Elimination of voltage delay and stabilization of impedance by electrolyte additives in alkali metal electrochemical cells

Abstract

The present invention relates to a galvanic cell comprising: an alkali metal as an active electrode material, in particular as an active negative electrode material, and an electrolyte having a boron compound, wherein the boron compound is a compound according to formula (1), (2), (3), (4), (7) or (8):

Description

[0001] The present invention relates to boron-based electrolyte additives for alkali metal electrochemical galvanic cells (primary cells) and to the corresponding alkali metal electrochemical galvanic cells.

[0002] A monotonic pulse process (curve) is usually desirable in an electrochemical cell. A monotonic pulse curve is one in which the voltage curve remains constant under pulse conditions or drops to a minimum value at the end of a pulse and the minimum voltage of the first pulse in a pulse train is higher than the minimum voltage of the last pulse. The voltage curve of the pulse train is usually rectangular ( Figure 1 ).

[0003] Voltage delay is an undesirable characteristic in the discharge curve of implantable alkali metal batteries under current pulse discharge conditions. Voltage delay is caused by the formation of a relatively high resistance coating on the negative electrode surface, which leads to an increase in the internal resistance of the battery. Voltage delay occurs only when the battery is subjected to high pulse current density and the battery voltage drops disproportionately during the process (i.e., the voltage at the beginning of the first pulse is lower than the voltage at the end of the pulse) or when the first pulse is lower than the minimum voltage of the last pulse ( Figure 2 ) to observe this effect.

[0004] Voltage lag usually first appears in alkali metal / metal oxide and alkali metal / mixed metal oxide cells at DoD (depth of discharge) above 40% of their capacity discharge or under pulsed load after long storage. In some cases, this can lead to voltage lag or non-monotonic behavior under certain pulsed discharge conditions, for example due to dissolution of the positive electrode active material or due to the formation of a high resistance coating on the negative electrode surface due to discharge products in the battery electrolyte.

[0005] Electrolyte additives such as phosphates, dicarbonates, nitrites, alkyl phosphates, and organic additives having hydroxyl (—OH) and carboxyl groups for suppressing or reducing the voltage delay of alkali metal / transition metal oxides (e.g., Li / SVO) and alkali metal / mixed oxide x and / or transition metal oxide or Li / SVO cells are known in the prior art.

[0006] The aforementioned additives are typically used in alkali metal / transition metal oxide systems, in particular in lithium / silver vanadium oxide (Li / SVO) and lithium / silver vanadium oxide hybrid cathodes (Li / SVO hybrid cathodes), where an increase in impedance and thus voltage delay occurs due to a high resistance coating formed by metal deposits such as vanadium, silver and / or metal alloys on the electrode surface. However, the aforementioned additives are not suitable for alkali metal / carbon monofluoride (Li / CFx) systems, where voltage delay occurs due to lithium fluoride deposits on the negative electrode surface.

[0007] Organic borates are also known in the prior art as electrolyte additives or electrolyte conducting salts for reducing self-discharge and for reducing / eliminating voltage delays after storage of Li / CFx cells at room temperature and elevated temperatures (e.g. from US 7740986 B2). However, electrolytes based on organic borates show increased cell resistance compared to standard electrolytes (see Example 01).

[0008] Against this background, it was an object of the present invention to provide an electrolyte additive for galvanic cells, in particular galvanic cells comprising lithium as active electrode material, which reduces and preferably eliminates the voltage delay and reduces the cell impedance.

[0009] This object is achieved by a galvanic cell having the features of claim 1 and by the use of a boron compound having the features of claim 9. Suitable embodiments are provided in the respective dependent claims and in the following description.

[0010] According to claim 1, a galvanic cell is provided which comprises an alkali metal as active electrode material, in particular as active negative electrode material, and an electrolyte having a boron compound, in particular an organoboron compound.

[0011] The term "galvanic cell" is used in the context of this specification in its generally known technical sense. It refers in particular to a primary cell which cannot be recharged after discharge. A galvanic cell is sometimes also referred to as a primary battery.

[0012] The boron compound is in particular a non-ionic compound, that is to say it is preferably not a salt of a boron-containing acid.

[0013] According to the present invention, it is particularly provided that the boron compound is a compound according to formula (1), (2), (3), (4), (7) or (8):

[0014]

[0015] wherein R1, R2, R3, R4 and R5 are independently selected from hydrogen, alkyl, alkenyl, cycloalkyl, thioether, heterocyclic compound, aryl and heteroaryl, wherein R1, R2, R3, R4 or R5 is not thiophene.

[0016] In one embodiment of the galvanic cell according to the invention, it is provided that R1, R2, R3, R4 and R5 are independently unsubstituted or mono- or poly-substituted by at least one substituent selected from the group consisting of alkyl, fluoroalkyl, alkoxy, carbonyl, carboxyl, thiol, thioalkoxide, aryl, ether, thioether, nitro, cyano, amino, azido, amidino, hydrazine, hydrazone, carbamoyl, sulfo, sulfamoyl, sulfonamido, alkylaminosulfonyl, alkylsulfonamido and / or halogen. Preferred substituents include halogen, fluoroalkyl and cyano or nitrile groups, wherein R1, R2, R3, R4 or R4 is not thiophene.

[0017] In one embodiment of the primary cell according to the invention, the boron compound is a compound according to formula (1), wherein R1 is unsubstituted or substituted alkyl, in particular C1-C6 alkyl, in particular methyl, cyclopropyl or cyclohexyl, or aryl, in particular phenyl, benzyl or naphthyl, with one or more C1-C4 alkyl, -F, -Cl, -Br, -I, -CN, -CF3 or -OCF3, and R2-R4 and R5 are each independently C1-C4 alkyl.

[0018] In one embodiment of the galvanic cell according to the invention, the compound according to formula (1) is

[0019] -4,4,5,5-tetramethyl-2-(3,4,5-trifluorophenyl)-1,3,2-dioxaborolane;

[0020] -2-(bromomethyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0021] -2-cyclopropyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0022] -2-cyclohexyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0023] -4,4,5,5-tetramethyl-2-(naphthalen-1-ylmethyl)-1,3,2-dioxaborolane;

[0024] -2-Benzyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0025] -2-phenyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0026] -4,4,5,5-tetramethyl-2-(1-naphthyl)-1,3,2-dioxaborolane;

[0027] -2-(4-chlorophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0028] -2-(4-fluorophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0029] -4,4,5,5-tetramethyl-2-(3,4,5-trifluorophenyl)-1,3,2-dioxaborolane;

[0030] -2-(4-bromophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0031] -2-(3,5-dichlorophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0032] -2-(2-iodophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0033] -4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzonitrile;

[0034] -4,4,5,5-tetramethyl-2-[3-(trifluoromethoxy)phenyl]-1,3,2-dioxaborolane;

[0035] -2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)aniline;

[0036] -2-[2-(trifluoromethyl)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0037] -2-[3,5-bis(trifluoromethyl)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; or

[0038] -2-Fluoro-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzonitrile,

[0039] Preferred is 4,4,5,5-tetramethyl-2-(3,4,5-trifluorophenyl)-1,3,2-dioxaborolane.

[0040] In one embodiment of the galvanic cell according to the invention, the boron compound is provided to be a compound according to formula (2), wherein R1 to R4 and R5 are each independently C1 to C4 alkyl.

[0041] In one embodiment of the primary cell according to the invention, the compound according to formula (2) is

[0042] -2-ethoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0043] -2-methoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; or

[0044] -2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane.

[0045] In one embodiment of the primary cell according to the invention, the boron compound is a compound according to formula (3), wherein R1 is an alkyl, alkenyl, in particular allyl or aryl, in particular benzyl, phenyl, or benzoate which is unsubstituted or substituted by one or more C1-C4 alkyl, -F, -Cl, -Br, -I, -CN, -CF3 or -OCF3 or a compound according to formula (3), and R2 and R3 are each independently a C1-C4 alkyl.

[0046] In one embodiment of the primary cell according to the invention, the compound according to formula (3) is

[0047] -2-allyl-5,5-dimethyl-1,3,2-dioxaborinane;

[0048] -5,5-dimethyl-2-phenyl-1,3,2-dioxaborinane;

[0049] -2,2'-(1,4-phenylene)bis[5,5-dimethyl-1,3,2-dioxaborinane];

[0050] -2-(2-chlorophenyl)-5,5-dimethyl-1,3,2-dioxaborinane;

[0051] -2-(1,3,2-dioxaborolan-2-yl)benzonitrile;

[0052] -2-(2-fluorophenyl)-5,5-dimethyl-1,3,2-dioxaborinane;

[0053] -2-(4-fluorophenyl)-5,5-dimethyl-1,3,2-dioxaborinane;

[0054] -4,4'-bis(5,5-dimethyl-1,3,2-dioxaborin-2-yl)biphenyl;

[0055] -ethyl 2-(5,5-dimethyl-1,3,2-dioxaborin-2-yl)benzoate;

[0056] -2-(5,5-dimethyl-1,3,2-dioxaborin-2-yl)-6-(trifluoromethyl)benzonitrile; or

[0057] -4-(trifluoromethyl)-2-(5,5-dimethyl(dinethyl)-1,3,2-dioxaborin-2-yl)benzonitrile.

[0058] In one embodiment of the galvanic cell according to the invention, the boron compound is provided to be a compound according to formula (4), wherein R1, R2 and R3 are each independently of one another a C1-C4 alkyl group.

[0059] In one embodiment of the primary cell according to the invention, the compound according to formula (4) is

[0060] -2-isopropoxy-4,4,6-trimethyl-1,3,2-dioxaborinane;

[0061] -2-ethoxy-4,4,6-trimethyl-1,3,2-dioxaborinane; or

[0062] -2-methoxy-4,4,6-trimethyl-1,3,2-dioxaborinane.

[0063] In one embodiment of the primary cell according to the invention, the boron compound is a compound according to formula (7), wherein R1-R3 are each independently of one another an alkyl group, in particular a C1-C4 alkyl group, in particular a methyl group, or an aryl group, in particular a phenyl group, which is unsubstituted or substituted by one or more -F, -Cl, -Br, -I, -CN, -CF3 or -OCF3.

[0064] In one embodiment of the primary cell according to the invention, the compound according to formula (7) is

[0065] -trimethylcyclotriboroxine (boroxine);

[0066] -2,4,6-triphenylcyclotriboroxane,

[0067] -2,4,6-tris(4-fluorophenyl)cyclotriboroxane;

[0068] -2,4,6-tris(3,4,5-trifluorophenyl)cyclotriboroxine;

[0069] -2,4,6-tris(3,4-difluorophenyl)cyclotriboroxine; or

[0070] -2,4,6-tris(3,4-dichlorophenyl)cyclotriboroxane.

[0071] In one embodiment of the galvanic cell according to the invention, the boron compound is provided to be a compound according to formula (8), wherein R1 to R3 are each independently C1 to C4 alkyl.

[0072] In one embodiment of the galvanic cell according to the invention, the compound according to formula (8) is provided to be 2,4,6-trimethoxycyclotriboroxine.

[0073] In one embodiment of the primary cell according to the present invention, the boron compound is provided in an amount of 0.001 mol*l -1 To 0.5mol*l -1 A concentration within a range of 1:1 is present in the electrolyte.

[0074] In one embodiment of the galvanic cell according to the invention, it is provided that the alkali metal serving as the active electrode material is lithium and that the galvanic cell is a lithium cell.

[0075] In one embodiment of the galvanic cell according to the invention, provision is made for the electrolyte to be a non-aqueous electrolyte.

[0076] In one embodiment of the primary cell according to the present invention, it is provided that the non-aqueous electrolyte

[0077] - comprising a first solvent selected from esters, ethers, dialkyl carbonates and mixtures thereof, in particular tetrahydrofuran, methyl acetate, diethylene glycol dimethyl ether (bis(2-methoxyethyl) ether), triethylene glycol dimethyl ether (tris(2-methoxyethyl) ether), tetraethylene glycol dimethyl ether (tetrakis(2-methoxyethyl) ether), 1,2-dimethoxyethane, 1,2-diethoxyethane, 1-ethoxy, 2-methoxyethane, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, or mixtures thereof, and

[0078] - comprising a second solvent, which is selected from cyclic carbonates, cyclic esters, cyclic amides and mixtures thereof, in particular propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyrolactone, N-methylpyrrolidone or mixtures thereof, or a polar non-aqueous solvent such as acetonitrile, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, or mixtures thereof.

[0079] In one embodiment of the primary cell according to the invention, it is provided that the electrolyte comprises an anhydrous alkali metal salt, in particular an anhydrous lithium salt, preferably LiClO4, LiPF6, LiBF4, LiAsF6, LiSbF6, LiClO4, LiAlCl4, LiGaCl4, LiC(SO2CF3)3, LiN(SO2CF3)2, LiSCN, LiO3SCF2CF3, LiC6F5SO3, LiO2CF3, LiSO3F, LiB(C6H5)4, LiCF3SO3 or a mixture thereof.

[0080] In one embodiment, the galvanic cell according to the invention further comprises a carbon monofluoride as the active electrode material, in particular as the active cathode material. The carbon monofluoride can be present by itself (bulk) or with a metal oxide, preferably a transition metal oxide such as MnO2, SVO (silver oxide and vanadium pentoxide), copper silver vanadium oxide, cobalt oxide, nickel oxide, copper oxide, copper sulfide, iron sulfide, iron disulfide, titanium disulfide, or a mixture thereof to form a hybrid cathode.

[0081] In one embodiment, the galvanic cell according to the invention comprises a positive electrode binder, in particular polytetrafluoroethylene, polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), a polyolefin, preferably a thermoplastic elastomer, in particular an ethylene / propylene diene terpolymer, or a mixture thereof.

[0082] In one embodiment, the galvanic cell according to the invention comprises carbon, in particular in the form of graphite, graphite powder or carbon black, or aluminum, in particular aluminum powder, titanium, in particular titanium powder, stainless steel, in particular stainless steel powder, or mixtures thereof as conductivity additive.

[0083] According to claim 9, a boron compound, in particular an organoboron compound, is provided for use as an electrolyte additive for galvanic cells having an alkali metal as active electrode material.

[0084] According to the present invention, it is particularly provided that the boron compound is a compound according to formula (1), (2), (3), (4), (7) or (8):

[0085]

[0086]

[0087] wherein R1, R2, R3, R4 and R6 are each independently selected from hydrogen, alkyl, alkenyl, cycloalkyl, thioether, heterocyclic compound, aryl and heteroaryl, wherein R1, R2, R3, R4 or R5 is not thiophene.

[0088] In one embodiment of the use according to the invention, it is provided that R1, R2, R3, R4 and R5 are each independently unsubstituted or mono- or polysubstituted by at least one substituent selected from the group consisting of alkyl, fluoroalkyl, alkoxy, carbonyl, carboxyl, thiol, thioalkoxide, aryl, ether, thioether, nitro, cyano, amino, azido, amidino, hydrazine, hydrazone, carbamoyl, sulfo, sulfamoyl, sulfonylamino, alkylaminosulfonyl, alkylsulfonylamino and / or halogen, wherein R1, R2, R3, R4 or R5 is not thiophene.

[0089] In one embodiment of the use according to the invention, the boron compound is provided as a compound according to formula (1), wherein R1 is unsubstituted or substituted alkyl, in particular C1-C6 alkyl, in particular methyl, cyclopropyl or cyclohexyl, or aryl, in particular phenyl, benzyl or naphthyl: one or more C1-C4 alkyl, -F, -Cl, -Br, -I, -CN, -CF3 or -OCF3, and R2 to R4 and R5 are each independently C1-C4 alkyl.

[0090] In one embodiment of the use according to the invention, it is provided that the compound according to formula (1) is

[0091] -4,4,5,5-tetramethyl-2-(3,4,5-trifluorophenyl)-1,3,2-dioxaborolane;

[0092] -2-(bromomethyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0093] -2-cyclopropyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0094] -2-cyclohexyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0095] -4,4,5,5-tetramethyl-2-(naphthalen-1-ylmethyl)-1,3,2-dioxaborolane;

[0096] -2-Benzyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0097] -2-phenyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0098] -4,4,5,5-tetramethyl-2-(1-naphthyl)-1,3,2-dioxaborolane;

[0099] -2-(4-chlorophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0100] -2-(4-fluorophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0101] -4,4,5,5-tetramethyl-2-(3,4,5-trifluorophenyl)-1,3,2-dioxaborolane;

[0102] -2-(4-bromophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0103] -2-(3,5-dichlorophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0104] -2-(2-iodophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0105] -4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzonitrile;

[0106] -4,4,5,5-tetramethyl-2-[3-(trifluoromethoxy)phenyl]-1,3,2-dioxaborolane;

[0107] -2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)aniline;

[0108] -2-[2-(trifluoromethyl)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0109] -2-[3,5-bis(trifluoromethyl)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; or

[0110] -2-Fluoro-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzonitrile,

[0111] Preferred is 4,4,5,5-tetramethyl-2-(3,4,5-trifluorophenyl)-1,3,2-dioxaborolane.

[0112] In one embodiment of the use according to the invention, it is provided that the boron compound is a compound according to formula (2), wherein R1 to R4 and R5 are each independently of one another a C1-C4 alkyl group.

[0113] In one embodiment of the use according to the invention, it is provided that the compound according to formula (2) is

[0114] -2-ethoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane;

[0115] -2-methoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; or

[0116] -2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane.

[0117] In one embodiment of the use according to the invention, the boron compound is provided as a compound according to formula (3), wherein R1 is an alkyl, alkenyl, in particular allyl or aryl, in particular benzyl, phenyl, or benzoate which is unsubstituted or substituted by one or more C1-C4 alkyl, -F, -Cl, -Br, -I, -CN, -CF3 or -OCF3, and R2 and R3 are each independently C1-C4 alkyl.

[0118] In one embodiment of the use according to the invention, it is provided that the compound according to formula (3) is

[0119] -2-allyl-5,5-dimethyl-1,3,2-dioxaborinane;

[0120] -5,5-dimethyl-2-phenyl-1,3,2-dioxaborinane;

[0121] -2,2'-(1,4-phenylene)bis[5,5-dimethyl-1,3,2-dioxaborinane];

[0122] -2-(2-chlorophenyl)-5,5-dimethyl-1,3,2-dioxaborinane;

[0123] -2-(1,3,2-dioxaborolan-2-yl)benzonitrile;

[0124] -2-(2-fluorophenyl)-5,5-dimethyl-1,3,2-dioxaborinane;

[0125] -2-(4-fluorophenyl)-5,5-dimethyl-1,3,2-dioxaborinane;

[0126] -4,4'-bis(5,5-dimethyl-1,3,2-dioxaborin-2-yl)biphenyl;

[0127] -ethyl 2-(5,5-dimethyl-1,3,2-dioxaborin-2-yl)benzoate;

[0128] -2-(5,5-dimethyl-1,3,2-dioxaborin-2-yl)-6-(trifluoromethyl)benzonitrile; or

[0129] -4-(trifluoromethyl)-2-(5,5-dimethyl(dinethyl)-1,3,2-dioxaborin-2-yl)benzonitrile.

[0130] In one embodiment of the use according to the invention, it is provided that the boron compound is a compound according to formula (4), wherein R1, R2 and R3 are each independently of one another a C1-C4 alkyl group.

[0131] In one embodiment of the use according to the invention, it is provided that the compound according to formula (4) is

[0132] -2-isopropoxy-4,4,6-trimethyl-1,3,2-dioxaborinane;

[0133] -2-ethoxy-4,4,6-trimethyl-1,3,2-dioxaborinane; or

[0134] -2-methoxy-4,4,6-trimethyl-1,3,2-dioxaborinane.

[0135] In one embodiment of the use according to the present invention, the boron compound is provided as a compound according to formula (7), wherein R1 to R3 are each independently of one another an alkyl group, in particular a C1-C4 alkyl group, in particular a methyl group, or an aryl group, in particular a phenyl group, which is unsubstituted or substituted by one or more -F, -Cl, -Br, -I, -CN, -CF3 or -OCF3.

[0136] In one embodiment of the use according to the present invention, it is provided that the compound according to formula (7) is

[0137] -trimethylcyclotriboroxine;

[0138] -2,4,6-triphenylcyclotriboroxane,

[0139] -2,4,6-tris(4-fluorophenyl)cyclotriboroxane;

[0140] -2,4,6-tris(3,4,5-trifluorophenyl)cyclotriboroxine;

[0141] -2,4,6-tris(3,4-difluorophenyl)cyclotriboroxine; or

[0142] -2,4,6-tris(3,4-dichlorophenyl)cyclotriboroxane.

[0143] In one embodiment of the use according to the invention, it is provided that the boron compound is a compound according to formula (8), wherein R1 to R3 are each independently of one another a C1-C4 alkyl group.

[0144] In one embodiment of the use according to the invention, it is provided that the compound according to formula (8) is 2,4,6-trimethoxycyclotriboroxine.

[0145] In one embodiment of the use according to the invention, it is provided that the alkali metal serving as the active electrode material is lithium and the galvanic cell is a lithium cell.

[0146] Further features and advantages of the invention are described below based on the description of the drawings of exemplary embodiments. In the drawings:

[0147] Figure 1 Pulse curve of an electrochemical cell showing no voltage delay;

[0148] Figure 2 Pulse curve showing an electrochemical cell with voltage delay;

[0149] Figure 3 Shown is the impedance curve of a cell with an electrolyte additive known from the prior art (lithium bis(oxalato)borate (LiBOB));

[0150] Figure 4 Shows the impedance curve (a) of a battery having an electrolyte additive according to the present invention (4,4,5,5-tetramethyl-2-(3,4,5-trifluorophenyl)-1,3,2-dioxaborolane (TMTFPDDB), and the pulse discharge and pulse curve (B) at a discharge depth of 180 mAh;

[0151] Figure 5 The impedance curve (a) of a cell having another electrolyte additive according to the invention (trimethylcyclotriboroxine (TMB)) is shown, as well as the pulse discharge and pulse curve (b) at a 180 mAh depth of discharge. Example:

[0152] Compared with commercially available lithium primary batteries, lithium carbon monofluoride batteries (Li / CFx) have the highest theoretical specific capacity. The overall discharge equation is as follows:

[0153] CFx+xLi→C+xLiF

[0154] LiF is an anion and an electrical insulator that adheres to the surface of the positive electrode pores on the one hand and partially dissolves in the electrolyte on the other hand. At discharge depths between the MOL and EOL states, the fluoride concentration in the electrolyte increases, resulting in a high-resistance coating of lithium fluoride compounds on the negative electrode surface (Table 1). Under certain pulse discharge conditions, this can lead to voltage lag or non-monotonic behavior.

[0155] Table 1: Fluoride content on the surface of lithium negative electrode at different discharge depths

[0156]

[0157]

[0158] The present invention relates generally to electrochemical alkali metal cells, in particular to lithium / carbon monofluoride or lithium / carbon monofluoride metal oxide cells, suitable for applications with current pulse discharge and no voltage delay. More specifically, the present invention relates to electrochemical lithium metal cells with non-aqueous electrolytes, which prevent voltage delay by electrolyte additives.

[0159] The present invention particularly relates to dioxaborolan, diboron and cyclotriboroxane electrolyte additives for alkali metal electrochemical cells with carbon monofluoride (CFx) or CFx transition metal oxide hybrid positive electrodes (e.g., Li / CFx-MnO2, Li / CFx-SVO, etc.) as positive electrode active materials. The LiCFx system shows a voltage delay under pulse conditions before the end of life (EOL) state. In order to suppress the voltage delay and reduce the impedance increase, according to the present invention, dioxaborolan, diboron and cyclotriboroxane additives are particularly added to the electrolyte.

[0160] An advantage of the present invention is the formation of a solid electrolyte interface (SEI) film on the negative electrode (e.g., lithium metal), which protects the electrode surface, that is, the electrolyte additives are reduced on the negative electrode surface and protect it from forming a high resistance coating, which in turn serves to stabilize the internal resistance of the battery, improve the discharge power, and eliminate the voltage delay (Table 2).

[0161] Table 2: Boron content on the surface of lithium anode at EOL state

[0162] Battery ID Boron [μg] Battery 13 11.75 Battery 14 10.42

[0163] The present invention preferably relates to an electrochemical alkali metal cell as described above, which has a non-aqueous, ion-conducting electrolyte and at least one compound according to the general formulae (1), (2), (3), (4), (5), (6), (7) and (8).

[0164] The electrochemical cells used in the examples and comparative examples were made from the following components:

[0165]

[0166]

[0167] Embodiment 1 (comparative example):

[0168] Figure 3The impedance curves for discharge at a daily pulse load of 12.7 KOhm and 10 mA / 156 s are shown, wherein the measurements were carried out in each case with a standard electrolyte (without electrolyte additive) and with a standard electrolyte having 0.075 M lithium bis(oxalato)borate (LiBOB) as an additive. As mentioned at the outset, LiBOB is an electrolyte additive known from the prior art. It is clear here that the internal resistance of the cell increases with increasing discharge.

[0169] Embodiment 2:

[0170] Figure 4 Discharge data at a daily pulse load of 12.7 KOhm and 10 mA / 156 s are illustrated, wherein the impedance curve of the cell during discharge is shown in (a) and the pulse curve at 180 mAh is shown in (b). A standard electrolyte and a standard electrolyte with 0.075 M of an electrolyte additive according to the invention, which in this case is 4,4,5,5-tetramethyl-2-(3,4,5-trifluorophenyl)-1,3,2-dioxaborolane (TMTFPDDB) are used. It is clear that due to the electrolyte additive according to the invention, the internal resistance of the cell does not increase over a wide discharge range.

[0171] Embodiment 3:

[0172] Figure 5 Discharge data at a daily pulse load of 12.7 KOhm and 10 mA / 156 s are shown, wherein the impedance curve of the cell during discharge is shown in (a) and the pulse curve at 180 mAh is shown in (b). A standard electrolyte and a standard electrolyte with 0.075 M of the electrolyte additive according to the invention, which in this case is trimethylcyclotriboroxine (TMB), are used. It is also clear here that the internal resistance of the cell does not increase over a wide discharge range due to the electrolyte additive according to the invention.

[0173] In summary, it can be seen that, particularly by using dioxaborolane, diboron and cyclotriboroxine additives, voltage delay can be eliminated and cell impedance can be reduced.

[0174] In implantable batteries for cardiac therapy, cells that exhibit a voltage delay use only a portion of the total capacity (until the voltage delay occurs). By using dioxaborolane, diboron, and cyclotriboroxine electrolyte additives, the full discharge capacity of the implantable battery can be made available.

Claims

1. A primary battery comprising: - alkali metals as active electrode materials, - carbon monofluoride as active electrode material, and - an electrolyte comprising a boron compound, Characterized in that the boron compound is a compound according to formula (1), (2), (3), (4), (7) or (8): in R1, R2, R3, R4 and R5 are each independently selected from hydrogen, alkyl, alkenyl, cycloalkyl, thioether, heterocyclic compound, aryl and heteroaryl, wherein R1, R2, R3, R4 or R5 is not thiophene.

2. A primary cell according to claim 1, characterized in that Alkali metals are used as active negative electrode materials.

3. A primary cell according to claim 1, characterized in that Carbon monofluoride as the active cathode material.

4. A primary cell according to claim 1, characterized in that R1, R2, R3, R4 and R5 are each independently unsubstituted or mono- or polysubstituted by at least one substituent selected from the group consisting of alkyl, fluoroalkyl, alkoxy, carbonyl, carboxyl, thiol, thioalkoxide, aryl, ether, thioether other than thiophene, nitro, cyano, amino, azido, amidino, hydrazine, hydrazone, carbamoyl, sulfo, sulfamoyl, sulfonylamino, alkylaminosulfonyl, alkylsulfonylamino and / or halogen, wherein R1, R2, R3, R4 or R5 is not thiophene.

5. A primary cell according to claim 4, characterized in that The substituent is selected from halogen, fluoroalkyl and cyano.

6. A primary cell according to any one of claims 1 to 5, characterized in that The boron compound is - a compound according to formula (1), wherein R1 is an alkyl or aryl group which is unsubstituted or substituted by one or more C1-C4 alkyl, -F, -Cl, -Br, -I, -CN, -CF3 or -OCF3, and R2 to R5 are each independently C1-C4 alkyl; - a compound according to formula (2), wherein R1 to R5 are each independently C1-C4 alkyl; - a compound according to formula (3), wherein R1 is unsubstituted or substituted alkyl, alkenyl or aryl: C1-C4 alkyl, -F, -Cl, -Br, -I, -CN, -CF3 or -OCF3 or a compound according to formula (3), and R2 and R3 are each independently C1-C4 alkyl; - a compound according to formula (4), wherein R1, R2 and R3 are each independently C1-C4 alkyl; - a compound according to formula (7), wherein R1 to R3 are each independently of one another alkyl or aryl which is unsubstituted or substituted by one or more -F, -Cl, -Br, -I, -CN, -CF3, -OCF3; or - A compound according to formula (8), wherein R1 to R3 are each independently C1-C4 alkyl.

7. A primary cell according to claim 6, characterized in that The boron compound is a compound according to formula (1), wherein R1 is unsubstituted or substituted C1-C6 alkyl: one or more C1-C4 alkyl, -F, -Cl, -Br, -I, -CN, -CF3 or -OCF3, and R2 to R5 are each independently C1 C4 alkyl.

8. A primary cell according to claim 6, characterized in that The boron compound is a compound according to formula (1), wherein R1 is methyl, cyclopropyl or cyclohexyl, which is unsubstituted or substituted by one or more C1-C4 alkyl, -F, -Cl, -Br, -I, -CN, -CF3 or -OCF3, and R2 to R5 are each independently C1 C4 alkyl.

9. A primary cell according to claim 6, characterized in that The boron compound is a compound according to formula (1), wherein R1 is phenyl, benzyl or naphthyl which is unsubstituted or substituted by one or more C1-C4 alkyl, -F, -Cl, -Br, -I, -CN, -CF3 or -OCF3, and R2 to R5 are each independently C1 C4 alkyl.

10. A primary cell according to claim 6, characterized in that The boron compound is a compound according to formula (3), wherein R1 is unsubstituted or substituted allyl: C1-C4 alkyl, -F, -Cl, -Br, -I, -CN, -CF3 or -OCF3 or a compound according to formula (3), and R2 and R3 are each independently C1-C4 alkyl.

11. A primary cell according to claim 6, characterized in that The boron compound is a compound according to formula (3), wherein R1 is unsubstituted or substituted benzyl, phenyl, or benzoate: C1-C4 alkyl, -F, -Cl, -Br, -I, -CN, -CF3 or -OCF3 or a compound according to formula (3), and R2 and R3 are each independently C1-C4 alkyl.

12. A primary cell according to claim 6, characterized in that The boron compound is a compound according to formula (7), wherein R1 to R3 are each independently unsubstituted or substituted by one or more of -F, -Cl, -Br, -I, -CN, -CF3, -OCF3.

13. A primary cell according to claim 6, characterized in that The boron compound is a compound according to formula (7), wherein R1 to R3 are each independently methyl and are unsubstituted or substituted by one or more of -F, -Cl, -Br, -I, -CN, -CF3, -OCF3.

14. A primary cell according to claim 6, characterized in that The boron compound is a compound according to formula (7), wherein R1 to R3 are each independently phenyl which is unsubstituted or substituted by one or more of -F, -Cl, -Br, -I, -CN, -CF3, -OCF3.

15. A primary cell according to any one of claims 1 to 5, characterised in that The boron compound is -4,4,5,5-tetramethyl-2-(3,4,5-trifluorophenyl)-1,3,2-dioxaborolane; -2-(bromomethyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -2-cyclopropyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -2-cyclohexyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -4,4,5,5-tetramethyl-2-(naphthalen-1-ylmethyl)-1,3,2-dioxaborolane; -2-Benzyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -2-phenyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -4,4,5,5-tetramethyl-2-(1-naphthyl)-1,3,2-dioxaborolane; -2-(4-chlorophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -2-(4-fluorophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -4,4,5,5-tetramethyl-2-(3,4,5-trifluorophenyl)-1,3,2-dioxaborolane; -2-(4-bromophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -2-(3,5-dichlorophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -2-(2-iodophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzonitrile; -4,4,5,5-tetramethyl-2-[3-(trifluoromethoxy)phenyl]-1,3,2-dioxaborolane; -2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)aniline; -2-[2-(trifluoromethyl)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -2-[3,5-bis(trifluoromethyl)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -2-Fluoro-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzonitrile; -2-ethoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -2-methoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -2-allyl-5,5-dimethyl-1,3,2-dioxaborinane; -5,5-dimethyl-2-phenyl-1,3,2-dioxaborinane; -2,2'-(1,4-phenylene)bis[5,5-dimethyl-1,3,2-dioxaborinane]; -2-(2-chlorophenyl)-5,5-dimethyl-1,3,2-dioxaborinane; -2-(1,3,2-dioxaborolan-2-yl)benzonitrile; -2-(2-fluorophenyl)-5,5-dimethyl-1,3,2-dioxaborinane; -2-(4-fluorophenyl)-5,5-dimethyl-1,3,2-dioxaborinane; -4,4'-bis(5,5-dimethyl-1,3,2-dioxaborin-2-yl)biphenyl; -ethyl 2-(5,5-dimethyl-1,3,2-dioxaborin-2-yl)benzoate; -2-(5,5-dimethyl-1,3,2-dioxaborin-2-yl)-6-(trifluoromethyl)benzonitrile; -4-(trifluoromethyl)-2-(5,5-dimethyl-1,3,2-dioxaborin-2-yl)benzonitrile, -2-isopropoxy-4,4,6-trimethyl-1,3,2-dioxaborinane; -2-ethoxy-4,4,6-trimethyl-1,3,2-dioxaborinane; -2-methoxy-4,4,6-trimethyl-1,3,2-dioxaborinane; -trimethylcyclotriboroxine; -2,4,6-triphenylcyclotriboroxane, -2,4,6-tris(4-fluorophenyl)cyclotriboroxane; -2,4,6-tris(3,4,5-trifluorophenyl)cyclotriboroxine; -2,4,6-Tris(3,4-fluorophenyl)cyclotriboroxane; -2,4,6-tris(3,4-dichlorophenyl)cyclotriboroxine, or -2,4,6-trimethoxycyclotriboroxane.

16. A primary cell according to any one of claims 1 to 5, characterised in that The boron compound is in the amount of 0.001 mol*l -1 To 0.5mol*l -1 A concentration within a range of 1:1 is present in the electrolyte.

17. A primary cell according to any one of claims 1 to 5, characterised in that The alkali metal is lithium, and the primary battery is a lithium battery.

18. A primary cell according to any one of claims 1 to 5, characterised in that The electrolyte is a non-aqueous electrolyte.

19. A primary cell according to claim 18, characterized in that The nonaqueous electrolyte - comprising a first solvent selected from the group consisting of esters, ethers, dialkyl carbonates and mixtures thereof, and - comprising a second solvent, wherein the second solvent is selected from the group consisting of cyclic carbonates, cyclic esters, cyclic amides and mixtures thereof.

20. A primary cell according to claim 19, characterised in that The first solvent is selected from tetrahydrofuran, methyl acetate, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1-ethoxy, 2-methoxyethane, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, or a mixture thereof.

21. A primary cell according to claim 19, characterized in that The second solvent is selected from propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyrolactone, N-methylpyrrolidone or a mixture thereof, or a polar non-aqueous solvent.

22. A primary cell according to claim 21, characterised in that The polar non-aqueous solvent is selected from acetonitrile, dimethyl sulfoxide, dimethylformamide, dimethylacetamide or a mixture thereof.

23. A primary cell according to any one of claims 1 to 5, characterised in that The electrolyte includes an anhydrous alkali metal salt.

24. A primary cell according to claim 23, characterised in that The anhydrous alkali metal salt is an anhydrous lithium salt.

25. A primary cell according to claim 24, characterised in that The anhydrous lithium salt is selected from LiClO4, LiPF6, LiBF4, LiAsF6, LiSbF6, LiClO4, LiAlCl4, LiGaCl4, LiC(SO2CF3)3, LiN(SO2CF3)2, LiSCN, LiO3SCF2CF3, LiC6F5SO3, LiO2CF3, LiSO3F, LiB(C6H5)4, LiCF3SO3 or a mixture thereof.

26. Use of a boron compound as an electrolyte additive for a galvanic cell having an alkali metal as active electrode material and a carbon monofluoride as active electrode material, characterized in that The boron compound is a compound according to formula (1), (2), (3), (4), (7) or (8): in R1, R2, R3, R4 and R5 are each independently selected from hydrogen, alkyl, olefin, cycloalkyl, thioether, heterocyclic compound, aryl and heteroaryl, wherein R1, R2, R3, R4 or R5 is not thiophene.

27. Use of a boron compound according to claim 26 as an electrolyte additive for galvanic cells with alkali metals as active electrode material, characterized in that Carbon monofluoride as the active cathode material.

28. Use of a boron compound according to claim 26 as an electrolyte additive for galvanic cells with alkali metals as active electrode material, characterized in that R1, R2, R3, R4 and R5 are each independently unsubstituted or mono- or poly-substituted by at least one substituent selected from the group consisting of alkyl, fluoroalkyl, alkoxy, carbonyl, carboxyl, thiol, thioalkoxide, aromatic compound, ether, thioether, nitro, cyano, amino, azido, amidino, hydrazine, hydrazone, carbamoyl, sulfo, sulfamoyl, sulfonylamino, alkylaminosulfonyl, alkylsulfonylamino and / or halogen, wherein R1, R2, R3, R4 or R5 is not thiophene.

29. Use of a boron compound according to any one of claims 26 to 28 as an electrolyte additive for galvanic cells having alkali metals as active electrode materials, characterized in that The boron compound is - a compound according to formula (1), wherein R1 is an alkyl or aryl group which is unsubstituted or substituted by one or more C1-C4 alkyl, -F, -Cl, -Br, -I, -CN, -CF3 or -OCF3, and R2 to R5 are each independently C1-C4 alkyl; - a compound according to formula (2), wherein R1 to R5 are each independently C1-C4 alkyl; - a compound according to formula (3), wherein R1 is an alkyl, alkenyl or aryl group which is unsubstituted or substituted by one or more C1-C4 alkyl, -F, -Cl, -Br, -I, -CN, -CF3 or -OCF, and R2 and R3 are each independently C1-C4 alkyl; - a compound according to formula (4), wherein R1, R2 and R3 are each independently C1-C4 alkyl; - a compound according to formula (7), wherein R1 to R3 are each independently of one another alkyl or aryl which is unsubstituted or substituted by one or more -F, -Cl, -Br, -I, -CN, -CF3, -OCF3; or - A compound according to formula (8), wherein R1 to R3 are each independently C1-C4 alkyl.

30. Use of a boron compound according to claim 29 as an electrolyte additive for galvanic cells having alkali metals as active electrode materials, characterized in that The boron compound is a compound according to formula (1), wherein R1 is unsubstituted or substituted by one or more C1-C6 alkyl, -F, -Cl, -Br, -I, -CN, -CF3 or -OCF3, and R2 to R5 are each independently C1-C4 alkyl.

31. Use of a boron compound according to claim 29 as an electrolyte additive for galvanic cells having alkali metals as active electrode materials, characterized in that The boron compound is a compound according to formula (1), wherein R1 is unsubstituted or substituted with one or more C1-C4 alkyl, -F, -Cl, -Br, -I, -CN, -CF3 or -OCF3, and R2 to R5 are each independently C1-C4 alkyl.

32. Use of a boron compound according to claim 29 as an electrolyte additive for galvanic cells with alkali metals as active electrode material, characterized in that The boron compound is a compound according to formula (1), wherein R1 is unsubstituted or substituted phenyl, benzyl or naphthyl: one or more C1-C4 alkyl, -F, -Cl, -Br, -I, -CN, -CF3 or -OCF3, and R2 to R5 are each independently C1-C4 alkyl.

33. Use of a boron compound according to claim 29 as an electrolyte additive for galvanic cells with alkali metals as active electrode material, characterized in that The boron compound is a compound according to formula (3), wherein R1 is an allyl group which is unsubstituted or substituted by one or more C1-C4 alkyl groups, -F, -Cl, -Br, -I, -CN, -CF3 or -OCF, and R2 and R3 are each independently C1-C4 alkyl groups.

34. Use of a boron compound according to claim 29 as an electrolyte additive for galvanic cells having alkali metals as active electrode materials, characterized in that The boron compound is a compound according to formula (3), wherein R1 is unsubstituted or substituted benzyl, phenyl, or benzoate: one or more C1-C4 alkyl, -F, -Cl, -Br, -I, -CN, -CF3 or -OCF, and R2 and R3 are each independently C1-C4 alkyl.

35. Use of a boron compound according to claim 29 as an electrolyte additive for galvanic cells with alkali metals as active electrode material, characterized in that The boron compound is a compound according to formula (7), wherein R1 to R3 are each independently unsubstituted or substituted by one or more of -F, -Cl, -Br, -I, -CN, -CF3, -OCF3.

36. Use of a boron compound according to claim 29 as an electrolyte additive for galvanic cells with alkali metals as active electrode material, characterized in that The boron compound is a compound according to formula (7), wherein R1 to R3 are each independently methyl and are unsubstituted or substituted by one or more of -F, -Cl, -Br, -I, -CN, -CF3, -OCF3.

37. Use of a boron compound according to claim 29 as an electrolyte additive for galvanic cells with alkali metals as active electrode material, characterized in that The boron compound is a compound according to formula (7), wherein R1 to R3 are each independently phenyl which is unsubstituted or substituted by one or more of -F, -Cl, -Br, -I, -CN, -CF3, -OCF3.

38. Use of a boron compound according to any one of claims 26 to 28 as an electrolyte additive for galvanic cells having alkali metals as active electrode materials, characterized in that The boron compound is -4,4,5,5-tetramethyl-2-(3,4,5-trifluorophenyl)-1,3,2-dioxaborolane; -2-(bromomethyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -2-cyclopropyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -2-cyclohexyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -4,4,5,5-tetramethyl-2-(naphthalen-1-ylmethyl)-1,3,2-dioxaborolane; -2-Benzyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -2-phenyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -4,4,5,5-tetramethyl-2-(1-naphthyl)-1,3,2-dioxaborolane; -2-(4-chlorophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -2-(4-fluorophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -4,4,5,5-tetramethyl-2-(3,4,5-trifluorophenyl)-1,3,2-dioxaborolane; -2-(4-bromophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -2-(3,5-dichlorophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -2-(2-iodophenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzonitrile; -4,4,5,5-tetramethyl-2-[3-(trifluoromethoxy)phenyl]-1,3,2-dioxaborolane; -2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)aniline; -2-[2-(trifluoromethyl)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -2-[3,5-bis(trifluoromethyl)phenyl]-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -2-Fluoro-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzonitrile, -2-ethoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -2-methoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane; -2-allyl-5,5-dimethyl-1,3,2-dioxaborinane; -5,5-dimethyl-2-phenyl-1,3,2-dioxaborinane; -2,2'-(1,4-phenylene)bis[5,5-dimethyl-1,3,2-dioxaborinane]; -2-(2-chlorophenyl)-5,5-dimethyl-1,3,2-dioxaborinane; -2-(1,3,2-dioxaborolan-2-yl)benzonitrile; -2-(2-fluorophenyl)-5,5-dimethyl-1,3,2-dioxaborinane; -2-(4-fluorophenyl)-5,5-dimethyl-1,3,2-dioxaborinane; -4,4'-bis(5,5-dimethyl-1,3,2-dioxaborin-2-yl)biphenyl; -ethyl 2-(5,5-dimethyl-1,3,2-dioxaborin-2-yl)benzoate; -2-(5,5-dimethyl-1,3,2-dioxaborin-2-yl)-6-(trifluoromethyl)benzonitrile; -4-(trifluoromethyl)-2-(5,5-dimethyl-1,3,2-dioxaborin-2-yl)benzonitrile, -2-isopropoxy-4,4,6-trimethyl-1,3,2-dioxaborinane; -2-ethoxy-4,4,6-trimethyl-1,3,2-dioxaborinane; -2-methoxy-4,4,6-trimethyl-1,3,2-dioxaborinane; -trimethylcyclotriboroxine; -2,4,6-triphenylcyclotriboroxane, -2,4,6-tris(4-fluorophenyl)cyclotriboroxane; -2,4,6-tris(3,4,5-trifluorophenyl)cyclotriboroxine; -2,4,6-Tris(3,4-fluorophenyl)cyclotriboroxane; -2,4,6-tris(3,4-dichlorophenyl)cyclotriboroxine, or -2,4,6-trimethoxycyclotriboroxane.

39. Use of a boron compound according to any one of claims 26 to 28 as an electrolyte additive for galvanic cells having alkali metals as active electrode materials, characterized in that The primary battery is a lithium battery.

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