KR20150134287A - Electrolyte with multilayer structure and electrical storage device - Google Patents

Abstract

According to the present invention, - At least one first electrolyte layer characterized by a first relative permittivity? 1, - At least one second electrolyte layer characterized by a second relative dielectric constant? 2, and - The interface between the first electrolyte layer and the second electrolyte layer An electrolyte having a multi-layer structure, - The first relative dielectric constant? 1 and the second relative dielectric constant? 2 define the following measure, - The electrolyte of the first electrolyte layer and the electrolyte of the second electrolyte layer have a scale in the interface of 0.244 <0.5, preferably 0.371 <0.5, particularly preferably 0.436 <0.5, more preferably 0.475 <0.5, 0.488 < 0.5, and still more preferably 0.494 < 0.5, wherein? 1 is always the lower one of the relative permittivities of the adjacent medium and? To the electrolyte.

Description

ELECTROLYTE WITH MULTILAYER STRUCTURE AND ELECTRICAL STORAGE DEVICE [0002]

The present invention relates to an electrolyte having a multilayer structure, and an electrochemical storage device, particularly a battery cell, comprising such an electrolyte. Multilayer electrolytes are of particular interest in lithium-ion batteries.

The layer-by-layer structure of the electrolyte for a lithium ion battery may consist of a plurality of layers of liquid and / or solid electrolyte. In particular, such a structure may comprise two layers of liquid electrolyte (not necessarily the same composition) and a central layer of solid electrolyte as a separator.

Examples of liquid electrolytes include a mixture of ethylene carbonate and ethyl methyl carbonate (EC and EMC) and lithium hexafluorophosphate (LiPF ₆ ) as a conductive salt, as well as propylene carbonate and ethylene glycol dimethyl ether (PC and DME) and a conductive salt And lithium bis (trifluoromethylsulfonyl) imide (LiTFSI). Ethylene glycol dimethyl ether is also referred to as 1,2-dimethoxyethane, and for this, the abbreviation DME is sometimes chosen.

Examples of solid electrolytes include garnet-like systems such as:

Li _{7 + xy} M ^II _x M ^III _3-x M ^IV _2-y M _y ^V ₁₂ ,

In this formula,

M &lt; ^II &gt; is a divalent cation,

M ^III is a trivalent cation,

M ^IV is a tetravalent cation,

M ^V is a pentavalent cation,

E.g,

Lithium lanthanum zirconate Li _7-3x Al _x La ₃ Zr ₂ O ₁₂ or

Li _{7 - x} La ₃ (Ta / Nb) _x Zr _{2 - x} O ₁₂ . Further examples are so-called LiSiCon- crystal phase ^{_{Li 1 - x (M 5+,}} M 3+) and a system having an ^{_{x M 4 + 2-x (}} PO 4) 3, where M is ₅₊ Ta and / or Nb, M ³ + may be Al, Cr, Ga, Fe, and M ⁴ + may be Ti, Zr, Si, Ge. The use of sulfidic electrolytes is also possible.

With regard to the structure of these systems and related materials, Jennifer L. Schaefer, Yingying Lu, Surya S. Moganty, Praveen Agarwal, N. Jayaprakash, Lynden A. Archer, Electrolytes for high-energy lithium batteries, Appl. Nanosci. 2 (2012), p. 91-109], as well as DE 102 011 013 018 B3, US 2003 0205467 A1, US 2009 0317724.

Sulfide containing systems are described, for example, in US 2005 0107239 A1, US 2009 159839 A or JP 2008 120666 A.

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

It is not known in the prior art how this interfacial resistance can be systematically minimized.

Polymer electrolytes are known from EP 1134758 A1, which has side chains with large dipole moments. The resulting relative permittivity according to EP 1134758 A1 increases the ionic conductivity of the conductive salt dissolved in the polymer matrix. Furthermore, it is stated that this side chain reduces the interfacial resistance to the electrode to the same order as known from the liquid electrolyte. It is suggested that this is because of better chemical cohesion of the electrode and the electrolyte.

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

Lithium ion cells having LAGP as a solid electrolyte and ethylene carbonate: diethylene carbonate: ethyl methyl carbonate 1: 1: 1 as a liquid electrolyte were prepared according to the method described in Tonghuan Yang, Lin Sang, Fei Ding, Jing Zhang, Xingjiang Liu: Three- and four -electrode EIS analysis of water stable lithium electrode with solid electrolyte plate. In: Electrochimica Acta 81, 2012, pp. 179-185. - ISSN 0013-4686.

US 2006/01334492 describes an electrolyte having two layers of the same electrolyte.

An object of the present invention is to eliminate the disadvantages of the prior art and to specify what conditions must be satisfied in an electrolyte having a multilayer structure in order to achieve the lowest possible interface resistance.

0.5, 그러나 적어도 α > 0.436, 특히 α > 0.488, 즉 0.436 < α ≤ 0.5, 바람직하게는 0.488 < α ≤ 0.5의 범위 내인 경우가 특히 바람직하다. 이러한 거의 동일한 유전율의 경우, 비교적 넓은 범위의 0.2 V, 특히 1 V의 과전압이 상이한 전해질들의 계면 범위에서 달성된다. According to the present invention, this object is solved by the use of an electrolyte composition comprising at least one first electrolyte layer characterized by a first relative dielectric constant epsilon 1 and at least one additional electrolyte layer characterized by a second relative dielectric constant epsilon 2, Wherein the two relative permittivities? 1 and? 2 define a measure? =? 1 / (? 1 +? 2), and one The electrolyte of the electrolyte layer and the electrolyte of the other electrolyte layer have a scale of? 0.244 <?? 0.5, preferably 0.371 <? 0.5, particularly preferably 0.436 <? 0.5, very particularly preferably 0.475 < ≤ 0.5, more preferably 0.488 <α ≤ 0.5, even more preferably 0.494 <α ≤ 0.5, where ε 1 is always the lower of the relative permittivity of the adjacent medium and ε 2 is the relative dielectric constant of the adjacent medium Of the high side. This solution is not limited to a combination of a liquid electrolyte and / or a polymer and clearly includes inorganic materials such as glass, glass ceramic or (polycrystalline) ceramic. alpha value is alpha

0.5, but at least α> 0.436, in particular α> 0.488, that is, 0.436 <α ≤ 0.5, preferably 0.488 <α ≤ 0.5. For these nearly equal permittivities, a relatively wide range of 0.2 V, especially 1 V, overvoltages are achieved in the interface range of different electrolytes.

The present inventors have concretely understood that, in the case of an electrolyte having a multi-layer structure, adjacent electrodes can be understood as a dielectric continuum having a conductive salt or a conductive oxide distributed therein even if they comprise glass, glass ceramic or ceramic . This is particularly surprising because, in the case of partially crystalline structures, individual atomic framework structures play a major role and a continuum description is not expected. Also in this case, that is, when one or both of the two adjacent electrolytes are glass, glass ceramic, or ceramic, the relative dielectric constant of both electrolytes is preferably selected to be preferably the same value. Since the relative dielectric constant is temperature and frequency dependent, the selection is made for a particular working point or working range, i.e. for a specific frequency and / or for a specific temperature or frequency and / or temperature range.

However, the frequency-dependent variation of the relative permittivity of the matrix material described as background, that is, the dielectric continuum is generally limited to the individual frequency range. Charles Kittel, Introduction to solid-state physics, 5th edition, R. Oldenbourg-Verlag Munich Vienna, 1980, p. 441], as well as Ekaterina I. Izgorodina, Maria Forsyth, and Douglas R. MacFarlane, "On the components of the dielectric constants of ionic liquids ", Phys. Chem. Chem. Phys. 11, 2452-2458 (2009)], the contribution to the relative dielectric constant is first made by the electron polarization, i.e., the displacement of the electron shell to the core, as it goes from the higher side to the lower side of the frequency scale , Then the ionic polarization, that is, the displacement of the atoms with the partial charges of different sign to each other, followed by the dipole polarization, that is, the alignment of the permanent dipole and then the space charge polarization, As shown in FIG. The last is the ion conduction effect and therefore does not belong to the background mentioned above.

In ion conductors made of glass, glass ceramics or ceramics, only the first two contributions and the last one work. In order not to include the last, go from the top to the bottom of the frequency scale, as long as both the electron polarization and the ionic polarization are considered. This is the case under the infrared range and is described in Charles Kittel, Introduction to solid-state physics, 5th edition, R. Oldenbourg-Verlag Munich Vienna, 1980, p. 441], as well as Ekaterina I. Izgorodina, Maria Forsyth, and Douglas R. MacFarlane, "On the components of the dielectric constants of ionic liquids ", Phys. Chem. Chem. Phys. 11, 2452-2458 (2009). The relative dielectric constant is almost constant up to the frequency at which the space charge effect is started. This value is used as the relative dielectric constant of the background. In this case, for example, the electronic conductivity of the conductive salt or the conductive oxide is also naturally included; However, this factor is ignored for ion conductors made of glass, glass ceramics or ceramics which can not be easily produced without a conductive salt or a conductive oxide.

In the case of liquid electrolytes or polymer electrolytes which can be produced without conducting salts or conducting oxides, a nearly constant value found below the frequency range of dipole polarization (calculated from top to bottom) "switches on" . For polymer electrolytes that can not be produced without a conductive salt or a conductive oxide, the occasionally narrow frequency window between the frequency range of dipole polarization (which is calculated from top to bottom) and the point of space charge polarization must be used .

For example, in the case of a lithium ion battery, the energy level of ions providing charge transport of lithium ions on both sides can be initially measured, if there is an ideal case according to the present invention having the same relative dielectric constant on both sides of the interface.

Assuming that the energy level of these ions is determined solely by the dielectric and that the interaction with other ions, especially counter ions, can be neglected, if the external voltage is absent, the same activity on both sides of the interface, Is also located at the same energy level, which is roughly determined by the Born formula for free solvation enthalpy. In this regard, reference is made to M. M. Born, Volume and hydration heat of ions, Zeitschrift fuer Physik, No. 1, p. 45-48 (1920), the contents of which are incorporated herein by reference in their entirety.

When an additional voltage difference is applied to the multilayer electrolyte layer from the outside, for example, in K. Aoki, Theory of the ion transfer kinetics at a viscous immiscible liquid / liquid interface by means of the Langevin equation, Electrochimica Acta 41, No. 14, p. 2321-2327 (1996), this results in the voltage decreasing in the thin boundary layer on both sides of the interface, where it induces ion transport in inverse proportion to the interfacial resistance.

When the continuity of the relative dielectric constant is applied to the region of the boundary layer, the discontinuous portion of the electric field does not occur at the interface, which is preferable for the minimum interface resistance. In this connection, the above cited document [K. Aoki]. In an ideal case of an electrolyte having a multi-layer structure, the combination of different electrolytes, for example, liquid and solid electrolytes, is equally selected for all two related materials (or three materials in the case of different liquid electrolytes). The measurement of the relative dielectric constant can be performed, for example, in accordance with " Application Note 1369-1 " of October 28, 2008, Agilent, Santa Clara, CA. The disclosure of which is incorporated herein by reference in its entirety.

The scale?

(1)

(One)

Is used as a measure of the degree of agreement of the dielectric constant or dielectric constant. According to the present invention,? 1 is the lower one of the two relative permittivities involved, and? 2 is the higher one. For an ideal case of coincidence of ε1 and ε2, the scale is α = ½, and when ε₁ and ε₂ are different, α becomes smaller.

It is particularly preferable when the material having the first and second permittivities? 1 and? 2 includes different materials, preferably a solid electrolyte and a liquid electrolyte.

To obtain current through the interface, for example, see K. Aoki, Theory of the ion transfer kinetics at a viscous immiscible liquid / liquid interface by means of the Langevin equation, Electrochimica Acta 41, No. 14, p. The Butler-Volmer equation is analyzed as described in &lt; RTI ID = 0.0 &gt; J. &lt; / RTI &gt; 2321-2327 (1996). The disclosure of which is incorporated herein by reference in its entirety. For current through the interface, the following equation applies:

(2)

(2)

는 계면에서의 정규화된 전압이고,

_eq는 장이 외부에서 가해지지 않고 전압이 오직 (양측의 에너지 준위 및 활동도의 동등성이 유지될 필요는 없는 일반적인 경우에) 전하 수송체의 확산으로 인하여 수립될 때 정규화된 전압이 얻는 이의 평형 값이다. 차

-

_eq는 정규화된 과전압이다. 계면에서 정규화된 전압에 대하여, 이하의 식이 적용된다:Where the current density j ₀ is a constant, which depends in particular on the charge carrier density and (exponentially) temperature. In this regard, reference is made to 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, p. 2321-2327 (1996).

Is the normalized voltage at the interface,

_eq is the equilibrium value of the normalized voltage obtained when the field is not externally applied and the voltage is only established due to the diffusion of the charge carrier (in the general case where the energy level and activity equivalence of both sides need not be maintained) . car

-

_eq is the normalized overvoltage. For a normalized voltage at the interface, the following equation applies:

(3)

(3)

Where z is the charge number of the charge carrier. In the present embodiment, z = 1. F is the paradigm constant, R is the gas constant, T is the absolute temperature, and Φ _{1 , 2} is the potential in which the two adjacent media are present. The overvoltage (Φ ₁ - Φ ₂ ) - (Φ ₁ - Φ ₂ ) _eq is obtained from the normalized overvoltage as follows:

(4)

(4)

The exponential formula (2) can be expanded, for example, by a second order. This is as follows:

(5)

(5)

-

_eq에 대한 j의 커브의 선형 범위는 감소된다. 예를 들어, 3층 구조가 예를 들어 중앙의 고체 전해질과 양측의 두 개의 액체 전해질로 고려되는 경우, 각 경우 증가된 유효 계면 저항은 두 계면 중 하나에 영향을 미친다. 그 영향이 얼마나 큰지는 전압 관계(voltage relationship), 즉 각 과전압이 선형 범위로부터 얼마나 초과되는지에 의존한다. 3층 구조에 충분히 큰 전압이 인가되는 경우, 계면에서 증가된 유효 계면 저항은 전체 구조의 증가된 유효 저항으로 표현된다. 본 발명자들은 또한 선형 범위의 확대가 온도 의존적임에 주목하였다. 온도가 높을수록, 식 (5)의 이차항은 일차항에 비해 작아진다. In the case where the relative dielectric constants epsilon 1 and epsilon 2 coincide, the scale is obtained by reciprocal as j ₀ · zF / (RT) as the interface conductivity or the specific interfacial resistance as the scale α = ½ . If ε₁ is different from ε₂, then it is no longer α = ½, and due to the additional term not zero, it is possible to obtain an increased or reduced current, ie a reduced or increased effective An effective interfacial resistance is obtained (the present inventors denote the quotient of the formed current and the overvoltage irrespective of the linear relationship as effective interface resistance). therefore

-

The linear range of the curve of j for _eq is reduced. For example, when a three-layer structure is considered, for example, as a solid electrolyte at the center and two liquid electrolytes at both sides, the increased effective interface resistance in each case affects one of the two interfaces. How large the effect is depends on the voltage relationship, ie how much each overvoltage is from the linear range. When a sufficiently large voltage is applied to the three-layer structure, the effective interface resistance increased at the interface is expressed as the increased effective resistance of the entire structure. The present inventors have also noted that the expansion of the linear range is temperature dependent. The higher the temperature, the smaller the quadratic term in Eq. (5) becomes.

For the measured interfacial resistance, the above-mentioned temperature dependence of j ₀ also works.

-

_eq의 함수로서의 j가 최대에 도달하는 경우가 가정된다. 값(파라데이 상수 96485 C/mol, 기체 상수 8.314 J/(mol K))의 치환은 이 경우에서의 과전압과 α 사이의 관계를 제공한다:As an upper limit characterizing the constraint of the linear working range, in the opposite operation of the first order term and the second order term of the right side of equation (5)

-

_It is assumed that j as a function of _eq reaches a maximum. Substitution of the value (paradise constant 96485 C / mol, gas constant 8.314 J / (mol K)) provides the relationship between overvoltage and α in this case:

(6)

(6)

T = room temperature is given as follows:

Table 1

The approximate linearity of the current-voltage curve should be given as the minimum value of a as a function of the overvoltage range

0.5이거나 적어도 α > 0.488이며, 따라서 ε₁는 ε₂와 거의 같다. This means that for very different relative dielectric constants and therefore for << 0.5, only a very small linear range is possible. If there is a linear dependence of the current density j on the overvoltage, then in the linear range of the overvoltage above 1 V,

0.5 or at least α> 0.488, so ε₁ is almost equal to ε₂.

Interfacial resistance is available in measurement techniques and specifically using impedance spectroscopy. In impedance spectroscopy, the interface impedance can be measured as the interfacial impedance is separated from the volumetric impedance due to the high associated capacitance.

Therefore, according to the present invention, there is provided an electrolyte solution for use in a room temperature range, which has a multilayer structure including at least one electrolyte layer characterized by a relative dielectric constant epsilon 1 and at least one additional electrolyte layer characterized by a relative dielectric constant & , The electrolyte of one electrolyte layer and the electrolyte of the additional electrolyte layer have a scale of? 0.244 <?? 0.5, preferably 0.371?? <0.5, particularly preferably 0.436 <?? 0.5, 0.475 < / = 0.5, even more preferably 0.488 < / = 0.5, and still more preferably 0.49 < / = 0.5, The relative permittivity of the adjacent medium is always the lower one and the higher one is the higher. When the electrolyte contains a plurality of electrolyte layers having a plurality of interfaces, wherein each of the interfaces has a relative dielectric constant, the scale? _N = ε 1 _n / (ε 1 _n + ε 2 _n ), the condition must be imposed so that the value α _n is within the above-defined constraint. It is most preferable that the value of alpha is in the range of 0.436 < alpha &lt; 0.5, especially 0.488 &lt; alpha &lt; 0.5. In this case, a relatively large linear range overvoltage is achieved in the interface region where the overvoltage linearly flows up to 0.2 V, preferably to 1 V.

In order to provide the largest linear working range possible over the temperature range of at least -40 ° C to + 85 ° C, preferably -70 ° C to + 100 ° C, a temperature range of from -40 ° C to + 85 ° C, , The temperature dependent value of? _N over the temperature range of -70 DEG C to +100 DEG C, i.e. 228K to 398K, is in the range of 0.5 to 0.256 * T / 298K &lt;? _N ? 0.5, preferably 0.5 to 0.128 * T / 298K <? _N ? 0.5, particularly preferably 0.5-0.064 * T / 298K <? _N ? 0.5, very particularly preferably 0.5-0.025 * T / 298K <? _N ? 0.5, more preferably 0.5-0.012 * T / 298K <? _N ? 0.5, more preferably 0.5-0.006 * T / 298K <? _N <0.5, which is 0.05 V or less, preferably 0.1 V or less, particularly preferably 0.2 V or less, Very particularly preferably not more than 0.5 V, more preferably not more than 1 V, even more preferably not more than 2 V, Emitter is obtained. In this case, T is inserted at the specified temperature of the unit K. This requirement applies not only to the temperature range but also to the frequency range in which the electrochemical energy storage device is used, since the relative dielectric constant is also frequency dependent as indicated above.

It is particularly preferable that the first electrolyte having the first permittivity? 1 is a solid electrolyte and the other electrolyte having a second permittivity? 2 is a liquid electrolyte.

Preferably a glass material or a ceramic material, in particular a polymer material provided with a glass ceramic material or a conductive filler, in particular a glass according to the invention or a powder or granular material made from glass ceramics or ceramics according to the invention, .

Particularly in applications in the field of electrochemical energy storage devices, solid electrolytes containing Li, such as lithium aluminum germanium phosphate, lithium lanthanum succinate or LiSICon crystal phases, i.e., lithium super ionic conductor, LiSICon) crystal phase is very particularly preferred.

It is preferable that a carbonate-containing solvent having a mixture of at least one non-aqueous solvent, particularly at least one fluoride conductive salt, preferably LiPF ₆ , is used as the liquid electrolyte. Examples of the solvent include ethylene carbonate, butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), vinylene carbonate (VC), methyl ethyl carbonate (EMC), 1,2-dimethoxyethane ), 1,2-diethoxyethane (DEE),? -Butyrolactone (? -BL), sulfolane, acetonitrile, N-methyl-2-pyrrolidone (NMP), dimethylsulfoxide (TEGD) as an illustrative solvent, such as ethyl acetate (EA), 1,3-dioxolane (DOL), tetrahydrofuran (THF), tetra (ethylene glycol) -dimethyl ether do. The solvent may be used alone or as a suitable mixture. An exemplary mixture is an electrolyte mixture with a ratio of EC / DMC of 50/50 (wt.%) Or EC of (DMC + EMC) <1. LiPF ₆ may be used alone or in combination with other conductive salts. The latter example _{LiBF4, LiAsF 6, LiClO 4,} LiB (C 6 H 5) 4, Li CH 3, SO 3, Li CF3 SO3, Li N (SO 2 CF 3) 2, Li C (SO 2 CF 3 ) ₃ , LiAlCl ₄ , LiSiF ₆ Li [(OCO) ₂ ] ₂ B, LiDFOB, LiCl, and LiBr.

Non-aqueous LiPF ₆ or the concentration of conductive salt mixture ruthless the solvent is 0.1 M (mol / dm ³⁾ to ^{5.0 M (mol / dm 3)} , preferably from 0.5 M (mol / dm ³⁾ to 3.0 M (mol / dm ³ ), But is not limited thereto.

In addition to the electrolyte having a multilayer structure and a minimized interface resistance, the present invention also provides a multilayer structure having at least one electrolyte layer characterized by a relative dielectric constant epsilon 1 and at least one additional electrolyte layer characterized by a relative dielectric constant [epsilon] Wherein the relative permittivity is within a specified range of the scale a of 0.244 to 0.5.

An electrochemical energy storage device comprising three electrolyte layers as a whole, that is, an electrochemical energy storage device including two liquid electrolyte layers and a solid electrolyte layer disposed between the liquid electrolyte layers is particularly preferable, wherein the relative dielectric constants epsilon 1, epsilon 2, Ε3 are chosen such that they are substantially coinciding and thus provide the electrochemical energy storage device with the largest possible linear working range and minimized interface resistance.

The invention will be described in detail in the following description without being limited by reference to the exemplary embodiments and the drawings.

In the drawing:
1A to 1D show a Nyquist diagram of an electrolyte having a multilayer structure using lithium aluminum germanium phosphate glass ceramic as a solid electrolyte. (PC) or 1,2-dimethoxyethane (DME) at different temperatures of -40 DEG C (FIG. 1A), -20 DEG C (FIG. 1B), 0 DEG C It is used as a liquid electrolyte.

1A-1D show two combinations of lithium aluminum germanium phosphate glass ceramic (LAGP) and liquid electrolyte (PC in one case and DME in the other case) as exemplary embodiments. This involves a three-layer structure, where the solid electrolyte LAGP is placed between two identical liquid electrolytes-PC in one case and DME- in the other case. In both cases the conductive salt is LiTFSI (1 mol per kg of solvent). The electrolyte with a multilayer structure can be measured by measuring the complex impedance using a Novocontrol alpha analyzer (frequency range from 0.01 Hz to 20 MHz) (from one side of the solid electrolyte and two from the other side) 4 - point measurement using two measuring electrodes in the liquid electrolyte zone) was used to investigate the magnitude and occurrence of interfacial resistance and the volume resistivity of the solid electrolyte. Refer to Mirko Hofmann, Integrated impedance spectroscopy of aerobic cell cultures in biotechnological high throughput screenings, thesis, RWTH Aachen, Faculty of Electrical Engineering and Information Technology, 2009, for the principle of four-point measurement.

The relative dielectric constant of propylene carbonate (PC) is 64.4. Reference is made to Fujinaga, K. Izutsu, "Propylene Carbonate purification and tests for purity, Pure and Applied Chemistry 27 No. 1 (1971), p. 273-280" Are included herein. The relative dielectric constant of 1,2-dimethoxy methane (DME) is 7.2. In this regard, reference is made to R. Montadi, M. Matsu, I.S. Arthur, S.-J. Hwang, "Magnesium Borohydride: From Hydrogen Storage to Magnesium Battery ", Angewandte Chemie International Edition 51, No. 2; 39 (2012), p. 9780-9783, the disclosure of which is incorporated herein by reference in its entirety.

From the viewpoint of the temperature dependence of the interfacial resistance which decreases exponentially with temperature, the frequency dependent measurement leading to the Nyquist curve is carried out at different temperatures (-40 캜, -20 캜, 0 캜, 20 캜, 1d). The lowest temperature of -40 ° C is the lowest limit of the temperature scale of -40 ° C to 85 ° C, which is important in automotive applications. The sample size of the electrolyte having one liquid electrolyte layer / one solid electrolyte layer / one liquid electrolyte layer was 2 mm in height and 7.65 mm in diameter.

Locus 1 (Nyquist plot) measured at -40 ° C shows two strongly overlapping semicircles 10 and 12 at higher frequencies, as well as at a lower frequency, more strongly separated from the other two 14.1 (for liquid electrolyte DME), and 14.2 (for liquid electrolyte PC). The measured voltage was 0.1 V.

The Nyquist evaluation yielded the following resistance or capacitance values for the three semicircles:

The third semicircle 14.1, 14.2 represents the interfacial resistance. It is to be inferred from different positions in the Nyquist plot of FIG. 1A-1D for the combined liquid electrolyte DME / solid electrolyte LAGP / liquid electrolyte DME (position 100) and liquid electrolyte PC / solid electrolyte LAGP / liquid electrolyte PC (position 200) As can be appreciated, position 200 has a highly discriminating semicircular &lt; RTI ID = 0.0 &gt; 14.2 &lt; / RTI &gt; It is also represented by the parameter a according to the invention. Therefore,? = 0.395 is obtained for the electrolyte pair DME / LAGP. Alpha = 0.145 is obtained for the electrolyte pair PC / LAGP. In the first case, α is close to 0.5 and therefore in the linear range, and in the second case it is much lower. Interfacial resistance is particularly severely increased in PC / LAGP where it is mismatched.

A low interfacial resistance is obtained when the relative dielectric constant, which is achieved by the choice of the adaptation of the liquid electrolyte to the solid electrolyte and the selection of a suitable solvent, DME for the solid electrolyte LAGP, according to the invention. This is represented by a value close to 0.5.

However, in a further exemplary embodiment where the Nyquist line is not obtained, the solid electrolyte is LLZO (lithium lanthanum zirconate). The relative dielectric constant value of the solid electrolyte LLZO is 22.4. In order to adjust? In the range according to the present invention, a mixture of PC and DME as a solvent is selected as a liquid electrolyte and a relative dielectric constant is set to 22.4. The relative dielectric constant of a mixture is the average of the individual permittivities weighted by the mole fraction.

Therefore, the mixture of PC and DME is composed of 0.266 parts or 26.6 mol% of PC and 0.734 parts or 73.4 mol% of DME since it is 0.266 * 64.4 + 0.734 * 7.2 = 22.4. Instead, for example, when 28 mol% of PC and 72 mol% of DME are mixed, the relative dielectric constant of the liquid electrolyte of 23.216 is obtained. At this time, the value of alpha becomes 0.491. As a further example, when 35 mol% of PC and 65 mol% of DME are mixed, the relative dielectric constant of the liquid electrolyte of 27.22 is obtained. At this time, the value of alpha is 0.451.

Conversely, if the relative dielectric constant of the solid electrolyte is to be matched to the liquid electrolyte, this is achieved by selecting a suitable solid electrolyte.

In the present invention, the surprising results that can be ascertained from the exemplary embodiments show that even for partially crystalline solid electrolytes, the interfacial resistance to the liquid electrolyte can be minimized by matching the relative dielectric constant.

In the present invention, the first constraint on the permittivity is that the interface resistance is minimized for the multilayer electrolyte and the linear behavior of the current profile through the interface during application of a voltage over a large temperature range of -40 DEG C to + 85 DEG C, It is given within what can be expected as a function.

Claims (10)

At least one first electrolyte layer characterized by a first relative permittivity? 1,
- at least one second electrolyte layer characterized by a second relative dielectric constant? 2, and
An interface between the first electrolyte layer and the second electrolyte layer
An electrolyte having a multi-layer structure,
The first relative dielectric constant? 1 and the second relative dielectric constant? 2 define the following measure?

The electrolyte of the first electrolyte layer and the electrolyte of the second electrolyte layer have a scale of? 0.244 <? 0.5, preferably 0.371 <? 0.5, particularly preferably 0.436 <? 0.5, 0.475 < / = 0.5, particularly preferably 0.488 < / = 0.5, and still more preferably 0.494 < / = 0.5, wherein epsilon 1 is always the lower one of the relative dielectric constant of the adjacent medium, Of the relative dielectric constant of
&Lt; / RTI &gt; 2. The electrolyte membrane according to claim 1, wherein the electrolyte comprises a plurality of electrolyte layers having a plurality of interfaces,

With respect to a scale at the interface between α _n is 0.244 <α _n ≤ 0.5, preferably 0.371 <α _n ≤ 0.5, particularly preferably 0.436 <α _n ≤ 0.5, 0.475 and more preferably <α _n ≤ 0.5, in particular Preferably in the range of 0.488 <? _N ? 0.5, more preferably in the range of 0.494 <? _N ? 0.5, wherein? 1 _n is always the lower one of the relative permittivities of the adjacent medium and? _2n is the higher one of the relative permittivities of the adjacent medium &Lt; / RTI &gt; 3. The electrolyte of claim 2, wherein the scale? _N is substantially the same for 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 method according to any one of claims 1 to 4, wherein the scale α or the scale α _n for all the temperatures T in the temperature range 258 K to 383 K, preferably 228 K to 398 K, is 0.5 - 0.256 * T / 298 K <α 298K < / = 0.5, more preferably 0.5 - 0.128 * T / 298K < 0.5, particularly preferably 0.5-0.064 * T / 298K & , More preferably 0.5-0.012 * T / 298K < 0.5, still more preferably 0.5-0.006 * T / 298K < The electrolyte according to claim 4 or 5, characterized in that the solid electrolyte comprises one of the following materials:
- inorganic materials, especially
- glass material or
- Glass ceramic material or
- a ceramic material, and
- Polymers provided with organic materials, especially conductive fillers. 7. The method of claim 6, wherein the solid electrolyte comprises Li and is a system comprising, inter alia, lithium aluminum germanium phosphate, lithium lanthanum zirconate or a Li Super Ionic Conductor (LiSICon) crystal phase Electrolytes that will be. The electrolyte according to any one of claims 4 to 7, characterized in that the liquid electrolyte is a carbonate-containing solvent having a mixture of one or more non-aqueous solvents, in particular one or more fluoride conductive salts, preferably LiPF ₆ . . An electrochemical energy storage device, particularly a battery cell, comprising an electrolyte having a multilayer structure according to any one of claims 1 to 8. 10. The electrochemical energy storage device according to claim 9, wherein the battery cell comprises three or more electrolyte layers which are two solid electrolyte layers disposed between two liquid electrolyte layers and two liquid electrolyte layers.

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