GB2504954A

GB2504954A - Electrolyte additives for electrochemical cells

Info

Publication number: GB2504954A
Application number: GB1214489.5A
Authority: GB
Inventors: Hilmi Buqa; Sabine Wussler; Michael Holzapfel
Original assignee: Leclancha S A
Current assignee: Leclancha S A
Priority date: 2012-08-14
Filing date: 2012-08-14
Publication date: 2014-02-19
Also published as: GB201214489D0

Abstract

The field of the invention relates to an electrochemical cell electrolyte, an electrochemical cell comprising this electrochemical cell electrolyte, a method for manufacturing an electrochemical cell and use of the electrochemical cell electrolyte and the electrochemical cell. The electrochemical cell electrolyte comprises an electrolyte salt, an electrolyte solvent to and an electrolyte additive wherein the electrolyte additive comprises N-containing heterocycles and/or aminated aromatic compounds at a concentration of 0.01 % to 5.0 % each. The cell may be a Li ion cell.

Description

Field of the Invention

[0001] The field of the invention relates to an electrochemical cell electrolyte, an electrochemical cell comprising this electrochemical cell electrolyte, a method for manufacturing an electrochemical cell and use of the electrochemical cell electrolyte and the electrochemical cell as descnbed in the respective independent claims.

Background of the invention

[0002] Beyond consumer electronics, Li-ion batteries are growing in popularity for stationary applications as storage of renewable energy, grid levelling, large hybrid diesel Is engines, military, hybrid electric vehicles (HEV-s), and aerospace applications due to their high energy density.

[0003] The electrolyte is a critical component in electrochemical cells as it allows its functioning by ion conduction for charge equilibration at charge/discharge. The electrolyte is thermodynamically not stable at the anode and cathode surface in the charged state of the battery. A lithium-ion battery can only function correctly as there is a solid electrolyte interface (SEI) formed on the surface of the graphite anode which permits Li'-conduction while keeping the electrolyte from diffusing to the anode surface, On the surface of the cathode there is a SEI formed, too, which is, however, less well investigated.

[0004] Lithium titanate (LTO, Li4Ti5O12) can be used as an alternative anode material instead of graphite. It allows obtaining very safe lithium batteries that will not catch fire or explode in case of a thermal problem or short circuit. Lithium titanate cells also show a very high calendar and cycle life time. This is due to several reasons. One of these reasons is that only a very thin SEI is formed, or even none at all. The electrolyte is generally considered stable at the working potential of a lithium titanate anode, but this is questionable regarding the findings described below.

[0005] Lithium-ion batteries show a significant gas evolution during the first cycle (the so-s called formation cycle). This gas evolution is due to the SEI formation on the graphite anode.

Once the SEI is formed no gas will be evolved during further cycling. This is due to the fact that potential reduction of traces of electrolyte on the graphite surface generally creates solid or liquid products that are dissolved in the electrolyte or deposited inlon the SEI. But no gases evolve which could accunwlate.

[0006] The situation is different in cells containing a lithium titanate anode. Here a very slight reaction occurs on continuous cycling in the course of which gaseous products evolve, these are only slightly soluble in the electrolyte and, thus, accumulate. These gases are mostly hydrogen, CO. C,J-l,, CO2. They can form an internal pressure in a cell with a hard case or swelling in the case of a pouch cell. Both phenomena are indesirable and can lead to safety problems and limited cycling stability, respectively. The problem of gas evolution increases with the size and capacity of the cell.

[0007] The exact mechanism for the evolution of these gasses is not exactly known, but it is believed that electrolyte solvents are reduced by Ti3 ions on the surface of the lithium titanate in a catalytic mechanism. This is backed by the fact that gassing is increased when the titanate is fully charged and also for higher temperatures (easier diffusion of the solvent, faster reaction) (Y. Qin, Z. Chen, I. Belharouak, and K. Amine (P0: "Mechanism of LTO Gassing and potential solutions", Argonne National Laboratory, 2011 DOE Annual Peer Review Meeting Poster).

[00081 It has also been shown that the amount of gas evolved depends on the salt component of the electrolyte. For example, by using LiBF4, less gas evolves compared with LiPF6.

However, the reason for this phenomenon is unclear (Y. Qin, Z. Chen, and K. Amine: "Functionalized Surface Modification agents to Suppress Gassing Issue of Li4Ti5O12-based Lithium-Ion Chemistry", Argonne National Laboratory, FY 2011 Annual Progress Report.

321-324).

[0009] Different approaches are known in the state of the art to reduce the gassing of lithium titanate based lithium batteries: 1.) One approach is the use of a formation cycle with a higher potential. By using this method the potential of the lithium titanate anode is pushed below 1.0 V and the formation of an SET on the titanate surface is forced. During continued cycling, thus, the direct contact between electrolyte solvent and titanate surface is reduced.

2.) A further approach involves the use of additives in the electrolyte that form a SEI, as vinylene carbonate (VC), propane sultone (PS). Thus, an SE! is formed, and the direct contact between electrolyte solvent and titanate surface is reduced.

3.) Yet another approach would be the modification of the LTO surface by adding ftmnctional additives which react directly with the LTO.

[0010] One example of these approaches is the patent US 7875395 B2. This document discloses gas reduction in an electrochemical cell by using vinylene carbonate as an electrolyte additive with possible addition of 1,3-propane sultone at the time of initial charge/discharge. The use of cyclic carbonates other than vinylene carbonate as well as linear carbonates is also disclosed.

[00111 Zhang et al. ("Develop Electrolyte Additives (ANL)", Argonne National Laboratory, FY 2011 Annual Progress Report, 359-363) also use electrolyte additives as an efficient method to improve the cell performance and safety properties without significantly changing the electrolyte composition. However, they favour additives which promote formation of an SET.

[0012] Qin et al. ("Functionalized Surface Modification agents to Suppress Gassing Issue of Li4Ti5O12-based Lithium-Ion Chemistry", see above) proposed surface modification of LTO by a chlorosilane additive, leading to significant gas reduction.

[00131 All these approaches, however, suffer from side effects: Regarding the first and second approach, a thick SET increases the ohmic resistance in the cell and lowers the cycling efficiency. And with respect to the second and third approach, propane sultone is carcinogenic and the modification of the LTO surface can lead to higher ohnic resistance and less cycling stability.

[0014] Inagaki et al. (JP 4159954B2, same family as US 2005/0064282 Al and US 7,910,247 B2) disclose a negative electrode comprising an electrode current collector and a negative electrode layer on one or both sides of the collector. The electrode layer in turn contains an electrode active material (for example, LTO) and an electronic conductor. The electronic conductor includes a carbonaceous material with a specific d-spacing and a specific crystallite size. The electrode active material has an electrode working potential which is at least 1 V nobler than a lithium electrode potential. This specific composition leads to less gas evolution even if a protective film is not formed. However, the "less gas evolution" is based on the use of the carbonaceous material in the electronic conductor. The electrode active material, e. g. LTO, would still give rise to gas evoiution.

[00151 JP 4284232 B2 deals with a secondary battery with high temperature cycle characteristics which is equipped with an outer jacket material. Amongst others, a negative electrode is housed in the outer jacket material with a negative active material having a potential nobler than 1.0 V than the lithium electrode potential and with a negative electrode conductor using a nonstochiometric titanium oxide. There is a separator between the negative and the positive electrode. The titanium oxide in this cell, however, gives rise to the assumption that gas evolution will occur in a cell according to this disclosure.

[0016] US 2005/0221170 Al (other family members are JP 4667071 B2 and KR 102006044479 A) discloses a secondary battery wherein the negative electrode contains a conductive agent and a negative electrode active material comprising lithium titanium oxide.

The conductive agent comprises graphitized vapour grown carbon fibre with a specific lattice constant. This assembly prevents degradation of the secondary battery. There should be no surface film formed on the graphitized vapour grown carbon fibre or on the titanium oxide.

However, as titanium oxide is used in this cell it is very likely that gas evolution can be observed.

Object of the Invention [0017] The problem to be solved by the present invention is the provision of an electrochemical cell electrolyte which reduces gas evolution in an electrochemical cell and which allows safe performance of the cell with high cycling stability and efficiency.

[0018] This problem is solved by the features as contained in the independent patent claims, with advantageous embodiments being described by the features as contained in the dependent patent claims.

Description of the Invention

[0019] Provided is an electrochemical cell electrolyte comprising an electrolyte salt, an electrolyte solvent and an electrolyte additive wherein the electrolyte additive comprises N-containing heterocycles and/or aminated aromatic compounds at a concentration of 0.01 % to 5.0 % each.

[0020] The electrochemical cell electrolyte is intended for use in an electrochemical cell. An electrochemical cell (or battery) within the meaning of the present disclosure may be a primary cell or a secondary cell (i. e. an accumulator).

[0021] The electrolyte additive may also comprise N-containing heteroeycles andlor aminated aromatic compounds at a concentration of 0.01 to 1.0 % each.

[0022] Surprisingly, an electrochemical cell electrolyte according to the present invention reduces gas evolution in an electrochernical cell. Reduction of gas evolution means that less gases which are mostly hydrogen, CO, CH or CO2 evolve within the electrochemical cell. It is known that film-forming additives such as vinylene carbonate and propane sultone reduce the gassing in electrochemical cells, such as titanate cells, due to the formation of a relatively thick SEI. These additives are reported to be effective in concentrations generally larger than 1% in the electrolyte, as for lower concentrations no effective SEI is formed.

S

[0023] It was completely unexpected that even the addition of small amounts (< 1%) of N-containing heterocycles and/or aminated aromatic compounds can significanfly reduce the gassing of electrochemical cells, such as titanate cells. This finding cannot be explained as the effective concentrations, e.g. 0.2%, are that low that no SEI, which is thick enough to protect the surface of the anode (of a material such as titanate), can be formed.

[0024] The mechanism responsible for the reduction of gassing is unknown up to now, but it is probable, that in case of an anode material such as LTO the catalytic reduction employing Ti3-ions of the surface of the LTO is influenced. The N-containing heterocycles and/or aminated aromatic compounds can be thought to poison the catalytic activity of the anode surface. This mechanism can work already for low concentrations of the additive, as the additive is not consumed during the reaction.

[00251 Reduced gassing in electrochemical cells is advantageous because it can lead to less swelling of the cells, increased cooling efficiency, increased safety of the cells (gas can contain a large proportion of hydrogen, which can create a safety risk when liberated) and a higher cycle life of the cells. Thus, performance and safety of the electrochemical cell are enhanced. Less swelling of the cell due to gas evolution results in less changes of the thickness of the cell. As a consequence, such a cell needs less space in a housing or battery module and cooling of the cell within the housing or the battery module will be easier.

[0026] The electrolyte salt may be selected from the group comprising lithium perchlorate (LiC1O4), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), lithium hexafluoroantimonate (L1SbF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis[trifluoromethyl)sulfonyl]imide (LiN(CF3SO2)2), lithium bis[(pentafluoroethyl)sulfonyl]imide (LiN(C2F5S02)2), lithium bisoxalatoborate (LiBOB), lithium difluorooxalatoborate (LIdFOB), lithium trifluoro trisentafluoroethyl)phosphate (LiFAP) and lithium tetraphenylborate (Li(C4-ls)4B).

[0027] The electrolyte solvent may be selected from the group comprising ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC), linear carbonate such as dimethyl carbonates (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), cyclic ethers such as tetrahydrofuran (THF) and 2-methyltetrahydrofliran (2-Me-THF), linear ethers such as dimethoxyethane (DME), lactones such as y-butyrolactone (GBL), valerolactone, acetonitrile and sulfolane and mixtures thereof.

[0028] A person skilled in the art is aware of the concentrations which are suitable for the electrolyte salt and the electrolyte solvent as part of the electrochemical cell electrolyte. The person skilled in the art also knows suitable ratios for mixtures of the electrolyte solvents.

One example for an electrolyte solvent with an electrolyte salt is ethylene carbonate (EC) and propylene carbonate (PC), ECJPC with 1M LiPF6.

[0029] The N-containing heterocycles may be selected from the group comprising pyrrole, 2-methyl-1-pyrroline, 1 -methylpyrroline, 1 -vinyl-2-pyrrolidinone, pyridine. 2-picoline, 3-picoline, 4-picoline, 2-vinylpyridine, 4-vinylpyridine, dimethyl-pyridine-amine (DMPA), boran-pyridine-complex and mixtures thereof [0030] The aminated aromatic compounds may be selected from the group comprising aniline, toluidine, diphenylamine, naphtylamine, alkylanilines and dialkylanilines.

[00311 The electrochemical cell electrolyte of the present disclosure may be used with any type of electrochemical cells and a person skilled in the art may adapt the properties of the electrochemical cell electrolyte to different applications, i. e. to the size and material of the electrochemical cells used.

[00321 An electrochemical cell comprising the electrochemical cell electrolyte as disclosed above, an anode, a cathode and a separator is also provided.

[0033] The anode may be of a material comprising Li4Ti5O12, Li2Ti3O7. LiTiO2, hO2, TiO2(OH) and mixtures thereof.

[0034] Thus, the electrochemical cell may be a lithium titanate based electroehemical cell.

[0035] The anode material may additionally be coated with carbon.

[0036] The anode material may also be a mixture of the anode material as disclosed above and carbonaceous material, and the carbonaceous material may be selected from the group comprising graphite, hard carbon, amorphous carbon, carbon-contaiitg core-shell material and silicon containing material.

[00371 The anode of the electrochemical cell may be cast from a slurry containing organic solvent or water as solvent.

[0038] The cathode may be of a material comprising LiCoO2, LiNiO2, LiNijCoMnO2.

LiNi1CoAlO2 LiMn2O4, LiM2MniO4, LiMPO4, wherein M comprises Fe, Mn, Co or Ni, LiAMPO4, wherein A comprises B, P, Si, Ti, Zr, Hf, Cr, Mo or W, and mixtures thereof [0039] The cathode material may additionally be coated with carbon, oxides or phosphates.

[0040] The cathode of the electrochemical cell may be cast from a slurry containing organic solvent or water as solvent.

[0041] The separator may comprise ceramic and/or glass particles, such as ceramic lithium aluminium titanium phosphate. The advantage is that soil shorts in the cell are avoided or delocalized on the single (ceramic and/or glass) particles.

[0042] The invention is, however, not limited to the above materials and any electrode or separator material known can be used with the present disclosure.

[0043] A method for manufacturing an electrochemical cell is provided, wherein the method comprises the following steps: -providing at least one anode, at least one cathode and at least one separator between the at least one anode and the at least one cathode; and -filling an electrochemical cell electrolyte between the anode and the cathode, wherein the electrochemical cell electrolyte comprises an electrolyte salt, an electrolyte solvent and an electrolyte additive wherein the electrolyte additive comprises N-containing heterocycles and/or arninated aromatic compounds at a concentration of 0.01 % to 5.0 % each.

[0044] It is to be understood that the electrochemical cell is filled in such a way that the electrochemical cell electrolyte is in contact with the anode and the cathode.

[0045] The electrolyte additive comprised by the above method may also comprise N-containing heterocycles and/or aminatcd aromatic compounds at a concentration of 0.01 to 1.0 % each.

[0046] Any electrochemical cell electrolyte as disclosed above may be employed.

[0047] The steps of providing the at least one anode, the at least one cathode and the at least one separator may comprise laminating the at least one anode, the at least one cathode and the at least one separator to each other.

[0048] A use of an clectrochemical cell electrolyte as disclosed above in an electrochemical cell comprising an anode, wherein the anode material is selected from the group comprising Li4Ti5Oi2, Li2Ti3O7, LiTiO2, Ti02, TiO2(OH) and mixtures thereof, is also provided.

[0049] A use of an electrochemical cell as disclosed above in consumer electronics, stationary applications as storage of renewable energy, grid levelling, large hybrid diesel engines, military, hybrid electric vehicles (HEV-s), and aerospace applications, is also provided. It is to be understood that the present disclosure also comprises any other suitable application. The applications may depend on the size and the energy density of the electrochemical cell. Small-and large-scale electrochemical cells are comprised by the

present disclosure.

[0050] Consumer electronics within the meaning of present disclosure comprises but is not limited to electronic equipment intended for everyday use, for example in entertainment, communications and office productivity. Electronic equipment comprises but is not limited to personal computers, telephones, MP3 players, audio equipment, televisions, calculators, GPS automotive electronics, digital cameras and players and recorders using video media such as DVDs, VCRs or camcorders.

[00511 The invention will now be described on the basis of the embodiments and the figures.

It will be understood that the embodiments and aspects of the invention described herein are only examples and do not limit the protective scope of the claims in any way. The invention is defined by the claims and their equivalents. It will be understood that features of one aspect or embodiment of the invention can be combined with a feature of a different aspect or aspects and/or embodiments of the invention.

Summary of the Figures

Fig. 1 Comparison of gassing between pyridthe-containing and pyridine-free electrolyte (cycling at elevated temperatures) Fig. 2 Comparison of gassing between pyridine-containing and pyridine-free electrolyte (floating in charged state at elevated temperatures) ExamDles Example 1: Manufacture of electrochemical cells [0052] The manufacture of electrochemical cells for use with an electrochemical cell electrolyte according to the invention is exemplified. l6Ah pouch cells with a lithium titanate anode (Li4TisOj2) and a NCA cathode (lithium nickel cobalt aluminum oxide LiNij.., Co>AlO2) serve as an example.

[0053] The cells are made from laminated bicells, containing one anode and a cathode on either side of the anode, laminated together by a ceramic separator. The separator is made of a porous polymer foil that contains a high amount of ceramic lithium aluminium titanium phosphate.

[0054] The electrodes are made by the following way: 1) anode: a slurry containing active material, conductive additive, binder and a solvent is cast on a copper or aluminium foil. The foil is then dried. The same action is repeated on the other side of the copper or aluminium foil. The foil is then calendered.

The solvent can be water or acetone.

2) cathode: a slurry containing active material, conductive additive, binder and a S solvent is cast on an aluminium foil. The foil is then dried and calandered. The solvent can be water or acetone.

100551 The bicells are made the following way: Separator foil is laminated on both sides of the anode and then cathode foils are laminated on both sides of the anode/separator assembly.

[0056] The bicells are then stacked, Al and Cu tabs are welded on the current collector foils, the stacks put in pouches, filled with electrolyte and sealed. The sealed cells are then tempered, submitted to a formation cycle, aged and evacuated. The electrolyte is ethylene carbonate (EC) and propylene carbonate (PC) at a ratio of EC/PC with lM LiPF6.

Example 2: Measurement of gassing [0057] Electrochemieal cells manufactured as described above have been employed for gassing experiments. The gassing experiments are conducted as follows. Two different methods are applied: [0058] Method 1: cycling at elevated temperatures [0059] The volume of the fresh cell is measured. The cells are put in an oven at 45°C and are cycled at a rate of C/2. In regular intervals the cell is taken from the oven and the cell volume is measured again. The difference in volume is reported in the graphs (see below).

[0060] Method 2: floating in the charged state at elevated temperatures [0061] The volume of the fresh cell is measured. The cells are then put in an oven at 50°C and kept at 2,7V, i.e. in the fully charged state. This is to force the gassing of titanate. It is known that gassing of titanate is heavier in the charged state and at elevated temperatures. In regular intervals the cell is taken from the oven and the cell volume is measured again. The difference in volume is reported in the graphs (see below).

[0062] Figure 1 and Figure 2 show the exemplary application of both methods, respectively, for comparison of gassing between pyridine-containing and pyridine-free electrolyte. The term "additive" designates pyridine as described in the following: [00631 In Figure 1 two cells are compared. Both cells have anodes and cathodes that have been coated with acetone-based slurry. One cell has EC/PC -I M LiPF6 as electrolyte, the other cell has EC/PC -lM LiPF6 -and 0.2% pyridine as electrolyte. Both cells were tested using method 1 for the determination of gassing (cycling at elevated temperatures). It can be seen, that even the addition of small amounts of pyridine (0.2%) considerably reduces the gassing of the cell.

[0064] In Figure 2 also two cells are compared. Both cells have anodes and cathodes that have been coated with water-based slurry. One cell has ECIPC -IM LiPF6 as electrolyte, the other cell has ECIPC -1M LiPF6 -and 0.2% pyridine as electrolyte. Both cells were tested using method 2 for the determination of gassing (floating in charged state at elevated temperatures). It can be seen, that even the addition of small amounts of pyridine (0.2%) considerably reduces the gassing of the cell.

Claims

Claims 1. An electrochemical cell electrolyte comprising an electrolyte salt, an electrolyte solvent and an electrolyte additive wherein the electrolyte additive comprises N-containing heterocycles and/or aminated aromatic compounds at a concentration of 0.01 % to 5.0% each.
2. The electrochemical cell electrolyte according to claim 1, wherein the electrolyte additive comprises N-containing heterocycles and/or aminated aromatic compounds at a concentration of 0.01 to 1.0 % each.
3. The electrochemical cell electrolyte according to claim I or 2, wherein the electrolyte salt is selected from the group comprising lithium perchiorate (LiC1O4), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), lithium hexafluoroantimonate (LiSbF5), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis[(trifluoromethyl)sulfonyl]imide (LiN(CF3SO2)2). lithium bis{(pentafluoroethyl)sulfonyl]imide (LIN(C2F5S02)2), lithium bisoxalatoborate (LiBOB), lithium difluorooxalatoborate (LidFOB), lithium trifluoro tris(pentafluoroethyphosphate (LiFAP) and lithium tetraphenylborate (Li(C6H5)4B).
4. The electrochemical cell electrolyte according to any of the preceding claims, wherein the electrolyte solvent is selected from the group comprising ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (YC), linear carbonate such as dimethyl carbonates (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), cyclic ethers such as tetrahydrofuran (THE) and 2-methyltetrahydrofüran (2-Me-THF), linear ethers such as dimethoxyethane (DME), lactones such as y-butyrolactone (GBL), valerolactone. acetonitrile and sulfolane and mixtures thereof
5. The electrochemical cell electrolyte according to any of the preceding claims, wherein the N-containing heterocycles are selected from the group comprising pyrrole, 2-methyl-i -pyrroline, 1 -niethylpyrroline, 1 -vinyl-2-pyrrolidinone, pyridine, 2-picoline, 3-picoline, 4-picoline, 2-vthylpyridine, 4-vinylpyridine, dimethyl-pyridine-amine (DMPA), boran-pyridine-complex and mixtures thereof
6. The electrochemical cell electrolyte according to any of the preceding claims, wherein the aminated aromatic compounds are selected from the group comprising aniline, toluidine, diphenylamine, naphtylamine, alkylanilines and dialkylanilines.
7. An electrochemical cell comprising the electrochemical cell electrolyte according to any of the preceding claims, an anode, a cathode and a separator.
8. The electrochemical cell according to claim 7, wherein the anode is of a material comprising Li4Ti5O12, Li2Ti3O7, LiTiO2, Ti02, TiO2(OH) and mixtures thereof
9. The electrochemical cell according to claim 8, wherein the anode material is additionally coated with carbon.
10. The electrochemical cell according to claim 8 or 9, wherein the anode material is a mixture of the anode material according to claims 8 or 9 and carbonaceous material, wherein the carbonaceous material is selected from the group comprising graphite, hard carbon, amorphous carbon, carbon-containing core-shell material and silicon containing material.
11. The electrochemical cell according to any of claims 7 to 10, wherein the cathode is of a material comprising LiCoO2, LiNiO2, LiNii.CoMnO2, LiNii.CoAlO2 LiMn2O4, LiM2Mn4O4, LiMPO4, wherein M comprises Fe, Mn, Co or Ni, LiAMPO4, wherein A comprises B. P, Si, Ti, Zr, Hf, Cr, Mo or W, and mixtures thereof
12. The electrochemical cell according to claim 11, wherein the cathode material is additionally coated with carbon, oxides or phosphates.
13. The electrochemical cell according to any of claims 7 to 12, wherein the separator comprises ceramic and/or glass particles, such as ceramic lithium aluminium titanium phosphate.
14. A method for manufacturing an electrochemical cell, the method comprising the following steps: -providing at least one anode, at least one cathode and at least one separator between the at least one anode and the at least one cathode; and -filling an electrochemical cell electrolyte between the anode and the cathode, wherein the electrochemical cell electrolyte comprises an electrolyte salt, an electrolyte solvent and an electrolyte additive wherein the electrolyte additive comprises N-containing heterocycles and/or aminated aromatic compounds at a concentration of 0.01 % to 5.0% each.
15. The method according to claim 14, wherein the electrolyte additive comprises N-containing heterocycles and/or aminated aromatic compounds at a concentration of 0.01 to l.0%each.
16. The method according to claim 14 or 15, wherein the electrochemical cell electrolyte is an electrochemical cell electrolyte according to any of claims I to 6.
17. The method according to any of claims 14 to 16, wherein the steps of providing the at least one anode, the at least one cathode and the at least one separator comprise laminating the at least one anode, the at least one cathode and the at least one separator to each other.
18. A use of an electrochemical cell electrolyte according to any of claims ito 6 in an electrochemical cell comprising an anode, wherein the anode material is selected from the group comprising Li4Ti5O12, Li2Ti3O7, LiTiO2, Ti02, TiO2(OFI) and mixtures thereof
19. A use of an electrochemical cell according to any of claims 8 to 14 in consumer electronics, stationary applications as storage of renewable energy, grid levelling, large hybrid diesel engines, military, hybrid electric vehicles (IIEV-s), and aerospace applications.