WO2020058529A1

WO2020058529A1 - Amorphous solid li+ electrolyte, process for production of the amorphous solid electrolyte and usage of the amorphous solid electrolyte

Info

Publication number: WO2020058529A1
Application number: PCT/EP2019/075534
Authority: WO
Inventors: Bernhard Roling; Stefan SPANNENBERGER; Vanessa MISS; Nico Kaiser
Original assignee: Philipps-Universität Marburg
Priority date: 2018-09-21
Filing date: 2019-09-23
Publication date: 2020-03-26

Abstract

The invention comprises an amorphous ion conductive inorganic solid exhibiting a conductivity between 3 mS/cm and 10 mS/cm or more. The amorphous inorganic solid comprises the chemical elements lithium (Li), sulfur (S), phosphor (P) and - optionally - iodine (I), having the general formula xLil + (1-x) (0.75Li₂S + 0.2 P₂S₅) whereat the index x may accept any value between 0.0 and 0.5. The invention further comprises a method for manufacturing the amorphous ion conductive inorganic solid and the use of the amorphous ion conductive inorganic solid for the manufacturing of lithium-ion-batteries.

Description

Patent Application

Amorphous Solid Li⁺ Electrolyte, Process for production of the Amorphous Solid Electrolyte and usage of the Amorphous Solid Electrolyte

The invention relates to an amorphous solid electrolyte (“Amorphous Solid Elec- trolyte”) containing lithium ions enabling the conductivity, a process for the produc- tion of the amorphous solid electrolyte and the usage of the amorphous solid electrolyte.

Description

Field of the invention

The field of the invention is the area of energy storage, namely the storage of electrochemical energy. The available methods for short and long-time storage (times scales between seconds and several months) of renewable electrical energy by electrochemical means are still insufficient for thoroughly implementing a sustainable energy management system. Also, electrochemical energy storage systems providing high power density and allowing up to thousands of charging- discharging cycles - as are necessary in the automotive sector for e-mobility - are still considered to be insufficient.

Background of the technology

A progressive use of renewable sources for electrical energy production calls the development of next generation energy storage systems. While for stationary ap- plications a solution without electrochemical devices is a possible option, especially in the field of electric mobility, where the use of lithium ion batteries is state of the art, new approaches are required to ensure adequate power and safety. All- solid-state-batteries (ASSBs) hold promise to fulfil these requirements, and are likely to become the next generation automotive energy source. However, to successfully establish ASSBs, the use of non-inflammable solid electrolytes (abbreviated“SE”) which offer high Li⁺-conductivities and a sufficient compatibility to metallic lithium is a key factor. The mentioned compatibility means either a thermodynamic stability towards Li metal or, which is more likely, a formation of an insulating interlayer with negligible ionic resistance at the electrode/electrolyte inter face.

While several SE compositions with excellent ionic conductivities have been reported throughout the last years, forming the state of the art, especially the sulfidic crystalline materials tend do show difficult and/or cost-intensive preparation steps like long term heat treatment, or time consuming purification. Additionally, high grain boundary resistivity is a well-known problem in many crystalline systems.

The best known amorphous Li⁺ solid electrolytes only reach conductivity values of about 2.7*1 O^'3 S/cm (as is known to the person skilled in the art), while the best crystalline materials exhibit conductivities of 10 mS/cm and higher. Thus the believe that a material has to be of crystalline structure in order to reach the highest values of ionic conductivity is deeply seated within the state of the art and constitutes fundamental knowledge of any person skilled in the art.

As shown by several groups of scientists, L12S-P2S5 (abbreviated“LPS”) based glass-ceramics, i.e. crystallized glasses, are possible candidates to satisfy high Li⁺-conductivities

along with a simple synthesis. Especially a proper temperature treatment of LPS glasses prepared by mechanochemical milling is a famous example to increase the Li⁺-conductivity dramatically due to the formation of glass- ceramics containing superionic U7P3S11 crystals. In general, an addition of Lil to the LPS-System favours high ionic conductivities (cf. EP 2 779 298 B1) and has been shown to enable good compatibility in contact to metallic lithium. In contrast to U7P3S11 crystals formed within the LPS-System, one would expect a crystalline Li4PS4l-phase to form upon annealing of the LPSI-system.

But despite greatest efforts and most intense scientific and technical research it was not possible up to date to increase the Li⁺-conductivity of amorphous LPS- based materials to values of 2.7 mS/cm or beyond; according to the state of the art there seemed to be a fundamental maximum value reachable in the amorphous state of only about 2.7 mS/cm.

An objective of the present invention is to provide amorphous materials (amorphous solid electrolytes, respectively ion conductive inorganic solids) being composed of the elements lithium, iodine, sulphur and phosphorus that exhibit an extraordinary high Li⁺-conductivity of about 6.5 mS cnr¹ or more, i. e. at least 3 mS cm^-1.

Additional experiments have shown that the objective technical effect of the invention can also be achieved with amorphous materials containing no iodine. There- fore the objective of the present invention is also to provide amorphous materials (amorphous solid electrolytes, respectively ion conductive inorganic solids) being composed of the elements lithium, sulphur and phosphorus that exhibit a Li⁺- conductivity of at least 0.6 mS cm^-1, respectively an increased conductivity which is at least 300 per cent of the Li⁺-conductivity of the corresponding crystalline material.

Content of the invention

In order to achieve the above objective, the present invention provides new types of amorphous materials composed of these elements which are summarized under the acronym“LPSI”; one of the most preferable compositions within this LPSI- system is: 0.33 Lil + 0.67 (0.75 LhS + 0.25 P2S5), which achieves the above mentioned conductivity of (for example) 6.5 mS cnr¹ via a simple one step heat treatment under conservation of its amorphous structure. The composition as de- scribed afore means that 0.33 mol of Lil are mixed with 0.67 mol of a mixture of 0.75 mol LhS with 0.25 mol P2S5 and is treated according to the method described below. It is well known to the person skilled in the art that the exemplarily found value of 6.5 mS-crrr¹ allows for expecting at least values of about 10 mS crrr¹ or more being reached by various other execution examples within the scope of the invention or its equivalents as revealed.

In contrast to the LPS-System (where U7P3S11 are formed) surprisingly the formation of a crystalline LUPS-tl-phase is not increasing the Li⁺-conductivity of the solid electrolyte material within a broad range of composition of the LPSI-system.

Thus, the extraordinary high value of Li⁺-conductivity is not based on crystalline structures of the LPSI-system, but still resting upon the amorphous structure of the LPSI-system. This is proven by electrochemical impedance spectroscopy (EIS) and powder X-ray diffractometry (XRD) data presented herein below. Thus the surprisingly high values of Li⁺-conductivity reached by the materials according to this invention is not correlated to the formation of a glass-ceramic.

Fig. 1A shows XRD pattern for the as-prepared glass as well as for the same sample after several temperature cycles between 20 °C and 180 °C. As shown from differential scanning calorimetry (Fig. 1C), the LlPSI glass crystallizes at about 170 °C. The XRD data shows that it is possible to precipitate L14PS4I crystals from the glass through annealing at 180 °C. However, the glass is not very sensitive to crystallization. Long-term temperature treatment, including several repeated heat up and cool down cycles and various hold times at 180°C, is required to obtain a state of crystallinity comparable to Fig. 1A. Fig. 1 B shows the time dependent evolution of the Li⁺-conductivity tr_L.+ at 25 °C for the sample shown in Fig.

1A.

Due to the ongoing precipitation of L14PS4I crystals after each temperature cycle, the overall ionic conductivity converges to that of the pure crystalline phase for long annealing times. The first heat up cycle, for example yields a remarkable increase in ff_Li+ up to 2.1 x 10 ³ S-cnrr¹, which is about 2.6 times higher than the initial value obtained for the pristine, i. e. not tempered (treated by applying heat), sample (8 x 10⁴ S-errr¹), and about 17 times higher than the conductivity of pure U4PS4I (1.2 x 10⁴ S cnr¹). That a_u± of the crystalline phase is much lower than that of the glass is highly unexpected. Classical explanations for the Li⁺- conductivity of tempered glasses discussed in literature, like the precipitation of superionic crystals which enhances &_u+ , or fast ion transport at the glass/crystal interface (Adams et al. 1995) do not apply here. In the Ag⁺ ion conducting glass system discussed in Adams et al., the degree of crystallinity at the conductivity maximum is about 15-25%, while in the amorphous Li⁺ ion conducting solid electrolyte according to the invention, the degree of crystallinity is clearly below 15%. Furthermore, the conductivity enhancement in the Ag⁺ ion conducting system is by a factor of about 2, while the conductivity in the amorphous solid electrolyte system according to the invention is enhanced by a factor of about 7.2, compared to the pristine glass.

Fig. 2A shows exemplary Arrhenius plots of the ionic conductivity for the as- prepared LPSI-system (continuous curve) and for the same sample after an simple one-step annealing process at 180 °C (amorphous solid electrolyte, dashed curve), respectively. The optimized temperature treatment yields a Li⁺-conductivity of about 6.5 x 10^~3 S cnr¹, which is about 7.2 times the initial value before heat treatment. The activation energy is lowered from 0.31 eV for the pristine glass to 0.28 eV for the annealed sample. The XRD measurements in Fig. 2B reveal that the material remains basically in an amorphous state during heat treatment. Alt- hough a small crystalline signal is observed after annealing, such an exceptional increase in conductivity cannot be explained within the state of the art, e. g. by an interfacial effect at the glass/crystal interface, especially not for a system in which the crystalline phase is much less conductive than the glass phase.

For characterising the inventive material a degree of crystallinity is defined as follows: The intensity of the most intensive Bragg peak of U4PS4I (2Q = 21°, cf. Fig. 1A) is normalized to the intensity of the same peak after annealing for 8 hours. It is obvious to the person skilled in the art that after 8 hours, the degree of crystallinity is close to 100% (cf. graphs in Fig. 1A). Using this definition (i. e. setting the degree of crystallinity of a sample with a composition according to the scope re- vealed herein after annealing for 8 hours to be 100%), the degree of crystallinity for the material according to the invention at the conductivity maximum is below 15%. The so far optimized temperature treatment (annealing conditions) comprise heating from room temperature (about 20 - 25 °C) in about 25 minutes up to about 180 °C, holding this temperature of about 180 °C for about 5 - 10 minutes and then cooling down to room temperature (about 20 - 25 °C) with a cooling rate of about 2 k/min. The entire annealing process (temperature treatment) is performed under inert gas atmosphere, e. g. argon, and atmospheric pressure of about 1013 mbar.

Fig. 3 shows representative exemplary results of the EIS measurements for the pristine glass (filled squares), and the corresponding same sample after optimized heat treatment (the amorphous solid electrolyte, crosses). Since the material is a very good Li⁺-conductor, the semi-circle formed by the measured curve, which is related to the bulk conduction process, is completely observed only at very low temperatures. Thus the shown data is recorded at a sample temperature of -120 °C. Both spectra are characterized by a semi-circle followed by a steep in- crease in the low frequency part due to electrode polarization. The semi-circles represent the bulk conduction process with capacitances of 28 pF crrr² for the pristine glass and 39 pF crrr² for the annealed glass, respectively. These capacitance values indicate the Li⁺ ion transport takes place in the bulk of the amor phous phase. It is well known to the person skilled in the art, how to perform a fit- ting analysis of the impedance spectra and how to interpret the resulting values so that it is not necessary to describe it in more detail herein.

Thus the example discussed above (cf. Fig. 3), having a certain composition with- in the revealed scope, shows an increase of capacitance of about 40% upon an- nealing according to one example of the inventive method. It is well known by the person skilled in the art that this increase of capacitance is dependent on the composition and details of the annealing process so that the increase of capacitance can vary between 10% - 100% or 20% - 80% or 30% - 70% or 40% - 60%, depending on the precise composition and/or details of the annealing process. A conductivity enhancement upon short annealing at 180 °C is also found for the compositions x Lil + (1-x) (0.75 LhS + 0.25 P2S5) with x = 0.25, 0.20, and 0.15. The factor by which the conductivity increases decreases with decreasing x. For x = 0.1 , no conductivity enhancement is observed. Thus this value (x = 0.1) is marking the lower boundary of the range for values of x. Table 1 shows exemplarily the stoichiometric calculations for some examples.

Additional experiments have shown that the objective technical effect of the inven- tion can also be achieved with amorphous materials containing less iodine as described above or even no iodine at all (c.f. entries for sample with calculated molecular weight of 90.03 in table 1 and data shown in Figs. 4B). Therefore the objective of the present invention is also achieved by providing amorphous materials (amorphous solid electrolytes, respectively ion conductive inorganic solids) being composed of the elements lithium, sulphur and phosphorus that exhibit a Li⁺- conductivity of at least 0.6 mS cm^-1, respectively an increased conductivity which is at least 300 per cent of the Li⁺-conductivity of the corresponding crystalline material (cf. data presented in Figs. 4 and 4B). The corresponding crystalline material (the reference material to the mainly amorphous material according to the invention) is prepared in the same way as the material according to the invention, except that the annealing temperature is equivalent to the Temperature where crystallization is taking place, Tcryst.. Tcryst. is above the annealing temeperature accord ing to the invention, e.g. above 180 °C, and sometimes below the annealing temperature according to the invention. The latter is the case for compositions comprising more than about 40 per cent Lil by weight. In these cases (content of Lil roughly above 40%) it is observed that the Li⁺-conductivity is decreasing in accordance with the increasing degree of crystallinity.

The experimental findings, resp. technical effects, are summarized as follows:

- Fig. 4B shows that in any composition an enhancement of the conductivity is taking place after the annealing at, e.g., 180°C.

- Also, it is shown in Fig. 4B that the conductivity is basically enhanced with an increase of the Lil content. - The maximum increasement of the conductivity is shown by the composi- tion 0.33 Lil + 0.67 (0.75 U₂S + 0.25 P2S5).

- The increasement of the conductivity according to the invention decreases at a Lil content of 40% and higher after the annealing at, e.g., 180°C.

- The reason of this behavior is that the crystallization temperature of these compositions is, e.g., 180°C or lower which is shown in Fig. 5.

- In addition, Fig. 6 shows an increase of the crystallinity on the XRD pattern after the annealing at, e.g., 180°C, so the decrease of the conductivity at higher contents of Lil is caused by the crystallization of these materials.

The experimental findings therefore show that if Tcryst. of the material is below the annealing temperature of the material according to the invention, the technical effect of the invention, i.e. the surprising and extraordinary increase of conductivity while keeping the material in an amourphous state) is partly eliminated through crystallization (cf. Data in Fig. 4B and Fig. 6). This behavior allows to exactly adjust the Li⁺-conductivity of the material according to the invention independently from the chemical composition of the material according to the invention, for the same value of LF-conductivity can be achieved with at least two different materials according to the invention regarding the chemical composition. Because the phys- ical properties of any material, e.g. thermal expansion, melting point etc., is dependent from the chemical composition (as is known to the person skilled in the art), the material of the invention with a certain desired Li⁺-conductivity can be produced with different physical properties, e.g. thermal expansion, melting point etc. This is a major technical improvement beyond the state of the art.

Table 1 : stoichiometric calculations of some example-compositions, using the following values for atomic weight: Li=6.941 a.u., 1=126.9045 a.u., P=30.9738 a.u.,

S=32.065 a.u.

Thus the invention can be summarized as follows:

The invention comprises an ion conductive inorganic solid comprising the chemi- cal elements lithium (Li), sulfur (S) and phosphor (P), whereat

- i) the content of lithium is between 5 % and 15 % by mass and

ii) the content of sulfur is between 25 % and 75 % by mass and

iii) the content of phosphor is between 5 % and 20 % by mass

in such a way that the contents of lithium, sulfur and phosphor

sum up to at least 90 % of the composition of the

ion conductive inorganic solid

and

- the ion conductive inorganic solid is mainly of amorphous structure,

expressed in degree of crystallinity, whereat the degree of crystallinity is below 15% and

- the ion conductive inorganic solid exhibits a Li⁺-conductivity of at least

0.6 mS/cm.

The invention further comprises an ion conductive inorganic solid according to claim 1 comprising the chemical elements lithium (Li), sulfur (S), phosphor (P) and iodine (I), whereat

- i) the content of lithium is between 5 % and 15 % by mass and

ii) the content of sulfur is between 25 % and 75 % by mass and

iii) the content of phosphor is between 5 % and 20 % by mass and

iv) the content of iodine is between 0.001 % and 60 % by mass

in such a way that the contents of lithium, sulfur, phosphor and iodine sum up to at least 90 % of the composition of the

ion conductive inorganic solid

and

- the ion conductive inorganic solid is mainly of amorphous structure,

- the ion conductive inorganic solid exhibits a Li⁺-conductivity of at least

0.6 mS/cm.

The invention comprises an ion conductive inorganic solid comprising the chemical elements lithium (Li), sulfur (S), phosphor (P) and iodine (I), whereat

- i) the content of lithium is between 5 % and 15 % by mass and

ii) the content of sulfur is between 25 % and 65 % by mass and

iii) the content of phosphor is between 5 % and 20 % by mass and

iv) the content of iodine is between 10 % and 60 % by mass

in such a way that the contents of lithium, sulfur, phosphor and iodine sum up to at least 90 % of the composition of the ion conductive inorganic solid and

- the ion conductive inorganic solid is mainly of amorphous structure,

expressed in degree of crystallinity, whereat the degree of crystallinity is below 15% and the ion conductive inorganic solid exhibits a Li⁺-conductivity of at least

3 mS/cm.

Due to the findings described earlier within this description the amorphous conductive inorganic solid as described in the previous paragraph may additionally or alternatively be described by use of the capacitance which is about 30 pF-cnr² or more, measured by impedance spectroscopy. This technical feature (capacitance) may alternatively be described as having a value of about 1.4 (between 1.1 - 2.0) times higher than the value of the pristine glass.

Thus the ion conductive inorganic solid may also additionally or alternatively be described by showing an increase of capacitance upon annealing - but still having mainly amorphous structure - of about 10% - 100%, preferred of about 20% - 80%, more preferred of about 30% - 70% and most preferred of about 40% - 60%.

The invention further comprises an ion conductive inorganic solid as previously described, having a molar composition of x Lil + (1-x) (0.75 LteS + 0.25 P2S5) whereat x has a value between 0.5 and 0.1 , preferred between 0.4 and 0.1 , most preferred between 0.35 and 0.14.

The invention further comprises an ion conductive inorganic solid as previously described, having a molar composition of 0.33 Lil + 0.67 (0.75 LteS + 0.25 P2S5) or a molar composition of 0.25 Lil + 0.75 (0.75 U2S + 0.25 P2S5) or a molar composition of 0.20 Lil + 0.80 (0.75 LteS + 0.25 P2S5) or a molar composition of 0.15 Lil + 0.85 (0.75 LteS + 0.25 P2S5).

The invention further comprises the usage of the ion conductive inorganic solid as previously described for the production of lithium ion batteries.

The invention further comprises the usage of the ion conductive inorganic solid as previously described for the production of all-solid-state-batteries. The invention further comprises a method for manufacturing an ion conductive inorganic solid as previously described, characterized in that the method comprises the following steps:

a) providing the desired amounts of lithium halogenide (LiX), lithium sulfide

(U₂S) and phosphorous pentasulfide (P2S5) whereat the halogen X is independently chosen from the list comprising chlorine (Cl), bromine (Br) and iodine (I);

b) mixing the educts provided according to step a) by means of

mechanical milling for at least 1 h whereat the mechanical milling is

performed automatically by use of a mechanical mill and/or manually by use of a mortar;

c) applying temperature to the intermediate product from step b) - i. e annealing the intermediate product from step b) - at least

once for at least 1 minute whereat the applied temperature is between

150 °C and 220 °C, preferred between 160 °C and 210 °C,

more preferred between 170 °C and 190 °C and most preferred between 175 °C and 185 °C.

The invention further comprises a method for manufacturing an ion conductive inorganic solid as previously described, characterized in that the method compris- es the following steps

a) providing the desired amounts of lithium sulfide

(U2S) and phosphorous pentasulfide (P2S5);

b) mixing the educts provided according to step a) by means of

mechanical milling for at least 1 h whereat the mechanical milling is

c) applying temperature to the intermediate product from step b) at least

once for at least 1 minute whereat the applied temperature is between

150 °C and 220 °C, preferred between 160 °C and 210 °C,

more preferred between 170 °C and 190 °C and most preferred between 175 °C and 185 °C. The invention further comprises a method as previously described, characterized in that step b) is performed under inert gas.

The invention further comprises a method as previously described, characterized in that step b) is performed under exclusion of dispersion media.

The invention further comprises a method as previously described, characterized in that step c) is performed under inert gas. The inert gas may be nitrogen (N2), argon (Ar) or any other inert gas suitable for the desired purpose as is well known to the person skilled in the art without leaving the scope of the invention or its equivalents.

The invention further comprises a method as previously described, characterized in that the application of temperature to the intermediate product according to step c) comprises:

i) heating (for example from room temperature, i.e. 20 - 25 °C) within 10 to 40 minutes,

preferred within 20 to 30 minutes, most preferred during 25

minutes, up to 180 °C,

ii) holding the temperature of 180 °C for 1 to 20 minutes, preferred for

5 to 10 minutes,

iii) cooling down (for example to room temperature, i.e. 20 - 25 °C) with a

cooling rate between

0.5 K/minute and 10 K/minute, preferred with a cooling rate between

1 K/minute and 5 K/minute, most preferred with a cooling rate

of 2 K/minute. Detailed embodiments of the invention

With respect to the air and moisture sensitivity of the materials, all preparation steps are conducted under inert gas atmosphere using an argon-filled glovebox (e.g. UniLab, MBraun, Garching, Germany); any other inert gas suitable for the purpose of excluding moisture and oxygen may also be used without leaving the scope of the invention or its equivalents, e. g. nitrogen (N2).

The revelation of the used laboratory equipment here and below in elaborating the examples is for aspects of clarity only. It is well known to the person skilled in the art, that the revealed laboratory (resp. manufacturing) equipment or sources and purity of substances are not meant to confine the scope of the invention or its equivalents.

The U2S-P2S5-UI glasses are prepared by the means of mechanical milling using a high energy planetary ball mill (e.g. Pulverisette 7, Fritsch, Idar-Oberstein, Germany). A stoichiometric mixture of reagent grade LhS (98%, abcr GmbH, Karls- ruhe, Germany), P2S5 (99%, Sigma Aldrich, Taufkirchen, Germany) and Lil (99%, Alfa Aesar, Karlsruhe, Germany) powders is placed into an air-tight Zirkonia pot (20 ml volume) with 10 Zr02 balls (10 mm diameter) and is then milled at a rotational speed of 500 rpm for about 8 hours (5min milling; 15min rest; 99 cycles). Afterwards, the received product is once again ground in an agate mortar to obtain the final glass-powders. Contrary to the usual proceeding according to the state of the art, i. e. adding an organic solvent to the components within the jar mill and performing the milling process in the presence of an organic solvent/dispersant, there is no organic solvent/dispersant added to the educts before milling.

For the electrochemical characterization, the as-prepared powders are pressed into pellets with a diameter of 6 mm by applying a pressure of 276 MPa for 30 min at room temperature (e.g. at 20 - 25 °C) by means of a hydraulic press (e.g. P/O/Weber, Remshalden, Germany) using polished stainless steel extrusion dies. The thickness of the pellets is determined using a micrometer caliper (e.g. Mi- tutoyo, Neuss, Germany). To ensure a sufficient electronic contact during the measurements, the pellets are coated with a gold layer on both faces using a sputter coater (e.g. 108auto, Cressington, Watford, England) inside a glovebox. The pellets are then placed inside a home-build, air-tight sample cell in a two- electrode arrangement. Impedance measurements are carried out using an Alpha- AK impedance analyzer (e.g. Novocontrol, Montabaur, Germany) in a frequency range from 1 MHz to 0.1 Hz with an applied AC voltage of 10 mV/root mean square). The temperature is varied in the range from -120 X to 180 X using - for example - the Novocontrol Quatro Cryosystem. The maximum temperature offset during the measurements is fixed to a limit of ±1 X. For evaluation of the obtained spectra, the impedance analysis software RelaxIS (RHD Instruments, Darmstadt, Germany) is exemplarily used.

X-ray diffraction measurements (XRD) are performed using a powder diffractometer, e.g. STOE STADI MR (STOE, Darmstadt, Germany) using Cu-Ka radiation in a Debye-Scherrer geometry. The powder samples are sealed inside a XRD glass sample tube (e.g. Hilgenberg, Malsfeld, Germany) under Argon atmosphere.

Differential thermal analyses (DTA) is performed using a thermal analyser system, e.g. Mettler Toledo DSC 1 (Mettler-Toledo, Columbus, USA). The powder samples are sealed inside Al pans under Argon atmosphere and heated up to 350 X with a heating rate of 10 X/min. During the measurements inert gas atmosphere is provided by a N2 gas flow.

Description of the drawings

Fig. 1A: Exemplary XRD pattern of an as-prepared glass as well as of the same sample after 8h of alternate annealing at 180°C.

Fig. 1B: Exemplary corresponding time-dependent evolution of the room temperature conductivity of the sample shown in Fig. 1A. The abscissa declares the sum of the 180 °C hold times.

Fig. 1C: Exemplary DTA curve of a sample with composition 0.33 Lil + 0.67

(0.75 LhS + 0.25 P2S5) glass in a temperature range from room temperature up to 350 °C. The heating rate at that measurement was 17 X/min. Fig. 2A: Exemplary Arrhenius plots of the ionic conductivity, for the as-prepared glass (continuous curve) as well as for the same sample after annealing at 180 °C according to the inventive process (amorphous solid electrolyte, dashed curve). The lines (both, continuous one and dashed one) represent the best linear fit. Since the ionic conductivity of the annealed glass is very high, room temperature conductivity was extrapolated from measurements between -120 °C and 0 °C. Both fits exhibit regression coefficients > 0.9999. The extrapolated values are: 6.5 mS/cm for the sample annealed according to the inventive process, and 0.9 mS/cm for the same sample before annealing.

Fig. 2B: Exemplary XRD pattern of the same sample as shown in Fig. 2A, before annealing (upper graph) and after annealing (amorphous solid electrolyte, lower graph) showing that nearly no crystallisation has oc- curred.

Fig. 3: Exemplary Nyquist plot of the complex impedance behaviour for the as- prepared glass (filled squares) and the same sample after annealing at 180 °C (amorphous solid electrolyte, crosses), respectively. The spectra are recorded at a temperature of -120 °C. The semi-circle described by the measuring points indicates the bulk conduction process, while the low frequency part is characterised by electrode polarization. Lowest shown frequencies are 0.1 Hz for both samples.

Fig. 4: Exemplary composition dependence of the Li⁺-conductivity at 25 °C for the xLil + (1-x) (0.75LfeS + 0.25 P2S5) glass as prepared by high energy ball milling.

Fig. 4B: Exemplary composition dependence of the Li⁺-conductivity at 25 °C for the xLil +(1-x) (OJSL S + 0.25 P2S5) glass as prepared by high energy ball milling and after a single annealing step at 180 °C.

Fig. 5: Exemplary DSC curve of the x Li I + (1-x) (0.75 U2S + 0.25 P2S5) glass in a temperature range from room temperature up to 350 °C. The heating rate at each measurement was 15 °C/min.

Fig. 6: XRD pattern of the same sample as shown in Fig. 4B, each composition is measured as the as prepared material and after the annealing at 180°C. Only the materials 60% U3PS4 + 40% Lil, 55% U3PS4 + 45% Lil and 50% LbPS₄ + 50% Lil after annealing at 180°C show partly crystal- lisation, the other compositions show nearly no crystallisation.

Claims

C!a!ms

An ion conductive inorganic solid comprising the chemical elements lithium (Li), sulfur (S) and phosphor (P), whereat

- i) the content of lithium is between 5 % and 15 % by mass and

ii) the content of sulfur is between 25 % and 75 % by mass and iii) the content of phosphor is between 5 % and 20 % by mass

in such a way that the contents of lithium, sulfur and phosphor sum up to at least 90 % of the composition of the

ion conductive inorganic solid

and

- the ion conductive inorganic solid is mainly of amorphous structure,

- the ion conductive inorganic solid exhibits a Li⁺-conductivity of at least 0.6 mS/cm.

An ion conductive inorganic solid according to claim 1 comprising the chemical elements lithium (Li), sulfur (S), phosphor (P) and iodine (I), whereat

- i) the content of lithium is between 5 % and 15 % by mass and

ii) the content of sulfur is between 25 % and 75 % by mass and iii) the content of phosphor is between 5 % and 20 % by mass and iv) the content of iodine is between 0.001 % and 60 % by mass in such a way that the contents of lithium, sulfur, phosphor and iodine sum up to at least 90 % of the composition of the

ion conductive inorganic solid

and

- the ion conductive inorganic solid is mainly of amorphous structure,

An ion conductive inorganic solid according to claim 2 comprising the chemi- cal elements lithium (Li), sulfur (S), phosphor (P) and iodine (I), whereat

- i) the content of lithium is between 5 % and 15 % by mass and ii) the content of sulfur is between 25 % and 65 % by mass and iii) the content of phosphor is between 5 % and 20 % by mass and iv) the content of iodine is between 10 % and 60 % by mass

ion conductive inorganic solid

and

- the ion conductive inorganic solid is mainly of amorphous structure, expressed in degree of crystallinity, whereat the degree of crystallinity is below 15% and

- the ion conductive inorganic solid exhibits a Li⁺-eonductivity of at least 3 mS/cm.

An ion conductive inorganic solid according to claim 2 or claim 3, having a molar composition of x Lil + (1-x) (0.75 LhS + 0.25 P2S5) whereat x has a value between 0.5 and 0.1 , preferred between 0.4 and 0.1 , most preferred between 0.35 and 0.14.

An ion conductive inorganic solid according to claim 2 or claim 3,

having a molar

composition of 0.33 Lil + 0.67 (0.75 LhS + 0.25 P2S5) or a molar composition of 0.25 Lil + 0.75 (0.75 LhS + 0.25 P2S5) or a molar composition of 0.20 Lil + 0.80 (0.75 LhS + 0.25 P2S5) or a molar composition of 0.15 Lil + 0.85 (0.75 LhS + 0.25 P2S5).

Usage of the ion conductive inorganic solid according to any one of the preceeding claims for the production of lithium ion batteries.

Usage of the ion conductive inorganic solid according to any one of the preceeding claims 1 - 5 for the production of all-solid-state-batteries.

A method for manufacturing an ion conductive inorganic solid according to any one of the preceeding claims 2 - 5, characterized in that the method comprises the following steps

a) providing the desired amounts of lithium halogenide (LiX), lithium sulfide (LhS) and phosphorous pentasulfide (P2S5) whereat the halogen X is independently chosen from the list comprising chlorine (Cl), bromine (Br) and iodine (I);

b) mixing the educts provided according to step a) by means of mechanical milling for at least 1 h whereat the mechanical milling is performed automatically by use of a mechanical mill and/or manually by use of a mortar;

c) applying temperature to the intermediate product from step b) at least once for at least 1 minute whereat the applied temperature is between

150 °C and 220 °C, preferred between 160 °C and 210 °C,

9. A method for manufacturing an ion conductive inorganic solid according to claim 1 , characterized in that the method comprises the following steps a) providing the desired amounts of lithium sulfide

(LhS) and phosphorous pentasulfide (P2S5);

b) mixing the educts provided according to step a) by means of

mechanical milling for at least 1 h whereat the mechanical milling is performed automatically by use of a mechanical mill and/or manually by use of a mortar;

c) applying temperature to the intermediate product from step b) at least once for at least 1 minute whereat the applied temperature is between 150 °C and 220 °C, preferred between 160 °C and 210 °C,

10. A method according to any one of the preceeding claims 8 - 9, characterized in that step b) is performed under inert gas.

11. A method according to any one of the preceeding claims 8 - 9, characterized in that step b) is performed under exclusion of dispersion media.

12. A method according to any one of the preceeding claims 8 - 9, characterized in that step c) is performed under inert gas.

13. A method according to any one of the preceeding claims 8 - 9, characterized in that the application of temperature to the intermediate product according to step c) comprises

i) heating within 10 to 40 minutes,

preferred within 20 to 30 minutes, most preferred during 25

minutes, up to 180 °C,

ii) holding the temperature of 180 °C for 1 to 20 minutes, preferred for 5 to 10 minutes,

iii) cooling down with a cooling rate between

0.5 K/minute and 10 K/minute, preferred with a cooling rate between 1 K/minute and 5 K/minute, most preferred with a cooling rate of 2 K/minute.