Compounds

Abstract

A compound of formula (I): # imgabs0 # wherein: X is Al or B; m + is a metal cation; and R1 is, independently at each occurrence, a linear C3 or C4 fluorinated alkyl group. The compounds of formula (I) can be used in electrolytes in metal or metal ion batteries.

Description

Background Art

[0001] WO 2022 / 243470 discloses an electrolyte comprising solvated lithium ions.

[0002] WO 00 / 53611 discloses polyfluoroalkoxides for use as electrolytes in batteries and other electrochemical devices.

[0003] M Rohde et al., "Li[B(OCH2CF3)4]: Synthesis, Characterization and Electrochemical Application as a Conducting Salt for LiSB Batteries", ChemPhys Chem, Vol. 16(3), 2015, pp. 666-675 discloses Li[B(OCH2CF3)4] as a water-stable and thermally stable lithium ion electrolyte salt for LiS batteries.

[0004] EP2827430 discloses compounds of formula (I):

[0005]

[0006] WO2022 / 161996 discloses an SO2-based electrolyte containing at least one conductive salt of the following formula:

[0007] Summary of the Invention

[0008] The present disclosure provides a compound of formula (I):

[0009]

[0010] in:

[0011] X is Al or B;

[0012] M + is a metal cation; and

[0013] R 1 is independently at each occurrence a linear C3 or C4 fluorinated alkyl group.

[0014] Optionally, at least one R 1 It is a straight-chain C3 alkyl group having less than 6 fluorine atoms.

[0015] Optionally, at least one R 1 A group containing the formula -CF2H.

[0016] Optionally, at least one R 1It is a group of formula -CH2CF2CF2H.

[0017] Optionally, X is B.

[0018] Optionally, M + It's lithium-ion.

[0019] The present disclosure provides an electrolyte comprising a compound of formula (I) as described herein dissolved in one or more solvents.

[0020] The present disclosure provides a metal ion battery comprising an anode, a cathode, and an electrolyte as described herein, the electrolyte being disposed between the anode and the cathode.

[0021] The present disclosure provides a metal battery comprising an anode, a cathode, and an electrolyte as described herein, the electrolyte being disposed between the anode and the cathode. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic diagram of a battery comprising a compound as described herein; and

[0023] Figure 2 shows exemplary initial and steady-state Nyquist plots for an exemplary battery cell;

[0024] Figure 3 is a graph of ionic conductivity versus solvent:Li+ ratio for cells containing Compound Example 1 and Comparative Compound 1; and

[0025] Figure 4 is a graph of the lithium transference number versus solvent:Li+ ratio for cells containing Compound Example 1 and Comparative Compound 1. DETAILED DESCRIPTION

[0026] Unless the context clearly requires otherwise, throughout the specification and claims, the words "comprise," "comprising," and the like should be interpreted in an inclusive sense, and not in an exclusive or exhaustive sense; that is, in the sense of "including but not limited to." In addition, when used in this application, the words "herein," "above," "below," and words of similar meaning refer to this application as a whole and not to any particular parts of this application. Where the context permits, words in specific embodiments using the singular or plural may also include the plural or singular, respectively. The word "or" with respect to a list of two or more items encompasses all of the following interpretations of the word: any item in the list, all items in the list, and any combination of items in the list. When used in this application, a reference to a layer being "above" another layer means that the layers may be in direct contact or that one or more intervening layers may be present. When used in this application, a reference to a layer being "on" another layer means that the layers are in direct contact. References to elements of the periodic table include any isotopes of that element.

[0027] The teachings of the technology provided herein can be applied to other systems, and need not be applied to the system described below. The elements and actions of the various examples described below can be combined to provide further implementations of the technology. Some alternative implementations of the technology can include not only the additional elements of those implementations mentioned below, but also fewer elements.

[0028] These and other changes can be made to the technology in light of the detailed description that follows. Although this specification describes certain examples of the technology and describes the best mode contemplated, no matter how detailed the specification appears, the technology can be practiced in a variety of ways. As described above, the use of specific terms when describing certain features or aspects of the technology should not be taken to imply that the terms are redefined herein to be limited to any specific characteristics, features, or aspects of the technology associated with the terms. In general, the terms used in the claims that follow should not be interpreted as limiting the technology to the specific examples disclosed in the specification unless the detailed description section explicitly defines the terms. Therefore, the actual scope of the technology covers not only the disclosed examples, but also all equivalent ways of practicing or implementing the technology under the claims.

[0029] To reduce the number of claims, certain aspects of the technology are presented below in certain claim forms, but the applicant contemplates the various aspects of the technology in any number of claim forms.

[0030] In the following description, for the purpose of explanation, numerous specific details are set forth in order to provide a thorough understanding of the implementation of the disclosed technology. However, it will be apparent to one skilled in the art that embodiments of the disclosed technology can be practiced without some of these specific details.

[0031] Compounds of formula (I)

[0032] The compound of formula (I) is:

[0033]

[0034] X is Al or B, preferably B.

[0035] M + is a metal cation. M + Preferably it is an alkali metal cation, more preferably Li + .

[0036] R 1 is independently at each occurrence a linear C3 or C4 fluorinated alkyl group.

[0037] R 1 It may be the same or different at each occurrence. 1 same.

[0038] Compounds of formula (I) may be formed by reacting a compound of formula (II) with one or more compounds of formula (IIIa) or (IIIb):

[0039]

[0040] It should be understood that the O atom in formula (IIIa) and (IIIb) is directly connected to R 1 The C atoms in the bond.

[0041] The compound of formula (IIIa) is a primary alcohol.

[0042] The compound of formula (IIIb) is an aldehyde.

[0043] Exemplary compounds of formula (II) include, but are not limited to, lithium aluminum hydride (LiAlH4) and lithium borohydride (LiBH4).

[0044] solvent

[0045] The electrolyte containing one or more solvents and the compound of formula (I) may comprise one or more solvents selected from the group consisting of: carbonate, C 2-10 Alkylene esters, di(C 1-10alkyl) esters, such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate; linear, branched or cyclic compounds containing two or more ether groups, such as 1,3-dioxolane, 2,5-dimethoxytetrahydrofuran, glyme (dimethoxyethane), diglyme, triglyme and tetraglyme; cyclic lactones and mixtures thereof.

[0046] Optionally, the ratio of moles of solvent: moles of M+ in the electrolyte is no greater than 20:1, optionally less than or equal to 15:1 or less than or equal to 10:1.

[0047] polymer

[0048] The electrolyte as described herein may comprise a polymer, in which case the electrolyte may be a gel.

[0049] The polymer may be selected from any known ion-conducting polymer, including but not limited to: poly(alkylene oxides), such as poly(ethylene oxide) and poly(propylene oxide); and fluorinated polymers such as PVDF, PVDF-HFP; PMMA; polyacrylonitrile; polycarbonate; polyethylene; polypropylene; poly(vinyl methyl ketone); polyvinyl pyrrolidone; polyether ether ketone; polyisoprene; polybutadiene; polystyrene-block-polyisoprene-block-polystyrene; poly(1-vinyl pyrrolidone-co-vinyl acetate); polystyrene-block-polybutadiene-block-polystyrene; polystyrene-block-poly(ethylene oxide)-block-polystyrene; and copolymers and mixtures thereof.

[0050] The polymer is preferably a neutral polymer, ie a polymer not substituted with ionic groups, and is particularly preferably not a single ion conducting polymer containing anionic groups.

[0051] Battery

[0052] Figure 1 A battery comprising a compound of formula (I) is shown. The battery may be a metal battery or a metal ion battery, preferably a lithium battery or a lithium ion battery. The battery is suitably a secondary (rechargeable) battery.

[0053] The battery includes an anode current collector 101 having an anode 103 supported on its surface; a cathode current collector 109 having a cathode 107 disposed on its surface; and a layer 105 disposed between the anode and cathode, the layer comprising an electrolyte containing a compound as described herein.

[0054] Layer 105 may comprise a porous separator in which an electrolyte (eg, a liquid electrolyte or a gel electrolyte) is absorbed. If the electrolyte comprises a solid, such as a gel comprising a polymer and a compound of formula (I), the porous separator may or may not be present.

[0055] Optionally, the number of moles of solvent: the number of moles of electrolyte in the battery + The ratio of moles of is no greater than 20:1, optionally less than or equal to 15:1 or less than or equal to 10:1.

[0056] In the case of metal batteries, the anode is a layer of metal (eg, lithium) that forms over the anode current collector during charging of the battery and peels off during discharge of the battery.

[0057] In the case of metal ion batteries (eg, lithium ion batteries), the anode comprises an active material (eg, graphite) for absorbing metal ions.

[0058] The cathode may be selected from any cathode known to the skilled person.

[0059] The anode and cathode current collectors may be any suitable conductive material known to those skilled in the art, for example one or more layers of a metal or metal alloy such as aluminum or copper.

[0060] A battery can be formed by providing an electrolyte as described herein on a surface of one of the anode and cathode and providing the other of the anode and cathode and an associated current collector over the electrolyte.

[0061] The metal battery precursor can be formed by providing an electrolyte as described herein on the surface of an anode current collector; and providing a cathode and a cathode current collector above the electrolyte. After applying a charging bias, a metal anode can be formed between the electrolyte and the anode current collector.

[0062] Figure 1 Batteries are shown in which the anode and cathode are separated by only a single layer comprising or consisting of an electrolyte (e.g., a separator comprising an electrolyte). In other embodiments, one or more further layers may be provided between the anode and cathode.

[0063] For simplicity, Figure 1 A cell is shown in which the anode and cathode are separated by only a single layer 105, but it will be appreciated that during use a solid electrolyte interface will typically form on the anode surface.

[0064] A battery as described herein or a battery pack comprising a plurality of batteries as described herein may be used, but is not limited to, to power an electric vehicle or a stationary object.

[0065] Examples

[0066] Electrolyte Example 1

[0067] Compound Example 1 was prepared according to the following reaction scheme:

[0068]

[0069] The reaction is carried out under a nitrogen atmosphere. A solution of lithium borohydride in tetrahydrofuran (4.2mL, 8.4mmol, 2M) is added dropwise to a solution of 2,2,3,3-tetrafluoropropan-1-ol (3mL, 33.6mmol) in 9.30mL of tetrahydrofuran. The mixture is stirred at room temperature for 1 hour. It is then heated to 65 ° C for 1 hour. Other lithium borohydride (0.45mL, 0.9mmol, 2M in THF) is added dropwise. The mixture is stirred at 65 ° C for 1 hour, and stirred at room temperature overnight. Propylene carbonate (0.9mL, 10.9mmol) is added. At 30 ° C (3.3x 10 -2 Excess solvent was removed under reduced pressure at 400 mbar for 3 hours to give a thick clear oil. Additional propylene carbonate was added to obtain a stable clear liquid.

[0070] In deuterated THF 1 H NMR (600 MHz) Figure 2 ): δ (ppm), 1.38 (d, CH3, from propylene carbonate 10.08H), 1.77 (m, CH2, from THF 0.17H), 3.60 (m, CH2 from THF, 0.18H), 3.76 (t, J = 13.88 Hz, 8H), 3.95 (m, CH, from propylene carbonate 3H), 4.48 (t, CH, from propylene carbonate 3H), 4.77 (m, CH, from propylene carbonate 2.66H), 6.12 (tt, J = 53.23 Hz, J = 5.66 Hz, 4H).

[0071] From the integration of the NMR peaks, it was calculated that for four molecules of TFP corresponding to one lithium cation in the product electrolyte, there were 3.13 molecules of propylene carbonate as residual solvent.

[0072] Button Cell Example - General Method

[0073] Ionic conductivity and lithium transference number were measured using 2032-type coin cells manufactured in a strictly dry and oxygen-free argon-filled MBraun glove box using casings purchased from Cambridge Energy Solutions.

[0074] A stainless steel gasket is inserted into the bottom of the coin cell, followed by a lithium disc and a fluoro-silicone template (purchased from Silex Silicones). The template is a 15.5mm diameter disc with a 5mm diameter hole cut in the middle (the thickness of the template in the cell after crimping is 360μm). The hole is filled with 30μl of electrolyte. The lithium disc is placed on top of the template, followed by the stainless steel gasket, wave spring, and coin cell cover. Finally, the coin cell is crimped.

[0075] The electrolyte formulation used to form the button cell comprises Compound Example 1 or Comparative Compound 1, and a solvent or solvent mixture as listed in Tables 1 to 4.

[0076] The electrolyte included Compound Example 1 shown above or Comparative Compound 1 shown below.

[0077]

[0078] For each compound, we prepared cells with different solvent:Li+ molar ratios.

[0079] Measurement

[0080] Electrochemical impedance spectroscopy (EIS) measurements were performed at room temperature. The electrolyte impedance was measured in the frequency range of 1 Hz to 1 MHz with an amplitude of 5 mV.

[0081] Calculate the ionic conductivity from these data using the following formula:

[0082]

[0083] in:

[0084] 1.l is the thickness of the material between the two lithium disks, which corresponds to the thickness of the template in the rolled cell.

[0085] 2. A is the area of the membrane, which corresponds to the circular hole cut in the middle of the template.

[0086] 3. R is the impedance of the electrolyte.

[0087] The impedance of the electrolyte is determined by estimating the intercept of the first semicircle of the Nyquist plot with the x-axis. This is the lower left corner of an illustrative Nyquist plot for a coin cell.

[0088] The lithium transfer number (LTN) was measured using the above-mentioned 2032-type button cell according to the method of Evans (J. Evans et al., POLYMER, 1987, Vol. 28).

[0089] Before LTN measurements were performed, the device was allowed to sit overnight for approximately 19 hours to ensure stabilization of the interface between the electrolyte and the lithium disk.

[0090] After standing:

[0091] 1. Measure the first EIS spectrum.

[0092] 2. A DC current measurement is then performed (the applied constant voltage is adjusted individually for each cell in order to achieve an initial current of approximately 0.5 uA. The measurement is terminated once the current has decreased to a steady state.

[0093] 3. The sequence is then concluded with a second EIS measurement.

[0094] EIS measurements were performed at room temperature in the frequency range of 1 Hz to 1 MHz with an amplitude of 5 mV.

[0095] The LTN value is calculated based on the model developed by Evans et al. according to the following formula:

[0096]

[0097] Among them (reference Figure 2 illustrative Nyquist plot shown in ):

[0098] 1.R 0 is the initial impedance obtained from the first EIS spectrum (determined by estimating the x-intercept of the Nyquist plot of the second semicircle (right side)).

[0099] 2.R s is the steady-state impedance obtained from the second EIS after applying a DC bias (determined by estimating the x-axis intercept of the Nyquist plot of the second semicircle (right side)).

[0100] 3.I 0 is the initial current obtained when the voltage is stepped to the set value.

[0101] 4.I s is the steady-state current obtained at the end of the DC measurement.

[0102] result

[0103] The results of the cells containing Compound Example 1 are listed in Table 1, and the results of the cells containing Comparative Compound 1 are listed in Table 2, and Figure 3 and Figure 4 The results are listed in .

[0104] Table 1: Effect of propylene carbonate (PC) on the ionic conductivity and LTN of the battery cell containing compound example 1

[0105]

[0106] Table 2: Effect of propylene carbonate (PC) on the ionic conductivity and LTN of the battery containing comparative compound 1

[0107]

[0108] For both Compound Example 1 and Comparative Compound 1, increasing the molar ratio of PC:Li+ leads to an increase in ionic conductivity. Figure 3 For a given PC:Li+ molar ratio, the ionic conductivity of compound example 1 is higher than that of comparative compound 1.

[0109] In the case of comparative compound 1, when the solvent: Li + When the ratio of 2.7:1 to 6.0:1 increases, the increase in ionic conductivity is accompanied by a halving of LTN. Figure 4 As shown in , surprisingly, the LTN of compound Example 1 is stable over the range of solvent:Li+ molar ratios investigated.

Claims

1. A compound of formula (I): in: X is Al or B; M + is a metal cation; and R 1 is independently at each occurrence a linear C3 or C4 fluorinated alkyl group.

2. The compound according to claim 1, wherein at least one R 1 It is a straight-chain C3 alkyl group having less than 6 fluorine atoms.

3. A compound according to any one of the preceding claims, wherein at least one R 1 Contains a group of formula -CF2H.

4. A compound according to any one of the preceding claims, wherein at least one R 1 It is a group of formula -CH2CF2CF2H.

5. A compound according to any one of the preceding claims, wherein X is B.

6. A compound according to any one of the preceding claims, wherein M + It's lithium-ion.

7. An electrolyte comprising a compound according to any one of the preceding claims dissolved in one or more solvents. 8 . A metal ion battery comprising an anode, a cathode, and the electrolyte according to claim 7 , wherein the electrolyte is disposed between the anode and the cathode. 9 . A metal battery comprising an anode, a cathode, and the electrolyte according to claim 7 , wherein the electrolyte is disposed between the anode and the cathode.

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