JP6173381B2 - Electrolyte and electrical storage device with multilayer structure - Google Patents

Description

  The present invention relates to an electrolyte having a multilayer structure and an electrical storage device, and more particularly to a battery cell comprising such an electrolyte. Multilayer electrolytes are particularly attractive for lithium ion batteries.

  The layered structure of the electrolyte for a lithium ion battery may consist of multiple layers of liquid electrolyte and / or solid electrolyte. In particular, such a structure may include two layers (not necessarily of the same composition) of liquid electrolyte and a middle layer of solid electrolyte as a separator.

Examples of liquid electrolytes are mixtures of ethylene carbonate and ethyl carbonate (EC and EMC) with lithium hexafluorophosphate (LiPF ₆ ) as a conductivity salt, and conductive with propylene carbonate and ethylene glycol dimethyl ether (PC and DME). It is a mixture with lithium bis (trifluoromethylsulfonyl) imide (LiTFSI) as a salt. Since ethylene glycol dimethyl ether is also called 1,2-dimethoxyethane, the abbreviation DME is also selected in this regard.

An example of a solid electrolyte is a garnet type system, for example Li _{7 + xy} M ^II _x M ^III _3-x M ^IV _{2- y My} ^V O ₁₂ , where
M ^II is a divalent cation,
M ^III is a trivalent cation,
M ^IV is a tetravalent cation,
M ^V is a pentavalent cation,
For example, lithium lanthanum zirconate _{Li 7-3x Al x La 3 Zr 2} O 12 or _{Li 7-3x La 3 (Ta / Nb} ) x Zr 2-x O 12. A further example is a system with the so-called LiSICon crystalline phase Li _1-x (M ⁵⁺ , M ³⁺ ) _x M ^{4 + 2-x} (PO ₄ ) ₃ , where M ⁵⁺ is Ta and And / or Nb, M ³⁺ may be Al, Cr, Ga, or Fe, and M ⁴⁺ may be Ti, Zr, Si, or Ge. A sulfide-based electrolyte can also be used.

  For the structure of such systems and the materials involved, see Jennifer L. et al. Schaefer, Yingying Lu, Surya S .; Moganty, Praven Agarwal, N.M. Jayaprakash, Lynden A. et al. Archer, Electrolytes for high-energy lithium batteries, Appl. Nanosci. 2 (2012), pp. 91-109, and DE 1020110113018B3, US20030205467 or US20090317724.

  Sulfide systems are described, for example, in US20050107239A1, US200915959839 or JP2000081666A.

  In addition to the conductivity of the liquid or solid electrolyte involved, the interfacial resistance between the two types of electrolytes is also very important for the total resistance of an electrolyte having a multilayer structure.

  It is not found in the prior art how this interface resistance can be systematically made as small as possible.

  From EP 1 347 758 A polymer electrolytes with side chains with a large dipole moment are known. The resulting high dielectric constant described in EP 1134758 A1 increases the ionic conductivity of the conductivity salt dissolved in the polymer matrix. Moreover, this side chain reduces the interfacial resistance to the electrodes to the same order as is known from liquid electrolytes. The reason for this is that the chemical adhesion between the electrode and the electrolyte is considered to be further improved.

  A lithium-air battery with an ion-conducting solid electrolyte, which can include lithium aluminum germanium phosphate (LAGP), lithium aluminum titanium phosphate (LATP) or lithium titanium silicon phosphate (LATSP) is known from US 2014/0011101 A1. Yes. Dimethoxyethane (DME) is used as the organic electrolyte.

  A lithium ion cell having a 1: 1: 1 ratio of LAGP as a solid electrolyte and ethylene carbonate: diethylene carbonate: ethyl methyl carbonate as a liquid electrolyte is an Electrochimica Acta 81 by Tonghua Yang, Lin Sang, Fei Ding, Jing Zhang, Xingjiang Liu. 2012, pp. 179-185-ISSN 0013-4686, known from the Three-and four-electrode EIS analysis of water stable lithium with solid electrolyte plate.

  US 2006/01334492 describes an electrolyte having two layers, the electrolyte in both layers being the same.

DE1020111013018B3 US20030205467 US20090331724 US20050107239A1 US2009159839 JP8002206666A EP1134758A US2014 / 0011101A1 US2006 / 01334492

Jennifer L. Schaefer, Yingying Lu, Surya S .; Moganty, Praven Agarwal, N.M. Jayaprakash, Lynden A. et al. Archer, Electrolytes for high-energy lithium batteries, Appl. Nanosci. 2 (2012), pp. 91-109 Tonghuan Yang, Lin Sang, Fei Ding, Jing Zhang, Xingjiang Liu, Electrochimica Acta 81, 2012, pp. 179-185. -ISSN 0013-4686's Three-and four-electrode EIS analysis of water stable lithium with solid electolyte plate

  The object of the present invention is to avoid the disadvantages of the prior art and to define what conditions must be observed in order to achieve the lowest possible interfacial resistance in an electrolyte with a multilayer structure.

According to the invention, this problem is solved by at least one first electrolyte layer characterized by a _first dielectric constant ε ₁ and a second dielectric constant ε ₂ intended for use in the room temperature region. Solved by an electrolyte having a multilayer structure, including at least one further electrolyte layer characterized by: and an interface between the two electrolyte layers, where the two dielectric constants ε ₁ and ε ₂ are α = The standard value (measure) of ε ₁ / (ε ₁ + ε ₂ ) is defined, and the standard value α at the interface of the electrolyte of one electrolyte layer and the electrolyte of the other electrolyte layer is 0.244 <α ≦ 0. 0.5, preferably 0.371 <α ≦ 0.5, particularly preferably 0.436 <α ≦ 0.5, very preferably 0.475 <α ≦ 0.5, more preferably 0.488 <α ≦ 0.5. 0.5, more preferably in the range of 0.494 <α ≦ 0.5. It is selected such, where always, epsilon ₁ denotes a lower relative dielectric constant of the adjacent medium, and epsilon ₂ is higher relative permittivity of the adjacent medium. This solution is not limited to combinations of liquid electrolytes and / or polymers, but in particular includes inorganic materials such as glass, glass ceramics or (polycrystalline) ceramics. Particularly preferred is an α value of α≈0.5, provided that at least α> 0.436, in particular α> 0.488, ie 0.436 <α ≦ 0.5, preferably 0. This is a case where 488 <α ≦ 0.5. With such nearly constant dielectric constants, overvoltages in the relatively large range of 0.2V, in particular 1V, are achieved in the different electrolyte interface regions.

  That is, in the case of an electrolyte having a multi-layer structure, the present inventor disposes the adjacent conductivity salt or conductive oxide in the adjacent electrode even when they have glass, glass ceramic or ceramic. It was found that it can be understood as a dielectric continuum having. This was unexpected. This is because, in particular, in the partial crystal structure, it is assumed that the continuum description cannot be made because the individual atomic skeleton greatly affects. Therefore, in this case, i.e. when one or both of the two adjacent electrolytes are glass, glass ceramic or ceramic, preferably the same dielectric constant value is selected for both electrolytes. Since the dielectric constant depends on temperature and frequency, this selection is made at a specific point of action or region, i.e. a specific frequency and / or a specific temperature or a specific frequency region and / or temperature region.

  However, the background, ie the frequency-dependent change of the dielectric constant of the matrix material described as a dielectric continuum is generally limited to the individual frequency range. Charles Kittel, Introduction to solid-state physics, 5th edition, R.C. Oldenburg-Verlag Munich Vienna, 1980, page 441, and Ekaterina I., et al. Izgorodina, Maria Forsyth and Douglas R. MacFarlane, “The the components of the dielectric constants of ionic liquids: ionic polarization?”, Phys. Chem. Chem. Phys. As can be derived from 11, 452-2458 (2009), looking at the frequency scale from large to small, first the electron polarizability, ie the displaceability of the electron shell relative to the nucleus, then the ion polarizability, Displacement of atoms having partial charges with different signs, then dipole polarizability, ie, the orientation of permanent dipoles, and then space charge polarizability, ie, movement of ions to the interface, contributes to the dielectric constant. The latter is an effect of ionic conduction and therefore does not belong to the above background.

  In ionic conductors made of glass, glass ceramic or ceramic, only the first two contributions and the last contribution are affected. Do not include the last one, look at the frequency scale from large to small and continue until you take into account both electronic and ionic polarizability. This is the case below the infrared region (Charles Kittel, Introduction to solid-state physics, 5th edition, R. Oldenburg-Verlag Munich Vienna, 1980, page 441, and EkaterinaM. See MacFarlane, “On the components of the dielectric constants of ionic liquids: ionic polarization?”, Phys. Chem. Chem. Phys. 11, pages 2458 to 2458 (200). The dielectric constant is substantially constant up to the frequency at which the space charge effect occurs. This value is used as the background dielectric constant. In this case, it should be understood that the electronic polarizability of, for example, a conductivity salt or a conductive oxide is also included; however, this factor is a glass, glass that cannot be easily prepared without a conductivity salt or conductive oxide. No consideration is given to ceramic or ceramic ionic conductors.

  In the case of liquid electrolytes or polymer electrolytes that can be prepared without conducting salts or conducting oxides, a substantially constant found below the frequency region where dipole polarizability "appears" (calculated from top to bottom). The value is used as the dielectric constant. In the case of polymer electrolytes that cannot be prepared without a conductivity salt or conducting oxide, between the frequency range where the dipole polarizability “appears” (calculated from top to bottom) and the occurrence of space charge polarizability. Sometimes, a narrow frequency window must be used.

  When the ideal case according to the invention with equal dielectric constants exists on both sides of the interface, first the energy level of the ions responsible for charge transport, for example lithium ions in the case of lithium ion batteries, is measured on both sides. be able to.

  Given that the energy levels of these ions are measured only by dielectrics and do not need to look into interactions with other ions, especially counterions, the ions responsible for charge transport are also on both sides of the interface. In the absence of an external voltage and equal activity on both sides, they are at the same energy level, which is approximately measured by the Born equation of solvation free enthalpy. In this regard, M.M. Born, Volume and hydration heat ofions, Zeitshift fuel Physik, No. 1, pages 45-48 (1920). This entire content is incorporated herein by reference.

  If an additional potential difference is generated in the multilayer electrolyte layer (eg from the outside), K.I. Aoki, Theory of the transfer kinetics at a viscous immiscible liquid / liquid interface by means of the Langevin equation, Electro41. 14, pages 2321 to 2327 (1996), this results in the voltage dropping on both sides of the interface in a thin boundary layer and causing ion transport that is inversely proportional to the interface resistance.

  If the dielectric constant continuity is applied in the region of the boundary layer, there will be no electric field discontinuities at the interface, which is advantageous for minimal interface resistance. In this regard, K., cited above. See Aoki. In an ideal case, in the case of an electrolyte having a multilayer structure, different electrolytes are selected, for example a combination of liquid and solid electrolytes, where all two (or three if different liquid electrolytes are used). The relative permittivity of the materials involved is the same. The measurement of the dielectric constant can be performed, for example, according to Application Note 1369-1 "dated October 28, 2008 by Agilent, Sant Clara, California USA. The entire disclosure of this document is incorporated herein by reference. Shall.

が用いられる。本発明によれば、ε₁は、２つの関与する比誘電率の低い方であり、ε₂は、高い方である。ε₁及びε₂が一致する理想的なケースにおいては、基準値α＝１／２が当てはめられ、ε₁及びε₂が異なる場合、αはより小さくなる。 The reference value α according to the present invention is used as a reference for the relative permittivity or the degree of coincidence of permittivity

Is used. According to the present invention, ε ₁ is the lower of the two dielectric constants involved, and ε ₂ is the higher. In the ideal case where ε ₁ and ε ₂ match, the reference value α = ½ is fitted, and α is smaller when ε ₁ and ε ₂ are different.

Particularly preferred is that the materials having the first and second dielectric constants ε ₁ and ε ₂ are different materials, preferably a solid electrolyte and a liquid electrolyte.

［式中、電流密度ｊ₀は、なかでも電荷担体密度及び（指数関数的に）温度に依存する定数である］である。それゆえ、これに関しては、Ｋ．Ａｏｋｉ，Ｔｈｅｏｒｙ ｏｆ ｔｈｅ ｉｏｎ ｔｒａｎｓｆｅｒ ｋｉｎｅｔｉｃｓ ａｔ ａ ｖｉｓｃｏｕｓ ｉｍｍｉｓｃｉｂｌｅ ｌｉｑｕｉｄ／ｌｉｑｕｉｄ ｉｎｔｅｒｆａｃｅ ｂｙ ｍｅａｎｓ ｏｆ ｔｈｅ Ｌａｎｇｅｖｉｎ ｅｑｕａｔｉｏｎ，Ｅｌｅｃｔｒｏｃｈｉｍｉｃａ Ａｃｔａ ４１，Ｎｒ．１４，第２３２１頁〜第２３２７頁（１９９６）を参照されたい。場が外側からかけられず、かつ（エネルギー準位及び活性が両側で等しいことが必ずしも当てはまらない一般的なケースにおいて）電荷担体の拡散によってのみ電圧が生じる場合、ζは、界面での正規化された電圧であり、かつζ_eqは、正規化された電圧がとるその平衡値である。差ζ−ζ_eqは、正規化された過電圧である。界面での正規化された電圧に当てはめられるのは、

［式中、ｚは、電荷担体の電荷数である］である。本例においては、ｚ＝１である。Ｆは、ファラデー定数、Ｒは、気体定数、Ｔは、絶対温度であり、かつφ_1,2は、２つの隣接する媒質の電位差である。過電圧（φ₁−φ₂）−（φ₁−φ₂）_eqは、正規化された過電圧から

として得られる。 In order to obtain a current through the interface, for example K.K. Aoki, Theory of the transfer kinetics at a viscous immiscible liquid / liquid interface by men of the Langevinequation, Electro41. 14, pages 2321 to 2327 (1996), consider the Butler-Holmer equation. The entire disclosure of this document is incorporated herein by reference. It is then applied to the current through the interface

[Wherein the current density j ₀ is a constant depending on the charge carrier density and (exponentially) temperature, among others]. Therefore, in this regard, K.K. Aoki, Theory of the transfer kinetics at a viscous immiscible liquid / liquid interface by men of the Langevinequation, Electro41. 14, pages 2321 to 2327 (1996). If the field is not applied from the outside and the voltage is generated only by charge carrier diffusion (in the general case where the energy levels and activities are not necessarily equal on both sides), ζ is normalized at the interface Is the voltage, and ζ _eq is its equilibrium value taken by the normalized voltage. The difference ζ−ζ _eq is the normalized overvoltage. What is applied to the normalized voltage at the interface is

[Wherein z is the number of charges on the charge carrier]. In this example, z = 1. F is the Faraday constant, R is the gas constant, T is the absolute temperature, and φ _1,2 is the potential difference between two adjacent media. Overvoltage (φ ₁ −φ ₂ ) − (φ ₁ −φ ₂ ) _eq is calculated from normalized overvoltage

As obtained.

  The exponential equation (2) can be expanded to a quadratic term, for example.

となる。 in this case,

It becomes.

When the relative dielectric constants ε ₁ and ε ₂ coincide with each other, the reference value α = 1/2 is applied, and the Ohm's law is defined as interfacial conductivity by j ₀ · zF / (RT) or the reciprocal is a specific interface. Obtained as resistance. If ε ₁ is different from ε ₂ , ie α = 1/2 no longer applies, and therefore, depending on the sign of the overvoltage, α = 1/2 compared to the case of α = 1/2, depending on the sign of the overvoltage. Increased or decreased current, i.e. reduced or increased effective interfacial resistance is obtained (effective interfacial resistance is referred to as the quotient of overvoltage and current produced without regard to the linear relationship). Therefore, the linear region of curve j with respect to ζ-ζ _eq is reduced. For example, considering a three-layer structure with a solid electrolyte in the middle and two liquid electrolytes on both sides, in either case, an increased effective interfacial resistance occurs at one of the two interfaces. The magnitude of the effectiveness depends on the relationship with the voltage, i.e. on how far each overvoltage protrudes from the linear region. When a sufficiently large voltage is applied to the three-layer structure, the increased effective interface resistance at the interface is expressed as an increased effective resistance of the entire structure. Furthermore, it has been found that the extent of the linear region is temperature dependent. The higher the temperature, the smaller the quadratic term in (5) compared to the linear term.

In this case, the measured temperature dependence of j ₀ affects the measured interface resistance.

As the upper bound characterizing the boundary of the linear motion region, j reaches the maximum value depending on ζ-ζ _eq when the first and second order terms act on the right side of equation (5). A case is assumed. By fitting the values (Faraday constant 96485 C / mol, gas constant 8,314 J / (mol K)), a relationship arises between overvoltage and α in this case:

  At T = room temperature:

This means that the dielectric constants are very different and therefore only a small linear region is possible when α << 0.5. If there is a linear dependence of the current density j on the overvoltage, in this overvoltage linear region above 1 V, a value of α≈0.5, while at least α> 0.488, and thus ε ₁ is ε Nearly equal to ₂ .

  This interfacial resistance can be ascertained by measurement techniques, ie by impedance spectroscopy. In impedance spectroscopy, the interface impedance can be determined. This is because the interfacial impedance is based on the high capacitance associated with it and is separated from the volume impedances.

Therefore, according to the present invention, at least one first electrolyte layer characterized by a dielectric constant ε ₁ and at least one characterized by a dielectric constant ε ₂ intended for use in the room temperature region. An electrolyte having a multilayer structure is provided, comprising a further electrolyte layer, which has a reference value α at the interface of 0.244 <α ≦ 0.5, preferably 0.371α ≦ 0.5, particularly preferably 0.436 <α ≦ 0.5, more preferably 0.475 <α ≦ 0.5, particularly preferably 0.488 <α ≦ 0.5, still more preferably 0.49 <α ≦ 0.5. The electrolyte of one electrolyte layer and the electrolyte of the other electrolyte layer are selected to be in range, where ε ₁ is always the higher of the relative permittivity of the adjacent medium and ε ₂ is adjacent It is characterized by the higher relative dielectric constant of the medium To have. When the electrolyte includes a large number of electrolyte layers together with a large number of interfaces, where each interface has a dielectric constant, the reference value α _n = ε _1n / (ε _1n + ε _2n ) defined for each of the large numbers of interfaces. Imposes a requirement that the α _n value be in a predefined range. Highly preferred is when the α value is in the range of 0.436 <α ≦ 0.5, in particular 0.488 <α ≦ 0.5. In such a case, a linear region with a relatively large overvoltage is obtained in the interface region, where the overvoltage transitions up to 0.2V, preferably up to 1V.

In order to provide the largest possible linear operating range over the temperature range of at least −40 ° C. to + 85 ° C., preferably −70 ° C. to + 100 ° C., the temperature dependent value α _n is −40 ° C. to 85 ° C., ie 258 K to 383 K, preferably −70 ° C. to + 100 ° C., ie in the temperature range of 228 K to 398 K, up to 0.05 V, preferably up to 0.1 V, particularly preferably up to 0.2 V, very particularly preferably 0.5 V Inequality 0.5-0.256 ^* T / 298K <α _n ≦ 0.5 resulting from (6) by fitting the required linear region up to, more preferably up to 1V, and even more preferably up to 2V , Preferably 0.5-0.128 ^* T / 298K <α _n ≦ 0.5, particularly preferably 0.5-0.064 ^* T / 298K <α _n ≦ 0 0.5, very preferably 0.5-0.025 ^* T / 298K <α _n ≦ 0.5, more preferably 0.5-0.012 ^* T / 298K <α _n ≦ 0.5, still more preferably Is defined to satisfy 0.5−0.006 ^* T / 298K <α _n ≦ 0.5. In this case, T is applied to K in the temperature range indicated above. This requirement is not only imposed in the temperature region, but also in the frequency region where electrochemical storage energy devices are expected to be used. This is because the relative permittivity also depends on the frequency as described above.

Particularly preferred is the case where the first electrolyte having the first relative dielectric constant ε ₁ is a solid electrolyte and the other electrolyte having the second relative dielectric constant ε ₂ is a liquid electrolyte.

  The solid electrolyte is preferably a polymer with an inorganic material, in particular a glass material or a ceramic material, in particular a glass ceramic material, or a conductive filler, in particular a glass according to the invention or a powder or granules of the glass ceramic or ceramic according to the invention. Used.

  Highly preferred especially for applications in the area of electrochemical storage devices is a solid electrolyte containing Li, for example a system having a lithium aluminum germanium phosphate, lithium lanthanum zirconate or LiSICon crystalline phase, ie a lithium superionic conductor (LiSICon) is a system having a crystal phase.

As the liquid electrolyte, preferably a mixture of one or more non-aqueous solvents, in particular a carbonate-based solvent with at least one fluoride-based conductivity salt, preferably LiPF ₆ is used. Exemplary solvents include, for example, ethylene carbonate, butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), vinylene carbonate (VC), methyl ethyl carbonate (EMC), 1,2-dimethoxyethane (DME). 1,2-diethoxyethane (DEE), γ-butyrolactone (γ-BL), sulfolane, acetonitrile, N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), ethyl acetate (EA), 1, 3-dioxolane (DOL), tetrahydrofuran (THF), tetra (ethylene glycol) -dimethyl ether (TEGDME), tri (ethylene glycol) dimethyl (TEGD) are taken into account. The solvents can be used alone or as a suitable mixture. An exemplary mixture is an electrolyte mixture having an EC / DMC or EC to (DMC + EMC) ratio <1 in a 50/50 (mass%) ratio. LiPF ₆ can be used alone or in combination with other conductivity salts. Examples of the conductivity salt include LiBF ₄ , LiAsF ₆ , LiClO ₄ , LiB (C ₆ H ₅ ) ₄ , LiCH ₃ SO ₃ , LiCF ₃ SO ₃ , LiN (SO ₂ CH ₃ ) ₂ , LiC (SO ₂ CF ₃ ) ₃ , LiAlCl ₄ , LiSiF ₆ Li [(OCO) ₂ ] ₂ B, LiDFOB, LiCl and LiBr.

The concentration of the LiPF ₆ or conductivity salt mixture relative to the non-aqueous solvent is not limited, but is preferably 0.1 M (mol / dm ³ ) to 5.0 M (mol / dm ³ ), preferably 0.5 M ( mol / dm ³ ) to 3.0 M (mol / dm ³ ).

In addition to the electrolyte with interfacial resistance to the multilayer structure and the minimum, the present invention is at least characterized by at least one first electrolyte layer and the dielectric constant epsilon ₂ characterized by the dielectric constant epsilon ₁ 1 Also described is an electrochemical storage device, in particular a battery cell, comprising an electrolyte according to the invention having a multilayer structure with two further electrolyte layers, where the relative dielectric constant exhibits a reference value α of 0.244 to 0.5. It is in the range.

Particularly preferred is an electrochemical storage device comprising a total of three electrolyte layers, ie two liquid electrolyte layers and a solid electrolyte layer disposed between these liquid electrolyte layers, wherein 3 The dielectric constants ε ₁ , ε _{2 and} ε ₃ of the two electrolyte layers are such that they are approximately matched, thus providing an electrochemical storage device having the largest possible linear operating region and minimized interface resistance. Is selected.

  Below, although this invention is demonstrated in detail based on an Example and drawing, it is not limited to these.

Nyquist diagram of an electrolyte having a multilayer structure using lithium aluminum germanium glass ceramic as a solid electrolyte and propylene carbonate (PC) or 1,2-dimethoxyethane (DME) at −40 ° C. as a liquid electrolyte Figure showing Nyquist diagram of an electrolyte having a multilayer structure using lithium aluminum germanium glass ceramic as a solid electrolyte and propylene carbonate (PC) or 1,2-dimethoxyethane (DME) at −20 ° C. as a liquid electrolyte Figure showing A Nyquist diagram of an electrolyte having a multilayer structure using lithium aluminum germanium phosphate glass ceramic as a solid electrolyte and propylene carbonate (PC) or 1,2-dimethoxyethane (DME) as a liquid electrolyte at 0 ° C. Illustration A Nyquist diagram of an electrolyte having a multilayer structure using lithium aluminum germanium phosphate glass ceramic as a solid electrolyte and propylene carbonate (PC) or 1,2-dimethoxyethane (DME) at 20 ° C. as a liquid electrolyte. Illustration

  In FIGS. 1 a-1 d, two combinations of lithium aluminum germanium glass ceramic (LAGP) and liquid electrolyte (PC in some cases, DME in other cases) are shown as embodiments. This includes a three-layer structure, where the solid electrolyte LAGP is placed between two identical liquid electrolytes—in one case PC and in another case DME—. The conductivity salt is LiTFSl (1 mol per kg of solvent) in any case. Measurement of complex impedance using Novocontrol's Alpha analyzer (frequency range 0.01 Hz to 20 MHz) (using two measuring electrodes in two liquid electrolyte zones on one side and the other side of the solid electrolyte) With respect to the electrolyte having a multilayer structure, the generation and the magnitude of the volume resistance and interface resistance of the solid electrolyte were examined by the four-point measurement). The principle of the four-point measurement, like Mirko Hofmann, Integrated impedance spectroscopy of aerobic cell cultures in biotechnological high throughput screenings, thesis, RWTH Aachen, reference is made to the Faculty for Electrical Engineering and Information Technology, 2009.

  The relative dielectric constant of propylene carbonate (PC) is 64.4. In this regard, Fujinaga, K. et al. See Izutsu, “Propylene Carbonation and Tests for Purity, Pure and Applied Chemistry 27 No. 1 (1971), pp. 273-280”. This entire content is incorporated herein by reference. The relative dielectric constant of 1,2-dimethoxymethane (DME) is 7.2. In this regard, R.A. Montadi, M .; Matsu, I. et al. S. Arthur, S .; -J. Hwang, “Magnesium Boroidide: From Hydrogen Storage to Magnesium Battery”, Agewandte Chemie International Edition 51, No. 1 39 (2012), pages 9780 to 9783. This entire content is also incorporated into the present application by reference.

  In view of the temperature dependence of the interfacial resistance which decreases exponentially with temperature, the frequency dependent measurements that lead to the Nyquist diagram are carried out at different temperatures (40 ° C., −20 ° C., 0 ° C., 20 ° C., 1a-d Please refer to the figure below). The lowest temperature of -40 ° C is an important lower limit of the temperature scale for applications in the automotive range of -40 ° C to 85 ° C. The sample dimensions of an electrolyte with one liquid electrolyte layer / one solid electrolyte layer / one liquid electrolyte layer are 2 mm high and 7.65 mm in diameter.

  Trajectory 1 (Nyquist diagram) measured at −40 ° C. shows two strongly overlapping semicircles 10 and 12 at high frequencies and a semicircle 14.1 (liquid electrolyte) more strongly separated from the other two at low frequencies. DME), 14.2 (liquid electrolyte PC). The measurement voltage is 0.1V.

  From the evaluation by the Nyquist diagram, the following resistance values or capacitance values are obtained for these three semicircles.

  The third semicircles 14.1, 14.2 represent the interface resistance. As can be derived from the different trajectories of the Nyquist diagram in FIGS. 1a-1d for the combination of liquid electrolyte DME / solid electrolyte LAGP / liquid electrolyte DME (trajectory 100) and liquid electrolyte PC / solid electrolyte LAGP / liquid electrolyte PC (trajectory 200), The locus 200 has a semicircle 14.2 that is more strongly separated, that is, has a higher interface resistance, and has a stronger effect of reducing the current than the locus 100. This is also represented by the parameter α according to the invention. Thus, α = 0.395 is obtained for the DME / LAGP electrolyte pair. For the PC / LAGP electrolyte pair, α = 0.145 is obtained. In the first case, α is close to 0.5 and thus in the linear region, and in the second case it is much lower. The interfacial resistance is severely increased, especially in cases where PC / LAGP is ineligible.

  When the dielectric constant is adapted according to the present invention-this is in this case by adapting the liquid electrolyte to the solid electrolyte and selecting DME for a suitable solvent, ie the solid electrolyte LAGP. Achieved-low interfacial resistance is obtained. This is represented by an α value close to 0.5.

  In yet another embodiment, although no Nyquist diagram was obtained, the solid electrolyte is LLZO (lithium lanthanum zirconate). The value of the relative dielectric constant of the solid electrolyte LLZO is 22.4. In order to adjust α to the range according to the invention, a mixture of PC and DME as solvent is selected as the liquid electrolyte, and the dielectric constant is adjusted to 22.4. The relative dielectric constant of the mixture is the average of the individual dielectric constants weighted by the mole fraction.

Therefore, the mixture of PC and DME consists of 0.266 parts or 26.6 mol% PC and 0.734 parts or 73.4 mol% DME. This is because 0.266 ^* 64.4 + 0.734 ^* 7.2 = 22.4. Instead, for example, when 28 mol% PC and 72 mol% DME are mixed, a liquid electrolyte relative dielectric constant of 23.216 is obtained. At that time, the α value is 0.491. As a further example, when 35 mole% PC and 65 mole% DME are mixed, a liquid electrolyte dielectric constant of 27.22 is obtained. At that time, the α value is 0.451.

  Conversely, when the relative permittivity of the solid electrolyte is adapted to the liquid electrolyte, this is done by selecting an appropriate solid electrolyte.

  The present invention provides an unexpected result that can be seen from the embodiment that even in a partially crystalline solid electrolyte, the interfacial resistance to the liquid electrolyte can be minimized by simple adaptation of the dielectric constant. It is done.

を規定し、並びに
− 前記第一の電解質層の電解質及び前記第二の電解質層の電解質は、前記界面での前記基準値αが、０．２４４＜α≦０．５、好ましくは０．３７１＜α≦０．５、とりわけ好ましくは０．４３６＜α≦０．５、さらに好ましくは０．４７５＜α≦０．５、殊に好ましくは０．４８８＜α≦０．５、さらになお好ましくは０．４９４＜α≦０．５の範囲にあるように選択され、ここで、常に、ε ₁ は隣接する媒質の比誘電率の低い方であり、かつε ₂ は隣接する媒質の比誘電率の高い方であることを特徴とする、前記電解質。
［実施態様２］
前記電解質が、多数の電解質層を多数の界面とともに有し、ここで、多数ｎの各界面で規定される基準値

について、前記界面での前記基準値α _n が、０．２４４＜α _n ≦０．５、好ましくは０．３７１＜α _n ≦０．５、とりわけ好ましくは０．４３６＜α _n ≦０．５、さらに好ましくは０．４７５＜α _n ≦０．５、殊に好ましくは０．４８８＜α _n ≦０．５、さらになお好ましくは０．４９４＜α _n ≦０．５の範囲にあることが成立し、ここで、常に、ε _1n は隣接する媒質の比誘電率の低い方であり、かつε _2n は隣接する媒質の比誘電率の高い方であることを特徴とする、実施態様１記載の電解質。
［実施態様３］
前記基準値α _n が、すべての界面ｎで実質的に同じであることを特徴とする、実施態様２記載の電解質。
［実施態様４］
前記第一の電解質層の電解質が固体電解質であり、かつ前記第二の電解質層の電解質が液体電解質であることを特徴とする、実施態様１から３までのいずれか１項記載の電解質。
［実施態様５］
前記基準値α又は前記基準値α _n が、２５８Ｋ〜３８３Ｋ、好ましくは２２８Ｋ〜３９８Ｋの温度範囲のすべての温度Ｔにおいて、０．５−０．２５６ ^* Ｔ／２９８Ｋ＜α≦０．５、好ましくは０．５−０．１２８ ^* Ｔ／２９８Ｋ＜α≦０．５、とりわけ好ましくは０．５−０．０６４ ^* Ｔ／２９８Ｋ＜α≦０．５、極めて好ましくは０．５−０．０２５ ^* Ｔ／２９８Ｋ＜α≦０．５、さらに好ましくは０．５−０．０１２ ^* Ｔ／２９８Ｋ＜α≦０．５、さらになお好ましくは０．５−０．００６ ^* Ｔ／２９８Ｋ＜α≦０．５の範囲であることを特徴とする、実施態様１から４までのいずれか１項記載の電解質。
［実施態様６］
前記固体電解質が、以下の材料：
− 無機材料、とりわけ
− ガラス材料又は
− ガラスセラミック材料又は
− セラミック材料
− 並びに有機材料、とりわけ導電性充填剤を備えたポリマー
の１つを有することを特徴とする、実施態様４又は５記載の電解質。
［実施態様７］
前記固体電解質が、Ｌｉ、とりわけリン酸リチウムアルミニウムゲルマニウム、ジルコン酸リチウムランタン、又はリチウム超イオン伝導体（ＬｉＳＩＣｏｎ）結晶相を有する系を含むことを特徴とする、実施態様６記載の電解質。
［実施態様８］
前記液体電解質が、１種以上の非水系溶媒の混合物、とりわけ少なくとも１種のフッ化物系の電導度塩、好ましくはＬｉＰＦ ₆ を有するカーボネート系溶媒であることを特徴とする、実施態様４から７までのいずれか１項記載の電解質。
［実施態様９］
実施態様１から８までのいずれか１項記載の多層構造を有する電解質を含む電気化学エネルギー貯蔵デバイス、とりわけバッテリーセル。
［実施態様１０］
前記バッテリーセルが、少なくとも３つの電解質層、すなわち、２つの液体電解質層及びこれら２つの電解質層の間に配置された１つの固体電解質層を含むことを特徴とする、実施態様９記載の電気化学エネルギー貯蔵デバイス。 The invention shows for the first time a range of dielectric constants, within which the interfacial resistance is minimized in the multilayer electrolyte and especially when voltage is applied over a wide temperature range of −40 ° C. to + 85 ° C. The linear behavior of the current profile through the interface can be expected to be voltage dependent.
The following describes embodiments of the present invention:
[Embodiment 1]
At least one first electrolyte layer characterized by a _first dielectric constant ε ₁ ;
At least one second electrolyte layer characterized by a _second dielectric constant ε ₂ ;
The interface between the first electrolyte layer and the second electrolyte layer;
In an electrolyte having a multilayer structure, including
The first relative permittivity ε ₁ and the second relative permittivity ε ₂ are the reference value α

As well as
The reference value α at the interface of the electrolyte of the first electrolyte layer and the electrolyte of the second electrolyte layer is 0.244 <α ≦ 0.5, preferably 0.371 <α ≦ 0. 5, particularly preferably 0.436 <α ≦ 0.5, more preferably 0.475 <α ≦ 0.5, particularly preferably 0.488 <α ≦ 0.5, still more preferably 0.494 <. α ≦ 0.5, where ε ₁ is always the lower relative dielectric constant of the adjacent medium and ε ₂ is the higher relative dielectric constant of the adjacent medium. The electrolyte is characterized in that it is present.
[Embodiment 2]
The electrolyte has a large number of electrolyte layers together with a large number of interfaces, where a reference value defined by a large number n of interfaces.

The reference value α _n at the interface is 0.244 <α _n ≦ 0.5, preferably 0.371 <α _n ≦ 0.5, particularly preferably 0.436 <α _n ≦ 0.5. More preferably, 0.475 <α _n ≦ 0.5, particularly preferably 0.488 <α _n ≦ 0.5, still more preferably 0.494 <α _n ≦ 0.5. Embodiment 1 , wherein ε _1n is always the lower relative dielectric constant of the adjacent medium and ε _2n is the higher relative dielectric constant of the adjacent medium. Electrolyte.
[Embodiment 3]
The electrolyte according to embodiment 2, characterized in that the reference value α _n is substantially the same at all interfaces n.
[Embodiment 4]
4. The electrolyte according to any one of embodiments 1 to 3, wherein the electrolyte of the first electrolyte layer is a solid electrolyte, and the electrolyte of the second electrolyte layer is a liquid electrolyte.
[Embodiment 5]
The reference value α or the reference value α _n is 0.5−0.256 ^* T / 298K <α ≦ 0.5, preferably at all temperatures T in the temperature range of 258K to 383K, preferably 228K to 398K ^. 0.5-0.128 ^* T / 298K <α ≦ 0.5, particularly preferably 0.5-0.064 ^* T / 298K <α ≦ 0.5, very particularly preferably 0.5-0.025. ^* T / 298K <α ≦ 0.5, more preferably 0.5-0.012 ^* T / 298K <α ≦ 0.5, still more preferably 0.5-0.006 ^* T / 298K <α ≦ 5. The electrolyte according to claim 1, wherein the electrolyte is in the range of 0.5.
[Embodiment 6]
The solid electrolyte is made of the following materials:
-Inorganic materials, especially
-Glass material or
-Glass ceramic material or
-Ceramic materials
-And organic materials, in particular polymers with conductive fillers
6. The electrolyte according to embodiment 4 or 5, characterized in that it has one of the following:
[Embodiment 7]
Embodiment 7. The electrolyte according to embodiment 6, characterized in that the solid electrolyte comprises a system having Li, in particular lithium aluminum germanium phosphate, lithium lanthanum zirconate, or a lithium superionic conductor (LiSICon) crystal phase.
[Embodiment 8]
Embodiments 4 to 7 characterized in that the liquid electrolyte is a mixture of one or more non-aqueous solvents, in particular a carbonate-based solvent with at least one fluoride-based conductivity salt, preferably LiPF _6. The electrolyte according to any one of the above.
[Embodiment 9]
9. An electrochemical energy storage device, in particular a battery cell, comprising an electrolyte having a multilayer structure according to any one of embodiments 1-8.
[Embodiment 10]
10. Electrochemistry according to embodiment 9, characterized in that the battery cell comprises at least three electrolyte layers, i.e. two liquid electrolyte layers and one solid electrolyte layer arranged between the two electrolyte layers. Energy storage device.

Claims (10)

At least one first electrolyte layer characterized by a _first dielectric constant ε ₁ ;
At least one second electrolyte layer characterized by a _second dielectric constant ε ₂ ;
-An electrolyte having a multilayer structure including an interface between the first electrolyte layer and the second electrolyte layer;
The first relative permittivity ε ₁ and the second relative permittivity ε ₂ are the reference value α

And-the electrolyte of the first electrolyte layer and the electrolyte of the second electrolyte layer are such that the reference value α at the interface is in a range of 0.244 <α ≦ 0.5. Where ε ₁ is always the lower relative permittivity of the adjacent medium, and ε ₂ is the higher relative permittivity of the adjacent medium, and the first relative permittivity ε _The electrolyte according to claim ₁ , wherein the material having ₁ and the material having the second relative dielectric constant ε ₂ have different materials. The electrolyte has a large number of electrolyte layers together with a large number of interfaces, where a reference value defined by a large number n of interfaces.

It is established that the reference value α _n at the interface is in the range of 0.244 <α _n ≦ 0.5, where ε _1n is always the one with the lower relative dielectric constant of the adjacent medium The electrolyte according to claim 1, wherein ε _2n is the higher relative dielectric constant of the adjacent medium. The electrolyte according to claim 2, wherein the reference value α _n is substantially the same at all interfaces n.   The electrolyte according to any one of claims 1 to 3, wherein the electrolyte of the first electrolyte layer is a solid electrolyte, and the electrolyte of the second electrolyte layer is a liquid electrolyte. The reference value α or the reference value α _n is in a range of 0.5−0.256 ^* T / 298K <α ≦ 0.5 at all temperatures T in the temperature range of 228K to 398K ^. The electrolyte according to any one of claims 1 to 4. The solid electrolyte is made of the following materials:
5. Electrolyte according to claim 4 , characterized in that it comprises one of a polymer with an electrically conductive filler , as an inorganic material, as a glass material or as a glass ceramic material or as a ceramic material and as an organic material. Wherein the solid electrolyte, characterized in that it comprises a L i, claim 6 electrolyte according. The electrolyte according to any one of claims 4 , 6, and 7, wherein the liquid electrolyte is a mixture of one or more non-aqueous solvents. Having a multilayer structure of any one of claims 1 to 8 containing an electrolyte, electrochemical energy storage device is a battery cell.   10. Electricity according to claim 9, characterized in that the battery cell comprises at least three electrolyte layers, i.e. two liquid electrolyte layers and one solid electrolyte layer arranged between the two liquid electrolyte layers. Chemical energy storage device.

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