Sodium salts with borate or aluminate anions

Abstract

A compound of formula (I) or (II): # imgabs0 # X is Al or B; r1 is independently a substituent at each occurrence, and the two R1 groups may be linked to form a ring, with the proviso that at least one R1 is a partially fluorinated linear or branched C1-20 alkyl group wherein one or more non-adjacent, non-terminal C atoms other than the C atoms bonded to O in X-O may be replaced by O, and wherein the fluorinated C1-20 alkyl group comprises at least one group of the formula-CF2H or-CFH2; and R2 is independently at each occurrence a divalent organic group. The compounds of formula (I) or (II) may be used in electrolytes of sodium or sodium ion batteries.

Description

Background Art

[0001] Lithium batteries and lithium-ion batteries containing lithium salts have been the subject of extensive research. However, the scarcity of lithium is a drawback. Therefore, batteries containing more abundant metals (such as sodium, magnesium, and potassium) have been studied.

[0002] D. Ould et al., "Sodium Borates: Expanding the Electrolyte Selection for Sodium-Ion Batteries", Angew. Chem. Int. ed. 2022, 61, e202202133 discloses sodium alkoxyborates for sodium ion batteries. WO 2021 / 138370 discloses lithium metal batteries with ionic liquid electrolytes containing sodium additives.

[0003] EP3783720 discloses an electrolyte solution comprising sodium or potassium bis(oxalato)borate and an organic solvent comprising pyrrolidone and / or a phosphoric acid compound.

[0004] US2021 / 036358 discloses an SO2-based electrolyte for rechargeable batteries containing a conductive salt of formula (I), wherein M is selected from alkali metals, alkaline earth metals, Group 12 metals, and aluminum:

[0005]

[0006] US2018 / 019498 discloses a non-aqueous electrolyte solution for a secondary battery, which contains at least one of a borate ester, an acid anhydride, a cyclic carbonate having an unsaturated bond, a cyclic carbonate having a halogen atom, a cyclic sulfonate, and an amine having an acetoacetyl group. Summary of the Invention

[0007] The present disclosure provides a compound of formula (II):

[0008]

[0009] Where X is Al or B, and R 2 is independently at each occurrence a divalent organic group selected from: unsubstituted or substituted C 6-20 Arylene or C 5-20 heteroarylene;

[0010] Unsubstituted or substituted C 1-20 Alkylene, in which one or more non-adjacent C atoms other than the C atom bonded to the O of the borate ester may be replaced by O, and one or more H atoms may be replaced by F; and C 1-20 -alkylene-C6-20 Arylene or C 1-20 -alkylene-C 5-20 Heteroarylene, wherein C 1-20 One or more non-adjacent C atoms in the alkylene group other than the C atom bonded to the O of the borate ester may be replaced by O. 1-20 -alkylene is unsubstituted or substituted; and C 6-20 The arylene group is substituted or unsubstituted.

[0011] Optionally, at least one R 2 is a group of formula (III):

[0012]

[0013] where R 3 is H or a substituent at each occurrence, and Ar 1 is unsubstituted or substituted C 6-20 Arylene or C 5-20 Heteroarylene groups.

[0014] Optionally, Ar 1 is unsubstituted or substituted 1,2-phenylene.

[0015] Optionally, each R 2 is a group of formula (III).

[0016] The present disclosure provides a compound of formula (I):

[0017]

[0018] wherein X is Al or B; and

[0019] R 1 is independently a substituent at each occurrence, and both R 1 The groups may be linked to form a ring, provided that at least one R 1 is a partially fluorinated linear or branched C 1-20 an alkyl group in which one or more non-adjacent, non-terminal C atoms other than the C atom bonded to O in XO may be replaced by O, and in which the fluorinated C 1-20 The alkyl group includes at least one group of the formula -CF2H or -CFH2.

[0020] Optionally, each R 1 is a partially fluorinated linear or branched C 1-20 Alkyl, in which one or more non-adjacent, non-terminal C atoms other than the C atom bonded to O in XO may be replaced by O, and in which the fluorinated C 1-20The alkyl group includes at least one group of the formula -CF2H or -CFH2.

[0021] The present disclosure provides an electrolyte comprising a compound of formula (I) or (II) and one or more solvents.

[0022] Optionally, the one or more solvents include carbonate C 2-10 Alkylene esters and di(C 1-10 At least one of the alkyl) esters.

[0023] Optionally, the electrolyte contains at least one mole of sodium cations per 10 moles of solvent.

[0024] Optionally, the concentration of the compound of formula (I) or (II) is at least 0.25 moles per liter.

[0025] The present disclosure provides a battery comprising an anode, a cathode, and an electrolyte comprising a compound of formula (I) or (II), the electrolyte being disposed between the anode and the cathode.

[0026] Optionally, the cell contains no more than 10 moles of total solvent per mole of Na+. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic diagram of a battery including a compound according to an embodiment of the present disclosure;

[0028] Figure 2 A circuit for determining the impedance of an electrolyte is shown;

[0029] Figure 3A shows Nyquist plots of cells containing Compound Examples 1 and 2 according to some embodiments of the present disclosure; and

[0030] Figure 3B Shown Figure 3A A magnified view of the Nyquist plot. DETAILED DESCRIPTION

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] Figure 1 A battery is shown. The battery may be a sodium battery or a sodium-ion battery. The battery is suitably a secondary (rechargeable) battery.

[0037] The cell comprises an anode current collector 101 in contact with an anode 103 on its surface; a cathode current collector 109 in contact with a cathode 107; and a layer 105 comprising or consisting of an electrolyte as described herein, disposed between the anode and cathode.

[0038] In some embodiments, layer 105 is a gel layer comprising a polymer; a solvent; and a compound of formula (I).

[0039] In some embodiments, layer 105 is a porous membrane that includes an electrolyte as described herein absorbed into the porous membrane.

[0040] In the case of sodium-ion batteries, the anode contains an active material (such as graphite) for absorbing metal ions.

[0041] In the case of a sodium battery, anode 103 is a sodium layer that forms over the anode current collector during charging of the battery and peels off during discharging of the battery.

[0042] The cathode may be selected from any cathode known to the skilled person.

[0043] 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.

[0044] For simplicity, Figure 1 A cell is shown in which the anode and cathode are separated only by a layer comprising or consisting of a gel, however it will be appreciated that during use a solid electrolyte interface will typically form on the anode surface.

[0045] In other embodiments, one or more additional layers may be disposed between the anode and the electrolyte and / or between the cathode and the electrolyte.

[0046] 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.

[0047] Compounds of formula (I)

[0048] Formula (I) is:

[0049]

[0050] X is Al or B.

[0051] R 1 is independently at each occurrence a substituent, wherein both R 1 The groups may be linked to form a ring.

[0052] Preferably, each R 1 Independently selected from:

[0053] Straight chain, branched chain or cyclic C 1-20 Alkyl, in which one or more non-adjacent, non-terminal C atoms other than the C atom bonded to O in XO may be replaced by O, and one or more H atoms may be replaced by F;

[0054] Optionally substituted C 6-20 Aryl or C 5-20 heteroaryl; and C 1-20 Alkylene-C 6-20 Aryl or C 1-20 Alkylene-C 5-20 Heteroaryl, wherein C 1-20 One or more non-adjacent, non-terminal C atoms in the alkylene group other than the C atom bonded to the O of the borate ester may be replaced by O, and C 1-20 One or more H atoms in the alkylene group may be replaced by F, and C 6-20 Aryl or C 5-20 Heteroaryl groups can be unsubstituted or substituted.

[0055] If present, C 6-20 Aryl or C 5-20 The substituents of the heteroaryl group are preferably and independently selected from the substituents R 5 , where R 5 Independently selected from F and C at each occurrence 1-12 A group consisting of alkyl groups, wherein C 1-12 One or more non-adjacent, non-terminal C atoms of the alkyl group may be replaced by O, S, NR 4 , CO, COO or CONR 4 Replace, where R 4 C independently at each occurrence 1-12 Hydrocarbyl group, and C 1-12 One or more H atoms in the alkyl group may be replaced by F.

[0056] As used herein, a "non-terminal C atom" of an alkyl chain refers to a methyl group at the chain terminus of a straight-chain alkyl chain or each methyl group at the chain terminus of a branched-chain alkyl group.

[0057] C as described anywhere herein 1-12 The hydrocarbyl group is preferably selected from C 1-12 Alkyl; phenyl; and one or more C 1-6 Phenyl substituted with an alkyl group.

[0058] In which at least two R 1 In the case where the group is not connected, preferably each R 1 is independently at each occurrence a partially fluorinated linear or branched C 1-20 an alkyl group in which one or more non-adjacent, non-terminal C atoms other than the C atom bonded to O in XO may be replaced by O, and in which the fluorinated C 1-20 The alkyl group includes at least one group of the formula -CF2H or -CFH2.

[0059] In some embodiments, two pairs of R 1 The groups are attached, and the compound of formula (I) has formula (II):

[0060]

[0061] where R 2 is independently at each occurrence a divalent organic group.

[0062] Preferably, R 2 Selected from:

[0063] Unsubstituted or substituted C 6-20 Arylene or C 5-20 heteroarylene;

[0064] Unsubstituted or substituted C 1-20 Alkylene, in which one or more non-adjacent C atoms other than the C atom bonded to the O of the borate ester may be replaced by O, and one or more H atoms may be replaced by F; and C 1-20 -alkylene-C 6-20 Arylene or C 1-20 -alkylene-C 5-20 Heteroarylene, wherein C 1-20 One or more non-adjacent C atoms in the alkylene group other than the C atom bonded to the O of the borate ester may be replaced by O. 1-20 -alkylene is unsubstituted or substituted; and C 6-20 Arylene or C 5-20 A heteroarylene group can be substituted or unsubstituted.

[0065] C 6-20 Arylene or C 5-20Heteroarylene may be unsubstituted or substituted with one or more substituents. Preferred substituents, if present, are selected from R as described above. 5 .

[0066] R 2 Preferably selected from: Ar 1 , where Ar 1 is independently at each occurrence an optionally substituted C 6-20 Arylene or C 5-20 Heteroarylene groups, such as 1,2-phenylene, which may be unsubstituted or substituted with one or more substituents; formula Ar 1 -Ar 1 biarylene groups, such as 2,2'-linked biphenylene, which may be unsubstituted or substituted with one or more substituents; ethylene; propylene; and groups of formula (III):

[0067]

[0068] where R 3 H, F, or C on each occurrence 1-6 Alkyl, in which one or more H atoms may be replaced by F; and Ar 1 It is C 6-20 Arylene group, preferably unsubstituted or substituted 1,2-phenylene.

[0069] In a preferred embodiment, at least one R 3 , optionally each R 3 , is C 1-6 Perfluoroalkyl group.

[0070] Preferably, each Ar of formula (I) 1 is a phenylene group, more preferably a 1,2-linked phenylene group which is unsubstituted or substituted by one or more substituents.

[0071] If present, Ar 1 The substituents are preferably and independently selected from R 5 .

[0072] The compound of formula (I) or (II) can be prepared by reacting a compound of formula (IV) with a compound of formula (Va) or (Vb) (wherein R 1 group is not attached) or with a compound of formula (VIa), (VIb) or (Vic) (in the case of a compound of formula (II)) to form:

[0073]

[0074] The compound of formula (Va) may be a primary, secondary or tertiary alcohol.

[0075] The compound of formula (Vb) may be an aldehyde or a ketone.

[0076] Exemplary compounds of formula (IV) include, but are not limited to, sodium aluminum hydride (NaAlH4) and sodium borohydride (NaBH4).

[0077] solvent

[0078] The electrolyte containing one or more solvents and a compound of formula (I) or (II) may include one or more selected from carbonate C 2-10 Alkylene esters, di(C 1-10 Solvents containing propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate and fluorinated analogs thereof; 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; diethylene glycol diethyl ether; succinonitrile; cyclic lactones and mixtures thereof.

[0079] Optionally, the ratio of moles of solvent:moles of Na+ of the electrolyte is no greater than 20:1, optionally less than or equal to 15:1 or less than or equal to 10:1.

[0080] polymer

[0081] The electrolyte as described herein may comprise a polymer, in which case the electrolyte may be a gel.

[0082] 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.

[0083] The polymer is suitably a neutral polymer, ie a polymer which is not substituted with ionic groups, and in particular is suitably not a single ion conducting polymer comprising anionic groups.

[0084] Examples

[0085] Compound Example 1

[0086]

[0087] The reaction is carried out under a nitrogen atmosphere. At room temperature, a solution of NaBH4 (151mg, 4mmol, 0.34M) in anhydrous tetrahydrofuran is added dropwise to a solution of (1,1,1,3,3,3-hexafluoro-2-hydroxypropyl-2-yl) phenol (2.08g, 8mmol) in 12mL of tetrahydrofuran. The mixture is then stirred at room temperature for 3 hours, and at 65°C for 3 hours. Dropwise addition of NaBH4 (55mg, 1.45mmol, 0.72M) in THF is added. The reaction mixture is then stirred at room temperature overnight. After the reaction is complete, propylene carbonate (1.4mL, 16mmol) 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.

[0088] In THF-d8 1 H NMR (600 MHz): δ (ppm), 1.37 (d, CH3, from propylene carbonate 20.7H), 3.96 (m, CH, from propylene carbonate 6.7H), 4.50 (t, CH, from propylene carbonate 6.7H), 4.80 (m, CH, from propylene carbonate 6.1H), 6.73 (m, 4H), 7.16 (td, J = 7.6 Hz, J = 1.7 Hz, 2H), 7.33 (d, J = 7.8 Hz, 2H).

[0089] From the integration of the NMR peaks, it was calculated that for two molecules of (1,1,1,3,3,3-hexafluoro-2-hydroxypropan-2-yl)phenol corresponding to one sodium cation, there were 6.70 molecules of propylene carbonate as residual solvent per sodium cation.

[0090] Compound Example 2

[0091]

[0092] The reaction was carried out under a nitrogen atmosphere. At room temperature, a solution of NaBH4 (203mg, 5.37mmol, 0.45M) in anhydrous tetrahydrofuran was added dropwise to a solution of 2,2,3,3,4,4,5,5-octafluoropentan-1-ol (OFP) (3mL, 21.5mmol) in 12mL of tetrahydrofuran. The mixture was stirred at room temperature for 1 hour and at 65°C for 4 hours. The reaction mixture was further stirred at room temperature overnight. After the reaction was complete, propylene carbonate (0.68mL, 8.06mmol) was added. The mixture was then heated at 30°C (3.3x 10 -2Excess 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.

[0093] In THF-d8 1 H NMR (600 MHz): δ (ppm), 1.39 (d, CH3, from propylene carbonate 14.7H), 3.90 (t, J = 15.01 Hz, 7.7H), 3.97 (m, CH, from propylene carbonate 7.8H), 4.50 (t, CH, from propylene carbonate 4.7H), 4.80 (m, CH, from propylene carbonate 4.2H), 6.62 (tt, J = 51.4 Hz, J = 5.8 Hz, 4H).

[0094] From the integration of the NMR peaks, it was calculated that for four molecules of octafluoropentyloxy ligand corresponding to one sodium cation in the product, there were 4.80 molecules of propylene carbonate as residual solvent per sodium cation.

[0095] Cell formation

[0096] 2032-size coin cells were fabricated in a strictly dry, oxygen-free, argon-filled MBraun glove box using housings purchased from Cambridge Energy Solutions.

[0097] A stainless steel gasket is inserted into the bottom of the button cell, followed by a fluoro-silicone template (purchased from Silex Silicones). The template is in the shape of 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 the electrolyte formulation. The stainless steel gasket, wave spring, and button cell cover are placed on top of the template. Finally, the button cell is crimped.

[0098] The electrolyte formulation used to form the button cell includes Compound Example 1, Compound Example 2, Comparative Compound 1, or Comparative Compound 2.

[0099]

[0100] Electrochemical impedance spectroscopy (EIS)

[0101] EIS measurements of the coin cell were performed at room temperature using a potentiostat (Interface 1010E, Gamry Instruments).

[0102] The frequency range of the EIS spectra was 1 Hz to 1 MHz, with an amplitude of 5 mV.

[0103] Ionic conductivity is calculated using the following formula:

[0104]

[0105] in:

[0106] l- the thickness of the material between the two stainless steel discs, corresponding to the thickness of the separator,

[0107] A - area of the hole on the partition,

[0108] R – resistance of the electrolyte.

[0109] To determine the impedance, compare the Nyquist plot of each cell to Figure 2 The equivalent circuit shown in FIG1 is fitted, where the impedance of resistor 1 is regarded as the ionic resistance of the electrolyte in the system.

[0110] Resistor 1 corresponds to the x-intercept of the first semicircle on the x-axis of the Nyquist plot.

[0111] The Nyquist plots for compound examples 1 and 2 are Figure 3A The enlarged view is shown in Figure 3B Shown in.

[0112] The ionic conductivities are listed in Table 1.

[0113] Table 1

[0114]

[0115] As shown in Table 1, surprisingly, Compound Example has significantly higher ionic conductivity than Comparative Compound 1, and Compound Example 2 has similar ionic conductivity to Comparative Compound 2, despite the significantly larger size of the sodium cations of Compound Examples 1 and 2 compared to the lithium cations of Comparative Compounds 1 and 2.

[0116] Furthermore, the inventors of the present invention surprisingly found that compound Example 1 can be dissolved in propylene carbonate to obtain a highly concentrated solution, whereas D. Ould et al. (supra) disclosed that Na[B(OCH2(CF2)2CF3)4] has poor solubility in a 1:1 mixture of ethylene carbonate and diethyl carbonate.

Claims

1. A compound of formula (II): Where X is Al or B, and R 2 is independently at each occurrence a divalent organic group selected from: Unsubstituted or substituted C 6-20 Arylene or C 5-20 heteroarylene; Unsubstituted or substituted C 1-20 Alkylene, in which one or more non-adjacent C atoms other than the C atom bonded to the O of the borate ester may be replaced by O, and one or more H atoms may be replaced by F; and C 1-20 -alkylene-C 6-20 Arylene or C 1-20 -alkylene-C 5-20 Heteroarylene, wherein C 1-20 One or more non-adjacent C atoms in the alkylene group other than the C atom bonded to the O of the borate ester may be replaced by O. 1-20 -alkylene is unsubstituted or substituted; and C 6-20 The arylene group is substituted or unsubstituted.

2. The compound according to claim 1, wherein at least one R 2 is a group of formula (III): where R 3 is H or a substituent at each occurrence, and Ar 1 is unsubstituted or substituted C 6-20 Arylene or C 5-20 Heteroarylene groups.

3. The compound according to claim 2, wherein Ar 1 is unsubstituted or substituted 1,2-phenylene.

4. The compound according to claim 2 or 3, wherein each R 2 is a group of formula (III).

5. A compound of formula (I): wherein X is Al or B; and R 1 is independently a substituent at each occurrence, and both R 1 The groups may be linked to form a ring, provided that at least one R 1 is a partially fluorinated linear or branched C 1-20 an alkyl group in which one or more non-adjacent, non-terminal C atoms other than the C atom bonded to O in XO may be replaced by O, and in which the fluorinated C 1-20 The alkyl group includes at least one group of the formula -CF2H or -CFH2.

6. The compound according to claim 5, wherein each R 1 is a partially fluorinated linear or branched C 1-20 an alkyl group in which one or more non-adjacent, non-terminal C atoms other than the C atom bonded to O in XO may be replaced by O, and in which the fluorinated C 1-20 The alkyl group includes at least one group of the formula -CF2H or -CFH2.

7. An electrolyte comprising a compound according to any one of the preceding claims and one or more solvents.

8. The electrolyte of claim 7, wherein the one or more solvents include carbonate C 2-10 Alkylene esters and di(C 1-10 At least one of the alkyl) esters.

9. The electrolyte according to claim 7 or 8, wherein the electrolyte contains at least one mole of sodium cations per 10 moles of solvent.

10. The electrolyte according to any one of claims 7 to 9, wherein the concentration of the compound of formula (I) or (II) is at least 0.25 mol / l.

11. A battery comprising an anode, a cathode, and the electrolyte according to any one of claims 7 to 10, the electrolyte being provided between the anode and the cathode.

12. The battery of claim 11, wherein the battery contains no more than 10 moles of total solvent per mole of Na+.

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