭素数１〜２４のモノ若しくはポリヒドロキシアルキル基又はそのリチウムアルコキシド、炭素数２〜２４のアルケニル基、炭素数２〜２４のモノ若しくはポリヒドロキシアルケニル基又はそのリチウムアルコキシド、炭素数３〜６のシクロアルキル基、又はアリール基であり、そしてＸ^４は、水素、リチウム、又は炭素数１〜１２のアルキル基である。｝

{In Formula (3), R ³ represents an alkyl group having 1 to 24 carbon atoms, a mono- or polyhydroxyalkyl group having 1 to 24 carbon atoms or a lithium alkoxide thereof, an alkenyl group having 2 to 24 carbon atoms, and 2 to 2 carbon atoms. 24 mono- or polyhydroxyalkenyl groups or lithium alkoxides thereof, cycloalkyl groups having 3 to 6 carbon atoms, or aryl groups, and X ⁴ is hydrogen, lithium, or alkyl groups having 1 to 12 carbon atoms. }

｛式（４）中、Ｒ^４は、炭素数１〜２４のアルキル基、炭素数１〜２４のモノ若しくはポリヒドロキシアルキル基又はそのリチウムアルコキシド、炭素数２〜２４のアルケニル基、炭素数２〜２４のモノ若しくはポリヒドロキシアルケニル基又はそのリチウムアルコキシド、炭素数３〜６のシクロアルキル基、又はアリール基であり、そしてＸ^５及びＸ^６は、各々独立に、水素、リチウム、又は炭素数１〜１２のアルキル基である。｝

{In the formula (4), R ⁴ represents an alkyl group having 1 to 24 carbon atoms, a mono- or polyhydroxyalkyl group having 1 to 24 carbon atoms or a lithium alkoxide thereof, an alkenyl group having 2 to 24 carbon atoms, or 2 to 2 carbon atoms. 24 mono- or polyhydroxyalkenyl group or a lithium alkoxide thereof, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group, and X ⁵ and X ⁶ are each independently hydrogen, lithium, or 1 to 3 carbon atoms. 12 alkyl groups. }

  The sulfonic acid derivative represented by each of the general formulas (1) and (2) will be described below.

Examples of the sulfonic acid derivative represented by the formula (1) include:
Methanesulfonic acid, ethanesulfonic acid, 1-propanesulfonic acid, 2-propanesulfonic acid, 1-butanesulfonic acid, 2-butanesulfonic acid, 3-butanesulfonic acid, 2-methyl-2-propanesulfonic acid, 1- Pentanesulfonic acid, 1-hexanesulfonic acid, 1-heptanesulfonic acid, alkylsulfonic acid such as 1-octanesulfonic acid, hydroxymethanesulfonic acid, 2-hydroxyethanesulfonic acid, 3-hydroxypropanesulfonic acid, 4-hydroxybutane Monohydroxyalkyl sulfonic acids such as sulfonic acid, 5-hydroxypentanesulfonic acid, 6-hydroxyhexanesulfonic acid, 7-hydroxyheptanesulfonic acid, 8-hydroxyoctylsulfonic acid;
2,3-dihydroxypropanesulfonic acid, 3,4-dihydroxybutanesulfonic acid, 2,4-dihydroxybutanesulfonic acid, 4,5-dihydroxypentanesulfonic acid, 3,5-dihydroxypentanesulfonic acid, 2,5-dihydroxy Dihydroxyalkylsulfonic acids such as pentanesulfonic acid, 5,6-dihydroxyhexanesulfonic acid, 4,6-dihydroxyhexanesulfonic acid, 3,6-dihydroxyhexanesulfonic acid, 2,6-dihydroxyhexanesulfonic acid;

Alkenesulfonic acids such as ethylenesulfonic acid, 1-propenesulfonic acid, 1-butenesulfonic acid, 1-pentenesulfonic acid, 1-hexenesulfonic acid, 1-heptenesulfonic acid, 1-octenesulfonic acid, 3-hydroxy- 1-propenesulfonic acid, 3-hydroxy-2-propenesulfonic acid, 4-hydroxy-2-butenesulfonic acid, 4-hydroxy-1-butenesulfonic acid, 5-hydroxy-3-heptenesulfonic acid, 5-hydroxy 2-heptenesulfonic acid, 5-hydroxy-1-heptenesulfonic acid, 6-hydroxy-4-hexenesulfonic acid, 6-hydroxy-3-hexenesulfonic acid, 6-hydroxy-2-hexenesulfonic acid, 6 Monohydroxyalkenyl sulfonic acids such as hydroxy-1-hexene sulfonic acid;
Cycloalkyl sulfonic acids such as cyclopropyl sulfonic acid, cyclobutyl sulfonic acid, cyclopentyl sulfonic acid, cyclohexyl sulfonic acid;
Benzenesulfonic acid, 2-methylbenzenesulfonic acid, 3-methylbenzenesulfonic acid, 4-methylbenzenesulfonic acid, 2,4-dimethylbenzenesulfonic acid, 2,5-dimethylbenzenesulfonic acid, 2-ethylbenzenesulfonic acid, 3 Benzene sulfonic acids (aryl sulfonic acids from C6 to C8) such as ethylbenzenesulfonic acid, 4-ethylbenzenesulfonic acid;
Etc.

  Examples of the sulfonic acid derivative represented by the formula (2) include methanedisulfonic acid, 1,2-ethanedisulfonic acid, 1,3-propanedisulfonic acid, 1,4-butanedisulfonic acid, and 1,5-pentanedisulfone. Acid, 1,6-hexanedisulfonic acid, 1,7-heptanedisulfonic acid, 1,8-octanedisulfonic acid, 1,9-nonanedisulfonic acid, 1,10-decanedisulfonic acid, 1,12-dodecanedisulfonic acid, 4,4'-biphenyldisulfonic acid, and the like.

  Examples of the sulfonic acid derivative represented by each of the formulas (1) and (2) include structural isomers of the sulfonic acid or disulfonic acid; lithium salts of the sulfonic acid or disulfonic acid; methyl esters of the sulfonic acid or disulfonic acid. Sulphonic acid alkyl esters such as ethyl ester and propyl ester may be used.

Above all, from the viewpoint of electrochemical stability,
R ¹ in Formula (1) is an alkyl group having 1 to 24 carbon atoms, an alkenyl group having 2 to 24 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group, and X ¹ is hydrogen , Lithium, or a compound having 1 to 12 carbon atoms; and R ² in formula (2) is an alkyl group having 1 to 24 carbon atoms, an alkenyl group having 2 to 24 carbon atoms, or 3 to 6 carbon atoms. A compound in which X ² and X ³ are each independently hydrogen, lithium, or an alkyl group having 1 to 12 carbon atoms is preferable.

More preferably, among the compounds represented by the general formula (1),
In the formula, R ¹ is an alkyl group having 3 to 4 carbon atoms, a mono or polyhydroxyalkyl group having 3 to 4 carbon atoms, or a lithium alkoxide thereof, an alkenyl group having 3 to 4 carbon atoms, or a mono or 3 to 4 carbon atom. A compound that is a polyhydroxyalkenyl group or a lithium alkoxide thereof, and X ¹ is hydrogen, lithium, or an alkyl group having 1 to 2 carbon atoms.

Particularly preferred sulfonic acid derivatives are:
C ₃ H ₇ SO ₃ X ²¹ and C ₃ H ₅ SO ₃ X ²¹ {wherein X ²¹ is hydrogen, lithium, or an alkyl group having 1 to 2 carbon atoms. And a compound represented by X ²² O ₃ SC ₆ H ₁₂ SO ₃ X ²³ and X ²² O ₃ SC ₆ H ₈ SO ₃ X ²³ {wherein X ²² and X ²³ are each independently hydrogen, It is lithium or an alkyl group having 1 to 2 carbon atoms. } A compound represented by
(Di) sulfonic acid derivatives selected from:

Next, the sulfurous acid derivative represented by each of the general formulas (3) and (4) will be described.
Examples of the sulfite derivative represented by the formula (3) include lithium methyl sulfite, lithium ethyl sulfite, lithium vinyl sulfite, lithium propyl sulfite, and lithium butyl sulfite.
Examples of the sulfurous acid derivative represented by the formula (4) include dilithium methanedisulfite, dilithium 1,2-ethanedisulfite, dilithium 1,3-propanedisulfite, and dilithium 1,4-butanedisulfite.

Examples of the method for incorporating the sulfur compound according to this embodiment into the negative electrode active material layer include:
(I) A method of mixing the sulfur compound in the negative electrode active material layer,
(II) a method of adsorbing the sulfur compound to the negative electrode active material,
(III) A method of electrochemically depositing the sulfur compound on the negative electrode active material, and the like.
Among them, a precursor capable of generating the sulfur compound described above by decomposition is added as an additive in the non-aqueous electrolyte solution, and the decomposition reaction of the precursor in the step of manufacturing the electricity storage device is utilized. Thus, a method of depositing the sulfur compound in the negative electrode active material layer by the method (III) is preferable.

As the precursor for forming the sulfonic acid derivative, sultone compounds represented by the general formulas (5) to (7) are preferable.
Among these, from the viewpoint of the ease of reductive decomposition on the negative electrode active material and the electrochemical stability of the formed sulfur compound, the precursor for forming the sulfonic acid derivative includes 1,3-propane sultone, 2, Use one or more selected from the group consisting of 4-butane sultone, 1,4-butane sultone, 1,3-butane sultone, 2,4-pentane sultone, 1,3-propene sultone, and 1,4-butene sultone It is preferable to use 1,3-propane sultone.

  As the precursor for forming the sulfite derivative, it is possible to use one or more selected from sulfites such as ethylene sulfite, vinylene sulfite, propylene sulfite, butylene sulfite, dimethyl sulfite, and diethyl sulfite. preferable.

Here, the total amount of the sulfur compound is 6.0 × 10 ⁻⁶ mol / g or more and most preferably 15.7 × 10 ⁻⁶ mol / g or more per unit mass of the negative electrode active material. . If the total amount of sulfur compounds is 6.0 × 10 ⁻⁶ mol / g or more per unit mass of the negative electrode active material, the non-aqueous electrolyte solution does not come into contact with the negative electrode active material, and the non-aqueous electrolyte solution undergoes reductive decomposition. Can be suppressed.

The total amount of the sulfur compound is 2,000 × 10 ⁻⁶ mol / g or less, more preferably 870 × 10 ⁻⁶ mol / g or less, and 800 ^×× per unit mass of the negative electrode active material. still more preferably less 10 ^-6 mol / g, and most preferably not more than 770 × ¹⁰ -6 mol / g. When the total amount of sulfur compounds is 2,000 × 10 ⁻⁶ mol / g or less per unit mass of the negative electrode active material, high input / output characteristics can be exhibited without inhibiting the diffusion of Li ions.

The negative electrode active material according to this embodiment is preferably predoped with lithium ions. In a particularly preferred embodiment, lithium ions are pre-doped into the composite porous material 2 in the negative electrode active material layer. This pre-doping amount is preferably 1,050 mAh / g or more and 2,050 mAh / g or less, more preferably 1,100 mAh / g or more and 2,000 mAh / g or less per unit mass of the composite porous material 2. More preferably, it is 1,200 mAh / g or more and 1,700 mAh / g or less, More preferably, it is 1,300 mAh / g or more and 1,600 mAh / g or less.
By pre-doping with lithium ions, the negative electrode potential is lowered, the cell voltage when combined with the positive electrode is increased, and the utilization capacity of the positive electrode is increased. Therefore, capacity and energy density are increased. If the amount of pre-doping exceeds 1,050 mAh / g, lithium ions are well pre-doped at irreversible sites in the negative electrode material that cannot be desorbed once lithium ions are inserted, and further, the negative electrode with respect to the desired amount of lithium The amount of active material can be reduced. Therefore, the negative electrode film thickness can be reduced, and high durability, good output characteristics, and high energy density can be obtained. Further, as the pre-doping amount increases, the negative electrode potential decreases, and the durability and energy density improve. If the pre-doping amount is 2,050 mAh / g or less, there is no possibility that side effects such as precipitation of lithium metal occur.

As a method of pre-doping lithium ions into the negative electrode, a known method can be used. For example, after forming a negative electrode active material into an electrode body, using the negative electrode body as a working electrode and using lithium metal as a counter electrode, an electrochemical cell in which a non-aqueous electrolyte solution is combined is produced, and lithium ions are electrochemically used. And a method of pre-doping. It is also possible to pre-dope lithium ions into the negative electrode by pressing a metal lithium foil on the negative electrode body and placing it in a non-aqueous electrolyte.
By doping lithium ions into the negative electrode active material, it is possible to satisfactorily control the capacity and operating voltage of the power storage element.

[Common elements for positive and negative electrodes]
As matters common to the positive electrode and the negative electrode, (1) the components other than the active material in the active material layer, (2) the current collector, and (3) the structure of the electrode body will be described in order below.

(1) Components other than the active material in the active material layer Each of the active material layers of the positive electrode and the negative electrode contains known components contained in the active material layer in known lithium ion batteries, capacitors, etc. in addition to the above active materials, respectively. Furthermore, it can contain. This known component is, for example, a binder, a conductive filler, a thickener and the like, and there is no particular limitation on the type thereof.
Hereinafter, the components other than the active material contained in the active material layers of the positive electrode and the negative electrode in the non-aqueous lithium storage element of this embodiment will be described in detail.

The active material layer can contain a conductive filler (for example, carbon black), a binder, and the like as necessary.
0-30 mass parts is preferable with respect to 100 mass parts of active materials, and, as for the usage-amount of an electroconductive filler, 1-20 mass parts is more preferable. From the viewpoint of high power density, it is preferable to use a conductive filler. When the amount used is 30 parts by mass or less, the ratio of the amount of the active material in the active material layer is increased, and the output density per volume of the active material layer tends to increase, which is preferable.

  In the active material layer, a binder is used in order to fix the above active material and the conductive filler used as necessary on the current collector as the active material layer. As this binder, for example, polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), fluororubber, styrene butadiene copolymer, cellulose derivative and the like can be used. The amount of the binder used is preferably in the range of 3 to 20 parts by mass and more preferably in the range of 5 to 15 parts by mass with respect to 100 parts by mass of the active material. When the amount of the binder used is 20 parts by mass or less, the binder does not cover the surface of the active material. Therefore, ions are preferably moved in and out of the active material layer, and high power density tends to be easily obtained. On the other hand, when the amount of the binder used is 3 parts by mass or more, the active material layer tends to be easily fixed on the current collector, which is preferable.

(2) Current collector As the current collector, a general current collector used in a power storage element can be used. The current collector is preferably a metal foil that does not deteriorate due to elution into the electrolytic solution, reaction with the electrolytic solution, or the like. There is no restriction | limiting in particular as such metal foil, For example, copper foil, aluminum foil, etc. are mentioned. In the electricity storage device of the present invention, the positive electrode current collector is preferably an aluminum foil and the negative electrode current collector is preferably a copper foil.
The current collector may be a metal foil having no holes, or may be a metal foil having a through hole (for example, a through hole of a punching metal) or an open part (for example, an open part of an expanded metal).
The thickness of the current collector is not particularly limited, but is preferably 1 to 100 μm. The thickness of the current collector of 1 μm or more is preferable because the shape and strength of the electrode body (positive electrode and negative electrode in the present invention) formed by fixing the active material layer to the current collector can be maintained. On the other hand, it is preferable that the current collector has a thickness of 100 μm or less because the mass and volume of the electricity storage element become appropriate and the performance per mass and volume tends to be high.

(3) Configuration of electrode body The electrode body is formed by providing an active material layer on one side or both sides of a current collector. In a typical embodiment, the active material layer is fixed to the current collector.
The electrode body can be manufactured by known electrode manufacturing techniques such as a lithium ion battery and an electric double layer capacitor. For example, various materials including an active material are made into a slurry form with water or an organic solvent, this slurry is applied on a current collector and dried, and then an active material layer is formed by pressing at room temperature or under heating as necessary. Is obtained. Without using a solvent, various materials including an active material can be dry-mixed, and the obtained mixture can be press-molded and then attached to a current collector using a conductive adhesive.

  The thickness of the positive electrode active material layer is preferably 15 μm or more and 100 μm or less, more preferably 20 μm or more and 85 μm or less per side. When the thickness is 15 μm or more, an energy density sufficient as a capacitor can be expressed. On the other hand, if this thickness is 100 μm or less, high input / output characteristics as a capacitor can be obtained.

  The thickness of the negative electrode active material layer is preferably 20 μm or more and 45 μm or less, more preferably 25 μm or more and 40 μm or less per side. If this thickness is 20 μm or more, good charge / discharge capacity can be exhibited. On the other hand, if the thickness is 45 μm or less, the energy density can be increased by reducing the cell volume.

In addition, when there are holes in the current collector as described later, the thickness of the active material layer of the positive electrode and the negative electrode is the average of the thickness per one side of the portion of the current collector that does not have holes, respectively. Value.
The bulk density of the negative electrode active material layer is preferably 0.60 g / cm ³ or more and 1.2 g / cm ³ or less, more preferably 0.70 g / cm ³ or more and 1.0 g / cm ³ or less. When the bulk density is 0.60 g / cm ³ or more, good strength can be maintained and good conductivity between the active materials can be expressed. Moreover, if it is 1.2 g / cm < ³ > or less, the void | hole which ion can diffuse favorably within an active material layer is securable.

[Separator]
The positive electrode body and the negative electrode body molded as described above are laminated or wound around a separator to form an electrode laminate having a positive electrode body, a negative electrode body, and a separator.
The separator in the present embodiment is preferably one of the following two aspects.

A 1st aspect is a case where the separator in this embodiment is a polyolefin porous membrane. The polyolefin porous film can have low resistance (that is, high power density) and high cycle characteristics.
The porosity of the porous film of this embodiment is preferably 30% to 70%, more preferably 55 to 70%. Setting the porosity to 30% or more is preferable from the viewpoint of following the rapid movement of lithium ions at the high rate when the porous film is used as a capacitor separator. On the other hand, setting the porosity to 70% or less is preferable from the viewpoint of improving the film strength, and is also preferable from the viewpoint of suppressing self-discharge when the porous film is used as a capacitor separator.
In this case, the thickness of the separator is preferably 10 μm or more and 50 μm or less. A thickness of 10 μm or more is preferable because self-discharge due to an internal micro short circuit tends to be small. On the other hand, the thickness of 50 μm or less is preferable because the output characteristics of the electricity storage element tend to be high.

A 2nd aspect is a case where the separator in this embodiment is a nonwoven paper etc. made from a cellulose. Cellulose nonwoven paper or the like is excellent in the liquid retaining property of the electrolytic solution, and can exhibit a high output density. Since there is no electrode contact due to thermal contraction of the separator, a device having excellent heat resistance can be obtained.
In this case, the thickness of the separator is preferably 10 μm or more and 50 μm or less. A thickness of 10 μm or more is preferable because self-discharge due to an internal micro short circuit tends to be small. On the other hand, the thickness of 50 μm or less is preferable because the output characteristics of the electricity storage element tend to be high.

[Exterior body]
A metal can, a laminate film, or the like can be used as the exterior body.
The metal can is preferably made of aluminum.
The laminate film is preferably a film in which a metal foil and a resin film are laminated, and an example of a three-layer structure comprising an outer layer resin film / metal foil / interior resin film is exemplified. The outer layer resin film is for preventing the metal foil from being damaged by contact or the like, and resins such as nylon and polyester can be suitably used. The metal foil is for preventing the permeation of moisture and gas, and foils of copper, aluminum, stainless steel and the like can be suitably used. The interior resin film protects the metal foil from the electrolyte contained in the interior, and melts and seals the exterior body during heat sealing. Polyolefin, acid-modified polyolefin, and the like can be suitably used.

[Non-aqueous lithium storage element]
The non-aqueous lithium storage element according to the present embodiment is configured such that the electrode laminate obtained as described above and the non-aqueous electrolyte are accommodated in the exterior body.
The non-aqueous lithium-type energy storage device according to this embodiment has both high input / output characteristics and high durability at high temperatures, as will be specifically verified in the examples described later. Therefore, the non-aqueous lithium storage element according to the present embodiment is, for example, in the field of a hybrid drive system in which an internal combustion engine, a fuel cell, or a motor in an automobile and the storage element are combined; It is suitable as a lithium ion capacitor in applications such as an assist power source.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

<Preparation of positive electrode body>
[Preparation of positive electrode body A using activated carbon 1]
The crushed coconut shell carbide was carbonized in a small carbonization furnace in nitrogen at 500 ° C. for 3 hours to obtain a carbide. The obtained carbide was put into an activation furnace, 1 kg / h of steam was heated in the preheating furnace and introduced into the activation furnace, and the temperature was raised to 900 ° C. over 8 hours for activation. The activated carbide was taken out and cooled in a nitrogen atmosphere to obtain activated activated carbon. The obtained activated carbon was washed with water for 10 hours and then drained. Then, after drying for 10 hours in an electric dryer maintained at 115 ° C., the activated carbon 1 was obtained by pulverizing for 1 hour using a ball mill.
It was 4.2 micrometers as a result of measuring the average particle diameter about this activated carbon 1 using the Shimadzu Corporation laser diffraction type particle size distribution measuring apparatus (SALD-2000J). The pore distribution of the activated carbon 1 was measured using a pore distribution measuring device (AUTOSORB-1 AS-1-MP) manufactured by Yuasa Ionics. The mesopore volume (V1) calculated by QSDFT using the desorption side isotherm was 0.52 cc / g, and the micropore volume (V2) was 0.88 cc / g. The BET specific surface area of the activated carbon 1 determined by the BET 1-point method was 2,360 m ² / g.
80.8 parts by mass of the activated carbon 1 above, 6.2 parts by mass of ketjen black, 10 parts by mass of PVDF (polyvinylidene fluoride), 3.0 parts by mass of PVP (polyvinylpyrrolidone), and NMP (N-methyl) Pyrrolidone) was mixed to obtain a slurry. The obtained slurry was applied to one or both sides of a current collector made of an aluminum foil having a thickness of 15 μm, dried and pressed to obtain a positive electrode body A having a positive electrode active material layer thickness of 55 μm per side. Obtained.

[Production of positive electrode body B using activated carbon 2]
The phenol resin was carbonized in a baking furnace at 600 ° C. for 2 hours in a nitrogen atmosphere. The fired product obtained was pulverized with a ball mill and classified to obtain a carbide having an average particle size of 7 μm.
This carbide and KOH were mixed at a mass ratio of 1: 5, and activated by heating in a firing furnace at 800 ° C. for 1 hour in a nitrogen atmosphere. Next, after stirring and washing in dilute hydrochloric acid adjusted to a concentration of 2 mol / L for 1 hour, boiling washing was performed in distilled water until it was stable between pH 5 and 6, and then dried to produce activated carbon 2. .
When this activated carbon 2 was measured in the same manner as activated carbon 1, mesopore volume V1 was 1.50 cc / g, micropore volume V2 was 2.28 cc / g, and BET specific surface area was 3,627 m ² / g. .
80.8 parts by mass of this activated carbon 2, 6.2 parts by mass of ketjen black, 10 parts by mass of PVDF (polyvinylidene fluoride), 3.0 parts by mass of PVP (polyvinylpyrrolidone), and NMP (N-methylpyrrolidone) ) To obtain a slurry. The obtained slurry was applied to one or both sides of a current collector made of an aluminum foil having a thickness of 15 μm, dried and pressed to obtain a positive electrode body B having a positive electrode active material layer thickness of 55 μm per side. Obtained.

<Preparation of negative electrode body>
[Preparation of Negative Electrode A Using Composite Porous Material 1]
About commercially available coconut shell activated carbon, pore distribution measuring apparatus (AUTOSORB-1 AS-1-MP) manufactured by Yuasa Ionics Co., Ltd. was used and nitrogen distribution was measured as an adsorbate. As described above, using the isotherm on the desorption side, the mesopore amount was determined by the BJH method, and the micropore amount was determined by the MP method. As a result, the mesopore volume (V1) was 0.198 cc / g, the micropore volume (V2) was 0.695 cc / g, V1 / V2 = 0.29, and the average pore diameter was 21.2 mm. The BET specific surface area determined by the BET 1-point method was 1,780 m ² / g.
150 g of this coconut shell activated carbon is placed in a stainless steel mesh jar and placed on a stainless steel bat containing 270 g of a coal-based pitch (softening point: 50 ° C.). The composite porous material 1 was obtained by performing heat treatment. This heat treatment was performed in a nitrogen atmosphere, and the temperature was raised to 600 ° C. in 8 hours and held at that temperature for 4 hours. Then, after cooling to 60 degreeC by natural cooling, the composite porous material 1 used as a negative electrode material was taken out from the furnace. When the obtained composite porous material 1 was measured in the same manner as the activated carbon 1, the BET specific surface area was 262 m ² / g, the mesopore volume (Vm1) was 0.1798 cc / g, and the micropore volume (Vm2) was 0.00. 0843 cc / g and Vm1 / Vm2 = 2.13.
83.4 parts by mass of the composite porous material 1, 8.3 parts by mass of acetylene black, 8.3 parts by mass of PVDF (polyvinylidene fluoride), and NMP (N-methylpyrrolidone) are mixed to prepare a slurry. Obtained. The obtained slurry was applied to both sides of the expanded copper foil, dried, and pressed to obtain a double-sided negative electrode body A having a negative electrode active material layer thickness of 60 μm. A lithium metal foil corresponding to 760 mAh / g per unit mass of the composite porous material 1 was attached to one side of the double-sided negative electrode body A. The amount of doping into the negative electrode active material of the electricity storage device assembled using this double-sided negative electrode body A was 680 mAh / g per unit mass of the composite porous material 1.

[Preparation of Negative Electrode B Using Composite Porous Material 2]
About commercially available coconut shell activated carbon, pore distribution was measured using nitrogen as an adsorbate using a pore distribution measuring device (AUTOSORB-1 AS-1-MP) manufactured by Yuasa Ionics. Using the desorption side isotherm, the mesopore amount was determined by the BJH method, and the micropore amount was determined by the MP method. As a result, the mesopore volume (V1) was 0.198 cc / g, the micropore volume (V2) was 0.695 cc / g, V1 / V2 = 0.29, and the average pore diameter was 21.2 mm. The BET specific surface area determined by the BET 1-point method was 1,780 m ² / g.
150 g of this activated carbon is placed in a stainless steel mesh basket, placed on a stainless steel bat containing 150 g of coal-based pitch (softening point: 90 ° C.), and placed in an electric furnace (effective size in the furnace 300 mm × 300 mm × 300 mm). The composite porous material 2 was obtained by installing and performing heat treatment. This heat treatment was performed in a nitrogen atmosphere, and the temperature was raised to 630 ° C. in 2 hours and kept at the same temperature for 4 hours. Subsequently, after cooling to 60 ° C. by natural cooling, the composite porous material 2 was taken out from the furnace.
This composite porous material 2 has a mass ratio of the deposited carbonaceous material to activated carbon of 38 mass%, a BET specific surface area of 434 m ² / g, a mesopore volume (Vm1) of 0.220 cc / g, and a micropore volume. (Vm2) was 0.149 cc / g. Furthermore, it was 2.88 micrometers as a result of measuring an average particle diameter using the Shimadzu Corporation laser diffraction type particle size distribution measuring apparatus (SALD-2000J).
83.4 parts by mass of the composite porous material 2 obtained above, 8.3 parts by mass of acetylene black, 8.3 parts by mass of PVDF (polyvinylidene fluoride), and NMP (N-methylpyrrolidone) were mixed. A slurry was obtained. The obtained slurry was applied to both sides of the expanded copper foil, dried, and pressed to obtain a double-sided negative electrode body B having a negative electrode active material layer thickness of 30 μm. A lithium metal foil corresponding to 1,500 mAh / g per unit mass of the composite porous material 2 was attached to one side of the double-sided negative electrode body B. The amount of doping into the negative electrode active material of the electricity storage device assembled using this double-sided negative electrode body B was 1,350 mAh / g per unit mass of the composite porous material 2.

[Preparation of negative electrode body C using porous carbon material 3]
A commercially available phenolic resin cured product and SiO ₂ fine particles (average particle size 40 nm) were prepared at a weight ratio of 35:65 and mixed so as to be sufficiently uniform in an agate mortar. The phenol resin was carbonized by performing a time heat treatment. The obtained material was washed with hydrofluoric acid to remove SiO ₂ fine particles and dried, and then pulverized with a ball mill pulverizer for about 8 hours to obtain a porous carbon material 3 serving as a negative electrode material. The obtained porous carbon material 3 has a primary particle diameter (D ₅₀ ) of 4.3 μm, a mesopore volume (Vm1) of 0.602 cc / g, a micropore volume (Vm2) of 0.007 cc / g, Vm1 / Vm2 = 86.0.
83.4 parts by mass of the porous carbon material 3 obtained above, 8.3 parts by mass of acetylene black, 8.3 parts by mass of PVDF (polyvinylidene fluoride), and NMP (N-methylpyrrolidone) were mixed. A slurry was obtained. The obtained slurry was applied on both sides of the expanded copper foil, dried, and pressed to obtain a double-sided negative electrode body C having a negative electrode active material layer thickness of 60 μm. A lithium metal foil corresponding to 700 mAh / g per unit mass of the porous carbon material 3 was attached to one side of the double-sided negative electrode body C. The amount of doping into the negative electrode active material of the electricity storage device assembled using this double-sided negative electrode body C was 600 mAh / g per unit mass of the porous carbon material 3.

[Preparation of Negative Electrode D]
A mixture obtained by kneading 100 parts by weight of graphite and 50 parts by weight of an optically isotropic pitch with a softening point of 110 ° C. and a metaphase amount (QI amount) of 13% in a non-oxidizing atmosphere Then, it was fired at 1,000 ° C. The fired kneaded material was pulverized to an average particle size of 5 μm to obtain a coated graphitized carbon material having a BET specific surface area of 15 m ² / g. The average particle size of the coated graphitized carbon material was measured using MT-3300EX manufactured by Nikkiso Co., Ltd.
The BET specific surface area of the coated graphitized carbon material was measured with an isotherm using nitrogen as an adsorbate using a pore distribution measuring device (AUTOSORB-1 AS-1-MP) manufactured by Yuasa Ionics.
Next, 80.0 parts by mass of the obtained coated graphitized carbon material, 8.0 parts by mass of acetylene black, 3.0 parts by mass of CMC (carboxymethylcellulose), and 9.0 parts by mass of styrene butadiene rubber (SBR) latex, And distilled water were mixed to obtain a slurry having a solid concentration of 18% by mass. Next, the slurry obtained above was applied to both surfaces of a 15 μm-thick etching copper foil, dried, and pressed to obtain a double-sided negative electrode body D. The thickness per one side of the negative electrode active material layer of the obtained negative electrode body D was 20 μm. The thickness of the negative electrode active material layer was determined by calculating the thickness of the copper foil from the average value of the thickness of the negative electrode measured at 10 locations on the negative electrode using a thickness gauge (Linear Gauge Sensor GS-551) manufactured by Ono Keiki Co., Ltd. The value obtained by subtracting. A lithium metal foil corresponding to 500 mAh / g per unit mass of the coated graphitized carbon material was attached to one side of the double-sided negative electrode body D. The amount of doping into the negative electrode active material of the electricity storage device assembled using this double-sided negative electrode body D was 350 mAh / g per unit mass of the coated graphitized carbon material.

<Example 1>
[Preparation of electrolyte]
As an organic solvent, a mixed solvent of ethylene carbonate (EC): methyl ethyl carbonate (EMC) = 33: 67 (volume ratio) is used, and the concentration ratio of LiN (SO ₂ F) ₂ and LiPF ₆ is relative to the total electrolyte. A solution obtained by dissolving each electrolyte salt so that the sum of the concentrations of 75:25 (molar ratio) and LiN (SO ₂ F) ₂ and LiPF ₆ is 1.2 mol / L is non-aqueous electrolysis. Used as a liquid.
The concentrations of LiN (SO ₂ F) ₂ and LiPF ₆ in the electrolytic solution prepared here were 0.3 mol / L and 0.9 mol / L, respectively.
Moreover, it becomes 2.5 mass% with respect to 1-propene 1, 3- sultone (PES) of the quantity (preparation amount) which will be 2.5 mass% with respect to all electrolyte solutions as an additive, and all electrolyte solutions. A solution obtained by dissolving an amount (preparation amount) of 1,3-propane sultone (PS) was used as a non-aqueous electrolyte.

[Assembly of storage element]
Each of the positive electrode body A and the negative electrode body A is cut into 100 mm × 100 mm, the uppermost surface and the lowermost surface use the single-sided positive electrode body A, and further use the double-sided negative electrode body A18 and the double-sided positive electrode body A17. The negative electrode body A and the positive electrode body A were laminated by sandwiching a polyolefin porous membrane separator (separator A, total 36 sheets) each having a thickness of 15 μm. Thereafter, electrode terminals were connected to the negative electrode body A and the positive electrode body A to form an electrode laminate. The laminated body was inserted into an outer package made of a laminate film, and the nonaqueous electrolyte solution was injected to seal the outer package, thereby assembling a nonaqueous lithium storage element.

[Measurement of Sultone Compound Content in Nonaqueous Electrolytic Solution of Nonaqueous Lithium-type Energy Storage Device]
Regarding the electricity storage device obtained in the above process, among several non-aqueous lithium electricity storage devices, after adjusting several devices to 2.9 V, a dew point of −90 ° C. or less installed in a room at 23 ° C., oxygen The electrolytic solution was taken out by dismantling in an Ar box controlled at a concentration of 1 ppm or less. The taken-out electrolyte solution was put into a 3 mmφ NMR tube (PN-002 manufactured by Shigemi Co., Ltd.), and a 5 mmφ NMR tube containing deuterated chloroform containing 1,2,4,5-tetrafluorobenzene (N-made by Japan Precision Science Co., Ltd.). 5), ¹ H-NMR measurement and ¹⁹ F-NMR measurement were performed by a double tube method. ¹ H NMR signal of 1,2,4,5-tetrafluorobenzene was observed by normalizing 7.1 ppm (2H) as an integral value 2 and ¹⁹ F NMR signal -141.3 ppm (4F) as an integral value 4. The electrolyte composition was determined from the integration ratio of each compound. By this method, the electrolyte solution in the non-aqueous lithium storage element is 1.5% by mass of 1-propene 1,3-sultone (PES) and 1.8% by mass with respect to the total electrolyte solution. And the total amount of sultone compounds was calculated to be 3.3% by weight.

[Quantification of sulfur compounds in negative electrode active material layer]
Ar is controlled at a dew point of −90 ° C. or less and an oxygen concentration of 1 ppm or less installed in a room at 23 ° C. The negative electrode body was taken out by dismantling in the box. The taken-out negative electrode body was immersed and washed with dimethyl carbonate (DMC), and then vacuum-dried in a side box without being exposed to the atmosphere.
The dried negative electrode body was transferred from the side box to the Ar box without being exposed to the atmosphere, and immersed and extracted with heavy water to obtain a negative electrode body extract. The analysis of the extract was performed by (1) IC / MS and (2) ¹ H-NMR. The concentration A (mol / ml) of each compound in the obtained negative electrode body extract and the heavy water used for extraction From the volume B (ml) and the mass C (g) of the active material of the negative electrode used for extraction, the following formula 1:
Abundance per unit mass (mol / g) = A × B ÷ C (Formula 1)
Thus, the abundance (mol / g) per unit mass of the negative electrode active material of each compound deposited on the negative electrode body was determined.
As a result, the R ₇ SO ₃ X amount, the HORSO ₃ X amount, and the XO ₃ SRO ₃ X amount were 5.8 × 10 ⁻⁶ mol / g, 12.8 × 10 ⁻⁶ mol / g, and 39, respectively. .2 × a ¹⁰ -6 mol / g, their total amount was 57.7 × ¹⁰ -6 mol / g.
In the formula R ₇ SO ₃ X, the formula HORSO ₃ X and the formula XO ₃ SRO ₃ X, R ₇ and R are each independently an alkyl group having 1 to 24 carbon atoms, mono or polyhydroxyalkyl having 1 to 24 carbon atoms. Or a lithium alkoxide thereof, an alkenyl group having 2 to 24 carbon atoms, a mono- or polyhydroxyalkenyl group having 2 to 24 carbon atoms or a lithium alkoxide thereof, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group, and X Are each independently hydrogen, lithium, or an alkyl group having 1 to 12 carbon atoms.
In addition, the active material mass in the negative electrode used for extraction was calculated | required with the following method.
The mixture (negative electrode active material layer) was peeled off from the current collector of the negative electrode body remaining after the heavy water extraction, and the peeled mixture was washed with water and vacuum dried. The mixture obtained by vacuum drying was washed with NMP or DMF, and the binder (PVDF) was removed from the mixture. Subsequently, the washed mixture was vacuum-dried again to remove the washing solvent, water was added to the mixture, and the negative electrode active material and the filler were separated by centrifugation. The obtained negative electrode active material was again vacuum-dried and then weighed to examine the mass of the negative electrode active material used for extraction.

[Capacitance measurement]
About the electrical storage element obtained by the said process, it charged to 3.8V by the constant current constant voltage charge by which the constant voltage charge time was ensured for 1 hour in the electric current value of 1.5C, and after that 1.5C to 2.2V Constant current discharge was applied at the current value. The capacitance F determined by calculation according to F = Q / (3.8-2.2) from the capacitance Q and voltage change at that time was 1,000 F.

[Calculation of Ra · F and Rc · F]
The electricity storage device obtained in the above process was charged at a constant current until reaching 3.8 V at a current value of 1.5 C at an environmental temperature of 25 ° C. for Ra and −30 ° C. for Rc, and then 3 A constant current and constant voltage charge applying a constant voltage of 8 V was performed for a total of 2 hours. Subsequently, a constant current was discharged to 2.2 V at a current value of 50C. In the discharge curve (time-voltage) obtained at this time, when the voltage at discharge time = 0 seconds obtained by extrapolating from the voltage values at the time of discharge time 2 seconds and 4 seconds by linear approximation is E0. , Voltage drop (ΔE) = 3.8−E0, and internal resistance Ra = ΔE / (50C (current value)), Rc = ΔE / (50C (current value)). Each was calculated.
The product Ra · F of the capacitance F and the internal resistance Ra at 25 ° C. was 1.40ΩF.
The product Rc · F of the capacitance F and the internal resistance Rc at −30 ° C. was 18.0ΩF.

[Calculation of Rb / Ra]
The electricity storage element for which the Ra · F was evaluated was stored at a cell voltage of 4.0 V and an environmental temperature of 60 ° C. for 2 months. Here, in order to maintain the cell voltage of 4.0 V, 4.0 V charging at a current value of 1.5 C was performed for 2 hours in total every week before and after the start of storage.
A constant-current constant voltage is applied to the storage element after storage for 4 months until it reaches 3.8 V at a current value of 1.5 C at an ambient temperature of 25 ° C. and then a constant voltage of 3.8 V is applied. Charging was performed for a total of 2 hours. Subsequently, a constant current was discharged to 2.2 V at a current value of 50C. In the discharge curve (time-voltage) obtained at this time, when the voltage at discharge time = 0 second obtained by extrapolating from the voltage values at the time of discharge time 2 seconds and 4 seconds by linear approximation is E0 Then, the internal resistance Rb after storage was calculated by calculation according to the drop voltage (ΔE) = 3.8−E0 and the internal resistance Rb = ΔE / (50C (current value)).
The ratio Rb / Ra calculated by dividing this Rb (Ω) by the internal resistance Ra (Ω) before storage determined in [Calculation of Ra · F] was 1.45.

[Measurement of gas generated during storage]
Next, with respect to the electricity storage device obtained in the above step, the amount of gas generated when stored for 4 months at a cell voltage of 4.0 V and an environmental temperature of 60 ° C. was measured at 25 ° C. As a result, the gas generation amount was 8.0 × 10 ⁻³ cc / F.

<Examples 2 to 19 and Comparative Examples 1 to 16>
Examples 2 to 19 and Comparative Examples 1 to 16 were the same as Example 1 except that the configuration of the laminate and the composition of the electrolyte solution were as shown in Table 1 with respect to Example 1. Each of the non-aqueous lithium-type energy storage devices was produced and evaluated in various ways. Table 1 also shows the evaluation results of the obtained non-aqueous lithium storage element.

The abbreviations of organic solvents and additives in Table 1 have the following meanings.
[Organic solvent]
E2MEC: Organic solvent in which ethylene carbonate and methyl ethyl carbonate are mixed at a volume ratio of 2: 1 [electrolyte salt]
LiPF6: lithium hexafluorophosphate LiFSI: lithium bis (fluorosulfonyl) imide [additive]
PES: 1-propene 1,3-sultone PS: 1,3-propane sultone BS: 2,4-butane sultone

<Example 20>
[Assembly of storage element]
Each of the positive electrode body B and the negative electrode body C is cut into 100 mm × 100 mm, the uppermost surface and the lowermost surface are using the single-sided positive electrode body B, and further, the double-sided negative electrode body C18 and the double-sided positive electrode body B17 are used. The negative electrode body C and the positive electrode body B were laminated by sandwiching a polyolefin porous membrane separator (separator A, total of 36 sheets) each having a thickness of 15 μm. Thereafter, electrode terminals were connected to the negative electrode body C and the positive electrode body B to form an electrode laminate. The laminated body was inserted into an outer package made of a laminate film, and the nonaqueous electrolyte solution was injected to seal the outer package, thereby assembling a nonaqueous lithium storage element.

[Quantification of LiPO ₂ F ₂ concentration]
Next, the electricity storage device obtained in the above step was stored at a cell voltage of 4.0 V and an environmental temperature of 60 ° C. for 2 weeks, then at a dew point of −90 ° C. and an oxygen concentration of 1 ppm or less installed in a 23 ° C. room. The non-aqueous electrolyte was taken out by dismantling in a controlled Ar box. The taken out non-aqueous electrolyte solution is put in a 3 mmφ NMR tube (PN-002 manufactured by Shigemi Co., Ltd.), and a 5 mmφ NMR tube containing deuterated chloroform containing 1,2,4,5-tetrafluorobenzene (manufactured by Japan Precision Science Co., Ltd.). N-5), and ¹ H NMR measurement and ¹⁹ F NMR measurement were performed by a double tube method. ¹ H NMR signal of 1,2,4,5-tetrafluorobenzene was observed by normalizing 7.1 ppm (2H) as an integral value 2 and ¹⁹ F NMR signal -141.3 ppm (4F) as an integral value 4. The electrolyte composition was determined from the integration ratio of each compound. The signal of LiPO ₂ F ₂ is observed at −85.7 ppm and −88.2 ppm by ¹⁹ F NMR.

[Quantification of Al concentration]
Next, the electricity storage device obtained in the above step was stored at a cell voltage of 4.0 V and an environmental temperature of 60 ° C. for 2 weeks, then at a dew point of −90 ° C. and an oxygen concentration of 1 ppm or less installed in a 23 ° C. room. The non-aqueous electrolyte was taken out by dismantling in a controlled Ar box. 0.2 g of the non-aqueous electrolyte was placed in a Teflon (registered trademark) container, and 4 cc of 60% nitric acid was added. Decomposition was performed using a microwave decomposing apparatus (Milestone General, ETHOS PLUS). This was made up to 50 ml with pure water. This non-aqueous electrolyte solution was measured by ICP / MS (Thermo Fisher Scientific, X Series 2) to determine the Al abundance (ppm) per unit mass of the non-aqueous electrolyte solution.

[Measurement of gas generated during storage]
Next, about the electrical storage element obtained at the said process, the gas generation amount before and behind storing for 4 months in the cell voltage 4.0V and environmental temperature 60 degreeC was measured at 25 degreeC.

により求めた。
さらに、Ｓａを測定した蓄電素子について、セル電圧４．０Ｖ及び環境温度６０℃において４か月間保存した。４か月保存後の蓄電素子に対して、環境温度２５℃で、１．５Ｃの電流値において３．８Ｖに到達するまで定電流充電し、その後４．０Ｖの定電圧を印加する定電流定電圧充電を、合計で３０分間行った。その後、セル電圧環境温度２５℃において、１６８時間保存した後の電圧Ｅｂを測定し、降下電圧（ΔＥ）＝４．０−Ｅｂを求めた。この時の自己放電係数Ｓｂを、下記数式：

により求めた。
高温保存後の自己放電係数Ｓｂを、高温保存前の自己放電係数Ｓａで除して算出した比Ｓｂ／Ｓａは１．０２であった。 [Calculation of self-discharge increase rate Sb / Sa]
Next, the self-discharge coefficient change rate Sb / Sa before and after the high temperature storage evaluation was determined for the electricity storage device obtained in the above process. With respect to Sa, constant current charging at constant temperature until reaching 3.8 V at an ambient temperature of 25 ° C. at a current value of 1.5 C, and then applying a constant voltage of 4.0 V for a total of 30 minutes. went. Thereafter, the voltage Ea after being stored for 168 hours at a cell voltage ambient temperature of 25 ° C. was measured to obtain a voltage drop (ΔE) = 4.0−Ea.
The self-discharge coefficient Sa at this time is expressed by the following formula:

Determined by
Further, the electricity storage element for which Sa was measured was stored for 4 months at a cell voltage of 4.0 V and an environmental temperature of 60 ° C. A constant current constant is applied to a storage element after storage for 4 months at an ambient temperature of 25 ° C. until a constant voltage of 3.8 V is reached at a current value of 1.5 C, and then a constant voltage of 4.0 V is applied. Voltage charging was performed for a total of 30 minutes. Thereafter, the voltage Eb after being stored for 168 hours at a cell voltage ambient temperature of 25 ° C. was measured to obtain a voltage drop (ΔE) = 4.0−Eb. The self-discharge coefficient Sb at this time is expressed by the following formula:

Determined by
The ratio Sb / Sa calculated by dividing the self-discharge coefficient Sb after high-temperature storage by the self-discharge coefficient Sa before high-temperature storage was 1.02.

  Various other evaluations were performed in the same manner as in Example 1. All evaluation results are shown in Table 2.

<Examples 21 to 26 and Comparative Examples 17 and 18>
For Example 20 above, Examples 21 to 26, Comparative Example 17 and Comparative Example 17 were the same as Example 20 except that the configuration of the laminate and the composition of the electrolytic solution were as shown in Table 2, respectively. Eighteen non-aqueous lithium storage elements were produced and evaluated in various ways. Table 2 also shows the evaluation results of the obtained non-aqueous lithium storage element.

  From the above examples, it was verified that the energy storage device according to the present embodiment is a non-aqueous lithium-type energy storage device that exhibits high input / output characteristics and has low gas generation and high internal resistance at high temperatures.

  The non-aqueous lithium storage element of the present invention can be suitably used in, for example, the field of a hybrid drive system that combines an internal combustion engine or a fuel cell, a motor, and a storage element in an automobile, and further assists for instantaneous power peak. .

Claims (8)

An electrode laminate including a negative electrode body, a positive electrode body, and a separator, and a non-aqueous electrolyte solution is housed in an exterior body.
The negative electrode body includes a negative electrode current collector, and a negative electrode active material layer including a negative electrode active material provided on one or both surfaces of the negative electrode current collector. The negative electrode active material contains lithium ions. Includes carbon materials that can be occluded and released,
The positive electrode body includes a positive electrode current collector and a positive electrode active material layer including a positive electrode active material provided on one or both surfaces of the positive electrode current collector, and the positive electrode active material includes activated carbon. ,
The non-aqueous electrolyte contains 0.5 mol / L or more lithium salt based on the total amount of the non-aqueous electrolyte,
The negative electrode active material layer has the following formulas (1) and (2):

{In Formula (1), R ¹ is an alkyl group having 1 to 24 carbon atoms, a mono- or polyhydroxyalkyl group having 1 to 24 carbon atoms, or a lithium alkoxide thereof, an alkenyl group having 2 to 24 carbon atoms, or 2 to 2 carbon atoms. 24 mono- or polyhydroxyalkenyl groups or lithium alkoxides thereof, cycloalkyl groups having 3 to 6 carbon atoms, or aryl groups, and X ¹ is hydrogen, lithium, or alkyl groups having 1 to 12 carbon atoms. }

{In formula (2), R ² represents an alkyl group having 1 to 24 carbon atoms, a mono- or polyhydroxyalkyl group having 1 to 24 carbon atoms or a lithium alkoxide thereof, an alkenyl group having 2 to 24 carbon atoms, and 2 to 2 carbon atoms. 24 mono- or polyhydroxyalkenyl groups, cycloalkyl groups having 3 to 6 carbon atoms, or aryl groups, and X ² and X ³ are each independently hydrogen, lithium, or an alkyl group having 1 to 12 carbon atoms. It is. }
And the following formulas (3) and (4):

{In Formula (3), R ³ represents an alkyl group having 1 to 24 carbon atoms, a mono- or polyhydroxyalkyl group having 1 to 24 carbon atoms or a lithium alkoxide thereof, an alkenyl group having 2 to 24 carbon atoms, and 2 to 2 carbon atoms. 24 mono- or polyhydroxyalkenyl groups or lithium alkoxides thereof, cycloalkyl groups having 3 to 6 carbon atoms, or aryl groups, and X ⁴ is hydrogen, lithium, or alkyl groups having 1 to 12 carbon atoms. }

{In the formula (4), R ⁴ represents an alkyl group having 1 to 24 carbon atoms, a mono- or polyhydroxyalkyl group having 1 to 24 carbon atoms or a lithium alkoxide thereof, an alkenyl group having 2 to 24 carbon atoms, or 2 to 2 carbon atoms. 24 mono- or polyhydroxyalkenyl group or a lithium alkoxide thereof, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group, and X ⁵ and X ⁶ are each independently hydrogen, lithium, or 1 to 3 carbon atoms. 12 alkyl groups. }
And at least one sulfur compound selected from the group consisting of sulfite derivatives represented by each of the above, and the total amount of the sulfonic acid derivative and the sulfite derivative is 6.0 × 10 6 per unit mass of the negative electrode active material ⁻⁶ mol / g to 2,000 × 10 ⁻⁶ mol / g,
And in the non-aqueous electrolyte, the following formulas (5) to (7):

{In Formula (5), R ^{11 to} R ¹⁶ represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, or a halogenated alkyl group having 1 to 12 carbon atoms. And n is an integer from 0 to 3. }

{In Formula (6), R ^{11 to} R ¹⁴ represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, or a halogenated alkyl group having 1 to 12 carbon atoms, and they may be the same or different from each other. And n is an integer from 0 to 3. }

{In Formula (7), R ^{11 to} R ¹⁶ represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, or a halogenated alkyl group having 1 to 12 carbon atoms, and they may be the same or different from each other. It may be. }
2 or more of sultone compounds represented by each of the above, the total content of the sultone compound is 0.5% by mass to 15% by mass with respect to the total amount of the non-aqueous electrolyte,
The non-aqueous lithium storage element.   The sultone compound represented by the formula (5) is 1,3-propane sultone, 2,4-butane sultone, 1,4-butane sultone, 1,3-butane sultone, or 2,4-pentane sultone, The sultone compound represented by 6) is 1,3-propene sultone or 1,4-butene sultone, and the sultone compound represented by the formula (7) is 1,5,2,4-dioxadi The non-aqueous lithium storage element according to claim 1, which is thiepan 2,2,4,4-tetraoxide (cyclodison). The said non-aqueous electrolyte solution contains LiN (SO ₂ F) ₂ at a concentration of 0.3 mol / L or more and 1.5 mol / L or less based on the total amount of the non-aqueous electrolyte solution. The non-aqueous lithium storage element described. The non-aqueous lithium storage element according to claim 1, wherein the non-aqueous electrolyte contains at least one of LiPF ₆ and LiBF ₄ . The non-aqueous electrolyte contains LiN (SO ₂ F) ₂ and LiPF ₆ ,
The Al concentration contained in the non-aqueous electrolyte is in the range of 1 ppm to 50 ppm based on the total amount of the non-aqueous electrolyte, and the LiPO ₂ F ₂ concentration contained in the non-aqueous electrolyte is the non-aqueous electrolyte. Based on the total amount of the aqueous electrolyte, it is in the range of 1 ppm to 100 ppm.
The non-aqueous lithium storage element according to claim 1. The non-aqueous lithium storage element according to claim 5, wherein a molar ratio between the LiN (SO ₂ F) ₂ and the LiPF ₆ is 9: 1 to 3: 7. The non-aqueous electrolyte solution is
Ethylene carbonate,
(A) an organic solvent comprising at least one selected from dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, and (a) at least one selected from dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate The non-aqueous lithium storage element according to claim 1, wherein a volume ratio is 20% or more based on a total amount of the organic solvent. An electrode laminate including a negative electrode body, a positive electrode body, and a separator, and a non-aqueous electrolyte solution is housed in an exterior body.
The negative electrode body includes a negative electrode current collector, and a negative electrode active material layer including a negative electrode active material provided on one or both surfaces of the negative electrode current collector. The negative electrode active material contains lithium ions. Includes carbon materials that can be occluded and released,
The positive electrode body includes a positive electrode current collector and a positive electrode active material layer including a positive electrode active material provided on one or both surfaces of the positive electrode current collector, and the positive electrode active material includes activated carbon. ,
The non-aqueous electrolyte contains 0.5 mol / L or more lithium salt based on the total amount of the non-aqueous electrolyte,
The negative electrode active material layer has the following formulas (1) and (2):

{In Formula (1), R ¹ is an alkyl group having 1 to 24 carbon atoms, a mono- or polyhydroxyalkyl group having 1 to 24 carbon atoms, or a lithium alkoxide thereof, an alkenyl group having 2 to 24 carbon atoms, or 2 to 2 carbon atoms. 24 mono- or polyhydroxyalkenyl groups or lithium alkoxides thereof, cycloalkyl groups having 3 to 6 carbon atoms, or aryl groups, and X ¹ is hydrogen, lithium, or alkyl groups having 1 to 12 carbon atoms. }

{In formula (2), R ² represents an alkyl group having 1 to 24 carbon atoms, a mono- or polyhydroxyalkyl group having 1 to 24 carbon atoms or a lithium alkoxide thereof, an alkenyl group having 2 to 24 carbon atoms, and 2 to 2 carbon atoms. 24 mono- or polyhydroxyalkenyl groups, cycloalkyl groups having 3 to 6 carbon atoms, or aryl groups, and X ² and X ³ are each independently hydrogen, lithium, or an alkyl group having 1 to 12 carbon atoms. It is. }
And the following formulas (3) and (4):

{In Formula (3), R ³ represents an alkyl group having 1 to 24 carbon atoms, a mono- or polyhydroxyalkyl group having 1 to 24 carbon atoms or a lithium alkoxide thereof, an alkenyl group having 2 to 24 carbon atoms, and 2 to 2 carbon atoms. 24 mono- or polyhydroxyalkenyl groups or lithium alkoxides thereof, cycloalkyl groups having 3 to 6 carbon atoms, or aryl groups, and X ⁴ is hydrogen, lithium, or alkyl groups having 1 to 12 carbon atoms. }

{In the formula (4), R ⁴ represents an alkyl group having 1 to 24 carbon atoms, a mono- or polyhydroxyalkyl group having 1 to 24 carbon atoms or a lithium alkoxide thereof, an alkenyl group having 2 to 24 carbon atoms, or 2 to 2 carbon atoms. 24 mono- or polyhydroxyalkenyl group or a lithium alkoxide thereof, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group, and X ⁵ and X ⁶ are each independently hydrogen, lithium, or 1 to 3 carbon atoms. 12 alkyl groups. }
And at least one sulfur compound selected from the group consisting of sulfite derivatives represented by each of the above, and the total amount of the sulfonic acid derivative and the sulfite derivative is 6.0 × 10 6 per unit mass of the negative electrode active material ⁻⁶ mol / g to 2,000 × 10 ⁻⁶ mol / g,
The nonaqueous electrolytic solution has the following formulas (5) to (7):

{In Formula (5), R ^{11 to} R ¹⁶ represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, or a halogenated alkyl group having 1 to 12 carbon atoms. And n is an integer from 0 to 3. }

{In Formula (6), R ^{11 to} R ¹⁴ represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, or a halogenated alkyl group having 1 to 12 carbon atoms, and they may be the same or different from each other. And n is an integer from 0 to 3. }

{In Formula (7), R ^{11 to} R ¹⁶ represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, or a halogenated alkyl group having 1 to 12 carbon atoms, and they may be the same or different from each other. It may be. }
At least two kinds of sultone compounds represented by each of the above, the total content of the sultone compound is 0.5% by mass to 15% by mass with respect to the total amount of the non-aqueous electrolyte solution,
The internal resistance at 25 ° C. after storage of the non-aqueous lithium storage element for 4 months at a cell voltage of 4 V and an environmental temperature of 60 ° C. is Rb (Ω), and the internal resistance at 25 ° C. before storage of the non-aqueous lithium storage element is When Ra (Ω), the internal resistance at −30 ° C. before storage is Rc (Ω), and the capacitance at 25 ° C. before storage is F (F), the following (a) to (d):
(A) The product Ra · F of Ra and F is 1.9 or less;
(B) Rb / Ra is 1.8 or less;
(C) The amount of gas generated when the non-aqueous lithium storage element is stored for 4 months at a cell voltage of 4 V and an environmental temperature of 60 ° C. is 26 × 10 ⁻³ cc / F or less at 25 ° C .; and (d) Rc And the product Rc · F of F and F is 24 or less;
A non-aqueous lithium electricity storage device characterized by satisfying all of the above.