JP2015146281A - Positive electrode mixture and all-solid type lithium sulfur battery - Google Patents
Positive electrode mixture and all-solid type lithium sulfur battery Download PDFInfo
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- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 73
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Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
Description
本発明は、正極合材及び全固体型リチウム硫黄電池に関する。 The present invention relates to a positive electrode mixture and an all solid-state lithium-sulfur battery.
硫黄は、理論容量が約１６７２ｍＡｈ／ｇと非常に高いことが知られており、硫黄を正極活物質として使用したリチウム硫黄電池の研究が盛んに行われている。
リチウム硫黄電池は、電解質として液体電解質を用いた液体型リチウム硫黄電池と、固体電解質を用いた全固体型リチウム硫黄電池とに大別される。
Sulfur is known to have a very high theoretical capacity of about 1672 mAh / g, and lithium sulfur batteries using sulfur as a positive electrode active material have been actively studied.
Lithium-sulfur batteries are roughly classified into liquid lithium-sulfur batteries that use liquid electrolytes as electrolytes and all-solid-state lithium-sulfur batteries that use solid electrolytes.
液体型リチウム硫黄電池においては、リチウムイオンと硫黄との反応により生成した多硫化リチウムが電解質溶液中に溶け出し、電池の充放電容量や寿命に悪影響を与えることが問題となっていた。 In the liquid type lithium-sulfur battery, lithium polysulfide produced by the reaction between lithium ions and sulfur is dissolved in the electrolyte solution, which adversely affects the charge / discharge capacity and life of the battery.
これに対し、全固体型リチウム硫黄電池は、多硫化リチウムが電解質溶液に溶け出す問題が生じないため、電池の充放電容量の維持や長寿命化に適している。また、可燃性の有機溶媒を含まないため液漏れや発火のおそれがなく安全性を確保できる点や、セパレータが不要である点等、全固体型リチウム硫黄電池の持つ優れた特性に注目が集まっている。
全固体型リチウム硫黄電池の正極合材層中においては、下記式（１）に示す可逆反応のうち、放電時には右向きの反応が、充電時には左向きの反応が、それぞれ優位に進行している。
Ｓ＋２Ｌｉ＋＋２ｅ− ⇔ Ｌｉ２Ｓ （１）
On the other hand, the all-solid-state lithium-sulfur battery is suitable for maintaining the charge / discharge capacity of the battery and extending its life because there is no problem that lithium polysulfide dissolves into the electrolyte solution. In addition, attention has been focused on the excellent characteristics of all-solid-state lithium-sulfur batteries, such as the absence of flammable organic solvents, which ensures safety without the risk of liquid leakage or ignition, and the need for a separator. ing.
In the positive electrode mixture layer of the all-solid-state lithium-sulfur battery, among the reversible reactions represented by the following formula (1), a rightward reaction during discharge and a leftward reaction during charging proceed in a dominant manner.
S + 2Li + + 2e − ⇔ Li 2 S (1)
しかしながら、全固体型リチウム硫黄電池では、負極、固体電解質層及び正極合材層が実質的に溶媒を含有せず、また、正極活物質として正極合材層に含まれる硫黄が電気絶縁性であるため、正極合材層における電子伝導性及びリチウムイオン伝導性が非常に低い。特に、正極合材中に硫黄を高い比率で充填した場合は、充放電に際して上記式（１）に示す反応の反応性が乏しく、十分な充放電容量を確保することができないという課題があった。 However, in the all-solid-state lithium-sulfur battery, the negative electrode, the solid electrolyte layer, and the positive electrode mixture layer substantially contain no solvent, and the sulfur contained in the positive electrode mixture layer as the positive electrode active material is electrically insulating. Therefore, the electronic conductivity and lithium ion conductivity in the positive electrode mixture layer are very low. In particular, when sulfur is charged at a high ratio in the positive electrode mixture, there is a problem that the reactivity of the reaction shown in the above formula (1) is poor at the time of charge and discharge, and a sufficient charge and discharge capacity cannot be secured. .
特許文献１には、全固体リチウム電池の正極に用いる電極材料として、硫黄、導電性物質、並びに、リチウム原子、リン原子及び硫黄原子を含む固体電解質を含む電極材料が提案されている。この文献では、上述した電極材料によれば、全固体リチウム電池の電池性能を高めることができるとされている。 Patent Document 1 proposes an electrode material containing sulfur, a conductive substance, and a solid electrolyte containing a lithium atom, a phosphorus atom, and a sulfur atom as an electrode material used for a positive electrode of an all-solid lithium battery. In this document, according to the electrode material described above, the battery performance of the all-solid lithium battery can be improved.
しかしながら、実際のところ、特許文献１に記載された全固体リチウム電池用電極材料では、スマートフォンやパソコン等の低出力用途を想定したとしても非実用的な低電流で使用する場合はまだしも、実用的な電流で使用する場合には充分な充放電容量を確保することが困難であった。
即ち、従来の正極合材層を備えた全固体型リチウム硫黄電池では、充放電容量について未だ改善の必要があり、実用的な高電流での使用にも耐え得る全固体型リチウム硫黄電池を実現する上で、硫黄の持つ優れた物性を活かしきれていないとの課題があった。
However, in fact, the all-solid-state lithium battery electrode material described in Patent Document 1 is not practical when used at a low current that is impractical even if it is assumed to be used for a low power output of a smartphone or a personal computer. When using with a large current, it was difficult to ensure a sufficient charge / discharge capacity.
In other words, the all-solid-state lithium-sulfur battery equipped with the conventional positive electrode mixture layer still needs to be improved in charge and discharge capacity, realizing an all-solid-state lithium-sulfur battery that can withstand practical use at high currents. In doing so, there was a problem that the excellent physical properties of sulfur could not be fully utilized.
本発明は、硫黄の持つ優れた物性を最大限に活かし、優れた正極合材当たりの充放電容量を有する全固体型リチウム硫黄電池の正極合材層に好適に用いることができる正極合材を提供することを目的とする。また、上記正極合材を含む正極合材層を備えた全固体型リチウム硫黄電池を提供することを目的とする。 The present invention maximizes the excellent physical properties of sulfur and uses a positive electrode mixture that can be suitably used for a positive electrode mixture layer of an all-solid-state lithium-sulfur battery having an excellent charge / discharge capacity per positive electrode mixture. The purpose is to provide. Moreover, it aims at providing the all-solid-state lithium-sulfur battery provided with the positive electrode compound material layer containing the said positive electrode compound material.
本発明者らは、全固体型リチウム硫黄電池に用いる正極合材について種々検討したところ、イオン伝導性物質と硫黄及び／又はその放電生成物と導電材とを含む正極合材において、イオン伝導性物質として、リン（Ｐ）、硫黄（Ｓ）、リチウム（Ｌｉ）及びヨウ素（Ｉ）を含み、Ｐの重量比が０．１４〜０．４０、かつ、Ｉの重量比が０．０３〜０．３０である複合化物を用い、導電材として比表面積が１１００ｍ２／ｇ以上のものを用いるとともに、硫黄及び／又はその放電生成物の配合量を特定量とすることにより、電気絶縁体の正極活物質を正極合材中に高い比率で充填した状態においても、リチウムイオンが正極合材中の反応界面へ移動する際の抵抗（イオン抵抗）を低く保ちつつも、硫黄、電子及びリチウムイオンが反応界面で反応する際の抵抗（反応抵抗）を低減することができるため、上記式（１）で示す反応の反応性が向上する結果、全固体型リチウム硫黄電池の正極合材当たりの充放電容量、特に高電流を流した際の充放電容量が向上するとの新たな知見を得、この知見に基づき本発明を完成した。 The inventors of the present invention have made various studies on a positive electrode mixture used in an all-solid-state lithium-sulfur battery. As a result, in a positive electrode mixture containing an ion conductive substance and sulfur and / or a discharge product thereof and a conductive material, The substance includes phosphorus (P), sulfur (S), lithium (Li) and iodine (I), the weight ratio of P is 0.14 to 0.40, and the weight ratio of I is 0.03 to 0. .30, a conductive material having a specific surface area of 1100 m 2 / g or more and a specific amount of sulfur and / or discharge products thereof are used as a positive electrode of an electrical insulator. Even when the active material is packed in a high ratio in the positive electrode mixture, the resistance (ion resistance) when lithium ions move to the reaction interface in the positive electrode mixture is kept low, while sulfur, electrons, and lithium ions are reduced. At the reaction interface As a result of improving the reactivity of the reaction represented by the above formula (1), the charge / discharge capacity per positive electrode mixture of the all-solid-state lithium-sulfur battery, particularly, The inventors obtained new knowledge that the charge / discharge capacity is improved when a high current is passed, and the present invention has been completed based on this knowledge.
なお、上述の特許文献１に記載された発明は、正極活物質として理論容量は大きいが電気絶縁体である硫黄を用いる場合において、導電性の高い固体電解質を用いることによりイオン抵抗を低減させているが、充放電特性に優れた全固体型リチウム硫黄電池とする上では、イオン抵抗だけでなく、反応抵抗も併せて低くする必要があり、正極合材にて、［Ａ］特定のイオン伝導性物質を用い、特定量の［Ｂ］硫黄及び／又はその放電生成物を用い、さらに［Ｃ］特定の比表面積を有する導電材を用いることにより、充放電特性に優れた全固体型リチウム硫黄電池を得るという技術的思想は、特許文献１には一切開示されていない。 Note that the invention described in Patent Document 1 described above reduces the ionic resistance by using a highly conductive solid electrolyte in the case of using sulfur as an electrical insulator, although the theoretical capacity is large as the positive electrode active material. However, in order to make an all-solid-state lithium-sulfur battery with excellent charge / discharge characteristics, it is necessary to reduce not only the ionic resistance but also the reaction resistance. All-solid-state lithium sulfur having excellent charge / discharge characteristics by using a conductive material, using a specific amount of [B] sulfur and / or its discharge product, and further using [C] a conductive material having a specific specific surface area The technical idea of obtaining a battery is not disclosed in Patent Document 1.
即ち、本発明の正極合材は、
［Ａ］リン（Ｐ）、硫黄（Ｓ）、リチウム（Ｌｉ）及びヨウ素（Ｉ）を含み、Ｐの重量比が０．１４〜０．４、かつ、Ｉの重量比が０．０３〜０．３０である複合化物であるイオン伝導性物質、
［Ｂ］硫黄及び／又はその放電生成物、並びに、
［Ｃ］比表面積が１１００ｍ２／ｇ以上である導電材を含み、
上記［Ｂ］成分の含有量は、上記［Ａ］成分、上記［Ｂ］成分及び上記［Ｃ］成分の合計量の４０重量％以上であり、
全固体型リチウム硫黄電池の正極合材層に用いられることを特徴とする。
That is, the positive electrode mixture of the present invention is
[A] contains phosphorus (P), sulfur (S), lithium (Li) and iodine (I), the weight ratio of P is 0.14 to 0.4, and the weight ratio of I is 0.03 to 0 An ion conductive material that is a composite that is .30.
[B] sulfur and / or its discharge product, and
[C] a conductive material having a specific surface area of 1100 m 2 / g or more,
The content of the component [B] is 40% by weight or more of the total amount of the component [A], the component [B] and the component [C],
It is used for a positive electrode mixture layer of an all-solid-state lithium-sulfur battery.
本発明の正極合材において、前記イオン伝導性物質［Ａ］、前記硫黄及び／又はその放電生成物［Ｂ］、並びに、前記導電材［Ｃ］の各成分の重量基準による含有割合（［Ａ］成分：［Ｂ］成分：［Ｃ］成分）は、２０〜５５：４０〜７０：５〜２０であることが好ましい。 In the positive electrode composite of the present invention, the content ratio of each component of the ion conductive material [A], the sulfur and / or the discharge product [B], and the conductive material [C] on a weight basis ([A ] Component: [B] component: [C] component) is preferably 20-55: 40-70: 5-20.
本発明の正極合材において、上記イオン伝導性物質［Ａ］は、Ｌｉ２Ｓ、Ｓ、Ｐ及びＬｉＩ；Ｓ、Ｐ及びＬｉＩ；Ｌｉ２Ｓ、ＰｘＳｙ及びＬｉＩ；並びに、ＰｘＳｙ及びＬｉＩからなる群より選択される少なくとも１つの組合せをメカニカルミリング処理することにより得られる複合化物（ここで、ｘ及びｙは、独立して、化学量論比を与える整数を表わす）であることが好ましい。 In the positive electrode mixture of the present invention, the ion conductive material [A] includes Li 2 S, S, P and LiI; S, P and LiI; Li 2 S, P x S y and LiI; and P x S a composite obtained by mechanical milling at least one combination selected from the group consisting of y and LiI (where x and y independently represent an integer giving a stoichiometric ratio) It is preferable.
本発明の全固体型リチウム硫黄電池は、本発明の正極合材を含む正極合材層、固体電解質層、負極及び集電体を備えることを特徴とする。 The all-solid-state lithium-sulfur battery of the present invention includes a positive electrode mixture layer including the positive electrode mixture of the present invention, a solid electrolyte layer, a negative electrode, and a current collector.
本発明の正極合材には、［Ａ］Ｐ、Ｓ、Ｌｉ及びＩを含み、Ｐ及びＩが特定の重量比である複合化物であるイオン伝導性物質、［Ｂ］硫黄及び／又はその放電生成物、並びに、［Ｃ］比表面積が１１００ｍ２／ｇ以上の導電材を含み、かつ、［Ｂ］成分の含有量が、［Ａ］〜［Ｃ］成分の合計量の４０重量％以上であるため、全固体型リチウム硫黄電池の正極合材層として用いた場合に、正極合材中に正極活物質である［Ｂ］硫黄及び／又はその放電生成物含有率が高い状態において、イオン抵抗を低く保ちつつ反応抵抗を低減させることができ、充放電特性に優れた全固体型リチウム硫黄電池を提供することができる。特に、低電流（例えば、０．１〜０．５ｍＡ／ｃｍ２程度）で使用した場合は勿論のこと、高電流（例えば、１ｍＡ／ｃｍ２以上）で使用した場合でも高い充放電容量を有する点で本発明は優れる。
また、本発明の全固体型リチウム硫黄電池は、本発明の正極合材を含む正極合材層を備えるため、充放電特性に優れる。
そして、このような正極合材及びこの正極合材を用いた全固体型リチウム硫黄電池は、例えば、電気自動車やハイブリッド自動車に使用することができるため、本発明によればＣＯ２削減に貢献することができる。
The positive electrode mixture of the present invention includes [A] P, S, Li and I, an ion conductive material which is a composite having P and I in a specific weight ratio, [B] sulfur and / or discharge thereof. The product and the conductive material having a [C] specific surface area of 1100 m 2 / g or more, and the content of the [B] component is 40% by weight or more of the total amount of the [A] to [C] components Therefore, when used as a positive electrode mixture layer of an all-solid-state lithium-sulfur battery, in a state where the positive electrode active material [B] sulfur and / or its discharge product content is high in the positive electrode mixture, the ionic resistance The reaction resistance can be reduced while keeping the temperature low, and an all-solid-state lithium-sulfur battery excellent in charge / discharge characteristics can be provided. In particular, low current (e.g., 0.1~0.5mA / cm 2 or so) of course when used in, has a high charge and discharge capacity even when used at a high current (e.g., 1 mA / cm 2 or higher) In this respect, the present invention is excellent.
Moreover, since the all-solid-state lithium-sulfur battery of this invention is equipped with the positive mix layer containing the positive mix of this invention, it is excellent in a charge / discharge characteristic.
Such a positive electrode mixture and an all-solid-state lithium-sulfur battery using the positive electrode mixture can be used for, for example, an electric vehicle or a hybrid vehicle. Therefore, according to the present invention, it contributes to CO 2 reduction. be able to.
＜＜正極合材＞＞
まず、本発明の正極合材について説明する。
本発明の正極合材は、全固体型リチウム硫黄電池の正極合材層に用いる正極合材であり、
［Ａ］Ｐ、Ｓ、Ｌｉ及びＩを含み、Ｐの重量比が０．１４〜０．４０、かつ、Ｉの重量比が０．０３〜０．３０である複合化物であるイオン伝導性物質、［Ｂ］硫黄及び／又はその放電生成物、並びに、［Ｃ］比表面積が１１００ｍ２／ｇ以上である導電材を含み、
上記［Ｂ］成分の含有量が、上記［Ａ］成分、上記［Ｂ］成分及び上記［Ｃ］成分の合計量の４０重量％以上であることを特徴とする。
<< Positive electrode mixture >>
First, the positive electrode mixture of the present invention will be described.
The positive electrode mixture of the present invention is a positive electrode mixture used for the positive electrode mixture layer of an all-solid-state lithium-sulfur battery,
[A] Ion conductive material which is a composite containing P, S, Li and I, the weight ratio of P being 0.14 to 0.40, and the weight ratio of I being 0.03 to 0.30 , [B] sulfur and / or discharge products thereof, and [C] a conductive material having a specific surface area of 1100 m 2 / g or more,
Content of said [B] component is 40 weight% or more of the total amount of said [A] component, said [B] component, and said [C] component, It is characterized by the above-mentioned.
＜イオン伝導性物質［Ａ］＞
上記イオン伝導性物質［Ａ］は、本発明の正極合材に固体電解質として含まれるものであり、Ｐ、Ｓ、Ｌｉ及びＩを含み、Ｐの重量比が０．１４〜０．４０、かつ、Ｉの重量比が０．０３〜０．３０である複合化物である。
本発明の正極合材では、イオン伝導性物質［Ａ］として、Ｐ、Ｓ、Ｌｉ及びＩを含み、Ｐの重量比が０．１４〜０．４０、かつ、Ｉの重量比が０．０３〜０．３０である複合化物を用いることが極めて重要であり、このような複合化物を用いることにより、上述した通り、正極合材層中で、イオン抵抗を低く保ちつつ反応抵抗を低減することができるため、全固体型リチウム硫黄電池とした際に正極合材当たりの充放電容量を向上させることができる。
Ｐの重量比は、好ましくは０．１６〜０．３０であり、より好ましくは０．１７〜０．２６である。
Iの重量比は、好ましくは０．０６〜０．２７であり、より好ましくは０．１２〜０．２５である。
一方、上記イオン伝導性物質［Ａ］において、Ｐの重量比が０．１４〜０．４０の範囲外の場合や、Ｉの重量比が０．０３〜０．３０の範囲外の場合には、全固体型リチウム硫黄電池に用いた場合に充分な正極合材当たりの充放電容量を確保することができないことがある。
<Ion conductive material [A]>
The ion conductive material [A] is included as a solid electrolyte in the positive electrode mixture of the present invention, includes P, S, Li and I, and a weight ratio of P is 0.14 to 0.40, and , I is a composite having a weight ratio of 0.03 to 0.30.
In the positive electrode mixture of the present invention, P, S, Li, and I are included as the ion conductive substance [A], the weight ratio of P is 0.14 to 0.40, and the weight ratio of I is 0.03. It is extremely important to use a composite that is ˜0.30. By using such a composite, as described above, the reaction resistance can be reduced while keeping the ionic resistance low in the positive electrode mixture layer. Therefore, when it is set as an all-solid-type lithium-sulfur battery, the charge / discharge capacity per positive electrode mixture can be improved.
The weight ratio of P is preferably 0.16 to 0.30, and more preferably 0.17 to 0.26.
The weight ratio of I is preferably 0.06 to 0.27, more preferably 0.12 to 0.25.
On the other hand, in the ion conductive material [A], when the weight ratio of P is outside the range of 0.14 to 0.40 or when the weight ratio of I is outside the range of 0.03 to 0.30. When used in an all-solid-state lithium-sulfur battery, sufficient charge / discharge capacity per positive electrode mixture may not be ensured.
本発明において、「複合化物」とは、単に所定の成分が混合されたものではなく、所定の成分が混合されたものに機械的、熱的又は化学的なエネルギーが加えられ、所定の成分の全部又は一部に化学反応が生じたものをいう。
また、本明細書において、「複合化する」とは、単に所定の成分を混合することではなく、所定の成分を混合したものに機械的、熱的又は化学的なエネルギーを加えることにより、所定の成分の全部又は一部に化学反応を生じさせることをいう。
In the present invention, the “composite” is not simply a mixture of predetermined components, but mechanical, thermal, or chemical energy is added to a mixture of predetermined components, and A chemical reaction that has occurred in whole or in part.
In this specification, “composite” does not mean simply mixing predetermined components, but by adding mechanical, thermal, or chemical energy to a mixture of predetermined components. It causes chemical reaction to all or a part of the components.
上記複合化物は、Ｐ、Ｓ、Ｌｉ及びＩを含み、Ｐの重量比が０．１４〜０．４０、かつ、Ｉの重量比が０．０３〜０．３０である複合化物であれば特に限定されず、その具体例としては、Ｌｉ２Ｓ、Ｓ、Ｐ及びＬｉＩ；Ｓ、Ｐ及びＬｉＩ；Ｌｉ２Ｓ、ＰｘＳｙ及びＬｉＩ；並びに、ＰｘＳｙ及びＬｉＩからなる群より選択される少なくとも１つの組合せをメカニカルミリング処理することにより得られる複合化物（ここで、ｘ及びｙは、独立して、化学量論比を与える整数を表わす）等が挙げられる。
これらの複合化物は、特定の１種を単独で用いても良いし、２種以上を併用しても良い。
The composite is preferably a composite containing P, S, Li and I, wherein the weight ratio of P is 0.14 to 0.40 and the weight ratio of I is 0.03 to 0.30. Specific examples thereof include Li 2 S, S, P and LiI; S, P and LiI; Li 2 S, P x S y and LiI; and P x S y and LiI. And a compound obtained by mechanical milling at least one combination (where x and y independently represent an integer giving a stoichiometric ratio), and the like.
One type of these composites may be used alone, or two or more types may be used in combination.
上記複合化物において、ＰとＳとＬｉとＩとの合計量を１とした場合の各成分の含有量は、Ｐの重量比が０．１４〜０．４０、かつ、Ｉの重量比が０．０３〜０．３０となる限り特に限定されない。 In the composite, when the total amount of P, S, Li and I is 1, the content of each component is such that the weight ratio of P is 0.14 to 0.40 and the weight ratio of I is 0. There is no particular limitation as long as it is 0.03 to 0.30.
また、上記複合化物は、リチウム塩やリチウム窒化物を更に用いて得られたものでも良い。
上記リチウム塩としては特に限定されないが、例えば、Ｌｉ３ＰＯ４、Ｌｉ４ＳｉＯ４、Ｌｉ２Ｏ、ＬｉＢＨ４等が挙げられる。
また、上記リチウム窒化物としては特に限定されないが、例えば、Ｌｉ３Ｎ等が挙げられる。
The composite may be obtained by further using a lithium salt or lithium nitride.
Examples of the lithium salt is not particularly limited, for example, Li 3 PO 4, Li 4 SiO 4, Li 2 O, LiBH 4 , and the like.
Although not particularly restricted but includes lithium nitride, for example, Li 3 N and the like.
上記複合化物を得る方法としては、各成分の結合を簡便に再配列することができ、また、アモルファス状のイオン伝導性物質が得られることから、メカニカルミリング処理が好ましい。メカニカルミリング処理の具体例としては、例えば、遊星ボールミルを用いて、自転速度１５０〜５００ｒｐｍ、公転速度２００〜１０００ｒｐｍ（自転と逆回転）で０．５〜１０時間処理する方法等が挙げられる。
なお、複合化物が得られたどうかは、ラマン分光法により確認することができる。例えば、Ｌｉ２Ｓ、Ｐ２Ｓ５及びＬｉＩを用いて複合化物を得る場合、複合化に使用した原料であるＰ２Ｓ５由来の３００ｃｍ−１のピークが消失するか、又は、４００ｃｍ−１付近の主ピークに対して相対的に小さくなることから、Ｌｉ２ＳとＰ２Ｓ５とＬｉＩとが複合化したことを確認することができる。
As a method for obtaining the composite, a mechanical milling treatment is preferable because the binding of each component can be easily rearranged and an amorphous ion conductive material can be obtained. Specific examples of the mechanical milling process include, for example, a method in which a planetary ball mill is used to process at a rotation speed of 150 to 500 rpm and a revolution speed of 200 to 1000 rpm (rotation and reverse rotation) for 0.5 to 10 hours.
In addition, it can be confirmed by Raman spectroscopy whether the compounded substance was obtained. For example, when a composite is obtained using Li 2 S, P 2 S 5 and LiI, the 300 cm −1 peak derived from P 2 S 5 which is the raw material used for the composite disappears or 400 cm −1. Since it becomes relatively small with respect to the nearby main peak, it can be confirmed that Li 2 S, P 2 S 5 and LiI are complexed.
＜硫黄及び／又はその放電生成物［Ｂ］＞
本発明の正極合材は、上記硫黄及び／又はその放電生成物［Ｂ］を正極活物質として含有する。
上記硫黄としては、単体の硫黄等を用いることができる。
上記硫黄の放電生成物としては特に限定されないが、例えば、Ｌｉ２Ｓ８、Ｌｉ２Ｓ４、Ｌｉ２Ｓ２等の多硫化リチウムや、硫化リチウム（Ｌｉ２Ｓ）等を用いることができる。
これらの化合物は、単独で用いても良いし、２種以上を併用しても良く、更には単体の硫黄と併用しても良い。
<Sulfur and / or its discharge product [B]>
The positive electrode mixture of the present invention contains the sulfur and / or its discharge product [B] as a positive electrode active material.
As the sulfur, single sulfur or the like can be used.
No particular limitation is imposed on the discharge product of the sulfur, for example, lithium polysulphides of Li 2 S 8, Li 2 S 4, Li 2 S 2 , etc., may be used lithium sulfide (Li 2 S) and the like.
These compounds may be used alone or in combination of two or more, and may be used in combination with single sulfur.
＜導電材［Ｃ］＞
本発明の正極合材は、上記導電材［Ｃ］を電子伝導体として含有する。
上記導電材［Ｃ］としては特に限定されないが、例えば、活性炭、ファーネスブラック、カーボンナノチューブ、グラフェン等が挙げられる。
これらの中では、導電性に優れ、かつ、ＢＥＴ比表面積が大きいことから、活性炭、グラフェンおよびファーネスブラックが好ましく、活性炭および中空シェル構造を有するファーネスブラックがより好ましい。
<Conductive material [C]>
The positive electrode mixture of the present invention contains the conductive material [C] as an electronic conductor.
Although it does not specifically limit as said electrically conductive material [C], For example, activated carbon, furnace black, a carbon nanotube, graphene etc. are mentioned.
In these, since it is excellent in electroconductivity and BET specific surface area is large, activated carbon, a graphene, and furnace black are preferable, and activated carbon and furnace black which has a hollow shell structure are more preferable.
上記中空シェル構造を有するファーネスブラックとは、導電性ファーネスブラックの一種であり、空隙率は６０〜８０％程度の中空シェル状の構造を持つものをいう。ここで「中空シェル構造」とは、黒鉛結晶が薄く寄り集まって粒子形態の外殻を形成し、外殻の内側に空隙を有する構造をいう。上記中空シェル構造を有するファーネスブラックとしては、例えば、ケッチェンブラック（ライオン社製）等が挙げられる。 The furnace black having a hollow shell structure is a kind of conductive furnace black and has a hollow shell structure with a porosity of about 60 to 80%. Here, the “hollow shell structure” refers to a structure in which graphite crystals are thinly gathered to form an outer shell in the form of particles and have voids inside the outer shell. As furnace black which has the said hollow shell structure, ketjen black (made by Lion Corporation) etc. are mentioned, for example.
本発明に用いる上記導電材［Ｃ］のＢＥＴ比表面積は１１００ｍ２／ｇであり、１８００ｍ２／ｇ以上であることが好ましく、２５００ｍ２／ｇ以上であることがよりに好ましい。
上記ＢＥＴ比表面積が１１００ｍ２／ｇ未満であると、硫黄及び／又はその放電生成物との反応界面の面積が小さくなり、反応抵抗が増大し、充放電容量が小さくなることがある。
The conductive material [C] used in the present invention has a BET specific surface area of 1100 m 2 / g, preferably 1800 m 2 / g or more, and more preferably 2500 m 2 / g or more.
When the BET specific surface area is less than 1100 m 2 / g, the area of the reaction interface with sulfur and / or its discharge product may be reduced, the reaction resistance may be increased, and the charge / discharge capacity may be reduced.
本明細書において、ＢＥＴ比表面積とは、Ｂｒｅｎａｕｅｒ−Ｅｍｍｅｔ−Ｔｅｌｌｅ（ＢＥＴ）法により求めた比表面積をいい、具体的には、導電性カーボンのサンプルを液体窒素温度下において、サンプルに窒素ガスを吸着して得られる窒素吸着等温線を用いて求めた比表面積をいう。
上記ＢＥＴ比表面積を求めるための測定装置としては、例えば、自動比表面積／細孔分布測定装置（日本ベル株式会社製、ＢＥＬＳＯＲＰ−ｍｉｎｉ ＩＩ）を用いることができる。
In this specification, the BET specific surface area refers to the specific surface area determined by the Brenauer-Emmet-Telle (BET) method. Specifically, a conductive carbon sample is subjected to nitrogen gas at a liquid nitrogen temperature. The specific surface area determined using a nitrogen adsorption isotherm obtained by adsorption.
As a measuring device for obtaining the BET specific surface area, for example, an automatic specific surface area / pore distribution measuring device (BELSORP-mini II manufactured by Nippon Bell Co., Ltd.) can be used.
上記導電材［Ｃ］の比表面積は、充放電容量が向上する効果を顕著に享受することができることから１１００ｍ２／ｇ以上であり、１８００ｍ２／ｇ以上であることが好ましく、２５００ｍ２／ｇ以上であることがより好ましい。
一方、上記［Ｃ］導電材の比表面積の好ましい上限は、４０００ｍ２／ｇである。
The specific surface area of the conductive material [C] is a 1100 m 2 / g or more since it is possible to remarkably enjoyed the effect of charge and discharge capacity is improved, it is preferably 1800 m 2 / g or more, 2500 m 2 / g More preferably.
On the other hand, the preferable upper limit of the specific surface area of the [C] conductive material is 4000 m 2 / g.
本発明の正極合材において、上記硫黄及び／又はその放電生成物［Ｂ］（［Ｂ］成分）の含有量は、イオン伝導性物質［Ａ］（［Ａ］成分）、硫黄及びその放電生成物［Ｂ］（［Ｂ］成分）、並びに、導電材［Ｃ］（［Ｃ］成分）の合計量の４０重量％以上である。
上記［Ｂ］成分の含有量が上述した［Ａ］〜［Ｃ］成分の合計量の４０重量％未満では、硫黄当たりの充放電容量は大きくなるものの、正極合材当たりの充放電容量には限界があり、電池とした際に十分な性能に達しない可能性がある。
また、上記［Ｂ］成分の含有量は、上述した［Ａ］〜［Ｃ］成分の合計量の７０重量％以下であることが好ましい。［Ｂ］成分の含有量が［Ａ］〜［Ｃ］成分の合計量の７０重量％を超えると、イオン伝導性物質［Ａ］及び導電材［Ｃ］の正極合材に占める割合が小さくなり、充放電効率が低下することがある。
In the positive electrode mixture of the present invention, the content of the sulfur and / or the discharge product [B] ([B] component) is the same as that of the ion conductive material [A] ([A] component), sulfur and the discharge generation thereof. It is 40% by weight or more of the total amount of the object [B] ([B] component) and the conductive material [C] ([C] component).
When the content of the component [B] is less than 40% by weight of the total amount of the components [A] to [C] described above, the charge / discharge capacity per sulfur increases, but the charge / discharge capacity per positive electrode mixture is There is a limit, and there is a possibility that sufficient performance is not reached when it is made a battery.
Moreover, it is preferable that content of the said [B] component is 70 weight% or less of the total amount of the [A]-[C] component mentioned above. When the content of the [B] component exceeds 70% by weight of the total amount of the [A] to [C] components, the proportion of the ion conductive material [A] and the conductive material [C] in the positive electrode mixture decreases. The charge / discharge efficiency may be reduced.
本発明の正極合材において、イオン伝導性物質［Ａ］、硫黄及び／又はその放電生成物［Ｂ］、並びに、導電材［Ｃ］の各成分の重量基準による含有割合（［Ａ］成分：［Ｂ］成分：［Ｃ］成分）は、２０〜５５：４０〜７０：５〜２０が好ましい。
イオン伝導性物質［Ａ］の含有割合が上記範囲より小さいと、正極へ移動可能なリチウムイオンの量が減少し十分な充放電容量が得られないことがあり、一方、上記範囲より多いと、導電材［Ｃ］の正極合材に占める割合が小さくなり、正極合材当たりの充放電容量が小さくなることがある。
また、導電材［Ｃ］の含有割合が上記範囲より小さいと、正極へ移動可能な電子の量が減少し十分な充放電容量が得られないことがあり、一方、上記範囲より多いと、イオン伝導性物質［Ａ］の正極合材に占める割合が小さくなり、正極合材当たりの充放電容量が小さくなることがある。
In the positive electrode mixture of the present invention, the content ratio of each component of the ion conductive material [A], sulfur and / or its discharge product [B], and the conductive material [C] based on the weight ([A] component: [B] component: [C] component) is preferably 20 to 55:40 to 70: 5 to 20.
When the content ratio of the ion conductive material [A] is smaller than the above range, the amount of lithium ions that can move to the positive electrode may be reduced and a sufficient charge / discharge capacity may not be obtained. The proportion of the conductive material [C] in the positive electrode mixture is reduced, and the charge / discharge capacity per positive electrode mixture may be reduced.
In addition, if the content ratio of the conductive material [C] is smaller than the above range, the amount of electrons that can move to the positive electrode may decrease, and a sufficient charge / discharge capacity may not be obtained. The proportion of the conductive material [A] in the positive electrode mixture may be reduced, and the charge / discharge capacity per positive electrode mixture may be reduced.
このように、本発明の正極合材においては、イオン伝導性物質［Ａ］として、Ｐ、Ｓ、Ｌｉ及びＩを含み、Ｐの重量比が０．１４〜０．４０、かつ、Ｉの重量比が０．０３〜０．３０である複合化物を使用するとともに、上記正極合材中に、上述した特定量の硫黄及び／又はその放電生成物［Ｂ］を含有すること、さらに、比表面積が１１００ｍ２／ｇ以上である導電材を含有することが、本発明の効果を享受するうえで極めて重要である。 Thus, in the positive electrode mixture of the present invention, P, S, Li, and I are included as the ion conductive material [A], and the weight ratio of P is 0.14 to 0.40, and the weight of I. In addition to using a composite having a ratio of 0.03 to 0.30, the positive electrode mixture contains the above-mentioned specific amount of sulfur and / or its discharge product [B], and further has a specific surface area. It is extremely important to contain a conductive material having a thickness of 1100 m 2 / g or more in order to enjoy the effects of the present invention.
本発明の正極合材は、必要に応じて、バインダー、溶媒等の任意成分を含んでいても良い。 The positive electrode mixture of the present invention may contain optional components such as a binder and a solvent as necessary.
＜バインダー＞
上記バインダーとしては、特に限定されないが、熱可塑性樹脂や熱硬化性樹脂等を用いることができ、例えば、ポリエチレン、ポリプロピレン、ポリテトラフルオロエチレン（ＰＴＦＥ）、ポリフッ化ビニリデン（ＰＶＤＦ）、スチレンブタジエンゴム、テトラフルオロエチレン−ヘキサフルオロエチレン共重合体、テトラフルオロエチレン−ヘキサフルオロプロピレン共重合体（ＦＥＰ）、テトラフルオロエチレン−パーフルオロアルキルビニルエーテル共重合体（ＰＦＡ）、フッ化ビニリデン−ヘキサフルオロプロピレン共重合体、フッ化ビニリデン−クロロトリフルオロエチレン共重合体、エチレン−テトラフルオロエチレン共重合体（ＥＴＦＥ樹脂）、ポリクロロトリフルオロエチレン（ＰＣＴＦＥ）、フッ化ビニリデン−ペンタフルオロプロピレン共重合体、プロピレン−テトラフルオロエチレン共重合体、エチレン−クロロトリフルオロエチレン共重合体（ＥＣＴＦＥ）、フッ化ビニリデン−ヘキサフルオロプロピレン−テトラフルオロエチレン共重合体、フッ化ビニリデン−パーフルオロメチルビニルエーテル−テトラフルオロエチレン共重合体、エチレン−アクリル酸共重合体、ポリアクリル酸、ポリアクリル酸ナトリウム、ポリアクリル酸リチウム、ポリメタクリル酸、ポリメタクリル酸ナトリウム、ポリメタクリル酸リチウム等が挙げられる。
これらのバインダーは、単独で使用しても良いし、２種以上を併用してもよい。
<Binder>
Although it does not specifically limit as said binder, A thermoplastic resin, a thermosetting resin, etc. can be used, for example, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), styrene butadiene rubber, Tetrafluoroethylene-hexafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), vinylidene fluoride-hexafluoropropylene copolymer , Vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer (ETFE resin), polychlorotrifluoroethylene (PCTFE), vinylidene fluoride-pentaph Olefin copolymer, propylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer (ECTFE), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, vinylidene fluoride-perfluoromethyl Examples include vinyl ether-tetrafluoroethylene copolymer, ethylene-acrylic acid copolymer, polyacrylic acid, sodium polyacrylate, lithium polyacrylate, polymethacrylic acid, polysodium methacrylate, and polylithium methacrylate.
These binders may be used alone or in combination of two or more.
本発明の正極合材が上記バインダーを混合して得られたものである場合、その含有量は、特に限定されないが、上記正極合材中０．０１〜１０重量％であることが好ましい。 When the positive electrode mixture of the present invention is obtained by mixing the binder, the content thereof is not particularly limited, but is preferably 0.01 to 10% by weight in the positive electrode mixture.
＜溶媒＞
上記溶媒を混合して得られた正極合材では、正極合材層を作製しやすくなる。上記溶媒は、正極合材層を作製する際、乾燥により除去される。
上記溶媒としては、特に限定されないが、例えば、Ｎ，Ｎ―ジメチルアミノプロピルアミン、ジエチレントリアミン等のアミン系溶媒、テトラヒドロフラン等のエーテル系溶媒、メチルエチルケトン等のケトン系溶媒、酢酸メチル等のエステル系溶媒、ジメチルアセトアミド、１−メチル−２−ピロリドン等のアミド系溶媒、トルエン、キシレン、ｎ−ヘキサン、シクロヘキサン等の炭化水素系溶媒等が挙げられる。
これらの溶媒は、単独で使用しても良いし、２種以上を併用しても良い。
<Solvent>
In the positive electrode mixture obtained by mixing the solvent, a positive electrode mixture layer can be easily produced. The solvent is removed by drying when the positive electrode mixture layer is produced.
The solvent is not particularly limited. For example, amine solvents such as N, N-dimethylaminopropylamine and diethylenetriamine, ether solvents such as tetrahydrofuran, ketone solvents such as methyl ethyl ketone, ester solvents such as methyl acetate, Examples include amide solvents such as dimethylacetamide and 1-methyl-2-pyrrolidone, and hydrocarbon solvents such as toluene, xylene, n-hexane, and cyclohexane.
These solvents may be used alone or in combination of two or more.
本発明の正極合材が上記溶媒を混合して得られたものである場合、その含有量は、特に限定されないが、上記正極合材中１０〜９９重量％であることが好ましい。 When the positive electrode mixture of the present invention is obtained by mixing the solvent, the content is not particularly limited, but is preferably 10 to 99% by weight in the positive electrode mixture.
＜正極合材の作製方法＞
本発明の正極合材は、上記イオン伝導性物質［Ａ］、上記硫黄及び／又はその放電生成物［Ｂ］、並びに、上記導電材［Ｃ］、更には、必要に応じてバインダー、溶媒等の任意成分を混合することにより得ることができる。
これらを混合する方法としては、特に限定されず従来公知の方法を用いることができるが、例えば、遊星ボールミル（フリッチュ社製）、ハイブリダイゼーションシステム（奈良機械製作所社製）、コスモス（川崎重工業社製）、メカノフュージョンシステム（ホソカワミクロン社製）、ノビルタＮＯＢ（ホソカワミクロン社製）、メカノミル（岡田精工社製）、シータコンポーザ（徳寿工作所社製）、ナノソニックミル（井上製作所社製）、ニーダー（井上製作所社製）、スーパーマスコロイダー（増幸産業社製）、ナノメック・リアクター（テクノアイ社製）、コーネルデスパ（浅田鉄工所社製）、プラネタリミキサ（浅田鉄工所社製）、ミラクルＫＣＫ（浅田鉄工所社製）、振動ミル（マツボー社製）等を用いて混合する方法等が挙げられる。
<Method for producing positive electrode mixture>
The positive electrode mixture of the present invention includes the ion conductive material [A], the sulfur and / or the discharge product [B], the conductive material [C], and a binder, a solvent, and the like as necessary. It can obtain by mixing arbitrary components of.
A method for mixing these is not particularly limited, and a conventionally known method can be used. For example, planetary ball mill (manufactured by Fritsch), hybridization system (manufactured by Nara Machinery Co., Ltd.), cosmos (manufactured by Kawasaki Heavy Industries, Ltd.) ), Mechano-Fusion System (manufactured by Hosokawa Micron), Nobilta NOB (manufactured by Hosokawa Micron), Mechano Mill (manufactured by Okada Seiko Co., Ltd.), Theta Composer (manufactured by Tokusu Kosakusha), Nanosonic Mill (manufactured by Inoue Seisakusho Co., Ltd.), Kneader (Inoue) Mfg. Co., Ltd.), Super Mass Collider (Masuyuki Sangyo Co., Ltd.), Nanomec Reactor (Techno Eye Co., Ltd.), Cornell Despa (Asada Iron Works Co., Ltd.), Planetary Mixer (Asada Iron Works Co., Ltd.), Miracle KCK (Asada Iron Works) ), Mixing using a vibration mill (Matsubo), etc. It is.
上記正極合材の作製においては、各成分を混合した後、加熱処理を行ってもよい。
この理由は、正極合材が含有するイオン伝導性物質［Ａ］、硫黄及び／又はその放電生成物［Ｂ］、並びに、導電材［Ｃ］の接触界面を強固にすることができ、界面抵抗を低減することができるからである。
上記加熱処理は、特に限定されないが、例えば、アルゴン、窒素、空気等の雰囲気下、８０〜２５０℃、好ましくは１００〜２００℃の条件で、１秒間〜１０時間行うことができる。
上記加熱処理は、従来公知の加熱装置を用いて行えばよく、具体的には、例えば、定温乾燥機、送風乾燥機、減圧乾燥機、赤外線乾燥機等を用いて行えばよい。
In preparation of the positive electrode mixture, heat treatment may be performed after mixing the respective components.
This is because the contact interface of the ion conductive material [A], sulfur and / or its discharge product [B], and the conductive material [C] contained in the positive electrode mixture can be strengthened, and the interface resistance can be increased. This is because it can be reduced.
Although the said heat processing is not specifically limited, For example, it can carry out for 1 second-10 hours on 80-250 degreeC, 100-200 degreeC conditions in atmosphere, such as argon, nitrogen, air.
The heat treatment may be performed using a conventionally known heating device. Specifically, for example, a constant temperature dryer, an air dryer, a vacuum dryer, an infrared dryer, or the like may be used.
＜＜全固体型リチウム硫黄電池＞＞
次に、本発明の全固体型リチウム硫黄電池について説明する。
本発明の全固体型リチウム硫黄電池は、本発明の正極合材を含む正極合材層、固体電解質層、負極及び集電体を備える。
<< All solid-state lithium-sulfur battery >>
Next, the all solid-state lithium-sulfur battery of the present invention will be described.
The all solid-state lithium-sulfur battery of the present invention includes a positive electrode mixture layer including the positive electrode mixture of the present invention, a solid electrolyte layer, a negative electrode, and a current collector.
本明細書において、「全固体型」とは、電解質として高分子固体電解質及び／又は無機固体電解質を用いたものであり、負極、固体電解質層及び正極合材層に実質的に溶媒を含有しないものをいう。
なお、本明細書において、「実質的に溶媒を含有しない」とは、溶媒が微量に残存しても良いことを意味する。
In the present specification, the “all solid type” means a polymer solid electrolyte and / or an inorganic solid electrolyte as an electrolyte, and contains substantially no solvent in the negative electrode, the solid electrolyte layer, and the positive electrode mixture layer. Say things.
In the present specification, “substantially no solvent” means that a trace amount of the solvent may remain.
本発明の全固体型リチウム硫黄電池は、例えば、負極、固体電解質層、正極合
材層が順に積層され、その両側に集電体（負極集電体、正極集電体）が配置された構造とすることが出来る。
以下、集電体（負極集電体、正極集電体）、負極、固体電解質層、正極合材層のそれぞれについて順に説明する。
The all-solid-state lithium-sulfur battery of the present invention has, for example, a structure in which a negative electrode, a solid electrolyte layer, and a positive electrode mixture layer are sequentially laminated, and current collectors (negative electrode current collector and positive electrode current collector) are arranged on both sides thereof. It can be.
Hereinafter, each of the current collector (negative electrode current collector, positive electrode current collector), negative electrode, solid electrolyte layer, and positive electrode mixture layer will be described in order.
＜集電体＞
上記集電体としては、特に限定されないが、例えば、Ａｌ、Ｃｕ、Ｎｉ、ステンレス等を用いることができる。
負極集電体としては、リチウムと合金を作り難い点、及び、薄膜に加工しやすい点から、Ｃｕを用いることが好ましい。
正極集電体としては、薄膜に加工しやすく、安価であるという点でＡｌを用いることが好ましい。
<Current collector>
Although it does not specifically limit as said electrical power collector, For example, Al, Cu, Ni, stainless steel etc. can be used.
As the negative electrode current collector, Cu is preferably used because it is difficult to make an alloy with lithium and it can be easily processed into a thin film.
As the positive electrode current collector, Al is preferably used because it is easy to process into a thin film and is inexpensive.
＜負極＞
上記負極としては、リチウムイオンを吸蔵放出する材料を負極活物質として含んでいるものであれば、特に限定されるものではない。ここで、リチウムイオンを吸蔵放出する材料としては、例えば、金属リチウム、リチウム合金、金属酸化物、金属硫化物、リチウムイオンを吸蔵放出する炭素質物質等が挙げられる。
上記リチウム合金としては、例えば、アルミニウム、シリコン、スズ、マグネシウム、インジウム、カルシウム等とリチウムとの合金等が挙げられる。
上記金属酸化物としては、例えば、スズ酸化物、ケイ素酸化物、リチウムチタン酸化物、ニオブ酸化物、タングステン酸化物等が挙げられる。
上記金属硫化物としては、例えば、スズ硫化物やチタン硫化物等が挙げられる。
上記リチウムイオンを吸蔵放出する炭素質物質としては、例えば、黒鉛、コークス、メソフェーズピッチ系炭素繊維、球状炭素、樹脂焼成炭素等が挙げられる。
<Negative electrode>
The negative electrode is not particularly limited as long as it contains a material that absorbs and releases lithium ions as a negative electrode active material. Here, examples of the material that occludes and releases lithium ions include metallic lithium, lithium alloy, metal oxide, metal sulfide, and a carbonaceous substance that occludes and releases lithium ions.
Examples of the lithium alloy include alloys of lithium, aluminum, silicon, tin, magnesium, indium, calcium, and the like.
Examples of the metal oxide include tin oxide, silicon oxide, lithium titanium oxide, niobium oxide, and tungsten oxide.
Examples of the metal sulfide include tin sulfide and titanium sulfide.
Examples of the carbonaceous material that absorbs and releases lithium ions include graphite, coke, mesophase pitch-based carbon fiber, spherical carbon, and resin-fired carbon.
上記負極を得る方法としては、特に限定されないが、上記リチウムイオンを吸蔵放出する材料をプレスする方法、上記リチウムイオンを吸蔵放出する材料と溶媒とを含む負極前駆体分散液を負極集電体に塗布、乾燥後プレスする方法等が挙げられる。
上記負極前駆体分散液に含まれる溶媒としては、上述の正極合材に用いられるものと同様のものを用いることができる。
なお、溶媒は負極前駆体分散液の塗布を助けるために使用され、塗布後は乾燥により除去される。
The method of obtaining the negative electrode is not particularly limited, but a method of pressing the material that absorbs and releases lithium ions, and a negative electrode precursor dispersion containing the material that absorbs and releases lithium ions and a solvent are used as a negative electrode current collector. Examples thereof include a method of pressing after coating and drying.
As the solvent contained in the negative electrode precursor dispersion, the same solvents as those used for the positive electrode mixture can be used.
The solvent is used to assist the application of the negative electrode precursor dispersion and is removed by drying after the application.
＜固体電解質層＞
固体電解質層としては、高分子固体電解質及び／又は無機固体電解質からなるものが挙げられる。
上記無機固体電解質としては、例えば、導電率が０．１ｍＳ／ｃｍ以上である固体電解質を用いてもよい。上記固体電解質の具体例としては、導電率が０．１ｍＳ／ｃｍ以上であるものであれば特に限定されないが、リチウム塩、リチウム硫化物、リチウム酸化物、リチウム窒化物等が挙げられる。
<Solid electrolyte layer>
Examples of the solid electrolyte layer include those made of a polymer solid electrolyte and / or an inorganic solid electrolyte.
As the inorganic solid electrolyte, for example, a solid electrolyte having a conductivity of 0.1 mS / cm or more may be used. Specific examples of the solid electrolyte are not particularly limited as long as the electrical conductivity is 0.1 mS / cm or more, and examples thereof include lithium salts, lithium sulfides, lithium oxides, and lithium nitrides.
上記固体電解質は、リチウム塩、リチウム硫化物又はこれらの組合せであることが好ましい。その理由は、導電率が高く、粒界抵抗が小さいためである。 The solid electrolyte is preferably a lithium salt, a lithium sulfide, or a combination thereof. This is because the conductivity is high and the grain boundary resistance is small.
上記リチウム塩としては、特に限定されないが、例えば、ＬｉＢＨ４、ＬｉＩ等が挙げられる。
上記リチウム硫化物としては、特に限定されないが、例えば、上記ＰｘＳｙと複合化されたもの、具体的には、上記Ｌｉ２ＳとＰｘＳｙとの複合化物等が挙げられ、また、Ｌｉ２Ｓ及びＰｘＳｙとともに、さらにＧｅＳ２、ＳｉＳ２、Ｌｉ３ＰＯ４、Ｌｉ４ＳｉＯ４等を複合化したものであっても良い。
上記リチウム酸化物としては、特に限定されないが、例えば、Ｌｉ２Ｏ、Ｌｉ２Ｏ２等が挙げられる。
上記リチウム窒化物としては、特に限定されないが、例えば、Ｌｉ３Ｎ等が挙げられる。
これらの固体電解質は、単独で用いても良いし、２種以上を併用しても良い。
Examples of the lithium salt is not particularly limited, for example, LiBH 4, LiI and the like.
As the lithium sulfide is not particularly limited, for example, the P x S y with those conjugated, specifically, such composite compound of the Li 2 S and P x S y and the like, also In addition to Li 2 S and P x S y , GeS 2 , SiS 2 , Li 3 PO 4 , Li 4 SiO 4 and the like may be combined.
As the lithium oxide is not particularly limited, for example, Li 2 O, Li 2 O 2 and the like.
As the lithium nitride is not particularly limited, for example, Li 3 N and the like.
These solid electrolytes may be used alone or in combination of two or more.
上記無機固体電解質からなる固体電解質層は、例えば、上記固体電解質を加圧成形する方法、上記固体電解質を溶媒に分散させた後塗布・乾燥させる方法等により得ることができる。
上記固体電解質を加圧成形する方法としては、特に限定されないが、例えば、負極集電体と正極集電体とで固体電解質を挟み込んでプレスする方法、加圧成形機の治具でプレスする方法等が挙げられる。
上記固体電解質を溶媒に分散させた後塗布・乾燥させる方法により固体電解質層を得る場合には、乾燥後の固体電解質層を上記と同様の方法でプレスしてもよい。
上記固体電解質を分散させる溶媒としては、上述の正極合材に用いられるものと同様のものを用いることができる。
これらの方法により固体電解質層を得る際、固体電解質層の界面抵抗の低減、及び、緻密性の向上を目的に、任意のタイミングで加熱処理を行っても良い。
また、上記高分子固体電解質からなる固体電解質層としては、例えば、過塩素酸リチウムやリチウムビストリフルオロメタンスルホニルアミド等のリチウム塩を含むポリエチレンオキシド系ポリマー等が挙げられる。
The solid electrolyte layer made of the inorganic solid electrolyte can be obtained, for example, by a method of pressure-molding the solid electrolyte, a method of applying the coating after the solid electrolyte is dispersed in a solvent, and drying.
The method for pressure-forming the solid electrolyte is not particularly limited. For example, a method of sandwiching and pressing the solid electrolyte between the negative electrode current collector and the positive electrode current collector, a method of pressing with a jig of a pressure molding machine Etc.
When a solid electrolyte layer is obtained by a method in which the solid electrolyte is dispersed in a solvent and then applied and dried, the dried solid electrolyte layer may be pressed by the same method as described above.
As the solvent for dispersing the solid electrolyte, the same solvents as those used for the above-mentioned positive electrode mixture can be used.
When a solid electrolyte layer is obtained by these methods, heat treatment may be performed at an arbitrary timing for the purpose of reducing the interface resistance of the solid electrolyte layer and improving the denseness.
Examples of the solid electrolyte layer made of the polymer solid electrolyte include polyethylene oxide polymers containing lithium salts such as lithium perchlorate and lithium bistrifluoromethanesulfonylamide.
＜正極合材層＞
上記正極合材層は、例えば、正極集電体に上記正極合材を担持させる方法、上記正極合材を加圧成形する方法等により得ることができる。
正極集電体に上記正極合材を担持させる方法としては、特に限定されないが、例えば、正極合材を加圧成形する方法、有機溶媒等を用いてペースト化した正極合材を正極集電体に塗布、乾燥後プレスするなどして固着する方法等が挙げられる。
正極合材を加圧成形する方法としては、特に限定されないが、例えば、固体電解質層と正極集電体との間に正極合材を挟み込んでプレスする方法、加圧成形機の治具でプレスする方法等が挙げられる。
正極合材を正極集電体に塗布する方法としては、特に限定されないが、例えば、スリットダイ塗工法、スクリーン塗工法、カーテン塗工法、ナイフ塗工法、グラビア塗工法、静電スプレー法等が挙げられる。
これらの方法により正極合材層を得る際、正極合材層の界面抵抗の低減、及び、緻密性の向上を目的に、任意のタイミングで加熱処理を行っても良い。
<Positive electrode mixture layer>
The positive electrode mixture layer can be obtained, for example, by a method of supporting the positive electrode mixture on a positive electrode current collector, a method of pressure forming the positive electrode mixture, or the like.
The method of supporting the positive electrode mixture on the positive electrode current collector is not particularly limited. For example, a method of pressure-forming the positive electrode mixture, a positive electrode mixture paste using an organic solvent or the like is used as the positive electrode current collector. For example, there may be mentioned a method of fixing by applying, drying and pressing.
The method for pressure forming the positive electrode mixture is not particularly limited. For example, a method of pressing the positive electrode mixture between the solid electrolyte layer and the positive electrode current collector and pressing with a jig of the pressure molding machine And the like.
The method for applying the positive electrode mixture to the positive electrode current collector is not particularly limited, and examples thereof include a slit die coating method, a screen coating method, a curtain coating method, a knife coating method, a gravure coating method, and an electrostatic spray method. It is done.
When the positive electrode mixture layer is obtained by these methods, heat treatment may be performed at an arbitrary timing for the purpose of reducing the interface resistance of the positive electrode mixture layer and improving the denseness.
上記全固体型リチウム硫黄電池は、上述の負極集電体、負極、固体電解質層、正極合材層、正極集電体のほか、セパレータ等を有していても良い。
上記全固体型リチウム硫黄電池の形状は、特に限定されないが、例えば、コイン型、ボタン型、シート型、積層型、円筒型、偏平型、角型等が挙げられる。
The all solid-state lithium-sulfur battery may have a separator, in addition to the above-described negative electrode current collector, negative electrode, solid electrolyte layer, positive electrode mixture layer, and positive electrode current collector.
The shape of the all-solid-state lithium-sulfur battery is not particularly limited, and examples thereof include a coin type, a button type, a sheet type, a laminated type, a cylindrical type, a flat type, and a rectangular type.
＜全固体型リチウム硫黄電池の作製方法＞
上記全固体型リチウム硫黄電池の作製方法は、特に限定されないが、例えば、以下の方法等が挙げられる。
まず、負極集電体と正極集電体とで固体電解質を挟み込んでプレスし、固体電解質層を作製する。次に、固体電解質層の片側に正極合材を堆積し、その両端を集電体（固体電解質層側に負極集電体、正極合材側に正極集電体）で挟み込んでプレスし、固体電解質層の一方の面に正極合材層と正極集電体とを積層し、固体電解質層のもう一方の面に負極集電体を積層する。最後に、一旦、負極集電体を取り除き、固体電解質層の正極合材層側と反対側に負極を入れ、さらに、負極側に負極集電体を入れてプレスし、固体電解質層の他方の面に負極と負極集電体とを積層する。また、上記のように一層ずつプレスしても良いし、二層以上を堆積させて、複数層をまとめてプレスして積層させても良い。このような方法により、全固体型リチウム硫黄電池を作製することができる。
<Method for producing all solid-state lithium-sulfur battery>
The method for producing the all solid-state lithium-sulfur battery is not particularly limited, and examples thereof include the following methods.
First, a solid electrolyte is sandwiched between a negative electrode current collector and a positive electrode current collector and pressed to produce a solid electrolyte layer. Next, a positive electrode mixture is deposited on one side of the solid electrolyte layer, and both ends thereof are sandwiched between a current collector (a negative electrode current collector on the solid electrolyte layer side and a positive electrode current collector on the positive electrode mixture side), and pressed. A positive electrode mixture layer and a positive electrode current collector are laminated on one surface of the electrolyte layer, and a negative electrode current collector is laminated on the other surface of the solid electrolyte layer. Finally, once remove the negative electrode current collector, put the negative electrode on the side opposite to the positive electrode mixture layer side of the solid electrolyte layer, and further press the negative electrode current collector on the negative electrode side and press the other side of the solid electrolyte layer A negative electrode and a negative electrode current collector are stacked on the surface. Moreover, it may be pressed one layer at a time as described above, or two or more layers may be deposited and a plurality of layers may be pressed together and laminated. By such a method, an all solid-state lithium-sulfur battery can be produced.
＜全固体型リチウム硫黄電池の用途＞
上記全固体型リチウム硫黄電池の用途としては、特に限定されないが、例えば、ハイブリッド自動車や電気自動車等、高いエネルギー密度が要求される電気製品に好適に用いることができる。
<Applications of all-solid-state lithium-sulfur batteries>
The use of the all-solid-state lithium-sulfur battery is not particularly limited, but can be suitably used for electrical products that require high energy density, such as hybrid vehicles and electric vehicles.
以下に実施例を挙げて本発明を説明するが、本発明はこれら実施例のみに限定されるものではない。 EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.
１．イオン伝導性物質［Ａ］の調製
（合成例１）
Ｌｉ２Ｓ（フルウチ化学株式会社製）９９ｍｇとＰ２Ｓ５（アルドリッチ社製）７２０ｍｇとを遊星ボールミル（４５ｍｌ容器、４ｍｍφジルコニアボール９０ｇ）にて、自転速度２５０ｒｐｍ、公転速度５００ｒｐｍ（自転と逆回転）で１０時間処理し、さらにＬｉＩ（アルドリッチ社製）を１８１ｍｇ加えて１０時間処理して、リン重量比が０．２０、ヨウ素重量比が０．１７のイオン伝導性物質［Ａ］を得た。
1. Preparation of ion conductive substance [A] (Synthesis Example 1)
Li 2 S (manufactured by Furuuchi Chemical Co., Ltd.) 99 mg and P 2 S 5 (manufactured by Aldrich) 720 mg were rotated on a planetary ball mill (45 ml container, 4 mmφ zirconia ball 90 g) at a rotation speed of 250 rpm and a revolution speed of 500 rpm (rotation and reverse rotation). ), And 181 mg of LiI (manufactured by Aldrich) was added for 10 hours to obtain an ion conductive material [A] having a phosphorus weight ratio of 0.20 and an iodine weight ratio of 0.17. .
（比較合成例１）
１０００ｍｇのＰ２Ｓ５を遊星ボールミル（４５ｍｌ容器、４ｍｍφジルコニアボール９０ｇ）にて、自転速度２５０ｒｐｍ、公転速度５００ｒｐｍ（自転と逆回転）で１０時間処理することで、リン重量比が０．２８、ヨウ素重量比が０．００のイオン伝導性物質［Ａ］を得た。
(Comparative Synthesis Example 1)
By treating 1000 mg of P 2 S 5 with a planetary ball mill (45 ml container, 4 mmφ zirconia ball 90 g) at a rotation speed of 250 rpm and a revolution speed of 500 rpm (rotation and reverse rotation), the phosphorus weight ratio is 0.28, An ion conductive material [A] having an iodine weight ratio of 0.00 was obtained.
（合成例２）
Ｐ２Ｓ５ ９３７ｍｇとＬｉＩ ６３ｍｇとを遊星ボールミル（４５ｍｌ容器、４ｍｍφジルコニアボール９０ｇ）にて、自転速度２５０ｒｐｍ、公転速度５００ｒｐｍ（自転と逆回転）で１０時間処理することで、リン重量比が０．２６、ヨウ素重量比が０．０６のイオン伝導性物質［Ａ］を得た。
(Synthesis Example 2)
By treating P 2 S 5 937 mg and LiI 63 mg with a planetary ball mill (45 ml container, 4 mmφ zirconia ball 90 g) at a rotation speed of 250 rpm and a revolution speed of 500 rpm (rotation and reverse rotation), the phosphorus weight ratio is 0 26, an ion conductive material [A] having an iodine weight ratio of 0.06 was obtained.
（合成例３）
Ｐ２Ｓ５ ８６９ｍｇとＬｉＩ １３１ｍｇとを遊星ボールミル（４５ｍｌ容器、４ｍｍφジルコニアボール９０ｇ）にて、自転速度２５０ｒｐｍ、公転速度５００ｒｐｍ（自転と逆回転）で１０時間処理することで、リン重量比が０．２４、ヨウ素重量比が０．１２のイオン伝導性物質［Ａ］を得た。
(Synthesis Example 3)
By treating P 2 S 5 869 mg and LiI 131 mg in a planetary ball mill (45 ml container, 4 mmφ zirconia ball 90 g) at a rotation speed of 250 rpm and a revolution speed of 500 rpm (rotation and reverse rotation), the phosphorus weight ratio is 0 The ion conductive substance [A] having an iodine weight ratio of 0.12 was obtained.
（合成例４）
Ｐ２Ｓ５ ７９５ｍｇとＬｉＩ ２０５ｍｇとを遊星ボールミル（４５ｍｌ容器、４ｍｍφジルコニアボール９０ｇ）にて、自転速度２５０ｒｐｍ、公転速度５００ｒｐｍ（自転と逆回転）で１０時間処理することで、リン重量比が０．２２、ヨウ素重量比が０．１９のイオン伝導性物質［Ａ］を得た。
(Synthesis Example 4)
By treating P 2 S 5 795 mg and LiI 205 mg with a planetary ball mill (45 ml container, 4 mmφ zirconia ball 90 g) at a rotation speed of 250 rpm and a revolution speed of 500 rpm (rotation and reverse rotation), the phosphorus weight ratio is 0 .22, an ion conductive material [A] having an iodine weight ratio of 0.19 was obtained.
（比較合成例２）
Ｐ２Ｓ５ ６２４ｍｇとＬｉＩ ３７６ｍｇとを遊星ボールミル（４５ｍｌ容器、４ｍｍφジルコニアボール９０ｇ）にて、自転速度２５０ｒｐｍ、公転速度５００ｒｐｍ（自転と逆回転）で１０時間処理することで、リン重量比が０．１７、ヨウ素重量比が０．３６のイオン伝導性物質［Ａ］を得た。
(Comparative Synthesis Example 2)
By treating 624 mg of P 2 S 5 and 376 mg of LiI with a planetary ball mill (45 ml container, 4 mmφ zirconia ball 90 g) at a rotation speed of 250 rpm and a revolution speed of 500 rpm (rotation and reverse rotation), the phosphorus weight ratio is 0 .17, an ion conductive material [A] having an iodine weight ratio of 0.36 was obtained.
（合成例５）
Ｌｉ２Ｓ １８４ｍｇとＰ２Ｓ５ ５９３ｍｇとを遊星ボールミル（４５ｍｌ容器、４ｍｍφジルコニアボール９０ｇ）にて、自転速度２５０ｒｐｍ、公転速度５００ｒｐｍ（自転と逆回転）で１０時間処理し、さらにＬｉＩ ２２３ｍｇを加えて１０時間処理して、リン重量比が０．１７、ヨウ素重量比が０．２１のイオン伝導性物質［Ａ］を得た。
(Synthesis Example 5)
184 mg of Li 2 S and 593 mg of P 2 S 5 were treated with a planetary ball mill (45 ml container, 4 mmφ zirconia ball 90 g) at a rotation speed of 250 rpm and a revolution speed of 500 rpm (rotation and reverse rotation) for 10 hours, and LiI 223 mg was added. For 10 hours to obtain an ion conductive material [A] having a phosphorus weight ratio of 0.17 and an iodine weight ratio of 0.21.
（比較合成例３）
Ｌｉ２Ｓ ３２１ｍｇとＰ２Ｓ５ ３８８ｍｇとを遊星ボールミル（４５ｍｌ容器、４ｍｍφジルコニアボール９０ｇ）にて、自転速度２５０ｒｐｍ、公転速度５００ｒｐｍ（自転と逆回転）で１０時間処理し、さらにＬｉＩ ２９２ｍｇを加えて１０時間処理して、リン重量比が０．１１、ヨウ素重量比が０．２８のイオン伝導性物質［Ａ］を得た。
(Comparative Synthesis Example 3)
321 mg of Li 2 S and 388 mg of P 2 S 5 were treated with a planetary ball mill (45 ml container, 4 mmφ zirconia ball 90 g) at a rotation speed of 250 rpm and a revolution speed of 500 rpm (rotation and reverse rotation) for 10 hours, and further 292 mg of LiI was added. For 10 hours to obtain an ion conductive material [A] having a phosphorus weight ratio of 0.11 and an iodine weight ratio of 0.28.
（合成例６）
Ｌｉ２Ｓ ４４ｍｇとＰ２Ｓ５ ８１９ｍｇとを遊星ボールミル（４５ｍｌ容器、４ｍｍφジルコニアボール９０ｇ）にて、自転速度２５０ｒｐｍ、公転速度５００ｒｐｍ（自転と逆回転）で１０時間処理し、さらにＬｉＩ １３７ｍｇを加えて１０時間処理して、リン重量比が０．２３、ヨウ素重量比が０．１３のイオン伝導性物質［Ａ］を得た。
(Synthesis Example 6)
44 mg of Li 2 S and 819 mg of P 2 S 5 were treated with a planetary ball mill (45 ml container, 4 mmφ zirconia ball 90 g) at a rotation speed of 250 rpm and a revolution speed of 500 rpm (rotation and reverse rotation) for 10 hours, and further LiI of 137 mg was added. For 10 hours to obtain an ion conductive substance [A] having a phosphorus weight ratio of 0.23 and an iodine weight ratio of 0.13.
２．正極合材の作製
（比較例１）
イオン伝導性物質［Ａ］として合成例１で得たイオン伝導性物質、硫黄及び／又はその放電生成物［Ｂ］としての硫黄（アルドリッチ社製）、及び、導電材［Ｃ］として活性炭（比表面積３０００ｍ２／ｇ、関西熱化学社製）を用い、その組成比（重量比）が６０：３０：１０となるようにイオン伝導性物質［Ａ］１２０ｍｇ、硫黄及び／又はその放電生成物［Ｂ］６０ｍｇ、導電材［Ｃ］２０ｍｇを秤量し、遊星ボールミル（Ｆｒｉｌｓｃｈ社製ｐｒｅｍｉｕｍ ｌｉｎｅ Ｐ−７、公転半径０．０７ｍ、自転半径０．０２３５ｍ、自転と公転の比＝−２）にて５ｍｍのジルコニアボール約４０ｇとともに４５ｍｌのポットにて公転速度３７０ｒｐｍで４時間混合することにより、全固体型リチウム硫黄電池用の正極合材を得た。
2. Production of positive electrode mixture (Comparative Example 1)
Ion conductive material obtained in Synthesis Example 1 as ion conductive material [A], sulfur and / or sulfur as a discharge product [B] (manufactured by Aldrich), and activated carbon (ratio) as conductive material [C] A surface area of 3000 m 2 / g, manufactured by Kansai Thermal Chemical Co., Ltd.), and the ion conductive material [A] 120 mg, sulfur and / or its discharge product [weight ratio] is 60:30:10 [ B] 60 mg, conductive material [C] 20 mg were weighed and 5 mm in planetary ball mill (Premium line P-7 manufactured by Filsch, revolution radius 0.07 m, revolution radius 0.0235 m, ratio of revolution to revolution = -2). A positive electrode mixture for an all solid-state lithium-sulfur battery was obtained by mixing with about 40 g of the zirconia balls in a 45 ml pot at a revolution speed of 370 rpm for 4 hours.
（実施例１）
イオン伝導性物質［Ａ］として合成例１で得たイオン伝導性物質、硫黄及び／又はその放電生成物［Ｂ］としての硫黄（アルドリッチ社製）、及び、導電材［Ｃ］としてのケッチェンブラック（比表面積１２００ｍ２／ｇ、ライオン社製ＥＣ−６００ＪＤ）を用い、イオン伝導性物質［Ａ］、硫黄及び／又はその放電生成物［Ｂ］、並びに、導電材［Ｃ］の組成比（重量比）が５０：４０：１０となるように［Ａ］成分１００ｍｇ、［Ｂ］成分８０ｍｇ、［Ｃ］成分２０ｍｇを秤量し、比較例１と同様の混合処理条件により正極合材を得た。
Example 1
Ion conductive material obtained in Synthesis Example 1 as ion conductive material [A], sulfur and / or sulfur as a discharge product [B] (manufactured by Aldrich), and ketjen as conductive material [C] Using black (specific surface area 1200 m 2 / g, Lion Corporation EC-600JD), the composition ratio of the ion conductive material [A], sulfur and / or its discharge product [B], and the conductive material [C] ( 100 mg of [A] component, 80 mg of [B] component and 20 mg of [C] component were weighed so that the weight ratio was 50:40:10, and a positive electrode mixture was obtained under the same mixing conditions as in Comparative Example 1. .
（比較例２）
イオン伝導性物質［Ａ］として比較合成例１で得たイオン伝導性物質、硫黄及び／又はその放電生成物［Ｂ］としての硫黄（アルドリッチ社製）、及び、導電材［Ｃ］として活性炭（比表面積３０００ｍ２／ｇ、関西熱化学社製）を用い、イオン伝導性物質［Ａ］、硫黄及び／又はその放電生成物［Ｂ］、並びに、導電材［Ｃ］の組成比（重量比）が４０：５０：１０となるように［Ａ］成分８０ｍｇ、［Ｂ］成分１００ｍｇ、［Ｃ］成分２０ｍｇを秤量し、比較例１と同様の混合処理条件により正極合材を得た。
(Comparative Example 2)
Ion conductive material obtained in Comparative Synthesis Example 1 as the ion conductive material [A], sulfur and / or sulfur as the discharge product [B] (manufactured by Aldrich), and activated carbon (as the conductive material [C]) A specific surface area of 3000 m 2 / g, manufactured by Kansai Thermochemical Co., Ltd.), and the composition ratio (weight ratio) of the ion conductive substance [A], sulfur and / or its discharge product [B], and the conductive material [C]. Of the [A] component, 100 mg of the [B] component, and 20 mg of the [C] component were weighed so as to be 40:50:10, and a positive electrode mixture was obtained under the same mixing treatment conditions as in Comparative Example 1.
（実施例２）
イオン伝導性物質［Ａ］として合成例２で得たイオン伝導性物質を用いた以外は比較例２と同様の操作により正極合材を得た。
(Example 2)
A positive electrode mixture was obtained in the same manner as in Comparative Example 2 except that the ion conductive material obtained in Synthesis Example 2 was used as the ion conductive material [A].
（実施例３）
イオン伝導性物質［Ａ］として合成例３で得たイオン伝導性物質を用いた以外は比較例２と同様の操作により正極合材を得た。
(Example 3)
A positive electrode mixture was obtained in the same manner as in Comparative Example 2, except that the ion conductive material obtained in Synthesis Example 3 was used as the ion conductive material [A].
（実施例４）
イオン伝導性物質［Ａ］として合成例４で得たイオン伝導性物質を用いた以外は比較例２と同様の操作により正極合材を得た。
Example 4
A positive electrode mixture was obtained in the same manner as in Comparative Example 2 except that the ion conductive material obtained in Synthesis Example 4 was used as the ion conductive material [A].
（比較例３）
イオン伝導性物質［Ａ］として比較合成例２で得たイオン伝導性物質を用いた以外は比較例２と同様の操作により正極合材を得た。
(Comparative Example 3)
A positive electrode mixture was obtained in the same manner as in Comparative Example 2, except that the ion conductive material obtained in Comparative Synthesis Example 2 was used as the ion conductive material [A].
（実施例５）
イオン伝導性物質［Ａ］として合成例１で得たイオン伝導性物質を用いた以外は比較例２と同様の操作により正極合材を得た。
(Example 5)
A positive electrode mixture was obtained in the same manner as in Comparative Example 2 except that the ion conductive material obtained in Synthesis Example 1 was used as the ion conductive material [A].
（実施例６）
イオン伝導性物質［Ａ］として合成例５で得たイオン伝導性物質を用いた以外は比較例２と同様の操作により正極合材を得た。
(Example 6)
A positive electrode mixture was obtained in the same manner as in Comparative Example 2 except that the ion conductive material obtained in Synthesis Example 5 was used as the ion conductive material [A].
（比較例４）
イオン伝導性物質［Ａ］として比較合成例３で得たイオン伝導性物質を用いた以外は比較例２と同様の操作により正極合材を得た。
(Comparative Example 4)
A positive electrode mixture was obtained in the same manner as in Comparative Example 2, except that the ion conductive material obtained in Comparative Synthesis Example 3 was used as the ion conductive material [A].
（実施例７）
イオン伝導性物質［Ａ］として合成例６で得たイオン伝導性物質、硫黄及び／又はその放電生成物［Ｂ］としての硫黄（アルドリッチ社製）、及び、導電材［Ｃ］として活性炭（比表面積３０００ｍ２／ｇ、関西熱化学社製）を用い、イオン伝導性物質［Ａ］、硫黄及び／又はその放電生成物［Ｂ］、並びに、導電材［Ｃ］の組成比（重量比）が３０：６０：１０となるように［Ａ］成分６０ｍｇ、［Ｂ］成分１２０ｍｇ、［Ｃ］成分２０ｍｇを秤量し、比較例１と同様の混合処理条件により正極合材を得た。
(Example 7)
The ion conductive material obtained in Synthesis Example 6 as the ion conductive material [A], sulfur and / or sulfur as the discharge product [B] (manufactured by Aldrich), and activated carbon (ratio) as the conductive material [C] The surface area is 3000 m 2 / g, manufactured by Kansai Thermochemical Co., Ltd.), and the composition ratio (weight ratio) of the ion conductive substance [A], sulfur and / or its discharge product [B], and the conductive material [C] is 60 mg of [A] component, 120 mg of [B] component, and 20 mg of [C] component were weighed so as to be 30:60:10, and a positive electrode mixture was obtained under the same mixing treatment conditions as in Comparative Example 1.
（実施例８）
導電材［Ｃ］として活性炭（比表面積１９００ｍ２／ｇ、クラレケミカル社製ＹＰ−８０Ｆ）用いた以外は実施例７と同様の操作により正極合材を得た。
(Example 8)
A positive electrode mixture was obtained in the same manner as in Example 7, except that activated carbon (specific surface area 1900 m 2 / g, YP-80F manufactured by Kuraray Chemical Co., Ltd.) was used as the conductive material [C].
（比較例５）
導電材［Ｃ］としてアセチレンブラック（比表面積８５０ｍ２／ｇ、電気化学工業社製ＯＳＡＢ）用いた以外は実施例７と同様の操作により正極合材を得た。
(Comparative Example 5)
A positive electrode mixture was obtained in the same manner as in Example 7, except that acetylene black (specific surface area 850 m 2 / g, OSAB manufactured by Denki Kagaku Kogyo Co., Ltd.) was used as the conductive material [C].
３．全固体型リチウム硫黄電池の作製
ポリカーボネート製の円筒管治具（内径１０ｍｍΦ、外径２３ｍｍΦ、高さ２０ｍｍ）の下側から負極集電体としてＳＵＳ３０４製の円筒治具（１０ｍｍΦ、高さ１０ｍｍ）を差し込み、ポリカーボネート製の円筒管治具の上側から固体電解質（Ｄ）（５Ｌｉ２Ｓ−ＧｅＳ２−Ｐ２Ｓ５を５１０℃で８時間焼成した複合化物）７０ｍｇを入れて、さらに正極集電体としてＳＵＳ３０４製の円筒治具（１０ｍｍΦ、高さ１５ｍｍ）をポリカーボネート製の円筒管治具の上側から差し込んで固体電解質（Ｄ）を挟み込み、２００ＭＰａの圧力で３分間プレスすることにより直径１０ｍｍΦ、厚さ約０．６ｍｍの固体電解質層を形成した。
次に、上側から差し込んだＳＵＳ３０４製の円筒治具（正極集電体）を一旦抜き取り、ポリカーボネート製の円筒管内の固体電解質層の上に実施例１〜８及び比較例１〜５で作製した正極合材を硫黄重量として３．７５ｍｇとなるようにそれぞれ入れ、再び上側からＳＵＳ３０４製の円筒治具（正極集電体）を差し込み、２００ＭＰａの圧力で３分間プレスすることで、直径１０ｍｍΦ、厚さ約０．１ｍｍの正極合材層を形成した。
次に、下側から差し込んだＳＵＳ３０４製の円筒治具（負極集電体）を抜き取り、負極として厚さ０．２５ｍｍのリチウムシート（フルウチ化学社製）を穴あけポンチで直径８ｍｍΦに打ち抜いたものと厚さ０．３ｍｍのインジウムシート（フルウチ化学社製）を穴あけポンチで直径９ｍｍΦに打ち抜いたものを重ねてポリカーボネート製の円筒管治具の下側から入れて、再び下側からＳＵＳ３０４製の円筒治具（負極集電体）を差し込み、８０ＭＰａの圧力で３分間プレスすることでリチウム−インジウム合金負極を形成した。
以上のようにして、下側から順に、負極集電体、リチウム−インジウム合金負極、固体電解質層、正極合材層、正極集電体が積層された全固体型リチウム硫黄電池を作製した。
3. Production of an all-solid-state lithium-sulfur battery A cylindrical jig made of SUS304 (10 mmΦ, height 10 mm) is used as a negative electrode current collector from the lower side of a polycarbonate cylindrical tube jig (inner diameter 10 mmΦ, outer diameter 23 mmΦ, height 20 mm). 70 mg of a solid electrolyte (D) (composite of 5Li 2 S—GeS 2 —P 2 S 5 baked at 510 ° C. for 8 hours) was added from the upper side of the cylindrical tube jig made of polycarbonate, and a positive electrode current collector As a cylindrical jig made of SUS304 (10 mmΦ, height 15 mm) is inserted from the upper side of the cylindrical tube jig made of polycarbonate, the solid electrolyte (D) is sandwiched, and pressed at a pressure of 200 MPa for 3 minutes to have a diameter of 10 mmΦ and thickness. A solid electrolyte layer of about 0.6 mm was formed.
Next, the cylindrical jig (positive electrode current collector) made of SUS304 inserted from the upper side was once extracted, and the positive electrode produced in Examples 1-8 and Comparative Examples 1-5 on the solid electrolyte layer in the polycarbonate cylindrical tube. Each of the compounds was added to a sulfur weight of 3.75 mg, and a cylindrical jig (positive electrode current collector) made of SUS304 was inserted again from above, and pressed at a pressure of 200 MPa for 3 minutes. About 0.1 mm of the positive electrode mixture layer was formed.
Next, a cylindrical jig made of SUS304 (negative electrode current collector) inserted from the lower side was extracted, and a lithium sheet (manufactured by Furuuchi Chemical Co., Ltd.) having a thickness of 0.25 mm was punched as a negative electrode to a diameter of 8 mmΦ with a punch. A 0.3mm-thick indium sheet (Furuuchi Chemical Co., Ltd.) punched to 9mmφ in diameter with a punch, and placed on the bottom of a polycarbonate cylindrical tube jig. A tool (negative electrode current collector) was inserted and pressed at 80 MPa for 3 minutes to form a lithium-indium alloy negative electrode.
As described above, an all-solid-state lithium-sulfur battery in which the negative electrode current collector, the lithium-indium alloy negative electrode, the solid electrolyte layer, the positive electrode mixture layer, and the positive electrode current collector were stacked in this order from the bottom was produced.
４．評価方法
(充放電試験)
作製した全固体型リチウム硫黄電池を用い、充放電装置（ＡＣＤ−Ｍ０１Ａ、アスカ電子株式会社製）にて、カットオフ電圧をそれぞれ０．５Ｖ（放電）、２．５Ｖ（充電）とし、１．６ｍＡ／ｃｍ２（０．２Ｃレート）の電流密度で充放電を１０サイクル繰り返し、１０サイクル目の活物質重量当たり及び正極合材重量当たりの放電容量を測定し、表１に示す。
なお、表１には特に示していないが、１０サイクル目の正極合材重量当たりの充電容量は、１０サイクル目の正極合材重量当たりの放電容量とほぼ同じであった。
また、表１において、硫黄当たりの放電容量が、理論容量である１６７２ｍＡｈ／ｇを超えるものがいくつか存在するが、これは正極合材中のイオン伝導性物質の一部も活物質として働いているためと考えられる。
さらに、表１において、［Ａ］、［Ｂ］及び［Ｃ］はそれぞれイオン伝導性物質［Ａ］、硫黄及び／又はその放電生成物［Ｂ］及び導電材［Ｃ］を意味し、さらに、ＳＥはイオン伝導性物質を意味する。
4). Evaluation method
(Charge / discharge test)
Using the produced all-solid-state lithium-sulfur battery, the charge / discharge device (ACD-M01A, manufactured by Asuka Electronics Co., Ltd.) was used with cut-off voltages of 0.5 V (discharge) and 2.5 V (charge), respectively. Charging / discharging was repeated 10 cycles at a current density of 6 mA / cm 2 (0.2 C rate), and the discharge capacity per active material weight and positive electrode composite weight at the 10th cycle was measured.
Although not specifically shown in Table 1, the charge capacity per positive electrode composite weight at the 10th cycle was almost the same as the discharge capacity per positive electrode composite weight at the 10th cycle.
In Table 1, there are some discharge capacity per sulfur exceeding the theoretical capacity of 1672 mAh / g. This is because part of the ion conductive material in the positive electrode mixture works as an active material. It is thought that it is because.
Furthermore, in Table 1, [A], [B] and [C] mean ion conductive material [A], sulfur and / or its discharge product [B] and conductive material [C], respectively, SE means an ion conductive material.
５．結果と考察
実施例及び比較例で作製した正極合材の評価結果より、イオン伝導性物質、硫黄及び／又はその放電生成物、並びに、導電材を含む正極合材において、イオン伝導性物質として、リン、硫黄、リチウム、及びヨウ素を含有し、リン重量比が０．１４〜０．４０、かつ、ヨウ素の重量比が０．０３〜０．３０の範囲のイオン伝導性物質［Ａ］と、比表面積が１１００ｍ２／ｇ以上である導電材［Ｃ］を用い、硫黄及び／又はその放電生成物［Ｂ］の含有量を、イオン伝導性物質［Ａ］、硫黄及び／又はその放電生成物［Ｂ］、並びに、導電材［Ｃ］の合計量の４０重量％以上とした正極合材を使用し、全固体型リチウム硫黄電池の正極合材層に用いることにより、実用的な高電流を流した際の正極合材当たりの充放電容量に優れた全固体型リチウム硫黄電池を得ることができることが明らかとなった。
なお、本発明では、正極合材当たりの充放電容量が６７０ｍＡｈ／ｇ以上であれば良好な正極合材であると考えている。
5. Results and Discussion From the evaluation results of the positive electrode mixture produced in the examples and comparative examples, in the positive electrode mixture containing the ion conductive substance, sulfur and / or its discharge product, and the conductive material, as the ion conductive substance, An ion conductive material [A] containing phosphorus, sulfur, lithium, and iodine, having a phosphorus weight ratio of 0.14 to 0.40 and an iodine weight ratio of 0.03 to 0.30; Using a conductive material [C] having a specific surface area of 1100 m 2 / g or more, the content of sulfur and / or its discharge product [B] is changed to the ion conductive material [A], sulfur and / or its discharge product. [B] and a positive electrode mixture of 40% by weight or more of the total amount of the conductive material [C] are used for a positive electrode mixture layer of an all-solid-state lithium-sulfur battery. Excellent charge / discharge capacity per cathode mix when flowing It is possible to obtain a solid-state lithium sulfur battery was revealed.
In the present invention, if the charge / discharge capacity per positive electrode mixture is 670 mAh / g or more, it is considered to be a good positive electrode mixture.
Claims (4)
［Ｂ］硫黄及び／又はその放電生成物、並びに、
［Ｃ］比表面積が１１００ｍ２／ｇ以上である導電材を含み、
前記［Ｂ］成分の含有量は、前記［Ａ］成分、前記［Ｂ］成分及び前記［Ｃ］成分の合計量の４０重量％以上である、全固体型リチウム硫黄電池の正極合材層に用いられることを特徴とする正極合材。 [A] contains phosphorus (P), sulfur (S), lithium (Li) and iodine (I), the weight ratio of P is 0.14 to 0.40, and the weight ratio of I is 0.03 to 0 An ion conductive material that is a composite that is .30.
[B] sulfur and / or its discharge product, and
[C] a conductive material having a specific surface area of 1100 m 2 / g or more,
The content of the component [B] is 40% by weight or more of the total amount of the component [A], the component [B], and the component [C]. A positive electrode mixture characterized by being used.
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| CN110556572A (en) * | 2018-06-01 | 2019-12-10 | 丰田自动车株式会社 | Positive electrode mixture and method for producing same |
| US11495790B2 (en) | 2018-06-01 | 2022-11-08 | Toyota Jidosha Kabushiki Kaisha | Cathode mixture and method for producing the same |
| WO2021251031A1 (en) | 2020-06-09 | 2021-12-16 | 国立研究開発法人産業技術総合研究所 | Positive electrode mixture for composite all-solid-state lithium sulfur battery |
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