Aluminum-based additive for batteries

Abstract

An electrolyte composition comprising a non-aqueous organic solvent, a conductive electrolyte salt, and at least one additive of formula (I): (I), wherein M is a metal, X is H or -O-R, and R is an alkyl group, and an electrochemical device comprising the electrolyte composition.

Description

Technical Field

[0001] This invention relates to electrolyte additives, particularly electrolyte additives for lithium-ion batteries, novel electrolyte additives for lithium-ion batteries, particularly for batteries with nickel-rich cathode materials, and batteries or battery cells containing the additive. Background Technology

[0002] Lithium-ion batteries are widely used as electrochemical devices in a variety of applications, including but not limited to portable electronic devices, electric vehicles, hybrid electric vehicles, or stationary energy storage systems.

[0003] Lithium-ion batteries contain at least one electrolyte designed to provide an ion conduction pathway between at least one first half-cell containing at least one positive electrode and at least one second half-cell containing at least one negative electrode in an electrochemical device. Typically, individual battery cells are not sufficiently stable under high voltages (especially 4.5 V or higher).

[0004] The industry is using nickel-rich cathode materials 1 Interest in nickel-rich LiNi is growing, as it exhibits superior performance, particularly in energy density and / or power density. 0.8 Co 0.1 Mn 0.1 Materials such as O2 (NCM811) have been considered the most attractive cathode materials for lithium-ion batteries (LIBs). However, rapid capacity decay and poor rate performance limit their practical applications. 2 Capacity decay is related to surface reconstruction of the cathode material, which is often referred to as interfacial instability. 3 .

[0005] To stabilize nickel-rich oxide materials, various compounds can be used to coat the materials. 4 These coating steps are expensive and time-consuming. Furthermore, they reduce the contact and interaction between the positive electrode active material particles, thus having a detrimental effect on battery performance.

[0006] Therefore, there is a need to provide better stability for cathode materials in order to increase the number of cycles at the required capacity, while minimizing the cost of such materials. Summary of the Invention

[0007] Surprisingly, aluminum-based organic compounds mixed in the electrolyte composition have been found to significantly slow down the capacity decay of lithium-ion batteries. This protective effect is believed to be partly attributed to their ability to provide an in-situ aluminum coating on the electrode surface.

[0008] Therefore, one embodiment of the present invention relates to an electrolyte composition particularly suitable for lithium-ion batteries, comprising a non-aqueous organic solvent, a conductive electrolyte salt, and at least one additive of formula (I): (I) , Wherein, M is a metal, X is H or -OR, and R is an alkyl group. The metal is preferably an alkali metal such as Li, Na, or K, or an alkaline earth metal such as Ca2 and Mg. As can be directly understood, metal M can be advantageously chosen to be the same as the metal used as the charge carrier in the battery. For lithium-ion batteries, M will be lithium; for sodium-ion batteries, M will be sodium, and so on.

[0009] The additive of Formula I contains at least one and at most four alkoxy motifs RO. Preferably, the additive contains three or four alkoxy motifs or groups. R can be the same or different, and can be an alkyl group having one to ten, preferably one to five, carbon atoms. Preferably, R is selected from the group consisting of -CH3, CH2CH3, -CH(CH3)2 and -C(CH3)3.

[0010] As reported in the literature, the exact stoichiometry (the number of alkoxy ligands in the final aluminate anion) strongly depends on the alcohol used, and not necessarily on the amount of alcohol added. Small molecule alcohols such as methanol, ethanol, or propanol will typically form tetrasubstituted aluminates directly. ,For example:

[0011] Larger and bulkier alcohols, such as tert-butanol, phenol, and CH(CH3)2, are more likely to form trisubstituted aluminate groups. Therefore, when R is a sterically hindered group, such as tert-butyl-C(CH3)3, a trisubstituted aluminate group may be more readily available and may be preferred. When the RO group is small, such as methoxy, the additive may contain four alkoxy groups.

[0012] According to one embodiment, the additive of formula (I) can be: • M[Al(OR)4], where M is a metal, preferably Li, Na, or K, and R is -CH3, -CH2CH3, or -CH2CH2CH3; or • M[AlH(OR)3], where M is a metal, preferably Li, Na or K, and R is -tert-butyl, -phenyl or -isopropyl.

[0013] Preferably, M[AlH(OR)3], where M is Li, Na or K, and R is -tert-butyl.

[0014] One particularly effective additive is Li[AlH(OtBu)3], which has the following formula (II): (II) , Or Na[AlH(OtBu)3].

[0015] Those skilled in the art can select electrolyte salts from those commonly used in the field. According to specific embodiments of the invention, the electrolyte salt comprises or is composed of a lithium salt, preferably selected from the group consisting of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(oxalatoborate) (LiBOB), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), and mixtures thereof. Lithium hexafluorophosphate (LiPF6) is particularly preferred as the lithium salt, or as at least one of the lithium salts.

[0016] Those skilled in the art can also select non-aqueous organic solvents from those commonly used in the field. Preferably, the non-aqueous organic solvent is selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), tetrahydrofuran (THF), 1,2-dimethoxyethane (DME), 2-methyltetrahydrofuran (2Me-THF), trimethyl phosphate, triethyl phosphate, dimethyl methylphosphonate, diethyl ethylphosphonate, methyl acetate, methyl propionate, and mixtures thereof.

[0017] A particularly advantageous choice is a non-aqueous organic solvent comprising a mixture of ethylene carbonate and ethyl methyl carbonate. The proportions of the non-aqueous solvent mixture can be adjusted according to the specifications of the specific electrochemical device. When using a mixture of ethylene carbonate and ethyl methyl carbonate, the relative proportions of these components can range from 1:3 to 2:3, preferably from 2:5 to 1:2. A volume ratio of approximately 3:7 is particularly preferred.

[0018] According to one embodiment, the electrolyte composition may further contain at least one additional additive.

[0019] The additional additives may be additives commonly used to protect the negative electrode.

[0020] Advantageously, the at least one additive is selected from the group consisting of fluoroethylene carbonate, LiPO2F2, vinylene carbonate (VC), lithium difluorooxalate borate (LiODFB) and LiPF6.

[0021] Although compounds falling within the scope of Formula I are generally commercially available, compounds that are directly synthesized and / or freshly prepared have been found to exhibit better performance and can be used advantageously. "Freshly prepared" means that the additive was synthesized within 6 months, preferably within 1 month, more preferably within 1 week, or even advantageously within 1 day prior to the preparation of the composition. Alternatively, compounds that are protected from exposure to air and / or humid air after synthesis also exhibit high performance.

[0022] The method for in-situ preparation of compound I follows general chemical reaction:

[0023] In this case, M is an alkali metal, and n is 1, 2, 3, or 4. In short, aluminum hydride (e.g., LiAlH4) is dissolved in a solvent such as ether (e.g., diethyl ether) or THF. A dry alcohol (e.g., tert-butanol) is slowly added with stirring until the aluminate (e.g., ...) is dissolved in a solvent such as ether (e.g., diethyl ether) or THF. The precipitate is then dried.

[0024] The concentration of the additive in the electrolyte composition relative to the total weight of the electrolyte composition may be from 0.001% by weight to 5% by weight, preferably from 0.1% by weight to 3% by weight, more preferably about 2% by weight.

[0025] The present invention also relates to an electrochemical device or battery cell, such as a lithium-ion battery or battery cell, comprising: • A positive electrode containing a positive electrode material, and preferably a negative electrode current collector; • A negative electrode comprising a negative electrode material, and preferably a positive electrode current collector; and • Electrolyte composition, The electrolyte composition described herein is the electrolyte composition of the present invention as defined in the specification.

[0026] When the electrolyte is, to some extent, a liquid or gel, the device of the present invention preferably includes a diaphragm. As the diaphragm, materials in the form of porous membranes, nonwoven fabrics, or woven textiles can be used. Examples of the aforementioned diaphragm materials include polyolefin resins such as polyethylene and polypropylene, fluoropolymers, and nitrogen-containing aromatic polymers.

[0027] The electrochemical device may be a single rechargeable electrochemical battery cell. It may also be a combination of one or more electrochemical battery cells of the present invention to provide a (rechargeable) battery pack. Further details regarding the manufacture and use of rechargeable electrochemical battery cells, such as lithium-ion battery cells and batteries using the disclosed electrodes, are well known to those skilled in the art.

[0028] In the lithium-ion battery according to the present invention, the positive electrode material may include a positive electrode active material selected from LiV3O8, LiV2O5, and LiCo. 0.2 Ni 0.8 The group consisting of O2, LNM, LNMC, LiNiO2, LiFePO4, LiMnPO4, LiCoPO4, LiMn2O4, LiCoO2, and mixtures thereof. Preferably, the positive electrode active material comprises lithium nickel manganese oxide (LNMO) or a mixture thereof; for example, LiNi... 0.5 Mn 1.5 O4. Preferably, the positive electrode active material is selected from the group consisting of lithium nickel manganese cobalt (LNMC) oxides with or without an aluminum layer and mixtures thereof; particularly LiNi. 0.8 Mn 0.1 Co 0.1 O2.

[0029] In the lithium-ion battery according to the present invention, the negative electrode material may comprise a negative electrode active material selected from the group consisting of graphite, conductive carbon, silicon, silicon / graphite composite material, metallic lithium, lithium titanate, alloys of lithium with at least one of tin, germanium, magnesium, aluminum and zinc, and transition metal-doped zinc oxide or tin oxide and mixtures thereof.

[0030] In the lithium-ion battery according to the present invention, the positive electrode material may not be mixed with the compound of formula (I) as defined above and / or may not be coated.

[0031] In the lithium-ion battery according to the present invention, the current collector of the positive or negative electrode may comprise a metal foil, a metal mesh, expanded metal, or a metal foam. In a further embodiment, the current collector of the positive electrode comprises nickel, aluminum, stainless steel, copper, or a combination thereof.

[0032] In the sodium-ion battery of the present invention, the positive electrode or cathode active material may include metallic sodium, sodium alloy, or carbonaceous material capable of doping and dedoping sodium ions, such as hard carbon.

[0033] In the sodium-ion battery of the present invention, the negative electrode current collector can be made of aluminum or an aluminum alloy. Examples of shapes for the negative electrode current collector include, for example, foil, plate, mesh, grid, slats, perforated metal, or embossing, or combinations of these shapes (e.g., mesh plate). Irregularities can be formed on the surface of the negative electrode current collector by etching. Battery casings and battery structural supports made of aluminum or aluminum alloys can be used as negative electrode current collectors. Preferably, the aluminum alloy contains at least one metallic component selected from the group consisting of Mg, Mn, Cr, Zn, Si, Fe, and Ni.

[0034] In the sodium-ion battery of the present invention, the negative electrode or anode active material is a sodium inorganic compound, preferably a compound capable of doping and dedoping with sodium ions. For example, they can be compounds such as NaFeO2, NaMnO2, NaNiO2, and NaCoO2; Na 0.44 Mn 1-a M 1 a O2 and Na 0.7 Mn 1-a M 1 a O 2.05 oxides, wherein M 1 It is at least one transition metal element, 0≦a<1; Na6Fe2Si 12 O 30 and Na2Fe5Si 12 O 30 Oxide, Na2Fe2Si6O 18 and Na2MnFeSi6O 18 Oxides, such as Na2FeSiO6; phosphates, such as NaFePO4 and Na3Fe2(PO4)3; borates, such as NaFeBO4 and Na3Fe2(BO4)3; and fluorides, such as NaFeF6 and Na2MnF6.

[0035] In the sodium-ion battery of the present invention, the positive electrode current collector may include: a metal, such as nickel, aluminum, titanium, copper, gold, silver, platinum, aluminum alloy or stainless steel; a material formed by plasma spraying or arc spraying, such as carbonaceous material, activated carbon fiber, nickel, aluminum, zinc, copper, tin, lead or alloys thereof; and a conductive film obtained by dispersing a conductive agent in a resin such as rubber or styrene-ethylene-butylene-styrene copolymer (SEBS).

[0036] According to another embodiment, the present invention relates to the use of the additives or compounds of formula (I) described in this specification in the manufacture of electrochemical devices, particularly as components of electrolyte compositions and / or as part of or contained within said devices. The electrochemical devices are preferably lithium-ion or sodium-ion batteries, particularly rechargeable batteries.

[0037] A further object of the present invention is a method for protecting (at least partially protecting) electrode materials contained in an electrochemical device, as described in this specification, by adding an additive or compound of formula (I) above to the electrolyte material or electrolyte composition. This protection can be achieved by generating a protective layer in situ on the electrode material during device use.

[0038] The electrochemical cell or battery disclosed herein can be used in a variety of devices, including portable computers, personal digital assistants, mobile phones, motorized equipment (such as personal or household appliances and vehicles), instruments, lighting equipment (such as flashlights), and heating equipment. Attached Figure Description

[0039] Figure 1 X-ray diffraction (XRD) and infrared (IR) spectra of LTBA (labeled "homemade") obtained during the teaching synthesis according to Example 1 of the present invention and LTBA purchased from Sigma-Aldrich are shown.

[0040] Figure 2 An exploded view of a button battery and its components according to an embodiment of the present invention is shown.

[0041] Figure 3 The discharge capacity of the battery cell according to the present invention at a C / 3 rate for up to 200 cycles and the discharge capacity of the control battery cell are shown.

[0042] Figure 4 The nuclear magnetic resonance (NMR) spectra of the standard electrolyte (a) and the electrolyte of the present invention (b) are shown after adding 1000 ppm (parts per million) of water and aging for 24 hours.

[0043] Figure 5 The following are shown: (a) an electron microscope image of the electrode surface of the battery cell described in Example 2 after cycling, showing a layer of material covering the NMC particles, and (b) an energy dispersive X-ray spectrum of the NMC surface of the positive electrode of the battery cell of the present invention according to an embodiment of Example 1, showing the chemical composition of the electrode and demonstrating the presence of aluminum in the surface layer.

[0044] Figure 6 The diagram shows (a) a charge / discharge graph of a battery cell using an embodiment of the present invention in Example 3, and (b) its discharge capacity at C / 3 rate for up to 50 cycles, as well as the discharge capacity of a control battery cell, a battery cell using a self-made LTBA, and a battery cell using a sodium analog (NTBA).

[0045] Figure 7 The NMR spectrum of LTBA is shown, magnified to reveal a sextet peak near 3 ppm. This spectrum confirms the presence of Al-H in the LTBA compound.

[0046] Figure 8It is shown that a) the positive electrode NMC of the battery cell of the present invention according to the embodiment of Example 4 has a surface layer (measured by TED-EDX), and b) it is shown and confirmed that the surface layer on top of the NMC material consists of an aluminum-rich coating.

[0047] Figure 9 The surface of the NMC material is shown after 150 cycles in a) a comparative electrolyte (without LTBA) and b) an electrolyte (with LTBA) according to an embodiment of the present invention.

[0048] Figure 10 This demonstrates the performance of lithium-ion battery cells based on NMC cathode and graphite anode materials, using different electrolyte compositions containing one of the following additives: • LP57 (1M LiPF6 in a mixture of ethylene carbonate and ethyl methyl carbonate) • LP57 + 2wt% LTBA • LP57 + 2wt% LTBA + 1wt% LiPO2F2 • LP57 + 2wt% FEC (fluoroethylene carbonate) + 1wt% LiPO2F2. Detailed Implementation

[0049] Example 1: Synthesis of LTBA.

[0050] Lithium tri-(tert-butoxy)aluminium hydride (LTBA), linear formula [LiAlH[OC(CH3)3]3, is a known compound used as a reducing agent in organic chemistry, and has a half-developed formula (II): (II)

[0051] It is commercially available (CAS No.: 17476-04-9). In this example, LTBA is synthesized according to the following chemical reaction:

[0052] Lithium aluminum hydride (200 mg, 5.3 mmol, 1 equivalent) was dissolved in diethyl ether and filtered to obtain a clear solution. Dry tert-butanol (1.21 g, 1.56 mL, 16.3 mmol, 3.1 equivalent) was added dropwise with constant stirring, and hydrogen gas was observed to be released. After adding 3 equivalents of alcohol, the bubbling stopped and a white solid precipitated. The solid was recovered after 1 hour. Wash several times with fresh ether and dry under vacuum.

[0053] like Figure 1The XRD and IR spectra show that the LTBA obtained by the above synthesis is different from the commercial product obtained from Sigma Aldrich.

[0054] Example 2: Manufacturing of a battery cell according to the present invention.

[0055] To demonstrate the performance of the battery according to the present invention, Figure 1 The schematic diagram shown illustrates the assembly of a button cell. The button cell (1) comprises two housing parts: a positive electrode housing (14) and a negative electrode housing (3). The positive electrode film is located inside the positive electrode housing (14) and is made of an aluminum disc (12) with a diameter of 14 mm, which is covered with LiNi. 0.8 Mn 0.1 Co 0.1 A mixture (11) of O2 or NMC811 active material (95 wt%), conductive carbon (3 wt%), and polymer binder (polyvinylidene fluoride (PVDF), 2 wt%). A negative electrode is provided opposite the positive electrode, consisting of a supporting 15 mm diameter copper disc (5) covered with Imerys GHDR 15-4 active material graphite (94 wt%), conductive carbon Csp (2 wt%), and a mixture (7) of two polymer binders: styrene-butadiene rubber and carboxymethyl cellulose (2 wt%) each. Small metal springs (4) are provided on the opposite side of the surface of the copper disc (5) supporting the active mixture (7) of carbon, graphite, and binder materials to engage with the battery casing to hold the assembly of the battery cell (1) in place and provide uniform pressure thereon. An electrode separator (9) is made of glass fiber discs, impregnated with 150 µL of electrolyte, and positioned between the positive and negative electrodes.

[0056] The electrolyte was prepared by dissolving 1 M LiPF6 in a mixture of ethylene carbonate and ethyl methyl carbonate (volume ratio 3:7). This mixture was named LP57. 2% by weight of LTBA, which was synthesized according to Example 1 or purchased from Sigma Aldrich, was added to the mixture.

[0057] To provide comparative and reference data on the cycle stability of batteries according to the present invention, a standard button cell containing only LiPF6 as the electrolyte but otherwise identical to the description above was assembled. This cell was designated as a control electrolyte.

[0058] The button cells were assembled and sealed in an Ar-filled glove box. They were then removed and cycled in a potentiostat according to the following procedure: two complete charge / discharge cycles were performed between 2.5 V and 4.3 V at a current rate of C / 20 (C = 275 mA·h / gNMC). The individual cells were then continuously cycled at room temperature within the same voltage window at a constant current rate of C / 3.

[0059] Figure 3 The invention demonstrates a significantly improved discharge capacity achieved using the battery cells according to the invention. These results are surprising. Without being bound by these interpretations, investigations conducted by the inventors suggest that this beneficial effect may be related to several factors.

[0060] Due to the degradation of the LiPF6 electrolyte material, trace amounts of HF hydrofluoric acid and other products are generated during electrolyte aging in the battery cell. Subsequently, HF reacts with electrode and / or electrolyte materials in a harmful manner. The NMR spectra in the aging control electrolyte show signals from HF and electrolyte-degraded materials (see...). Figure 4 a). LTBA is believed to have an HF scavenging effect and prevent the presence and / or action of hydrofluoric acid (HF) in the electrolyte. This is supported by the fact that no signals indicating HF and degrading materials were found in the NMR spectra of the electrolyte of the present invention even after aging (see [link]). Figure 4 b).

[0061] Another beneficial effect of using the electrolyte of this invention appears to be that it provides a protective coating layer on the cathode material. Figure 5 The diagram shows that in a battery cell according to the invention, a layer of material is deposited on the surface of an NMC electrode, and the additive component LTBA appears to decompose and form a protective layer on the surface of the NMC electrode.

[0062] Example 3: Manufacturing of a battery cell according to the present invention.

[0063] According to another embodiment of the invention, a battery is manufactured using sodium tri-tert-butoxyaluminium hydride, or NTBA.

[0064] NTBA is obtained through the following chemical reaction:

[0065] Sodium aluminum hydride (200 mg, 3.7 mmol, 1 equivalent) was dissolved in tetrahydrofuran and filtered to obtain a clear solution. Dry tert-butanol (1.21 g, 1.56 mL, 16.3 mmol, 3.1 equivalent) was added dropwise with constant stirring, and hydrogen gas was observed to be released. After adding 3 equivalents of alcohol, the bubbling stopped and a white solid precipitated. The solid was recovered after 1 hour. It was washed several times with fresh tetrahydrofuran and dried under vacuum.

[0066] Assemble the same button cell as described in Example 2, except that the electrolyte composition contains 2% by weight NTBA instead of LTBA. Figure 6 As shown, the results are comparable to those obtained using LTBA.

[0067] Example 4: Manufacturing of a battery cell according to the present invention.

[0068] According to another embodiment of the present invention, a battery using LTBA as an additive in the electrolyte composition was manufactured.

[0069] Therefore, the same button cell as described in Example 2 was assembled, except that the electrolyte was prepared by dissolving 1 M LiPF6 in a mixture of ethylene carbonate and dimethyl carbonate (volume ratio 50 / 50). This mixture was named LP30. 2% by weight of LTBA, which was synthesized according to Example 1 or purchased from Sigma Aldrich, was added to this mixture. After one cycle, NMC 811 was washed with DMC, dried, and analyzed by transmission electron microscopy (TEM). Figure 2 a) shows the presence of a coating layer on top of the NMC material. The presence of aluminum in this layer is confirmed by EDX mapping (…). Figure 2 b) was confirmed. Therefore, these results demonstrate that when LTBA is used as an electrolyte additive, a protective coating layer is formed in situ on the NMC electrode surface. This Al-rich layer then protects the NMC material from further reaction with the electrolyte, thereby preventing electrode degradation.

[0070] For comparison and reference, a standard button cell containing only LiPF6 as the electrolyte (without LTBA) but otherwise identical to the description above was assembled. This cell was designated as the control electrolyte.

[0071] Figure 3 This shows the use of LTBA ( Figure 3 b) or not using LTBA ( Figure 3a) Differences in surface properties on NMC811 after 150 cycles as an electrolyte additive. Significant differences can be observed. In fact, large surface reconstruction with cation mixing was observed in the absence of LTBA, while this degradation was very little in the presence of LTBA.

[0072] Example 5: Manufacturing of a battery cell according to the present invention.

[0073] The performance of battery cells manufactured in the same manner as described in Example 2 has been evaluated for different electrolyte compositions.

[0074] The results show that introducing another additive, LiPO2F2, to simultaneously protect the negative electrode further enhances the performance improvement obtained using the LTBA additive. This performance is even superior to that obtained using LiPO2F2+ FEC, and it also has the advantage of avoiding the need for fluorinated additives to protect the positive electrode.

[0075] References 1. Oswald, S. and Gasteiger, H.A. J. Electrochem. Soc 2023, 170,030506. 2. Li, J., Dahn, JR, et al., J. Electrochem. Soc 2015, 162, A1401. 3. Xu, C., Grey, CP, et al., Nature Materials 2021, 20, 84-92. 4. Gao, Y., Park, J., Liang, X ., ACS Appl. Energy Mater. 2020, 3,8978-8987.

Claims

1. An electrolyte composition comprising a non-aqueous organic solvent, a conductive electrolyte salt, and at least one additive of formula (I): （I） ， in, M is a metal, X is H or -OR, and R is an alkyl group.

2. The electrolyte composition according to claim 1, wherein, In the formula (I), M is Li, Na, or K.

3. The electrolyte composition according to claim 1 or 2, wherein R is the same or different, and is an alkyl group having 1 to 10, preferably 1 to 5, carbon atoms, and more preferably -CH3, CH2CH3, -CH(CH3)2 or -C(CH3)3.

4. The electrolyte composition according to claim 1, wherein the at least one additive is Li[AlH(OtBu)3] or Na[AlH(OtBu)3].

5. The electrolyte composition according to any one of claims 1 to 4, wherein the electrolyte salt comprises a lithium salt, wherein the lithium salt is preferably selected from the group consisting of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(oxalato)borate (LiBOB), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), and mixtures thereof.

6. The electrolyte composition according to any one of claims 1 to 5, wherein the lithium salt comprises lithium hexafluorophosphate (LiPF6).

7. The electrolyte composition according to any one of claims 1 to 6, wherein the non-aqueous organic solvent is selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), tetrahydrofuran (THF), 1,2-dimethoxyethane (DME), 2-methyltetrahydrofuran (2Me-THF), trimethyl phosphate, triethyl phosphate, dimethyl methylphosphonate, diethyl ethylphosphonate, methyl acetate, methyl propionate, and mixtures thereof.

8. The electrolyte composition according to any one of claims 1 to 7, wherein the non-aqueous organic solvent comprises a mixture of ethylene carbonate and ethyl methyl carbonate, preferably in a volume ratio of 3:

7.

9. The electrolyte composition according to any one of claims 1 to 8, wherein the concentration of the at least one additive relative to the total weight of the electrolyte composition is 0.001% to 5% by weight, preferably 0.1% to 3% by weight, more preferably about 2% by weight.

10. An electrochemical device (1), comprising: - A positive electrode containing positive electrode material; - A negative electrode containing negative electrode material (7); and - Electrolyte, The electrolyte comprises an electrolyte composition according to any one of claims 1 to 9.

11. The electrochemical device (1) according to claim 10, wherein the device (1) is a lithium battery.

12. The lithium-ion battery according to claim 11, wherein the positive electrode material comprises a positive electrode active compound, the positive electrode active compound being selected from the group consisting of lithium nickel manganese oxides and mixtures thereof, and preferably selected from the group consisting of lithium nickel manganese cobalt oxides and mixtures thereof; the compound is even more preferably LiNi 0.8 Mn 0.1 Co 0.1 O2.

13. The lithium-ion battery according to claim 11 or 12, wherein the negative electrode material (7) comprises a negative electrode active compound selected from the group consisting of graphite, conductive carbon, silicon, silicon / graphite composite material, metallic lithium, lithium titanate, an alloy of lithium with at least one of tin, germanium, magnesium, aluminum and zinc, and transition metal-doped zinc oxide or tin oxide and mixtures thereof.

14. The lithium-ion battery according to any one of claims 11 to 13, wherein the positive electrode material is not mixed with and / or not coated with the compound of formula (I) as defined in claims 1 to 4.

15. Use of a compound of formula (I) as an additive in electrolyte compositions and / or in the manufacture of electrochemical devices: （I） ， in, M is a metal, X is H or -OR, and R is an alkyl group.

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