Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
  • H01M10/0566—Liquid materials
  • H01M10/0569—Liquid materials characterised by the solvents
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C43/00—Ethers; Compounds having groups, groups or groups
  • C07C43/02—Ethers
  • C07C43/03—Ethers having all ether-oxygen atoms bound to acyclic carbon atoms
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C43/00—Ethers; Compounds having groups, groups or groups
  • C07C43/02—Ethers
  • C07C43/03—Ethers having all ether-oxygen atoms bound to acyclic carbon atoms
  • C07C43/04—Saturated ethers
  • C07C43/13—Saturated ethers containing hydroxy or O-metal groups
  • C07C43/135—Saturated ethers containing hydroxy or O-metal groups having more than one ether bond
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
  • H01G11/54—Electrolytes
  • H01G11/58—Liquid electrolytes
  • H01G11/64—Liquid electrolytes characterised by additives
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
  • H01M10/0566—Liquid materials
  • H01M10/0567—Liquid materials characterised by the additives
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0025—Organic electrolyte
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0025—Organic electrolyte
  • H01M2300/0028—Organic electrolyte characterised by the solvent
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the invention relates to the field of lithium-ion batteries.
• Lithium-ion batteries (secondary batteries) are currently the leading technology in the field of rechargeable batteries, especially in the field of portable electronics.
• Conventional lithium-ion batteries usually use a graphite anode. The charge transport takes place via an electrolyte which comprises a lithium salt dissolved in a solvent.
• electrolyte which comprises a lithium salt dissolved in a solvent.
• electrolytes and conductive salts are known in the prior art.
• Conventional lithium-ion batteries currently use mostly lithium hexafluorophosphate (LiPFo).
• the operation of graphite anodes leads to a reductive decomposition of the electrolyte.
• the reaction products can form an adhesive and electronically insulating, but lithium-ion-conducting film on the electrode.
• Suitable electrolytes are characterized in that the formation of such a solid-electrolyte phase interface, the so-called solid electrolyte interphase (SEI) is induced on the electrode.
• SEI solid electrolyte interphase
• the Solid Electrolyte Interphase subsequently prevents the graphite from continuing with the
• Electrolyte reacts and thereby protects the electrolyte from further reductive decomposition and the anode from destruction by co-intercalation of the solvent.
• the present invention was based on the object to provide an electrolyte which overcomes at least one of the aforementioned disadvantages of the prior art.
• the object of the present invention was to provide a compound which supports the formation of a solid electrolyte interphase on graphite and thus enables a reversible cyclization of propylene carbonate-containing electrolytes.
• an electrolyte for an energy store comprising a conducting salt and a solvent, characterized in that the solvent comprises at least one compound according to the general formula (1) as indicated below:
• R 2 , R 3 , R 4 are the same or independently selected from the group
• Ci-6-alkyl comprising linear or branched Ci-6-alkyl, C2 -6 alkenyl, C2 -6 alkynyl, C3-6 cycloalkyl and / or phenyl, each unsubstituted or mono- or polysubstituted by a substituent selected from the group comprising F , CN and / or single or multiple fluorine-substituted Ci- 2 alkyl.
• Tetraalkoxyethanes according to the general formula (1) can form a stable solid electrolyte interphase which can protect graphite anodes from exfoliation and a propylene carbonate electrolyte from continuous reductive decomposition over 300 charging and discharging cycles.
• Ci-6-alkyl or “Ci-Cö-alkyl”, unless otherwise indicated, includes straight-chain or branched alkyl groups having 1 to 6 carbon atoms.
• C 3-6 -cycloalkyl is to be understood as meaning cyclic alkyl groups having 3 to 6 carbon atoms.
• C 2-6 alkenyl and C 2-6 alkynyl include straight or branched alkenyl or alkynyl groups having 2 to 6 carbon atoms and each having at least one double or triple bond, respectively.
• radicals R 1 , R 2 , R 3 and R 4 may be the same or different.
• the radicals R 1 , R 2 , R 3 and R 4 are the same.
• C 1 -C 8 -alkyl groups Preference is given to C 1 -C 8 -alkyl groups.
• Preferred C1-C5 alkyl groups include straight-chain or branched alkyl groups having 1 to 5 carbon atoms, preferably selected from the group consisting of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl and / or neopentyl.
• the alkyl, alkenyl or alkynyl groups may be unsubstituted or substituted one or more times, for example two or three times. In this case, the alkyl, alkenyl or alkynyl groups at different, preferably at the same, Carbon atoms be substituted several times.
• the substituent may be fluorine or CN (nitrile). In embodiments in which the groups R 1 , R 2 , R 3 , R 4 are substituted, these are preferably substituted by fluorine, for example mono- or polyfluorinated, or perfluorinated. In particular, C3-C6 alkyl substituents may have a CF3 group.
• Alkyl, alkenyl, alkynyl or cycloalkyl groups or phenyl may furthermore be monosubstituted or polysubstituted by small fluorine-substituted C 1-2 -alkyl groups, in particular CF 3 .
• R 1 , R 2 , R 3 , R 4 are the same or independently selected from the group consisting of unsubstituted or mono- or polysubstituted with fluorine, CN or CF 3 substituted Ci-Cs-alkyl, preferably Ci-C 3 alkyl , or phenyl.
• unsubstituted compounds are usually less expensive, and thus more economical as solvent or co-solvent in a lithium-ion battery.
• R 1 , R 2 , R 3 , R 4 are the same or independently selected from the group comprising methyl, ethyl, n-propyl and / or iso-propyl, in particular from methyl and ethyl.
• the compound of general formula (1) is selected from 1,1,2,2-tetramethoxyethane and / or 1,1,2,2-tetraethoxyethane.
• 1,1,2,2-Tetramethoxyethane is also referred to as tetramethyl-1,1,2,2-ethane tetracarboxylate according to IUPAC nomenclature
• 1,1,2,2-tetraethoxyethane as tetraethyl-1,1,2,2-ethane tetracarboxylate
• 1,1,2,2-Tetramethoxyethane and 1,1,2,2-tetraethoxyethane have the following formulas (2) and (3):
• 1,1,2,2-tetramethoxy- and 1,1,2,2-tetraethoxyethane have been found to be well suited to form an effective SEI on graphite as a co-solvent for propylene carbonate, which effectively suppresses the co-intercalation of Propylene carbonate in graphite causes.
• 1,1,2,2-tetramethoxyethane and 1,1,2,2-tetraethoxyethane are therefore suitable as co-solvent or SEI additive or as sole solvent for the lithium-ion technology.
• the solvent may contain the compound of general formula (1) in the range of> 0.1 wt.% To ⁇ 100 wt., Based on the total weight of the electrolyte solvent.
• the tetraalkoxyethanes are useful as the sole solvent.
• the tetraalkoxyethanes can be used as SEI additive.
• the solvent may be the compound of the general formula (1) in a range of> 0.1 wt .-% to ⁇ 10 wt .-%, or> 1 wt .-% to ⁇ 5 wt .-, based on the
• Tetraalkoxyethanes can be used as cosolvents for propylene carbonate-based electrolytes.
• the electrolyte comprises the compound according to the general formula (1) in the range of> 10 wt .-% to ⁇ 80 wt .-%, preferably in the range of> 20 wt .-% to ⁇ 50 wt .-, particularly preferably in Range of> 30 wt .-% to ⁇ 50 wt., Based on the total weight of the electrolyte solvent.
• proportions of 30% by weight of 1,1,2,2-tetramethoxyethane or 1,1,2,2-tetraethoxyethane as co-solvent can bring about an effective suppression of the co-intercalation of propylene carbonate into graphite.
• the possibility of using relatively small amounts of tetraalkoxyethane such as 1,1,2,2-tetramethoxyethane or 1,1,2,2-tetraethoxyethane makes this approach economically.
• the electrolyte has at least one conductive salt, preferably a lithium salt, and a
• Solvent comprising the compound according to the general formula (1).
• the compound according to the general formula (1) may be the solvent.
• the electrolyte can also have another solvent.
• the compound of general formula (1) functions as a cosolvent.
• the compound according to the general formula (1) may be present in only small proportions, and would then be in contrast to that still present
• Solvent referred to as an additive.
• the solvent serves as a solvent for the Elektrolytg. Lithium salt.
• solvent and solvent are used interchangeably herein.
• the electrolyte may contain a solvent selected from the group comprising non-fluorinated or partially fluorinated organic solvents, ionic liquids, a polymer matrix and / or mixtures thereof.
• a solvent selected from the group comprising non-fluorinated or partially fluorinated organic solvents, ionic liquids, a polymer matrix and / or mixtures thereof.
• the electrolyte comprises an organic solvent, in particular a cyclic or linear carbonate.
• the organic solvent is selected from the group comprising ethylene carbonate, ethylmethyl carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, acetonitrile, propionitrile, 3-methoxypropionitrile, glutaronitrile, adiponitrile, pimelonitrile, gamma-butyrolactone, gamma-valerolactone, dimethoxyethane, 1,3- Dioxolane, methyl acetate,
• the solvent is selected from the group comprising propylene carbonate, ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate and / or mixtures thereof.
• the electrolyte may in particular solvents such as
• Propylene carbonate which do not lead to the formation of an effective Solid Electrolyte Interphase.
• propylene carbonate and mixtures of propylene carbonate with ethylene carbonate, ethylmethyl carbonate, dimethyl carbonate and / or diethyl carbonate in particular mixtures of propylene carbonate with dimethyl carbonate.
• mixtures containing 50% by weight of 1,1,2,2-tetramethoxyethane and / or 1,1,2,2-tetraethoxyethane and 50% by weight of propylene carbonate, based on the total weight of the electrolyte solvent are preferred. Also, mixtures containing 1,1,2,2-tetramethoxyethane and / or 1,1,2,2-tetraethoxyethane, and propylene carbonate and
• Such mixtures can have good conductivity and provide passivation of graphite electrodes.
• tetraalkoxyethanes contributes to an increase in the intrinsic safety of the electrolyte system by increasing the auto-ignition temperature compared to linear carbonates such as dimethyl carbonate and diethyl carbonate.
• 1,1,2,2-tetramethoxyethane and 1,1,2,2-tetraethoxyethane to an autoignition temperature of 47-53 ° C and 71 ° C, while dimethyl carbonate and diethyl carbonate at temperatures of 18 ° C or 31 ° C can ignite itself.
• 1,1,2,2-tetramethoxyethane or 1,1,2,2-tetraethoxyethane as the cosolvent, the
• 1,1,2,2-tetramethoxyethane and 1,1,2,2-tetraethoxyethane have a melting point of -24 ° C and -35 ° C and a boiling point of about 155 ° C and 196 ° C, while dimethyl carbonate and diethyl carbonate melt only at temperatures of 5 ° C or - 74 ° C, but already at 91 ° C and 126 ° C boil.
• Ethylene carbonate has a melting temperature of 36 ° C.
• the electrolyte may also be a polymer electrolyte, for example, selected from the group consisting of polyethylene oxide, polyacrylonitrile, polyvinyl chloride, polyvinylidene fluoride, poly (vinylidene fluoride-co-hexafluoropropylene) and / or polymethylmethacrylate with addition of a conducting salt, or a gel-polymer electrolyte comprising a polymer , the abovementioned organic solvent and / or an ionic liquid and a conductive salt.
• the electrolyte can be formed from an ionic liquid and a conductive salt.
• the electrolyte according to the invention has at least one conducting salt, in particular a lithium salt.
• the conducting salt is preferably selected from the group consisting of LiPF 6 , LiBF 4 , LiAsF 6 , LiSbF 6 , LiC 10 4 , LiPtCl, LiN (SO 2 F) 2 , LiN (SO 2 CF 3 ) 2 , LiN (SO 2 C 2 F 5 ) 2 , LiC (S0 2 CF 3 ) 3 , LiB (C 2 0 4 ) 2 , LiBF 2 (C 2 0) and / or LiS0 3 CF 3 .
• the lithium salt is preferably selected from LiN (SO 2 CF 3 ) 2 (LiTFSI, lithium bis (trifluoromethanesulfonyl) imide, LiN (SO 2 F) 2 (LiFSI) and LiPF 6.
• concentration of the lithium salt in the electrolyte can be in conventional ranges, For example, in the range of> 1.0 M to ⁇ 1.5 M.
• the electrolyte comprises a compound in accordance with the general formula (1), in particular 1,1,2,2-tetramethoxyethane and / or 1,1,2,2-tetraethoxyethane, at least one lithium salt, and propylene carbonate or a mixture of organic solvents comprising propylene carbonate
• the electrolyte can be prepared, for example by mixing the compound according to the general formula (1) with
• the electrolyte may further contain at least one additive, in particular selected from the group comprising SEI formers, flame retardants and / or overload additives.
• the electrolyte may contain a compound according to the general formula (1) and another SEI-forming agent, for example selected from the group comprising fluoroethylene carbonate, chloroethylene carbonate, vinylene carbonate, vinyl ethylene carbonate, ethylene sulfide, propanesultone, propensultone, sulfites, preferably dimethyl sulfite and
• SEI-forming agent for example selected from the group comprising fluoroethylene carbonate, chloroethylene carbonate, vinylene carbonate, vinyl ethylene carbonate, ethylene sulfide, propanesultone, propensultone, sulfites, preferably dimethyl sulfite and
• the electrolyte may contain a compound according to the general formula (1) and another SEI-formner selected from the group comprising vinyl carbonate, fluoroethylene carbonate and / or ethylene sulfate. These connections can be battery power, such as the capacity, the
• the compounds according to the general formula (1) in particular 1,1,2,2-tetramethoxyethane and 1,1,2,2-tetraethoxyethane, are commercially available or can be prepared by methods familiar to the person skilled in the art.
• the electrolyte is particularly suitable for a battery or a rechargeable battery, in particular as an electrolyte for a lithium-ion battery or a lithium-ion rechargeable battery.
• Another object of the present invention relates to an energy storage, in particular electrochemical energy storage, selected from the group comprising lithium battery, lithium-ion battery, lithium-ion battery, lithium-polymer battery, lithium-ion capacitor or supercapacitor, comprising one
• the term “energy store” encompasses primary and secondary electrochemical energy storage devices, ie batteries (primary storage) and accumulators (secondary storage). [Sprach Im] In common usage, accumulators are often referred to by the term “battery” which is often used as a generic term. Thus, the term lithium-ion battery is used herein synonymously with lithium-ion battery, if not stated otherwise.
• electrochemical energy storage for the purposes of the present invention in particular, electrochemical capacitors (English: electrochemical capacitors) such as supercapacitors (English: Supercapacitors). Electrochemical capacitors, also referred to in the literature as supercapacitors, are electrochemical
• Energy Storage which is characterized by a higher power density compared to batteries, compared to conventional capacitors by a higher energy density.
• the energy store is in particular a lithium-ion battery. It could be shown that the formed solid electrolyte phase interface was stable on a graphite anode for at least 300 cycles. This enables economical operation of rechargeable batteries and use of the electrolyte.
• the energy store can be a compound according to the general formula (1) and carbon, in particular graphite, as electrode material and / or a
• Propylene carbonate-containing electrolyte include.
• a lithium-ion battery comprising a cathode, a graphite anode, a separator and an electrolyte comprising a tetraalkoxyethane according to the general formula (1), in particular 1,1,2,2-tetramethoxyethane or 1,1,2, is preferred.
• Weight ratio 1 1 or mixtures containing 1,1,2,2-tetramethoxyethane and / or 1,1,2,2-tetraethoxyethane, and propylene carbonate and dimethyl carbonate im
• lithium metal, lithium titanate spinel (LTO) and carbon in particular, graphite as the anode material and lithium iron phosphate (LFP) and lithium nickel manganese cobalt oxide (NMC) as the cathode material are usable.
• LTO lithium titanate spinel
• NMC lithium nickel manganese cobalt oxide
• a solid state electrolyte interface on an electrode of an electrochemical cell comprising an anode, a cathode and an electrolyte, wherein the cell is operated using the electrolyte of the invention.
• Another object of the invention relates to the use of a compound according to the general formula 1) as indicated below:
• R 1 , R 2 , R 3 , R 4 are the same or independently selected from the group comprising linear or branched C 1-6 -alkyl, C 1-6 -alkenyl, C 1-6 -alkynyl, C 3-6 -cycloalkyl and / or Phenyl, in each case unsubstituted or monosubstituted or polysubstituted by a substituent selected from the group comprising F, CN and / or mono- or polysubstituted by fluorine-substituted Ci-2-alkyl,
• an energy store in particular an electrochemical energy store selected from the group comprising lithium battery, lithium ion battery, lithium ion accumulator, lithium polymer battery, lithium ion capacitor or a
• the compound according to the general formula (1) can be used advantageously as an electrolyte additive, solvent or co-solvent, in particular in electrolytes which form no effective SEI without the addition of additive.
• the compound according to the general formula (1) can be advantageously used in an energy store, which
• Carbon in particular comprises graphite as electrode material and / or a propylene carbonate-containing electrolyte.
• the compound according to the general formula (1) reference is made to the above description.
• Particularly preferred are 1,1,2,2-tetramethoxyethane and 1,1,2,2-tetraethoxyethane. Examples and figures which serve to illustrate the present invention are given below.
• FIG. 1 in FIG. 1a shows the reductive stability window of an electrolyte containing 1 M
• PC Propylene carbonate
• TEE 1,1,2,2-tetraethoxyethane
• FIG. 2 shows the oxidative stability window in Pt / Li half cells of electrolytes
• FIG. 3 shows the oxidative stability window in a LiMmCVLi half cell for a
• Electrolytes containing 1 M LiFSI in a mixture of propylene carbonate and 1,1,2,2-tetraethoxyethane are Electrolytes containing 1 M LiFSI in a mixture of propylene carbonate and 1,1,2,2-tetraethoxyethane.
• Figure 4 shows the charge and discharge capacity (left ordinate axis) and Coulomb efficiency (right ordinate axis) versus the number of charge / discharge cycles for an electrolyte containing 1 M LiTFSI in a 1: 1 mixture of propylene carbonate and 1.1.2 , 2-tetraethoxyethane for a graphite / Li cell.
• Figure 5 shows the charge and discharge capacity and Coulomb efficiency versus the number of charge / discharge cycles for an electrolyte containing 1 M LiTFSI in a 1: 1 mixture of propylene carbonate and 1,1,2,2-tetraethoxyethane in a LFP / Graphite full cell.
• FIG. 6 shows the charge and discharge capacity and Coulomb efficiency against the number of charge / discharge cycles for an electrolyte containing 1 M LiFSI in a 1: 1 mixture of propylene carbonate and 1,1,2,2-tetraethoxyethane in a NMC / FIG. Graphite full cell.
• FIG. 7 b) shows a scanning electron micrograph of the cross section of superficial graphite secondary particles after one cycle in this electrolyte.
• FIG. 8 a shows the course of the cell voltage versus the time of the first cycle
• FIG. 8b shows a scanning electron microscope
• LiTFSI lithium bis (trifluoromethanesulfonyl) imide
• LiN 1,1,2,2-tetraethoxyethane
• PC Propylene carbonate
• DMC dimethyl carbonate
• 1,1,2,2-tetraethoxyethane a mixture of 50% by weight of 1,1,2,2-tetraethoxyethane and 50% by weight of propylene carbonate, or a mixture of 1,1,2,2 - Tetraethoxyethane, propylene carbonate and dimethyl carbonate in a weight ratio of 1: 1: 1 submitted.
• the respectively required amount of LiTFSI or LiFSI LiN (S0 2 F) 2
• comparative electrolytes containing 1 M LiTFSI or LiPF 6 in propylene carbonate were prepared.
• the conductivity of the electrolytes was examined using a 2-electrode conductivity cells (RHD Instruments, GC / Pt) in a temperature range of -35 ° C to + 60 ° C.
• the conductivity cells were first heated to 60 ° C and cooled at temperature intervals of 10 ° C to - 30 ° C and then to - 35 ° C.
• Table 1 shows the conductivity in the temperature range of - 35 ° C to + 60 ° C in the corresponding solvent mixtures.
• TAE Tetramethoxyethane
• the potential between the working and reference electrodes was first measured from equilibrium potential (OCP) to 0.025V vs.. Li / Li + lowered, then again from 0.025 V to 1.5 V vs. Li / Li + increased.
• OCP equilibrium potential
• the process of cyclic potential change between 0.025V and 1.5V vs. Li / Li + was repeated twice.
• the feed rate was 0.025 mV s -1 .
• FIG. 1a shows the reductive stability window of the electrolyte containing 50% by weight of 1,1,2,2-tetramethoxyethane (TME) and FIG. 1b) shows the reductive stability window of FIG. 1a).
• Electrolytes containing 50% by weight of 1,1,2,2-tetraethoxyethane (TEE). The current intensity is plotted against the potential over three cycles. As can be seen from Figures la) and lb), the electrolytes containing 50% by weight of propylene carbonate were stable and compatible with graphite electrodes. This shows that an effective passivation of graphite by 1,1,2,2-tetramethoxyethane and 1,1,2,2-tetraethoxyethane already in a 1: 1 mixture can be achieved with propylene carbonate. Reductive decomposition for TME and TEE was not evident from the cyclo voltammogram.
• Platinum electrode (0 0.1 cm, eDAQ) as a working electrode and lithium foil as a counter and reference electrode.
• the separator used was a glass fiber flow.
• Li / Li + increased.
• the feed rate was 0.1 mV s- 1 .
• FIG. 2 shows the oxidative stability window of the electrolytes. Plotted is the current against the potential. As can be seen from Figure 2, the electrolytes were up to a potential of 5V vs. Li / Li + stable.
• Example 5
• oxidative stability of 1,1,2,2-tetraethoxyethane using an LMO electrode The oxidative stability of an electrolyte containing 1 M LiFSI in a mixture of 1,1,2,2-tetraethoxyethane and propylene carbonate (IM LiFSI, PC: TEE (1: 1)) was investigated using lithium manganese oxide as the working electrode. The determination of the oxidative stability was carried out as described under Example 4 using linear sweep voltammetry in a three electrode cell from Swagelok ® type. Lithium foil served as a reference and counter electrode, with the potential between the working and reference electrodes from the open circuit voltage to 4.9 V vs. Li / Li + was increased.
• FIG. 3 shows the oxidative stability window of the electrolyte for a potential vs. Li / Li + in the range from 3.2 V to 5 V.
• Electrolytes based on a 1: 1 mixture of 1,1,2,2-tetraethoxyethane and propylene carbonate complete delithiation possible without additional evidence of parasitic Faradayscher reactions, up to a cut-off voltage of 4.3 V vs. Li / Li + .
• Cycle stability was assessed in a button cell assembly (Hohsen Corp., CR2032) using lithium-titanium and graphite electrodes (MCMB).
• the separator used was a glass fiber flow.
• the cyclizations were carried out in a voltage window of 0.025V to 1.5V.
• 3 formation cycles were run at 0.1C and 3 conditioning cycles at 0.25C and 3 conditioning cycles at 0.5C followed by 41 charge / discharge cycles at 1.0C.
• the constant current measurements were made on a Series 4000 (Maccor) battery tester at 20.0 ° C + 0.1 ° C.
• FIG. 4 shows the discharge and charge capacity of the graphite / Li cell as well as the Coulomb efficiency versus the number of cycles. As shown in FIG. 4, in the first cycle the electrolyte showed a high Coulomb efficiency of 87.3% and a low Coulomb efficiency
• Figure 5 shows the discharge and charge capacity and the Coulomb efficiency of the full cell against the number of cycles.
• the electrolyte showed a Coulomb efficiency of 88.4% in the first cycle, and a high Coulomb efficiency of> 99.9% over 300 cycles. Further, this result shows that there is compatibility with LFP cathode material.
• the cycle stability in whole cells was measured using a Litihum-Nickelo, 5- manganese 0, 3 Cobalt-0, 2-oxide cathode (NMC532) described to graphite than 40 charge / discharge cycles at 1,0C repeated as described in Example 7.
• FIG. The cyclizations were performed in a voltage window of 2.8V to 4.2V.
• the electrolyte used was 1 M LiFSI in a 1: 1 mixture of 1,1,2,2-tetraethoxyethane and propylene carbonate.
• FIG. 6 shows the discharge and charge capacity and the Coulomb efficiency of
• Button cell assembly (Hohsen Corp., CR2032) cycled against a lithium iron phosphate cathode (LFP) or a lithium-nickelo, 5-mangano, 3-cobalto, 2-oxide cathode (NMC532).
• the separator used was a polymer flow.
• the charge / discharge cycle was performed in a voltage window of 2.5V to 3.6V (LFP) or 2.8V to 4.2V (NMC532). The measurement was carried out at 25.0 ° C + 0.1 ° C on a Battery Tester Series 4000 (Maccor).
• the electrolyte used was 1 M LiTFSI in a 1: 1 mixture of 1,1,2,2-tetraethoxyethane and propylene carbonate.
• the comparative electrolytes used were a solution of 1 M LiPF 6 in propylene carbonate containing 2% by weight of the SEI additive fluoroethylene carbonate (FEC).
• FIG. 7 a shows the course of the cell voltage (graphite / LFP cell) against the capacity of the first cycle for the electrolyte containing 50 wt .-% 1,1,2,2-tetraethoxyethane and PC
• Figure 7 b a Scanning electron micrograph of the graphite surface (cross section of the secondary graphite particles).
• FIG. 7a) shows that in the first cycle reversible intercalation / deintercalation of Li + ions in the graphite was possible.
• Figure 7b shows that the surface of the graphite electrode was intact after the charge / discharge cycle. There were no signs of exfoliation.
• FIG. 7 a shows the course of the cell voltage (graphite / LFP cell) against the capacity of the first cycle for the electrolyte containing 50 wt .-% 1,1,2,2-tetraethoxyethane and PC
• Figure 7 b a Scanning electron micrograph of the graphite surface (cross section of the secondary graphit
• FIG. 8a shows the cell voltage of the comparison cell (graphite / NMC532, containing 1 M LiPFe in propylene carbonate containing 2% by weight fluoroethylene carbonate as electrolyte) for the first cycle versus time.
• FIG. 8b) shows a scanning electron micrograph of the graphite surface after the charge / discharge cycle.
• FIG. 8a shows a significantly lower reversibility of the Li + ion intercalation / deintercalation into the graphite.
• Figure 8b) clearly shows that the surface of the graphite electrode showed a strong exfoliation after a charge / discharge cycle in propylene carbonate even using the SEI additive FEC.

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• 2017
  • 2017-06-14 DE DE102017113141.8A patent/DE102017113141A1/de not_active Withdrawn
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