JP2020024881A - Composite solid electrolyte and all-solid lithium ion battery - Google Patents

Composite solid electrolyte and all-solid lithium ion battery Download PDF

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JP2020024881A
JP2020024881A JP2018149463A JP2018149463A JP2020024881A JP 2020024881 A JP2020024881 A JP 2020024881A JP 2018149463 A JP2018149463 A JP 2018149463A JP 2018149463 A JP2018149463 A JP 2018149463A JP 2020024881 A JP2020024881 A JP 2020024881A
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solid electrolyte
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JP7045280B2 (en
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悠貴友 山本
Yukitomo Yamamoto
悠貴友 山本
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JX Nippon Mining and Metals Corp
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    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Abstract

To provide a composite solid electrolyte having a satisfactory lithium ion conductivity in a pellet state and a good endurance against cracking without integrally sintering a positive electrode, a solid electrolyte and a negative electrode with them put together.SOLUTION: A composite solid electrolyte comprises: core particles made of a garnet type solid electrolyte; and a covering part covering the surface of each core particle. The covering part comprises at least one kind selected from LiMH-LiI and LiMH-PS, where M is B or Al. In the composite solid electrolyte, the covering part is 1-50 pts.mass to a total of 100 pts.mass of the core particles and the covering parts.SELECTED DRAWING: Figure 1

Description

本発明は、複合固体電解質及び全固体リチウムイオン電池に関する。   The present invention relates to a composite solid electrolyte and an all-solid lithium-ion battery.

近年におけるパソコン、ビデオカメラ、及び携帯電話等の情報関連機器や通信機器等の急速な普及に伴い、その電源として利用される電池の開発が重要視されている。該電池の中でも、エネルギー密度が高いという観点から、リチウムイオン電池が注目を浴びている。また、車載用等の動力源やロードレベリング用といった大型用途におけるリチウム二次電池についても、高エネルギー密度、電池特性向上が求められている。   With the rapid spread of information-related devices and communication devices such as personal computers, video cameras, and mobile phones in recent years, the development of batteries used as power sources for such devices has been emphasized. Among these batteries, lithium ion batteries are receiving attention from the viewpoint of high energy density. In addition, high energy density and improved battery characteristics are also required for lithium secondary batteries for large-scale applications such as power sources for vehicles and load leveling.

ただ、リチウムイオン電池の場合は、電解液は有機化合物が大半であり、たとえ難燃性の化合物を用いたとしても火災に至る危険性が全くなくなるとは言いきれない。こうした液系リチウムイオン電池の代替候補として、電解質を固体とした全固体リチウムイオン電池が近年注目を集めている。その中でも、固体電解質としてＬｉ2Ｓ−Ｐ2Ｓ5などの硫化物やそれにハロゲン化リチウムを添加した全固体リチウムイオン電池が主流となりつつある。 However, in the case of a lithium ion battery, most of the electrolyte is an organic compound, and even if a flame-retardant compound is used, it cannot be said that there is no danger of fire. As an alternative candidate for such a liquid lithium-ion battery, an all-solid-state lithium-ion battery having a solid electrolyte has recently attracted attention. Among them, sulfides such as Li 2 S—P 2 S 5 as solid electrolytes and all-solid lithium ion batteries to which lithium halide is added are becoming mainstream.

また、全固体リチウムイオン電池用の固体電解質として、立方晶のＬｉ7Ｌａ3Ｚｒ2Ｏ12（ＬＬＺＯ）は、バルクのリチウムイオン伝導度が１０-4Ｓ／ｃｍ前後と高く、有力視されている。 Further, cubic Li 7 La 3 Zr 2 O 12 (LLZO) as a solid electrolyte for an all-solid-state lithium-ion battery has a high lithium ion conductivity of about 10 −4 S / cm and is considered to be promising. I have.

特開２０１５−１３８７４１号公報JP-A-2013-138741 国際公開第２０１６／１５７７５１号International Publication No. 2016/1577751

ＬＬＺＯが１０-4Ｓ／ｃｍ前後のリチウムイオン伝導度を得るためには、ペレット化した後に１１００℃以上で一体化焼結を必要とする。しかしながら、これには多大な電力コスト及び設備コストを必要とするという問題がある。 In order to obtain a lithium ion conductivity of LLZO of about 10 −4 S / cm, integrated sintering at 1100 ° C. or more after pelletization is required. However, this has the problem of requiring significant power and equipment costs.

また、全固体電池を作製する際、電解質−電極間の界面抵抗を低減するために、正極、固体電解質、及び負極を合わせた状態での焼結が有効である。しかしながら、固体電解質としてＬＬＺＯを用いる場合、１０-4Ｓ／ｃｍ前後のリチウムイオン伝導度を得るために一体型焼結を１１００℃以上で行う必要があるため、焼結温度で融解及び分解が起こらない正極、及び負極を使わなければならず、その材料選択の幅が狭くなるという問題がある。 Further, when manufacturing an all-solid battery, sintering in a state where a positive electrode, a solid electrolyte, and a negative electrode are combined is effective in order to reduce the interface resistance between the electrolyte and the electrode. However, when LLZO is used as the solid electrolyte, it is necessary to perform integral sintering at 1100 ° C. or more in order to obtain lithium ion conductivity of about 10 −4 S / cm, so that melting and decomposition occur at the sintering temperature. A negative electrode and a negative electrode need to be used, and there is a problem that the range of material selection becomes narrow.

特許文献１に記載の技術では、Ｌｉ3xＬａ2/3-xＴｉＯ3（０≦ｘ≦１／６）及びＬｉ7Ｌａ3Ｚｒ2Ｏ12のいずれかに、イオン伝導性非晶質を混合し、一体化焼結を行うことで空隙を埋め界面抵抗を下げるという手法で、８００℃での焼結を実現している。また、特許文献２に記載の技術では、酸化物固体電解質と焼結温度の低い固体電解質（例えばＬｉ2Ｏ−ＳｉＯ2−Ｂ2Ｏ3）を混合し、６００℃で焼結することで、空隙を埋め界面抵抗を下げている。しかしながら、６００〜８００℃においても融解及び分解する正極材は多く、更なる一体化焼結温度の低下が求められている。 According to the technique described in Patent Document 1, an ion-conductive amorphous is mixed with either Li 3x La 2 / 3-x TiO 3 (0 ≦ x ≦ 1/6) or Li 7 La 3 Zr 2 O 12. Then, sintering at 800 ° C. is realized by a technique of filling voids and lowering interface resistance by performing integral sintering. According to the technique described in Patent Document 2, an oxide solid electrolyte and a solid electrolyte having a low sintering temperature (for example, Li 2 O—SiO 2 —B 2 O 3 ) are mixed and sintered at 600 ° C. The gap is filled to lower the interface resistance. However, many positive electrode materials melt and decompose even at 600 to 800 ° C., and a further reduction in the integrated sintering temperature is required.

ところで、複合固体電解質は、取り扱い時の負荷によって割れが生じるおそれがあり、特に薄膜等に形成した場合等、その傾向が強くなる。   Incidentally, the composite solid electrolyte may be cracked by a load during handling, and the tendency is particularly strong when the composite solid electrolyte is formed in a thin film or the like.

本発明の実施形態では、正極、固体電解質、及び負極を合わせた状態で一体焼結することなく、ペレットとした状態で良好なリチウムイオン伝導度を有し、且つ、耐割れ性が良好な複合固体電解質を提供することを目的とする。   In the embodiment of the present invention, a composite having good lithium ion conductivity in a pellet state and good crack resistance without being integrally sintered in a state where a positive electrode, a solid electrolyte, and a negative electrode are combined. An object is to provide a solid electrolyte.

本発明者は、種々の検討を行った結果、ガーネット型固体電解質からなるコア粒子と、コア粒子の表面を被覆する被覆部とを有し、被覆部をＬｉＭＨ4−ＬｉＩ及びＬｉＭＨ4−Ｐ2Ｓ5から選択される少なくとも１種で形成し、コア粒子と被覆部との総量に対する被覆部の量を制御した複合固体電解質によれば、上述の課題が解決されることを見出した。 As a result of various studies, the inventor of the present invention has a core particle made of a garnet-type solid electrolyte and a coating portion that covers the surface of the core particle, and the coating portion is formed of LiMH 4 —LiI and LiMH 4 —P 2. forming at least one selected from S 5, according to the hybrid solid electrolyte having a controlled amount of the coating portion to the total amount of the core particle coating unit, found that the above problems can be solved.

上記知見を基礎にして完成した本発明は実施形態において、ガーネット型固体電解質からなるコア粒子と、前記コア粒子の表面を被覆する被覆部とを有する複合固体電解質であり、前記被覆部はＬｉＭＨ4−ＬｉＩ及びＬｉＭＨ4−Ｐ2Ｓ5から選択される少なくとも１種からなり、前記ＭがＢ又はＡｌであり、前記複合固体電解質における前記被覆部の量は、前記コア粒子と前記被覆部との総量を１００質量部としたとき、１〜５０質量部である複合固体電解質である。 The present invention completed on the basis of the above findings is, in an embodiment, a composite solid electrolyte having a core particle made of a garnet-type solid electrolyte and a coating portion covering the surface of the core particle, wherein the coating portion is LiMH 4 -LiI and LiMH 4 -P 2 S 5 , wherein M is B or Al, and the amount of the coating portion in the composite solid electrolyte is between the core particles and the coating portion. When the total amount is 100 parts by mass, the composite solid electrolyte is 1 to 50 parts by mass.

本発明の複合固体電解質は別の実施形態において、前記ガーネット型固体電解質が、組成式：Ｌｉ7-3xＬａ3Ｚｒ2ＡｌxＯ12（式中、０≦ｘ＜３である）で示される。 In another embodiment of the composite solid electrolyte of the present invention, the garnet-type solid electrolyte is represented by a composition formula: Li 7-3x La 3 Zr 2 Al x O 12 (where 0 ≦ x <3). .

本発明の複合固体電解質は更に別の実施形態において、前記被覆部が、ＬｉＢＨ4−ＬｉＩ及びＬｉＢＨ4−Ｐ2Ｓ5から選択される少なくとも１種からなる。 In still another embodiment of the composite solid electrolyte of the present invention, the coating portion is made of at least one selected from LiBH 4 -LiI and LiBH 4 -P 2 S 5 .

本発明は別の実施形態において、正極層、負極層及び固体電解質層を備え、本発明の実施形態に係る複合固体電解質を前記固体電解質層に備えた全固体リチウムイオン電池である。   In another embodiment, the present invention is an all-solid-state lithium-ion battery including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer, and including the composite solid electrolyte according to the embodiment of the present invention in the solid electrolyte layer.

本発明によれば、正極、固体電解質、及び負極を合わせた状態で一体焼結することなく、ペレットとした状態で良好なリチウムイオン伝導度を有し、且つ、耐割れ性が良好な複合固体電解質を提供することができる。   ADVANTAGE OF THE INVENTION According to this invention, it does not sinter integrally in the state which combined the positive electrode, the solid electrolyte, and the negative electrode, has the favorable lithium ion conductivity in the state of a pellet, and has the favorable crack resistance. An electrolyte can be provided.

実施例１−１〜１−３、及び、比較例１−１〜１−３に係るペレットのイオン伝導度を示すグラフである。It is a graph which shows the ion conductivity of the pellet which concerns on Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-3. （ａ−１）比較例１−１のＳＥＭ像、（ｂ−１）実施例１−１のＳＥＭ像、（ａ−２）比較例１−１の二値化図、（ｂ−２）実施例１−１の二値化図をそれぞれ示す。(A-1) SEM image of comparative example 1-1, (b-1) SEM image of example 1-1, (a-2) binarized diagram of comparative example 1-1, (b-2) execution The binarized diagrams of Example 1-1 are shown.

（複合固体電解質）
本発明の実施形態に係る複合固体電解質は、ガーネット型固体電解質からなるコア粒子と、コア粒子の表面を被覆する被覆部とを有する。本発明の実施形態に係る複合固体電解質の被覆部はＬｉＭＨ4−ＬｉＩ及びＬｉＭＨ4−Ｐ2Ｓ5から選択される少なくとも１種からなり、ＭがＢ又はＡｌからなる。錯体水素化リチウムであるＬｉＭＨ4−ＬｉＩ及びＬｉＭＨ4−Ｐ2Ｓ5は成形性に富むため、コア粒子の表面を被覆する被覆部をＬｉＭＨ4−ＬｉＩ及びＬｉＭＨ4−Ｐ2Ｓ5で形成すると、ペレットとしたときに酸化物の空隙を埋めやすくなる。このため、酸化物の緻密さが向上し、耐割れ性が良好となる。 (Composite solid electrolyte)
A composite solid electrolyte according to an embodiment of the present invention has a core particle made of a garnet-type solid electrolyte and a coating portion that covers the surface of the core particle. The coating portion of the composite solid electrolyte according to the embodiment of the present invention is made of at least one selected from LiMH 4 -LiI and LiMH 4 -P 2 S 5 , wherein M is B or Al. LiMH 4 —LiI and LiMH 4 —P 2 S 5, which are complex lithium hydrides, are rich in moldability. Therefore, when the covering portion covering the surface of the core particles is formed of LiMH 4 —LiI and LiMH 4 —P 2 S 5 This makes it easier to fill the voids of the oxide when formed into pellets. For this reason, the density of the oxide is improved, and the crack resistance is improved.

本発明の実施形態に係る複合固体電解質における被覆部の量は、コア粒子と被覆部との総量を１００質量部としたとき、１〜５０質量部である。このような構成によれば、ペレットとしたときに酸化物の空隙をより埋めやすくなり、界面抵抗を小さくすることができる。このため、正極、固体電解質、及び負極を合わせた状態で一体焼結することなく、ペレットとした状態で良好なリチウムイオン伝導度を有し、且つ、耐割れ性が良好な複合固体電解質を提供することができる。当該被覆部の量が１質量部未満かつ５０質量部超であると、空隙率が多く割れやすいという問題が生じるおそれがあり、当該被覆部の量は１０〜４０質量部であることが好ましい。 The amount of the coating portion in the composite solid electrolyte according to the embodiment of the present invention is 1 to 50 parts by mass when the total amount of the core particles and the coating portion is 100 parts by mass. According to such a configuration, it becomes easier to fill the voids of the oxide when formed into a pellet, and the interface resistance can be reduced. Therefore, a composite solid electrolyte having good lithium ion conductivity in the form of a pellet and good crack resistance without being integrally sintered in a state where the positive electrode, the solid electrolyte, and the negative electrode are combined is provided. can do. If the amount of the covering portion is less than 1 part by mass and more than 50 parts by mass, there is a possibility that a problem that the porosity is large and the material is easily cracked may occur, and the amount of the covering portion is preferably 10 to 40 parts by mass.

本発明の実施形態に係る複合固体電解質のコア粒子を構成するガーネット型固体電解質が、組成式：Ｌｉ7-3xＬａ3Ｚｒ2ＡｌxＯ12（式中、０≦ｘ＜３である）で示されてもよい。コア粒子を構成するガーネット型固体電解質が上記組成を有すると、常温にて立方晶となるため、常温にて高いイオン伝導度を有することができるという効果が得られる。 The garnet-type solid electrolyte constituting the core particles of the composite solid electrolyte according to the embodiment of the present invention has a composition formula: Li 7-3x La 3 Zr 2 Al x O 12 (where 0 ≦ x <3). May be shown. When the garnet-type solid electrolyte constituting the core particles has the above composition, the garnet-type solid electrolyte becomes cubic at normal temperature, so that an effect of having high ionic conductivity at normal temperature can be obtained.

本発明の実施形態に係る複合固体電解質の被覆部は、ＬｉＢＨ4−ＬｉＩ及びＬｉＢＨ4−Ｐ2Ｓ5から選択される少なくとも１種であってもよい。被覆部の錯体水素化リチウムがＬｉＢＨ4−ＬｉＩ及びＬｉＢＨ4−Ｐ2Ｓ5から選択される少なくとも１種であると、ＬｉＢＨ4−ＬｉＩ及びＬｉＢＨ4−Ｐ2Ｓ5はＬＬＺよりも降伏しやすいため、圧力をかけた際に塑性変形しＬＬＺ粒子間の空隙が埋まるという効果が得られる。このため、ペレットとした状態で耐割れ性が良好となるという効果が得られる。 The coating portion of the composite solid electrolyte according to the embodiment of the present invention may be at least one selected from LiBH 4 —LiI and LiBH 4 —P 2 S 5 . When complexes of lithium hydride covering portion is at least one selected from LiBH 4 -LiI and LiBH 4 -P 2 S 5, LiBH 4 -LiI and LiBH 4 -P 2 S 5 is easy to breakdown than LLZ Therefore, an effect of plastically deforming when pressure is applied and filling voids between LLZ particles is obtained. For this reason, the effect that the crack resistance becomes favorable in the state of the pellet is obtained.

（リチウムイオン電池）
本発明の実施形態に係る複合固体電解質を用いて固体電解質層を形成し、当該固体電解質層、正極層及び負極層を備えた全固体リチウムイオン電池を作製することができる。 (Lithium ion battery)
A solid electrolyte layer is formed using the composite solid electrolyte according to the embodiment of the present invention, and an all-solid lithium-ion battery including the solid electrolyte layer, the positive electrode layer, and the negative electrode layer can be manufactured.

（複合固体電解質の製造方法）
次に、本発明の実施形態に係る複合固体電解質の製造方法について詳細に説明する。まず、錯体水素化リチウムとしてＬｉＭＨ4−ＬｉＩ及びＬｉＭＨ4−Ｐ2Ｓ5から選択される少なくとも１種（ここで、ＭがＢ又はＡｌである）をＴＨＦ（テトラヒドロフラン）等の溶媒に溶解させた後、当該溶液にガーネット型固体電解質を投入して撹拌する。このとき、錯体水素化リチウムとガーネット型固体電解質とを所望の割合に調製する。また、当該操作は、好ましくはアルゴンガスまたは窒素ガスのような不活性ガス雰囲気下で実施する。 (Method for producing composite solid electrolyte)
Next, a method for producing a composite solid electrolyte according to an embodiment of the present invention will be described in detail. First, at least one selected from LiMH 4 —LiI and LiMH 4 —P 2 S 5 (where M is B or Al) as a complex lithium hydride was dissolved in a solvent such as THF (tetrahydrofuran). Thereafter, a garnet-type solid electrolyte is charged into the solution and stirred. At this time, the complex lithium hydride and the garnet-type solid electrolyte are prepared in a desired ratio. The operation is preferably performed in an inert gas atmosphere such as an argon gas or a nitrogen gas.

次に、撹拌した溶液を加熱して溶媒を蒸発させ、ガーネット型固体電解質にＬｉＭＨ4−ＬｉＩ及びＬｉＭＨ4−Ｐ2Ｓ5から選択される少なくとも１種を被覆した複合固体電解質を得る。こうして得られた複合固体電解質を金型中に入れ、所定の圧力で成形しペレットを作製し、当該ペレットを固体電解質層とし、これを用いて固体電解質層、正極層及び負極層を備えた全固体リチウムイオン電池を作製することができる。 Next, the stirred solution is heated to evaporate the solvent to obtain a composite solid electrolyte in which a garnet-type solid electrolyte is coated with at least one selected from LiMH 4 —LiI and LiMH 4 —P 2 S 5 . The composite solid electrolyte thus obtained was placed in a mold, molded at a predetermined pressure to produce a pellet, and the pellet was used as a solid electrolyte layer, and a solid electrolyte layer, a positive electrode layer, and a negative electrode layer were provided using the pellet. A solid state lithium ion battery can be manufactured.

以下、本発明及びその利点をより良く理解するための実施例を提供するが、本発明はこれらの実施例に限られるものではない。
（実施例１−１）
Ａｒ雰囲気中で３ＬｉＢＨ4−ＬｉＩをＴＨＦに溶解させ、溶液にガーネット型固体電解質として、豊島製作所製立方晶Ｌｉ7-3xＬａ3Ｚｒ2ＡｌxＯ12（式中、０≦ｘ＜３である）を投入し撹拌した。３ＬｉＢＨ4−ＬｉＩとガーネット型固体電解質との割合は１０：９０（質量％）とした。
次に、Ａｒ雰囲気にて１５０℃まで加熱することでＴＨＦを蒸発させ、Ｌｉ7-3xＬａ3Ｚｒ2ＡｌxＯ12にＬｉＢＨ4−ＬｉＩを被覆させた複合固体電解質を得た。得られた複合固体電解質を金型中に入れ、３６．３ＭＰａで成形しペレットを得た。 Hereinafter, examples for better understanding of the present invention and its advantages will be provided, but the present invention is not limited to these examples.
(Example 1-1)
In an Ar atmosphere, 3LiBH 4 -LiI is dissolved in THF, and a garnet-type solid electrolyte is cubic Li 7-3x La 3 Zr 2 Al x O 12 manufactured by Toshima Seisakusho, where 0 ≦ x <3. ) Was added and stirred. The ratio of 3LiBH 4 -LiI to the garnet-type solid electrolyte was 10:90 (% by mass).
Next, THF was evaporated by heating to 150 ° C. in an Ar atmosphere to obtain a composite solid electrolyte in which LiBH 4 —LiI was coated on Li 7 −3 × La 3 Zr 2 Al x O 12 . The obtained composite solid electrolyte was placed in a mold and molded at 36.3 MPa to obtain pellets.

（実施例１−２）
実施例１−１で作製した複合固体電解質を金型中に入れ、５ＭＰａで成形しペレットを得た。 (Example 1-2)
The composite solid electrolyte prepared in Example 1-1 was placed in a mold and molded at 5 MPa to obtain pellets.

（実施例１−３）
実施例１−１で作製した複合固体電解質を金型中に入れ、２０ＭＰａで成形しペレットを得た。 (Example 1-3)
The composite solid electrolyte prepared in Example 1-1 was placed in a mold and molded at 20 MPa to obtain a pellet.

（実施例２）
３ＬｉＢＨ4−ＬｉＩとＬｉ7-3xＬａ3Ｚｒ2ＡｌxＯ12の割合を２０：８０（質量％）とした以外は実施例１−１と同様の条件で複合固体電解質を作製した。得られた複合固体電解質を金型中に入れ、３６．３ＭＰａで成形しペレットを得た。 (Example 2)
Except that the proportion of 3LiBH 4 -LiI and Li 7-3x La 3 Zr 2 Al x O 12 20:80 and (mass%) was prepared composite solid electrolyte under the same conditions as in Example 1-1. The obtained composite solid electrolyte was placed in a mold and molded at 36.3 MPa to obtain pellets.

（実施例３）
３ＬｉＢＨ4−ＬｉＩとＬｉ7-3xＬａ3Ｚｒ2ＡｌxＯ12の割合を５０：５０（質量％）とした以外は実施例１−１と同様の条件で複合固体電解質を作製した。得られた複合固体電解質を金型中に入れ、３６．３ＭＰａで成形しペレットを得た。 (Example 3)
The proportion of 3LiBH 4 -LiI and Li 7-3x La 3 Zr 2 Al x O 12 except that the 50:50 (wt%) was prepared composite solid electrolyte under the same conditions as in Example 1-1. The obtained composite solid electrolyte was placed in a mold and molded at 36.3 MPa to obtain pellets.

（実施例４）
Ａｒ雰囲気中で２ＬｉＢＨ4−ＬｉＩをＴＨＦに溶解させ、溶液にガーネット型固体電解質として、豊島製作所製立方晶Ｌｉ7-3xＬａ3Ｚｒ2ＡｌxＯ12（式中、０≦ｘ＜３である）を投入し撹拌し、２ＬｉＢＨ4−ＬｉＩとガーネット型固体電解質との割合を２０：８０（質量％）としたこと以外は実施例１−１と同様にしてペレットを得た。 (Example 4)
In an Ar atmosphere, 2LiBH 4 -LiI is dissolved in THF, and a garnet-type solid electrolyte is cubic Li 7-3x La 3 Zr 2 Al x O 12 manufactured by Toshima Seisakusho, where 0 ≦ x <3. ) Was added and stirred to obtain pellets in the same manner as in Example 1-1, except that the ratio of 2LiBH 4 -LiI and the garnet-type solid electrolyte was set to 20:80 (% by mass).

（比較例１−１）
豊島製作所製立方晶Ｌｉ7-3xＬａ3Ｚｒ2ＡｌxＯ12をそのまま金型中に入れ、３６．３ＭＰａで成形しペレットを得た。 (Comparative Example 1-1)
Cubic Li 7-3x La 3 Zr 2 Al x O 12 manufactured by Toshima Seisakusho was placed in a mold as it was, and molded at 36.3 MPa to obtain a pellet.

（比較例１−２）
豊島製作所製立方晶Ｌｉ7-3xＬａ3Ｚｒ2ＡｌxＯ12をそのまま金型中に入れ、５ＭＰａで成形しペレットを得た。 (Comparative Example 1-2)
Cubic Li 7-3x La 3 Zr 2 Al x O 12 manufactured by Toshima Seisakusho was placed in a mold as it was and molded at 5 MPa to obtain pellets.

（比較例１−３）
豊島製作所製立方晶Ｌｉ7-3xＬａ3Ｚｒ2ＡｌxＯ12をそのまま金型中に入れ、２０ＭＰａで成形しペレットを得た。 (Comparative Example 1-3)
Cubic Li 7-3x La 3 Zr 2 Al x O 12 manufactured by Toshima Seisakusho was directly placed in a mold and molded at 20 MPa to obtain pellets.

（比較例２）
Ａｒ雰囲気下のグローブボックス内で、ＬｉＢＨ4（シグマ・アルドリッチ社製、純度９０％）とＬｉＩ（シグマ・アルドリッチ社製、純度９９．９９９％）とを、ＬｉＢＨ4：ＬｉＩ＝３：１のモル比になるようにメノウ乳鉢にて混合した。次に、混合した出発原料をポットに投入し、さらにφ７ｍｍのメディアを２０個投入して、ポットを完全に密閉した。このポットを遊星型ボールミル機に取り付け、回転数４００ｒｐｍで５時間メカニカルミリングを行い、錯体水素化物固体電解質（３ＬｉＢＨ4−ＬｉＩ）を得た。得られた固体電解質を金型中に入れ、３６．３ＭＰａで成形しペレットを得た。 (Comparative Example 2)
In a glove box under an Ar atmosphere, LiBH 4 (Sigma-Aldrich, purity 90%) and LiI (Sigma-Aldrich, purity 99.999%) were mixed with a mole of LiBH 4 : LiI = 3: 1. The mixture was mixed in an agate mortar so as to obtain a ratio. Next, the mixed starting materials were charged into a pot, and 20 media having a diameter of 7 mm were further charged to completely close the pot. This pot was attached to a planetary ball mill, and mechanical milling was performed at a rotation speed of 400 rpm for 5 hours to obtain a complex hydride solid electrolyte (3LiBH 4 -LiI). The obtained solid electrolyte was placed in a mold and molded at 36.3 MPa to obtain pellets.

（比較例３）
ＬｉＢＨ4（シグマ・アルドリッチ社製、純度９０％）とＬｉＩ（シグマ・アルドリッチ社製、純度９９．９９９％）とを、ＬｉＢＨ4：ＬｉＩ＝２：１のモル比になるようにメノウ乳鉢にて混合した以外は、比較例２と同様にしてペレットを得た。 (Comparative Example 3)
LiBH 4 (manufactured by Sigma-Aldrich, purity 90%) and LiI (manufactured by Sigma-Aldrich, purity 99.999%) are mixed in an agate mortar so that the molar ratio of LiBH 4 : LiI = 2: 1 is obtained. Except for mixing, pellets were obtained in the same manner as in Comparative Example 2.

（評価）
こうしてできた各実施例及び比較例のサンプルを用いて下記の条件にて各評価を実施した。
−イオン伝導度の評価−
各サンプルの伝導度は、２５℃設定の恒温槽中にてＡＣインピーダンスアナライザーを用い、周波数が１０ＭＨｚ〜５０ＭＨｚ、振幅電圧が１００ｍＶとなるような条件で、ナイキストプロットの円弧より抵抗値を求め、伝導度を算出した。ＡＣインピーダンスアナライザーで測定する際の電極にはＬｉ電極を用いた。 (Evaluation)
Each evaluation was carried out under the following conditions using the samples of the examples and comparative examples thus obtained.
−Evaluation of ionic conductivity−
The conductivity of each sample was determined by using an AC impedance analyzer in a constant temperature bath set at 25 ° C. and determining the resistance value from the arc of the Nyquist plot under the conditions that the frequency was 10 MHz to 50 MHz and the amplitude voltage was 100 mV. The degree was calculated. A Li electrode was used as an electrode when measuring with an AC impedance analyzer.

−空隙率の評価−
実施例及び比較例を表１に記載の成形圧力（ＭＰａ）でペレットにした後、金蒸着し、ＦＥ−ＳＥＭを用いて試料を観察した。画像解析ソフトを用いて観察したＳＥＭ像を二値化し、空隙部分を黒色とした。全体のピクセル数と黒色部の割合から空隙率を算出した。図２は、（ａ−１）比較例１−１のＳＥＭ像、（ｂ−１）実施例１−１のＳＥＭ像、（ａ−２）比較例１−１の二値化図、（ｂ−２）実施例１−１の二値化図をそれぞれ示す。 −Evaluation of porosity−
After pelletizing the examples and comparative examples at the molding pressure (MPa) shown in Table 1, gold was vapor-deposited, and the samples were observed using FE-SEM. The SEM image observed using the image analysis software was binarized, and the voids were blackened. The porosity was calculated from the total number of pixels and the ratio of the black portion. FIG. 2 shows (a-1) an SEM image of Comparative Example 1-1, (b-1) an SEM image of Example 1-1, (a-2) a binarized diagram of Comparative Example 1-1, and (b). -2) A binarized diagram of Example 1-1 is shown.

−耐割れ性の評価−
各実施例及び比較例のサンプルをペレットの厚みが１ｍｍとなるように調整し、力を加えた際の割れにくさを四段階で評価した。このときの耐割れ性の評価は、最も割れにくいものをＡ、次に割れにくいものをＢ、その次に割れにくいものをＣ、最も割れやすいものをＤとした。また、評価Ａ及びＢまでは、人の手で容易に割ることが困難であり、これらは耐割れ性が良好であるとした。 −Evaluation of crack resistance−
The samples of Examples and Comparative Examples were adjusted so that the thickness of the pellets was 1 mm, and the degree of cracking when applying force was evaluated on a four-point scale. At this time, the crack resistance was evaluated as A, the most difficult to break, B, the next hardest to break, C, and the most easily crackable, D. In addition, it is difficult to easily split the evaluations A and B by a human hand, and it is assumed that these have good crack resistance.

Ｌｉ7-3xＬａ3Ｚｒ2ＡｌxＯ12の未焼結では空隙が約４０％見られたのに対し、３ＬｉＢＨ4−ＬｉＩを全体質量に対して１０ｗｔ％被覆したＬｉ7-3xＬａ3Ｚｒ2ＡｌxＯ12の空隙率は約２０％であり、空隙が減少していた。これは、３ＬｉＢＨ4−ＬｉＩがＬｉ7-3xＬａ3Ｚｒ2ＡｌxＯ12の空隙を埋めることで界面抵抗が減少し、Ｌｉ伝導パスを形成したことでイオン伝導度が向上したと考えられる。また、圧力を変えて作製した実施例１−１〜１−３、及び、比較例１−１〜１−３に係るペレットのイオン伝導度を図１に示した。
評価条件及び結果を表１に示す。 While about 40% of voids were observed in the unsintered Li 7-3x La 3 Zr 2 Al x O 12 , Li 7-3x La 3 Zr coated with 10% by weight of 3LiBH 4 —LiI based on the whole mass. The porosity of 2 Al x O 12 was about 20%, and the porosity was reduced. This interfacial resistance is reduced by 3LiBH 4 -LiI fill the gap Li 7-3x La 3 Zr 2 Al x O 12, it is considered to ionic conductivity is improved by the formation of the Li conduction path. FIG. 1 shows the ionic conductivity of the pellets according to Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-3 manufactured by changing the pressure.
Table 1 shows the evaluation conditions and results.

（評価結果）
実施例１−１〜１−３、２、３、４については、正極、固体電解質、及び負極を合わせた状態で一体焼結することなく、ペレットとした状態で良好なリチウムイオン伝導度を有し、耐割れ性が良好な複合固体電解質が得られた。
また、上記の実施例では、被覆部の錯体水素化リチウムとしてＬｉＢＨ4−ＬｉＩを用いたが、代わりにＬｉＢＨ4−Ｐ2Ｓ5、ＬｉＡｌＨ4−ＬｉＩまたはＬｉＡｌＨ4−Ｐ2Ｓ5を用いたとしても、同様なイオン伝導度及び耐割れ性が得られるものと予想される。これは、ＬｉＢＨ4−Ｐ2Ｓ5、ＬｉＡｌＨ4−ＬｉＩ及びＬｉＡｌＨ4−Ｐ2Ｓ5がＬｉＢＨ4−ＬｉＩと同様に、ＴＨＦ溶媒に溶解し、成形性に富み、常温で１０-3Ｓ／ｃｍオーダーのイオン伝導度を有しているためである。
一方、比較例１−１〜１−３については、ペレットがＬｉ7-3xＬａ3Ｚｒ2ＡｌxＯ12のみで形成されていて被覆部としての錯体水素化リチウムを有しておらず、イオン伝導度が劣っていた。
また、比較例２及び３については、ペレットが錯体水素化リチウムのみで形成されていてコア粒子としてのＬｉ7-3xＬａ3Ｚｒ2ＡｌxＯ12を有しておらず、耐割れ性が劣っていた。 (Evaluation results)
Examples 1-1 to 1-3, 2, 3, and 4 have good lithium ion conductivity in the form of pellets without sintering integrally with the combination of the positive electrode, the solid electrolyte, and the negative electrode. Thus, a composite solid electrolyte having good crack resistance was obtained.
Further, in the above embodiment, LiBH 4 -LiI was used as the complex lithium hydride of the covering portion, but LiBH 4 -P 2 S 5 , LiAlH 4 -LiI or LiAlH 4 -P 2 S 5 was used instead. It is expected that similar ionic conductivity and crack resistance can be obtained. This, LiBH 4 -P 2 S 5, LiAlH 4 -LiI and LiAlH 4 -P 2 S 5 is similar to the LiBH 4 -LiI, dissolved in THF solvent, rich in moldability, cold at 10 -3 S / This is because they have ion conductivity on the order of cm.
On the other hand, for Comparative Examples 1-1 to 1-3, the pellets were formed only of Li 7-3x La 3 Zr 2 Al x O 12 and did not have the complex lithium hydride as the coating portion, Conductivity was poor.
In Comparative Examples 2 and 3, the pellets were formed only of the complex lithium hydride, did not have Li 7-3x La 3 Zr 2 Al x O 12 as the core particles, and had poor cracking resistance. I was

Claims (4)

ガーネット型固体電解質からなるコア粒子と、
前記コア粒子の表面を被覆する被覆部とを有する複合固体電解質であり、
前記被覆部はＬｉＭＨ4−ＬｉＩ及びＬｉＭＨ4−Ｐ2Ｓ5から選択される少なくとも１種からなり、前記ＭがＢ又はＡｌであり、
前記複合固体電解質における前記被覆部の量は、前記コア粒子と前記被覆部との総量を１００質量部としたとき、１〜５０質量部である複合固体電解質。 Core particles comprising a garnet-type solid electrolyte;
A composite solid electrolyte having a coating portion that covers the surface of the core particles,
The coating portion is made of at least one selected from LiMH 4 —LiI and LiMH 4 —P 2 S 5 , wherein M is B or Al;
The amount of the coating portion in the composite solid electrolyte is 1 to 50 parts by mass when the total amount of the core particles and the coating portion is 100 parts by mass. 前記ガーネット型固体電解質が、組成式：Ｌｉ7-3xＬａ3Ｚｒ2ＡｌxＯ12
（式中、０≦ｘ＜３である）
で示される請求項１に記載の複合固体電解質。 The garnet-type solid electrolyte has a composition formula: Li 7-3x La 3 Zr 2 Al x O 12
(Where 0 ≦ x <3)
The composite solid electrolyte according to claim 1, wherein 前記被覆部が、ＬｉＢＨ4−ＬｉＩ及びＬｉＢＨ4−Ｐ2Ｓ5から選択される少なくとも１種からなる請求項１又は２に記載の複合固体電解質。 3. The composite solid electrolyte according to claim 1, wherein the coating portion is made of at least one selected from LiBH 4 —LiI and LiBH 4 —P 2 S 5. 4 . 正極層、負極層及び固体電解質層を備え、請求項１〜３のいずれか一項に記載の複合固体電解質を前記固体電解質層に備えた全固体リチウムイオン電池。   An all-solid lithium-ion battery including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer, wherein the solid electrolyte layer includes the composite solid electrolyte according to claim 1.
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111276737B (en) * 2020-02-18 2021-04-20 浙江大学 Garnet type composite electrolyte material and preparation method and application thereof
CN113991171A (en) * 2021-10-22 2022-01-28 浙江大学 Garnet type multi-element composite solid electrolyte and preparation method and application thereof
CN115799619A (en) * 2023-01-05 2023-03-14 河北光兴半导体技术有限公司 Oxide solid electrolyte and preparation method and application thereof

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WO2019212007A1 (en) * 2018-05-02 2019-11-07 日本特殊陶業株式会社 Ionic conductor and electricity storage device

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019212007A1 (en) * 2018-05-02 2019-11-07 日本特殊陶業株式会社 Ionic conductor and electricity storage device

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111276737B (en) * 2020-02-18 2021-04-20 浙江大学 Garnet type composite electrolyte material and preparation method and application thereof
CN113991171A (en) * 2021-10-22 2022-01-28 浙江大学 Garnet type multi-element composite solid electrolyte and preparation method and application thereof
CN115799619A (en) * 2023-01-05 2023-03-14 河北光兴半导体技术有限公司 Oxide solid electrolyte and preparation method and application thereof
CN115799619B (en) * 2023-01-05 2023-11-10 河北光兴半导体技术有限公司 Oxide solid electrolyte and preparation method and application thereof

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