GB2580553A - An electrolyte and a battery with said electrolyte - Google Patents

An electrolyte and a battery with said electrolyte Download PDF

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GB2580553A
GB2580553A GB2000738.1A GB202000738A GB2580553A GB 2580553 A GB2580553 A GB 2580553A GB 202000738 A GB202000738 A GB 202000738A GB 2580553 A GB2580553 A GB 2580553A
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electrolyte
carbonate
stabilizer
electrode
battery
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GB202000738D0 (en
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Yung Wang Kuei
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High Tech Battery Inc
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High Tech Battery Inc
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    • 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
    • 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
    • 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
    • H01M2300/0037—Mixture of solvents
    • H01M2300/0042—Four or more solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
    • 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

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  • Engineering & Computer Science (AREA)
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  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
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Abstract

An electrolyte for a lithium-ion battery comprises a lithium salt; a non-aqueous organic solvent which includes a carbonate-based solvent; a flame retardant; a film former; and a stabilizing medium. The flame retardant comprises PYR1RPF6 (N-Methyl-N-alkylpyrrolidinium Hexafluorophosphate Salt) at the amount of 1 to 15 wt.% of the electrolyte. The number of carbon atoms in the alkyl side chains, R, may be 2-10 and the PYR1RPF6 may have a melting point greater than 200°C. A further electrolyte for a lithium-ion battery comprises a lithium salt; a non-aqueous organic solvent which includes a carbonate-based solvent; PYR1RPF6 as a flame retardant; a film former; and a stabilizing medium; wherein the stabilising medium includes first, second and third stabilisers. A first stabilizer may comprise an ionic liquid with PYR1R+ as a cation and a boron-based anion such as BOB-, ODFB- or BMB-; for example PYR14BOB or PYR14ODFB. A third stabiliser may comprise PFPN, EDHP, HPCP or DOPO-HQ. A second stabiliser may comprise an ionic liquid with PYR1R+ as a cation and TFSI- or FSI- as an anion; for example PYR14TFSI or PYR13TFSI. The flame retardant may be PYR16PF6.

Description

Intellectual Property Office Application No. GII2000738.1 RTM Date June 2020 The following terms are registered trade marks and should be read as such wherever they occur in this document: Super P Intellectual Property Office is an operating name of the Patent Office www.gov.uk/ipo
AN ELECTROLYTE AND A BAT ILRY WITH SAID ELECTROLYTE
The present invention relates to an electrolyte for a rechargeable battery, for example particularly, but not exclusively, for a lithium-ion battery.
BACKGROUND OF THE INVENTION
Lithium-ion battery has extensive application in diverse fields of technology. It is progressively more challenging to enhance the performance of the battery, which involves fine balancing amongst various aspects. Side reactions creep in when new combination is used, for example, sudden redox reaction at specific yet broad range of potential applied. In addition to the costs for manufacture, two main concerns are the life cycle and the stability of the battery. It is obvious that safety is the first and foremost.
13 Recurrently, flammability and explosion of lithium-ion batteries make the headlines of newspapers and cause concerns. The problem is usually attributable to a poor combination of electrode and electrolyte.
A solution to enhance stability would be to use Lithium Iron Phosphate (LFP) as a material for the positive electrode. Cost and pollution concerns are minimal. The special olivine structure of LFP contributes significantly to the low flammability and explosion risk due to improper handling of the battery such as overcharging, over discharging and/or short circuit.
It is common to use nonaqueous organic solvent in the electrolyte of a lithium ion battery. A mixture of two or more carbonate-based electrolytes are prevalent. The commonly used organic solvents include ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), propylene carbonate (PC), or dimethyl carbonate (DMC). The addition of film former agents is also customary. The common film former agents include vinyl carbonate (VC) and fluoroethylene carbonate (FEC).
All of these organic solvents and film former agents have relatively high volatility and flammability. They are more likely to contribute to an explosion in case of improper handling of a battery.
The use of ionic liquids in the electrolyte of lithium ion battery is being extensively explored because of its low volatility and low-combustion properties. It remains as molten salt that exhibits liquid state below 100 degree Celsius and around room temperature. As such they are called room temperature ionic liquids (RTIL) or room 4 0 temperature molten salts.
-alky1-3-thedwlimidazolium is the most researched. faking I -alky1-3-methyhtnidazollum tetrafluotoborate as an example, in which the alkyl chain has a carbon number of 1 to 18. In general, the melting point should increase substantially as the number of carbon chains increases. However, this may not always be the case. The melting point of an ionic liquid with 1-alkyl-3-methylimidaze hum cation is substantially affected by the anion. There are many uncertainties.
In summary, the melting point of the ionic liquid depends on mu le factors includng the number of carbon in the cation and the anion. For example -ethy1-3-methylitnidazolium Cl has a melting point of 87 0 C, 1-ethyl-3-inethylimidazoliima IT& has a melting point of 62 0 C, 1-ethv1-3-methylimidazolium BF4 has a inching point of 15 degrees, 1-elnyl-3-methyl imidazolium AWL has a melting point of 7 degrees, and ethyl-3-methylimidazolium TFSI melting point -3 degrees, Another problem would be the size of the molecular group of the ionic liquid. There is a general trend that the larger die molecular group, the higher the viscosity and the lower the conductivity. The addition of carbonate electrolytes to overcome the inherent problem with the ionic liquid brings back the aforementioned concerns on combustion and possible explosion.
The invention seeks to inhibit or at least to mitigate such shortcomings by providing a stable electrolyte useful in battery for multiple fields.
SUMMARY OF THE INVENTION
According to the invention, there is provided an electrolyte for a lithium-ion battery comprising a lithium salt, a non-aqueous organic solvent which includes a carbonate-based solvent, a flame retardant, a film former and a stabilizing medium, wherein the flame retardant comprises PYRiRPF6 (N-Methyl-N-alkylpyrrolidinium Hexafluorophosphate Salt) at the amount of Ito 15 wt. % of the electrolyte. Preferably, R in PYRIRPF6 indicates the number of carbon atoms in the alkyl side chains, in which R is selected from any one of 2 to 10. More preferably, the PYRIRPF6 has a melting point greater than 200 °C. It is preferable that the R is 2, 5 or 6. Preferably, the stabilizing medium includes first and second stabilizer. The first stabilizer may comprise an ionic liquid with PYR 1:1 cation and a boron-based anion other than BFI.
Preferably, R is 2, 3, 4, 5 or 6. It is preferable that the boron-based anion is selected from a group consisting of bis(xoalateborate) (BOW), difluoro(oxalate)borate (ODFB-) and bis(mandelato)borate(BMW). Advantageously, the second stabilizer comprises an ionic liquid with PYRR-E cation. More advantageously, R is 3 or 4. Preferably, the second stabilizer comprises an ionic liquid with an anion selected from a group consisting of TFSI-and FSI-. More preferably, the amount of the first stabilizer is between 0 to 5 wt. % of the electrolyte. It is preferable that the amount of the second stabilizer is between 0 to 10 wt. % of the electrolyte. More preferably, it comprises a third stabilizer. The third stabilizer can be selected from a group consisting of 4 0 Ethoxy(pentafluoro) cyclotriphosphazene (PFPN), Ethylhexyl Diphenyl Phosphate (EHDP), Hexaphenoxycyclotriphosphazene (HPCP) and 10-(2,5-dihydroxypheny1) -10-hydro-9-oxa-10-phosphaphenanthrene-10-oxidation(DOPO-HQ). Preferably, the amount of PFPN is between 0.5 to 10 wt. °,f, of the electrolyte. More preferably, the amount of EHDP is between 0.5 to 5 wt. % of the electrolyte. It is preferable that the amount of HPCP is between 0.5 to 5 wt. % of the electrolyte. Preferably, the amount of DOPO-HQ is less than or equal to 1.5 wt. % of the electrolyte. More preferably, the amount of PFPN is 0.5 to 2.9 wt. % of the electrolyte. Yet more preferably, the non-aqueous organic solvent comprises carbonate-based organic solvents. In a preferred embodiment, the carbonate-based organic solvents is selected from a group consisting of ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), Propylene carbonate (PC), dimethyl carbonate (DMC) and a mixture thereof Preferably, the film former is selected from a group consisting of vinylene carbonate (VC) and fluoroethylene carbonate (FEC) More preferably, the lithium salt comprises lithium hexafluorophosphate (LiPF6) In another aspect of the invention, there is provided an electrolyte for a lithium-ion battery comprising: a lithium salt, a non-aqueous organic solvent which includes a carbonate-based solvent, a flame retardant, a film former and a stabilizing medium, wherein the flame retardant comprises PYRIRPF6 (N-Methyl-N-alkylpyrrolidinium Hexafluorophosphate Salt), the stabilizing medium includes first, second and third stabilizers. Preferably, the lithium salt comprises LiPF6, the carbonate-based organic 13 solvents is selected from a group consisting of ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), Propylene carbonate (PC), dimethyl carbonate (DNIC) and a mixture thereof; the film former is selected from a group consisting of vinylene carbonate (VC) and fluoroethylene carbonate (FEC); the PYR1uPF6 indicates the number of carbon atoms in the alkyl side chains, in which R is selected from any one of 2 to 10; the first stabilizer is selected from a group consisting of bi s(xoalateb orate (BOB), di fl uoro(oxal ate)borate (ODEB) and bis(mandelato)borate(BMB), the second stabilizer comprises an ionic liquid with an anion selected from a group consisting of TFSI-and FSI-; and the third stabilizer is selected from a group consisting of Ethoxy(pentafluoro) cyclotriphosphazene (PFPN), Ethylhexyl Diphenyl Phosphate (EHDP), Hexaphenoxycyclotriphosphazene (HPCP) and 10-(2,5-dihydroxypheny1) -10-hydro-9-oxa-10-phosphaphenanthrene-10-oxidation(DOPO-HQ). More preferably, the flame retardant is PYR16PF6; the first stabilizer is PYRI4BOB; the second stabilizer is PYR14ITS1 at a ratio of 1:0.5:1 wt %. It is preferable that the flame retardant is PYRI6PF6; the first stabilizer is PYR14ODFB; the second stabilizer is PYRHTFSI at a ratio of 1:0.5:1 wt %. Preferably, the flame retardant is PYR16PF6, the first stabilizer is PYR140DFB, the second stabilizer is PYR13TFSI at a ratio of 10:1:4 wt %. Yet more preferably, the carbonate-based organic solvent comprises EC, DNIC and DEC at 1:1:1 vol% and the film former comprises 3.5wt (14, of VC.
In a further aspect of the invention, there is provided a battery comprising: a positive electrode, a negative electrode, a separator, and an electrolyte as claimed in any one of claims 1 to 30. Preferably, the positive electrode comprises LiFePO4. More preferably, the negative electrode is formed from a material selected from a group consisting of carbon and carbon/silicon (SiC). Yet more preferably, the separator is a composite film formed from a material selected from a group consisting of Polypropylene (PP), Polyethylene (PE), ceramic, glass fiber and a combination thereof
BRIEF DESCRIPTION OF DRAWINGS
The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is table showing the synthesis of PYR12Br, PYRi23r, PY121413r, PYRisBr, PYR16Br, PYRi7Br, PYRI8Br, PYR19Br, PYRiloBr, Figure 2 is bar chart showing the self-extinguish time in second per gram and the melting point in degree Celsius of PYR.:21.)F6. PYR. LYI16, PY.R.:41.)F6, P VR 51T6. PY.R.16PF6, PYRI..713F6, TYR] sPF6, PYRI9P.F6 and PYRi JORF6; Figure 3 is a table showing the side reaction test results of PYR12PE, PYR13PF6 PYR iztPF6.PYR 5PF6,IPYR.16P.F6, PYR!8.PF6.PYR.:9PE.5 and PR NaS the flame retardant in the ionic liquid (al at 5v,1%., lOwt%, I 5,,Aitcli and 20\70:9; with organic electrolyte (OF) I m:LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DNIC)/diethyl carbonate (DEC)(1:1:1 vol%)+3.5wt% vinylene carbonate (VC) at 95wt%, 90wt%, 85wt% and 80wt%; Figure 4 is a cyclic voltammetry line graph showing the side reaction measurable at 0.5V to 1.0V of the battery with electrolyte comprises 90wt% of 1M LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DNIC)/diethyl carbonate (DEC)(1:1:1 20 vol%)+3.5wt% vinylene carbonate (VC) and 10 wt.% PYR16PF6; Figure 5 is a cyclic voltammetry line graph showing the side reaction measurable at 0.5V to 1.0V of the battery with electrolyte comprises 85wt% of 1M LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DNIC)/diethyl carbonate (DEC)(1:1:1 vol%)+3.5wt% vinylene carbonate (VC) and 15 wt.% PYR16PE6; Figure 6 is a cyclic voltammetry line graph showing the side reaction measurable at 0.4V to 1.0V of the battery with electrolyte comprises 70wt% of 1M LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DNIC)/diethyl carbonate (DEC)(1:1:1 30 vol%)+3.5wt% vinylene carbonate (VC) and 30 wt.% PYIt16PF6; Figure 7 is a table showing the 0.2C charge and discharge life cycle of a Negative A and Negative B electrodes of a battery with electrolyte comprises 1M LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DNIC)/diethyl carbonate (DEC)(1:1:1 vol%)+3.5 wt% vinylene carbonate (VC) alone or with PYR12PF6,PYRnPF6. P YR I 41P1'6, PYRI5PF6, PYRi6PF6, PY1(17PF6, PYR1SPF6, WiR19PF6 and/or PYR110PF6 in various proportions; Figure 8 is a table showing 0.2C charge and discharge life cycle of a Negative A and Negative B electrodes of a battery with electrolyte comprises 1M LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DNIC)/di ethyl carbonate (DEC)(] :1:1 vol%)+3.5wt% vinylene carbonate (VC) alone or with PYR12PF6, PYR15PFa. PY RI6P F6, and the addition of a first stabilizer PYR 413013; PYRi 40DH3 or PYRi41131M13 in various proportiong; Figure 9 is a table showing 0.2C charge and discharge life cycle of a battery with a Negative A electrode in an electrolyte comprises 1M LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC)(1:1:1 vol%)+3.5wt% vinylene carbonate (VC) alone or with VW:tug-To; and the addition of a first stabilizer PYRHBOB or PYRHODFB and a second stabilizer PYRHTFSI or PYRHFSI in various proportions and a Negative B electrode in an electrolyte comprises IM LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC)(1:1:1 vol%)+3.5wt% fluoroethylene carbonate (FEC) alone or with VYRIsPft" and the addition of a first stabilizer PYRL4BOB or PYR4ODFI3 and a second stabilizer PYR.HTFSI or PYRLIFSI in vatious proportions; Figure 10 is a table showing 0.2C charge and discharge life cycle of a battery with a Negative A electrode in an electrolyte comprises I M LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC)(1:1:1 vol%)+3.5wt% vinylene carbonate (VC) (OE) alone or with PYR16P116,1"iiR14130B" PY.R.LITSI: I at the ratio of (10:1:4 wt%) (EL) or an electrolyte comptiSes OE, IL and a third stabilizer Ethoxy(pentafluoro) cyclotriphosphazene (PEPN), Ethylhexyl Dipherwl Phosphate (EHDP), Hesiaphenoxycyclotriphosphazene (HPCP) or 1042,5-di hydrox yphenyI)-10-hydro-9-oxa-10-phosphaphonanthreneil 0-oxid a don (DOPO-HQ) in various amount; Figure II is a table showing the side reaction testing result with electrolyte comprises of 1M LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC)(1:1:1 vol%)+3.5wt% vinylene carbonate (VC) (OE) alone or with flame retardant and a first stabilizer, or OE with flame retardant and second stabilizer or OE with flame retardant, first and second stabilizer; Figure 12 is a cyclic voltammetw line graph at 0-2.5V at 1.0mV/s showing no side reaction measurable on the battery with electrolyte comprises I 00wt% of I M LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC)(1:1:1 vol%)+3.5wfl1) vinylene carbonate (VC); Figure 13 is a cyclic voltammetry line graph showing side reaction measurable at 0.5- 1.0 V on the battery with electrolyte comprises 85wt% of 1M LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC)(1:1:1 vol%)+3.5wt% vinylene carbonate (VC), lOwt11/0 of PYR,E.PFei and 'iv>, rie PYRI4BF Figure 14 is a cyclic voltammetry line graph showing no side reaction measurable on the battery with electrolyte comprises 80% of 11V1 LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC)(1:1:1 vol%)+3.5wt% vinylene carbonate (VC), 15wt% of PYRI6PF6and wt% PYRHODFB; Figure 15 is a cyclic voltammetry line graph showing no side reaction measurable on the battery with electrolyte comprises 80% of IM LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC)(I: I: I vol%)+3.5wt% vinylene carbonate (VC), 15wt% of PN'H",(.1>h. and 5-wt°01>YR: :BOB; Figure 16 is a cyclic voltammetry line graph showing side reaction measurable at 0.41,0 V on the battery with electrolyte comprises 85% of IM LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC)(1:1:1 vol%)+3.5wt% vinylene carbonate (VC), lOwt% of II'VRD.PF,, and 5wt% Eric It 417 S 1; Figure 17 is a cyclic voltammetry line graph showing side reaction measurable at 0.5-LO V on the battery with electrolyte comprises 85% of IM LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC)(1:1:1 vol%)+3.5wt% vinylene carbonate (VC), lOwt% of FY RifiP1:16 and 5v..4? P YR J4TE Si; Figure 18 is a cyclic voltammetry line graph showing no side reaction measurable on the battery with electrolyte comprises 80% of IM LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC)(1:1:1 vol%)+3.5wt% vinylene carbonate (VC), 14wt% of PYR,:"I'F". Iwt°,0 of PYRI4B013 and 5wt% PYRIOTSI; Figure 19 is a cyclic voltammetry line graph showing no side reaction measurable on the battery with electrolyte comprises 8041/0 of IM LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC)(1:1:1 vol%)+3.5wt% vinylene carbonate (VC), 9 wt% of PYRI6PET6, I wt% of 13YM41301E3 and I Owt% PYRIATS1; and Figure 20 is a table showing 0.2C charge and discharge life cycle of Electrode A in a battery with an electrolyte comprises IN1 LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DNIC)/diethyl carbonate (DEC)(1:1:1 vol%)+3.5wt% vinylene carbonate (VC) (OE) alone or with PYR16PF6,PYRI4BOB, PYR14TSFI at the ratio of 1:0.5:1 wt% ionic liquid (IL) or an electrolyte comprises OE, IL and a third stabilizer Ethoxy(pentafluoro) cyclotriphosphazene ((PFPN), Ethylhexyl Diphenyl Phosphate (EHDP), Hexaphenoxycyclotriphosphazene (HPCP) or I 0-(2,5-clihydroxy eny1)-1. 0-hydro-9-oxa-I 0-phosphaphenantlarene-1 0-oxidation (DOPO-HQ) in various amount Figure 21 is a table showing 0.2C charge and discharge life cycle of Electrode A in a battery with an electrolyte comprises 1M LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DNIC)/diethyl carbonate (DEC)(1:1:1 vol%)+3.5wt°710 vinylene carbonate (VC) (OE) alone or with PYR16PF6. PYRHODFB, PYRI3TSFI at the ratio of 1:0.5:1 wt% ionic liquid (IL) or an electrolyte comprises OE, IL and a third stabilizer 1 5 Ethoxy(pentafluoro) cyclotriphosphazene ((PFPN), Ethylhexyl Diphenyl Phosphate (EHDP), Hexaphenoxycyclotriphosphazene (HPCP) 2,5-di iy droxyplle nyI)-ID..
hydro-9-o \-a-1 0-phosphaphenanthrene-1 0-oNidation (DOPO-HQ) in various amount Figure 22 is a table showing 0.2C charge and discharge life cycle of Electrode A in a 2 0 battery with an electrolyte comprises 1M LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC)(1:1:1 vol%)+3.5wt% vinylene carbonate (VC) (OE) alone or with PYRI6PF6, PYRi4ODFB, PYR13TSFI at the ratio of 10:1:4 wt% ionic liquid (IL) or an electrolyte comprises OE, IL and a third stabilizer Ethoxy(pentafluoro) cyclotriphosphazene ((PFPN) Ethylhexyl Diphenyl Phosphate 2 5 (EHDP), Hexaphenoxycyclotriphosphazene (HPCP) or I 0(2,.5-di hydroxyp heny I)-1 0-hydro-9-oxa-10-phosphaphenanthrene-10-oxidation (DOPO-HQ) in various amount.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
PYR.IRPF6 series ionic hqtud is an identified candidate that otters an alternative to morn temperature ionic licuids because it has a relatively high melting point. PYRIRPF6 series ionic liquid also possesses the advantages of relatively low volatility and relatively high non-flammability. Proton solvents must be used in combination with PYRJRPF6 series ionic liquid at room temperature because PYRIRPF6 is in solid state at room Lem perature due to its relatively high melting. point. The liFf; increases the five retarda.ncy of the jOilie liquid and hence acts as a fire retardant.
Some of the.PY.Rip,PF6 series ionic liquid that are considered more suitable are each mixed with a carbonate electrolyte to be used in a lithium iron phosphate(LHO battery for electrical performance testing. Although cliarging and discheing are possibi e or can be performed, ilthium deposition occurs slowly over charging and discharging of the battery. The deposition lowers the number of battery cycles to be less than 100 times, hence the battery cannot he commercialized_ With reference to Figures 1 to 20. Ole following findings oiler a solution that mitigates all cif the aforementioned shortcomings. More specifically, the present invention offers a novel electrolyte formulation containing a PY,R.IRPF6 series ionic liquid for use in a commercializable lithium ion battery.
Below are the method of synthesis of certain PYRIRPF6 series ionic liquid.
Synthesis of N-methyl-N-alkylpyrrolidinium PYRIR: cation PF6-anion is a two-step synthesis With reference to Figure 1 the synthesis of PYRI2PF6.PYRI3PF6,PYR14PF6 PYR15PF6, PYR16PF6. PYR1 7PF6 PYR1 KPF6, PYR19PF6 and PYR1l0PF6 are provided in detail below.
Step 1 -synthesis of PYR1213r, PYRuBr, PYRI4Br, PY1415Br, PY1116Br, PYREBr, PY11.1813r, PYRI9Br, PYRI1013r.
The synthesis of N-ethyl-N-methylpyrrolidinium bromide (PYR.12Br).
N-methylpyrrolidine (NMPD) is purified by distillation at 85 °C. The purified Nmethylpyrrolidine and N-ethyl bromide (n-bromoethane) are mixed at a molar ratio of 1:1.1, followed by adding an equal volume of deionized water with n-bromoethane, and mixing and stirring in a 5 degree Celsius ice bath. After 2 hours, the supematant was N-ethyl-N-methylpyrrolidinium bromide (PYIt123r).
The synthesis of N-propyl-N-methylpyrrolidinium bromide (PYRnBr).
N-methylpyrrolidine (NIVIPD) is purified by distillation at 85 °C. The purified N-methylpyrrolidine and N-propyl bromide are mixed at a molar ratio of 1:1.1, followed by adding an equal volume of deionized water with n-bromopropane, and mixing and stirring in a 10 degree Celsius ice bath. After 2 hours, the supernatant was N-propyl-Nmethylpyrrolidinium bromide (PYR1313r).
4 0 The synthesis of N-butyl-N-methylpyrrolidinium bromide (PYRI4Br).
N-methylpyrrolidine (NMPD) is purified by distillation at 85 °C. The purified Nmethylpyrrolidine and N-butyl bromide are mixed at a molar ratio of 1:1.1, followed by adding an equal volume of deionized water with n-bromobutane, and mixing and stirring in a 10 degree Celsius ice bath. After 2 hours, the supernatant was N-butyl-N-methylpyrrolidinium bromide (PYR14Br).
The synthesis of N-pentyl-N-methylpyrrolidinium bromide (PYRisBr).
N-methylpyrrolidine (NMPD) is purified by distillation at 85 °C. The purified Nmethylpyrrolidine and N-pentyl bromide are mixed at a molar ratio of 1:1.1, followed by adding an equal volume of deionized water with n-bromopantane, and mixing and stirring in a 60 degree Celsius hot bath. After 2 hours, the supernatant was N-pentyl-Nmethylpyrrolidinium bromide (PYR15B0.
The synthesis of N-hexyl-N-methylpyrrolidinium bromide (PYR16Br).
N-methylpyrrolidine (NMPD) is purified by distillation at 85 °C. The purified Nmethylpyrrolidine and N-hexyl bromide are mixed at a molar ratio of 1:1.1, followed by adding an equal volume of deionized water with n-bromohexane, and mixing and stirring in a 60 degree Celsius hot bath. After 2 hours, the supernatant was N-hexyl-N- 1 3 methylpyrrolidinium bromide (PYRI6Br).
The s nthesis of N-he it 1-N-meth I olidinium bromide PYRpBr N-methylpyrrolidine (NMTPD) is purified by distillation at 85 °C. The purified N-methylpyrrolidine and N-heptyl bromide are mixed at a molar ratio of 1:1.1, followed by adding an equal volume of deionized water with n-bromoheptane, and mixing and stirring in a 70 degree Celsius hot bath. After 2 hours, the supernatant was N-heptyl-Nmethylpyrrolidinium bromide (PYR17Br).
The synthesis of N-octyl-N-methylpyrrolidinium bromide (PYR.18Br) N-methylpyrrolidine (NMPD) is purified by distillation at 85 °C. The purified Nmethylpyrrolidine and N-octyl bromide are mixed at a molar ratio of 1:1.1, followed by adding an equal volume of deionized water with n-bromooctane, and mixing and stirring in a 70 degree Celsius hot bath. After 2 hours, the supernatant was N-octyl-N-methylpyrrolidinium bromide (PY12,18Br).
The synthesis of N-nonyl-N-methylpyrrolidinium bromide (PYR19Br).
N-methylpyrrolidine (NNTPD) is purified by distillation at 85 °C. The purified N-methylpyrrolidine and Bromononame are mixed at a molar ratio of 1:1.1, followed by adding an equal volume of deionized water with bromononame, and mixing and stirring in a 70 degree Celsius hot bath. After 2 hours, the supernatant was N-nonyl-Nmethylpyrrolidinium bromide (PY12,19Br).
The synthesis of N-decyl-N-methylpyrrolidinium bromide (PYRimBr) N-methylpyrrolidine (NM1PD) is purified by distillation at 85 °C. The purified Nmethylpyrrolidine and Bromodecane are mixed at a molar ratio of 1:1.1, followed by 4 5 adding an equal volume of deionized water with n-bromodecane, and mixing and stirring in a 70 degree Celsius hot bath. After 2 hours, the supernatant was N-decyl-Nmethylpyrrolidinium bromide (PYRitoBr).
Step 2 -Synthesis of pyrrolidinium ionic liquids PYR12PF6 PYR13PF6 PYRRPF6 PYRI5PF6.PYRI6PF6 PYRI7PF6,PYRI8PF6 PY1149PF6 and PYR110PF6 Synthesis method of N-ethyl-N-methylpyrrolid'n um hexafluorophosphate (PYRI2PF6) Adding the N-ethyl-N-methylpyrrolidinium bromide salt synthesized in Step 1 to a molar amount (1M) of potassium hexafluorophosphate(KPF6), followed by addition of deionized water. The ratio of deionized water to the bromine salt is 1: 1 wt.%, stirred at room temperature until reaction is completed. The white precipitate is filtered and is placed in a container. Deionized water is added to wash the white precipitate which is then filtered out. The white precipitate is washed for three times. The white precipitate is then dried in a 60 degree vacuum oven until it reaches a moisture content of 20 ppm or less.
Synthesis method of N-propyl-N-methylpyrrolidinium hexafluorophosphate (PYRi3PF61 The N-propyl-N-methylpyrrolidinium bromide synthesized in Step I was added to a molar amount (1M) of potassium hexafluorophosphate(KPF6), followed by addition of deionized water. The ratio of deionized water to the bromine salt is 1: 1 wt.%. The mixture is stirred at room temperature until reaction is completed. the resulting white precipitate is filtered and is placed in a container. Deionized water is added to wash the white precipitate which is then filtered out. The white precipitate is washed for three times. The cleaned precipitate is dried in a 60 degree vacuum oven until it reaches a moisture content of 20 ppm or less.
Synthesis method of N-butyl-N-methylpyrrolidinium hexafluorophosphate (13YRI4PF0) The N-butyl-N-methylpyrrolidinium bromide synthesized in Step 1 is added to a molar amount (1M) of potassium hexafluorophosphate(KPF6), followed by an addition of deionized water. The ratio of deionized water to the bromine salt is 1: 1 wt.%. The mixture is stirred at room temperature until reaction is completed. The white precipitate is filtered and placed in a container. Deionized water is added to wash the white precipitate which is then filtered. The white precipitate is cleaned three times and is then dried in a 60 degree vacuum oven until it reaches a moisture content of 20 ppm or less.
Synthesis method of N-pentyl-N-methylpyrrolidinium hexafluorophosphate (PYR15PF(2) The N-pentyl-N-methylpyrrolidinium bromide synthesized in Step 1 is added to a molar amount (1M) of potassium hexafluorophosphate(KPF6), followed by addition of deionized water. The ratio of deionized water to the bromine salt is 1: 1 wt.%. The 4 5 mixture is stirred at room temperature until reaction is completed. The white precipitate is then filtered out and is placed in a container, deionized water is added for washing and the white precipitate is filtered out. The washing process is repeated three times.
-11 -The precipitate is then dried in a 60 degree vacuum oven until the moisture content is of 20 ppm or less.
Synthesis method of N-hexyl -N-m ethyl pyn-ol i di ni um hexafluorophosphate 5 (PYRI6PF6) The N-hexyl-N-methylpyrrolidinium bromide synthesized in Step 1 is added to a molar amount (1M) of potassium hexafluorophosphate(KPF6), followed by addition of deionized water. The ratio of deionized water to the bromine salt is 1: 1 wt.%. The mixture is stirred at room temperature until reaction is completed. The resulting white precipitate is filtered and is placed in a container. Deionized water is added to wash the white precipitate which is then filtered out. The washing process is repeated three times. Finally, the resulting white precipitate is dried in a 60 degree vacuum oven to a moisture content of 20 ppm or less.
Synthesis method of N-heptyl-N-m ethylpyrroli di nium hexafluorophosphate (PYRi-PF61 The N-heptyl-N-methylpyrrolidinium bromide synthesized in Step 1 is added to a molar 2 0 amount (1M) of potassium hexafluorophosphate(KPF6), followed by addition of deionized water. The ratio of deionized water to the bromine salt is 1: 1 wt.%. The mixture is stirred at room temperature until reaction is completed. The resulting the white precipitate is filtered. The white precipitate is removed and placed in a container. Deionized water is added for washing and the white precipitate is then filtered out. The washing process is repeated three times. Finally, the white precipitate is dried in a 60 degree vacuum oven to a moisture content of 20 ppm or less.
Synthesis method of N-octyl-N-methylpyrrolidinium hexafluorophosphate (PYRisPFL) The N-octyl-N-methylpyn-olidinium bromide synthesized in Step 1 is added to a molar amount (1M) of potassium hexafluorophosphate(KPF6), followed by addition of deionized water. The ratio of deionized water to the bromine salt is 1: 1 wt.%. The mixture is stirred at room temperature until reaction is completed. The white precipitate is filtered out and is placed in a container. Deionized water is added for washing and the white precipitate is then filtered out. The washing process is repeated three times.
Finally, the white precipitate is dried in a 60 degree vacuum oven to a moisture content of 20 ppm or less Synthesis method of N-nonyl-N-methylpyrrolidinium hexafluorophosphate (PYR19PF(2) The N-nonyl-N-methylpyrrolidinium bromide synthesized in Step 1 is added to a molar amount of potassium hexafluorophosphate(KPF6), followed by addition of deionized water. The ratio of deionized water to the bromine salt is 1: 1 wt.% The mixture is 4 5 stirred at room temperature until reaction is completed, and the resulting white precipitate is filtered out. The white precipitate is removed and placed in a container. Deionized water is added for washing and the white precipitate is then filtered out. The washing process is repeated three times. Finally, the precipitate is dried in a 60 degree vacuum oven to a moisture content of 20 ppm or less.
Synthesis method of N-decyl-N-methylpyrrolidinium hexafluorophosphate (PYR110PF6) The N-decyl-N-methylpyrrolidinium bromide synthesized in Step 1 is added to a molar amount of potassium hexafluorophosphate(KPF6), followed by addition of deionized water. The ratio of deionized water to the bromine salt is 1: 1 wt.%. The mixture is stirred at room temperature until reaction is completed, and the resulting white precipitate is filtered out. The white precipitate is removed and placed in a container. Deionized water is added for washing and the white precipitate is then filtered out. The washing process is repeated three times. Finally, the precipitate is dried in a 60 degree vacuum oven to a moisture content of 20 ppm or less.
Additives are introduced to the PYRi1<PF6 series ionic liquid to enhance the battery life cycle as \veil as to counter any negative side effects. The followings are the method of synthesis of the useful addiuves.
2 0 Synthesis method of N-butyl-N-methylpyrrolidinium hi ncieldtukiori (PYR14 BM B.) The N-butyl-N-methylpyrrolidinium bromide salt synthesized in Step 1 is added to a molar amount (1M) of NaBMB, followed by addition of deionized water. The ratio of deionized water to the bromine salt is 1:1 wt. %. The mixture is stirred at room temperature until reaction is completed. Dichloromethane is added to the mixture and the amount of dichloromethane added is the same as the amount of deionized water added to the bromine salt in the mixture The Dichloromethane is separated and washed with a small amount of deionized water. The deionized water is then removed. The washing process is repeated for three times, followed by heating. The dichloromethane is removed by evaporation to obtain PYRNBMB. The product is placed in a 60 degree vacuum oven until its moisture content is of 100 ppm or less.
Synthesis method of N-butyl-N-methylpyrrolidinium bis(oxalate)borate (PYR14B0B) 35 The N-butyl-N-methylpyrrolidinium bromide salt synthesized in Step 1 is added to an equimolar of NaBOB, followed by the addition of deionized water for mixing. The ratio of deionized water to the bromide salt is 1:1 wt. %. The mixture is stirred at room temperature until reaction is completed Dichloromethane is added to the mixture and 4 0 the amount of dichloromethane added is the same as the amount of deionized water added to the bromine salt in the mixture. The Dichloromethane is separated and washed with a small amount of deionized water. The deionized water is then removed. The washing process is repeated for three times, followed by heating. The dichloromethane is removed by evaporation to obtain PYRI4BOB. The product is placed in a 60 degree vacuum oven until its moisture content is of 100 ppm or less.
Synthesis method of N-butyl-N-methylpyrrolid n um difluoro(oxalate)ho e (PYRHODFB) The N-butyl-N-methylpyrrolidinium bromide salt synthesized in Example 1 is added to an equimolar of Na0DFB, followed by the addition of deionized water for mixing. The ratio of the deionized water to the bromide salt is 1:1 wt. %. The mixture is stirred at room temperature until the reaction is completed. Dichloromethane is added to the mixture and the amount of dichloromethane added is the same as the amount of deionized water added to the bromine salt in the mixture. The Dichloromethane is separated and washed with a small amount of deionized water. The deionized water is then removed. The washing process is repeated for three times, followed by heating.
The dichloromethane is removed by evaporation to obtain PYRFIODFB. The product is placed in a 60 degree vacuum oven until its moisture content is of 100 ppm or less.
Synthesis method of N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyflimide (PYR14TFSI) The N-butyl-N-methylpyrrolidinium bromide salt synthesized in Step 1 is added to the an equimolar of LifFSI, followed by the addition of deionized water for mixing. The ratio of deionized water to the bromine salt is 1:1 wt. ?io. The mixture is stirred at room 2 0 temperature until the reaction is completed. PYRI4TFSI is not water soluble while LiBr is and therefore PYRI4TFSI (organic matter) can easily be separated. The organic matter is washed with deionized water, and separated, and the washing process is repeated three times. Finally, the product was dried in a 60 degree vacuum oven until its moisture content is of 20 ppm or less.
Synthesis method of N-butyl-N-methylpyrrolidinium b s(fluorosulfony)imide (PYR14FSI) The N-butyl-N-methylpyrrolidinium bromide salt synthesized in Step 1 is added to the equimolar LiFSI, followed by the addition of DI water, and the ratio of the DI water content to the bromide salt is 1:1 wt.%. After stirring at room temperature until the reaction is completed, the organic matter PYR14FSI (not water soluble) is separated from LiBr (water soluble), and PYR14FSI is washed with deionized water and separated, and the washing process is repeated three times. Finally, the product is dried in a 60 degree vacuum oven until its moisture content is of 20 ppm or less.
P YRJRPF6 with other carbon chains can be synthesized with the bromide salt in Step 1 in Step 2 synthesis method to produce the desired PYRARPF6 series ionic liquid Self-Extinguish Test of PYRPF6. R=2-10 series ionic liquids PYR1a.PF6, R=2-10 series ionic liquids were synthesized and detected by differential scanning calorimelly (DSC) which shows that the series of ionic liquids are in solid state at room temperature. They are mixed with an organic solvent (a prnion solvent) according to different ratios (5-20 wt.%) and tested for self-extinguish time (SET). With reference to Figure 2, the amount of PYRiRPF6 is 5.00, 10.00, 15.00 and 20.00 wt.%.
-N -
In Figure 2, the self-extinguishing test is performed by dropping a 1.2 g of the electrolyte on a 47 mm diameter glass fiber membrane with a thickness of 0.5 mm. Ignition timing test is then performed.
PYR17PF6 has a melting point of 260 degree Celsius. 5wt°4 of PYRI2PF6 has a self-extinguish time of about 25.1 seconds per gram. 1 Owt% of PYRI2PF6 has a self-extinguish time of about 24.6 seconds per gram. 15wt% of PYR12PF6 has a self-extinguish time of about 7 seconds per gram. 20wt'l4 of PYR12PF6 has a self-extinguish time of about 6 seconds per gram.
PYRI3PF6 has a melting point of 113 degree Celsius. 5w-t% of PYR13PF6 has a self-extinguish time of about 28.8 seconds per gram. 1 Owt% of PYR13PF6 has a self-extinguish time of about 28.1 seconds per gram. 15wt% of PYRI3PF6 has a self-extinguish time of about 8.6 seconds per gram. 20wt% of PYRI3PF6 has a self-extinguish time of about 6 seconds per gram.
PYRI4PF6 has a melting point of 89 degree Celsius. 5wt% of PYR.14PF6 has a self-extinguish time of about 27.4 seconds per gram. 1 Owt% of PYR14PF6 has a self-extinguish time of about 27 seconds per gram. 15wt% of PYRI4PF6 has a self- 2 0 extinguish time of about 8.6 seconds per gram. 20wt% of PYRI4PF6 has a self-extinguish time of about 6 seconds per gram.
PYRI5PF6 has a melting point of 206 degree Celsius. 5wt% of PYRI5PF6 has a self-extinguish time of about 25 seconds per gram. lOwt% of PYRi5PF6 has a self-extinguish time of about 24.5 seconds per gram. 15wt% of PYR15PF6 has a self-extinguish time of about 7 seconds per gram. 20wt% of PYRI5PF6 has a self-extinguish time of about 6 seconds per gram.
PYRI6PF6 has a melting point of 208 degree Celsius. 5wel/0 of PYR16PF6 has a self- 3 0 extinguish time of about 24.5 seconds per gram. 1 Owt% of PYR16PF6 has a self-extinguish time of about 23.9 seconds per gram. 15wt% of PYR16PF6 has a self-extinguish time of about 7 seconds per gram. 20wt% of PYRI6PF6 has a self-extinguish time of about 6 seconds per gram.
PYRi7PF6 has a melting point of 107 degree Celsius. 5welzo of PYRI7PF6 has a self-extinguish time of about 27 seconds per gram. lOwt(l1) of PYRITF6 has a self-extinguish time of about 26.8 seconds per gram. 15wt% of PYRI2PF6 has a self-extinguish time of about 8 seconds per gram. 20wt% of PYRI7PF6 has a self-extinguish time of about 6 seconds per gram.
PYR18PF6 has a melting point of 75 degree Celsius. 5wt% of PYR1sPF6 has a self-extinguish time of about 26.5 seconds per gram. 1 Owt% of PYR1gPF6 has a self-extinguish time of about 25.9 seconds per gram. 15wt% of PYRI8PF6 has a self-extinguish time of about 8.7 seconds per gram. 20wt% of PYR18PF6 has a self- 4 5 extinguish time of about 6 seconds per gram. -b -
PYRDPF6 has a melting point of 83 degree Celsius. 5wt% of PYR19PF6 has a self-extinguish time of about 28.1 seconds per gram, lOwt% of PY1219PF6 has a self-extinguish time of about 27.6 seconds per gram. 15wt% of PYR1913F6 has a self-extinguish time of about 7.5 seconds per gram. 20wt% of PYR19PF6 has a self-extinguish time of about 6 seconds per gram.
PYRI 10PF6 has a melting point of 92 degree Celsius. 5wt% of PYR [DPF6 has a self-extinguish time of about 28.2 seconds per gram. lOwt% of PYRit0PF6 has a self-extinguish time of about 27.3 seconds per gram. 15wt% of PYR110PF6 has a self- ) 0 extinguish time of about 7.1 seconds per gram. 20wt% of PYR110PE6 has a self-extinguish time of about 6 seconds per gram.
As shown in Figure 2, the addition of PYROF6, R=2-10, up to 15wt % have good self-extinguishing properties which is in general below 9 seconds per gram. When the added amount of PYRRPF6, R=2-10 reaches 20wt%, the self-extinguishing time reaches about 6 sec/g. When the added amount reaches 40w-t%, the self-extinguishing time reaches 5sec/g.
At lower concentration, Swt%, 1 Owt%, 15wt% of PYR1RPF6, R=2-10, the self-extinguishing times of PYRIRPE6, R=2-10, with melting point higher than 200 degree Celsius are better than the self-extinguishing times of PYR IRPF6, R=2-10, with melting point lower than 200 degree Celsius PYRRPF6 series ionic liquids is commercially attractive given that the synthesis is relatively straight forward and hence the costs for doing so is relatively low.
Battery Performance Test of battery with PY.112[RPli.c.. R:2 10 as the ionic I retardant in the electrolyte Charge and discharge battery performance test is conducted on the battery with PYR pPF6, RT-2 10 as the ionic liquid flame retardant using the Neware Battery Performance Test System. Side reaction test is also performed using Autolab 302N Electrochemical Workstation.
PYRiRPF6, R=2-10 ionic liquid flame retardant is mixed with an organic electrolyte (OE) comprises 1M LiPF6 with ethylene carbonate(EC) / dimethyl carbonate(DMC) / diethyl carbonate(DEC) at 1:1:1 vol% and 3.5wt% vinylene carbonate (VC). The overall amounts of PYRJRPFG, R=2-10 and OF in the 'batteries being tested are detailed in Figure 3. The battery performance test was conducted with the Neware Battery Performance Test System and any side reaction test was tested with the Autolab 302N Electrochemical Workstation.
in both the battery performance test, the battery contains a positive electrode, a negative electrode: a separator and an electroly e.
-16 -Positive electrode is a composition of electrode is 90 wt% LiFePO4+ 5 wt% Super PH-5 wt%,PVI)F.
Negative A electrode is a composition of the electrode is NM -8 92 1,vt?),--f-Super P 5 we/l)-4-3 weft, ,PV131f.
Separator is a ceramic coated polypropylene separator with a thickness of 20 urn.
Electrolyte is a mixture of organic electrolyte and ionic liquid, the organic electrolyte being 1M LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC)(1:1:1 vol%)+3.5wt% vinylene carbonate (VC) with different ratios of PYRIRPFi., for charge and discharge tests.
Charge and discharge conditions: 0.2C*-rate is charged and disc-that-Cut-off condition: The battery is Judged to he invalid when the cycle charge/discharge. capacity drops below 80% of the original capacity.
In the side reaction test also known as the side reaction peak test,is performed us three-electrode Test method Working electrode comprises Negative A which is IVIGMB 92 %+Super P 5. w-t1?.,b+3 wt% PVT.:* . Reference electrode comprise, hium metal Counter electrode coinonlses lithium met Scan range of the test 0-2. TV and the scan rate is 1 mV/s.
As summarized in Figure, side reaction is inevitable when the flame retardant PYR,BPF6, R=2-10, is added. The addition of any one of PYRIalP.F6. PYRisPF6 PYRI(PF6, PYR.:5PF(,. P1REETF6, PYRI)Ph6, PYR.isPF,, PYR1PF6 arid PYRE pj shows side reaction in the tested sample, irrespective of the overall amount of OE and 35:11, mixture i.e. 5wtllt, (of electrolyte), 10 wt% (of e ecw te) I5wt? b (of electrolyte) and 20wt% (of electrolyte). Furthermore, The addition of PYRIRPF6, R=2-10, has substantial negative impact on the cycle life of the battery, resulting in no more than 100 charge and discharge cycles before the charge and discharge capacity drops below 80% of the original capacity. The value is too low to have commercial value. Worth notirn:c., there is a general trend M which the latiger the amount of,PYR:2PF6,PYR, 3P16.
PYR1rPF6, PYR.,5PF6, PYR:6PF6: PYR:LPF6, PYR18PF6:. PYR19PF6 and PYRiNPF6, the lower the number of charge and discharge cycles before the charge and discharge capacity drops below 80% of the original capacity.
Referring to figures 4 to 6 which show the cyclic voltammetry of the battery with eiectrotyLe having differefit a nelii.LtS of PYR.IRPF6 where R-6. The cyclic voltammetries indicate that the side reactions peak between 0.4-1V. It can also be -17 -concluded that there is a direction relationship between the amount of PYRi5PF5 and the intensity of the side reaction peak. in general, the more the amount of PYRRIPF6 where R-6, the more obvious (higher intensity) the side reaction peak.
In Figure 4, there is shown a cyclic voltammetry graph of a battery. Electrolyte of the battery includes 1 OM. PYRI6PE6. The side reaction peak is shown at 0.5-1V with an intensity of -0.0014K Tn Figure 5. there is shown a cyclic lt Rielly graph of a battery. Electrolyte of the battery includes 15wt. % 0fPVR16PFr, The side reaction peak is shown at 0.5-1V with an intensity of -0.001.5A.
In Figure 6, there is shown a cyclic voltammetry graph of a battery. Electrolyte of the battery includes ilOwt. ?1i of PYRioPF6. The side reaction peak is shown at 0.5-1V with 13 an intensity of -0.0016A.
Ionic Liquid Flamm Retardant with meltinr& Point above 700 degree Celsius The fallowing tests aim at showing although charging arid discharging are possible or can be performed, the side reaction eventually lead to decrease in charging and discharging of battery cycle. The side reaction affects the life cycle of a battery. The side reaction can be a result of reduction and deposition reaction of PYRIRPFs and the pre-intercialation of PYRIRPF6. Both affects the intercalation and deintercalation of Lithium ion.
PYR11<PF5 where R=2, 5, 6 have melting points above 200 degree Celsius. Batteries formed front electrolyte haying different amounts of PYRLiPtY" PYR15-Pft or mixed with organic electrolyte(GE) comprises 1 M LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC)(1:1:1 vol%)+3.5wt% vinylene carbonate (VC) are tested. With reference to Figure 7, details of the composition of the electrolytes in each of the tested batteries (Samples Ito 11) are discussed below. The results of the tests are shown in Figure 7 and it is indicated that the battery charge and discharge cycle life performance is poor with the presence of YR 111t6, P'''Y'R..15P:FG, or PYR!il,PF6.
The Samples I to It and a control Sample A are tested with the Neware Battery Performance Test System. In the test system, the battery contains a positive electrode. a negative electrode, a separator and an electrolyte Positive electrode comprises a composition cif the electrode is 90 wt%FIFieEar \Art% Super PH-. 5 xvi% PVDIF Negative A electrode comprises a compositic of the electrode is MCMB 92 wt?,:ii+Super P 3 wt% PNT)F Negative B electrode comprises a composition of the electrode is MCV1 wt%+Super P 4 wt% VGCF-H10 wt% Siac/C+5 wt% SBR -18 -A separator co prises cerarn coated polypropylene separator with a thickness of 20 UM, Charge and discharge at 0.2C-rate.
Cut-off condition: The hatterv is considered invalid when the charge and discharge cycle capacity drops below 80% of the original capacity.
Electrolyte: Sample I to 11-Different amount of ry'Ri2PI'm PYR, 51)F6. or FY Ri61)176 mixed with organic solvent ((liE) WM1)6 ses 1NI LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DA/IC)/diethyl carbonate (DEC)(1:1:1 yol%)+3.5wt% yinylene carbonate (VC). Sample A--OF alone.
in the Sample A, the electrolyte contains 100% of organic electrolyte (OE), which is Without any PYRIRF6. The number of charge and discharge life cycle of Negative A electrode is 2163 and that of Negative B electrode is 513.
In the Sample I, 5wt% ofPYRiPFtc is added to 95-wt.3 of OE. The number of charge and discharge life cycle of Negative A electrode is 98 and that of Negative B electrode is 105, In Sample 2: 5wt% of PYRJ5P.F6 is added to 95wt% of OF. The The number of charge and discharge life c':/cie of Negative A electrode is 94 and that of Negative B eiectrode is 104.
in Sample 3, .5wt% of PPYR1411176 is added to 95%vt% of OE. The number of charge and discharge life cycle of Negative A electrode is 97 and that of Negative B electrode is 102.
In Sample 4, lOwta,-/0" of PYRI2PF6 is added to 90wt% of OE. The number of charge and discharge life cycle of Negative A electrode is 63 and that of Negative B electrode is 78.
In Sample 5, 10wt% of PYRI5PF6 is added to 90wt% of OE., The number of charge and discharge life cycle of Negative A electrode is 50 and that of Negative B electrode is 69.
In Sample 6, lOwt% of PYRL6P.5 is added to 90wi% of OE, 'The number of charge and discharge life cycle of Negative A electrode is 56 and that of Negative B electrode is 711.
In Sainp!e 7, 20wt% of PYRIPF6 is added to 80wt% of OF.. The number of charge and discharge life cycle of Negative A electrode is 38 and that of Negative B electrode is 37.
-19 -In Sample 8, 20wt% of PYRi5PE6 is added to 80wt% of OE. The number of charge and discharge life cycle of Negative A electrode is 40 and that of Negative B electrode is 40.
In Sample 9, nawt% of.PYRR,Pfit is added to 80wt?,ii of OE. The number of charge and discharge life cycle of Negative A electrode is 32 and that of Negative B electrode is 32_ in Sample 10, FYRIYEs: PYRisFF6: PYR 16-PEG: OR in the ratio of 10v49-4:5wt%:5wt%:80w1?4i is mixed. The number of charge and discharge life eye!, of Negative A electrode is 36 and that of Negative E electrode is 36.
in Sample II, PYR12PF6: PY.B..15PF6: PYRi6PF6: OR in the ratio of 5wt%,l_Owt?.:5w6:80wt% is mixed. The number of charge and discharge life cycle of Negative A electrode is 34 and that of Negative B electrode is 34.
Based on the above findings, in general, the higher the wt% of PYRiifics, PYRifitF6_ or PYRITE', in the electrolyte, the shorter the battery charge and discharge life cycle. By comparing with Sample A. Samples to II have significantly lower number of cycle life in both Negative A and Negative B electrodes. It is therefore concluded that the addition of PYRI2PF6, PYR15P1P6, Or PYRI6Phfc or even PYRritit F6, were R 2 to 10 in to the electrolyte renders the battery not commercializable by shortening the life cycle of the battery significantly.
Battery performance tests performed on batteries ctrolytes that contains at least one ItYRIa boron-based stabilizer In each of the tested batteries (Samples I to IS), the electrolyte comprise a mixture, of an organic electrolyte (OF) comprises 1Ni LiPF,_, with ethylene carbonate (EC)/dimethyl carbonate (DNIC)/diethyl carbonate (DEC)(1:1:1 vol%)+3.5wt% vinylene carbonate (VC) and one of PYR:2PF6, PYRSP15I. and PY-RisPFs which have melting points of above 200 degree Celsius. At least one PYRra, boron-based stabilizer is added to the electrolyte to improve or lengthen the life cycle of the batteries.
The specific amount of the first stabilizer in each of the Samples 1 to 15 batteries is provided in Figure 8. The battery is tested with the Neware Battery Performance Test System and the cycle life of -Negative A and Negative B electrodes are provided in Figure 8. Sample 16 is a control with 100% OF and is also tested with the Neware Battery Performance Test System.
'The presence f PYR:F boron-based stabilize (first stabilizer) nproves or lengthens the cycle life of each of the batteries in Samples Ito 15.
Battery oerlhrmance test: 'The battery contains a positive electrode, a negative electrode, a separator and an electrolyte.
-20 -Positive electrode comprises a composition of the electrode is 90 wt%LiFePar-i-5 wt% Super 5 wffii Negative A electrode comprises a composition of the electrode is MC /113 92 P 5 wi'1/0-1-3 wt% PV.DF.
Negative B electrode comprises a composition of the electrode is MCMB 80 wt%-i-Super P 4 wt%-i-wt9/i:, VG-CF+10 wt% Si Oxle+5 wit% SBR.
Separator comprises a ceramic coated polypropylene separator with a thickness of 20 am-Electrolyte: Organic electrolyte (9E) comprises 1M LiPT16 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC)(1:1:1 vol%)+3.5wt% vinylene carbonate (VC), one of PYRi2PF6, PYRpRh6, and PYRioPlyo and a first stabilizer which is a PYRni. boron-based ionic liquid.. The specific amount in wt. '!/1; of these constituents are provided in Figure 8.
The battery is charged and discnarged. Charge and discharge at 0.2C-rate.
ftc tit-off condition is when the battery s considered to be invalidi.e. when the, charge and discharge cycle capacity drops below 80% of the original capacity.
Referring to Figure 3: In Sample I, the OE: PYR12PF6:PYRiiBOB ratio is 80wtiiii: 5wif/l:5wt%. The number of charge anti discharge life cycle of Negative /1/2. electrode in the resu itMg battery is 572 and that of Negative fi electrode is 178.
In Sample 2, the OF: PYR12PF6:PY.R.140DFB ratio is 80wt%:15.wiThi:5w6b. The number of charge and discharge life cycle of -Negative A electrode in the resulting battery is 558 and that of Negative B electrode is 182.
In Sample 3, the OF: PYRI2P1176:PYRNBMB ratio is 80-wt%:15wei ic.5yvt5i). The number of charge and discharge life cycle of Negative A electrode in the resulting hattely is 542 and that of Negative B electrode is 175.
hi Sample 4, the OE PYRI5Pri6inla14llOB ratio l5wt%.3'viii%. The number of charge and discharge fife cycle of Negative A electrode in the resulting battery is 546 and that of Negatiye B electrode is 163.
In Sample 5, the OF.: PYRI5PF6:PYR"ODIFT1 ratio is 80wt%: 1 iwt%:5sAit?/._ The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 537 and that of Negative B electrode is 149. -21 -
In Sample 6, the OE: PYRniPF6:PYRi.iBIlviB ratio is 80w-t%:15wt%:5-wt%. The number ch.ar,ge and discharge life cycle of Ne,ga.tiy'e A. electrode in the fesulting battery is 523 and that of Negative B electrode is 152.
In Sample 7, the OE, PYRiu,PB,,,PYR11B013 ratio is 80wt%.15wt%,5w, . The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 539 and that of Negative B electrode is 184.
1-11 Sample 8, the OE: PYRIGPF6IPYRirODFB ratio is litvt%. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 542 and that of Negative B electrode is 172.
hi Sa.mple 9, the OE, ,PYRI6P,F6:PYR14IINTEI ratio is 80w/1,94:15s sit?,. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 512 and that of Negative B electrode is 167.
In Sample IQ the OE: PYRis.PFc,:PYR:4BOB ratio is 87wt%:I0 \ :3.3wt%. The number of charge and discharge life cycle of Ne,gative A electrodein the reiirulting battery is 785 and that of Negative B electrode is 198.
In Sample 11, the OF ill"R1sPF6:PYR14OOFB ratio is 87wit%:10v1/44%:3 IlLEMber of chant,,ie and discharge life cycle of Negative A electrode in the resulting battery is 769 and that of Negative B electrode is 221.
in Sample 12, the OE: PYRI5PF6:PYR1.1BIV1B ratio is 87\0%, Ow; l'i.e:3-wit% The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 743 and that of Negative B electrode is 203 In Sample 13,, the OE: PYR t/PIi6:PYR ti,BOB ratio is 94witc%ii:5wt'4 1 wt%. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 925 and that of Negative B electrode is 234.
In Sample 14, the OE: PYR ?Ph; PYR ratio is 94wt.?4,:5\ " 1 wt%. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 937 and that of Negative B electrode is 252.
In Sample IS, the OE: PYR12PF6:PYR14BNIB ratio is 94iwt%:5virt%: The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 909 and that of Negative B electrode is 226.
In Sample 16, which is a control, the electrolyte comprises only 100 wt% OE. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 2163 and that of Negative B electrode is 513 The results show that the cycle life of a battery with electrolyte termed from a mixture of OF and one of PYR.nPF6, PYRI5P1:6,, and,PYRuPR is noticeably improved by the addition of a PYRIR boron-based first stabilizer.
-22 -Battery nerformance tests performed on batteries with electrolytes that contain a first and a second stabilizer, it is concluded that similar result will be shown in batteries with electrolyte mixture of OE, PYRIRPF6 where R = 2 to 10 and a first stabilizer (PYR:R boron-based).
Battery Performance Test System.
The battery contains a pos:dve e ecitode, a negative electrode, a separator and an electrolyte.
The Positive electrode comprises a composition of 90 wt % LiFe.PO4+ 5 wt% Super 5 wt% PVDF.
The Negative A electrode comprises a composition of IMCMB 92 we/of:Super P wt% PVDF.
The Negative B electrode comprises a composition of MC., B 80 wl'',7:-+-Sup 4 w19,4+ 1 sAit.?,b VGGF-i-10 wt?,o SiONICH-5 wilb SER.
The separator comprises a ceramic coated polypropylene separator with a thickness of 20 urn.
The electrolytes at the negative electrode A and the negative electrode B are different.
They both comprise PYRI5PF6, a first PYRin boron-based stabilizer, PiR14BOB, PYRLsODEB or PYRIABME and a second stabilizer which is preferably PY.RIR 2IFS11 or PY-Rw.
The 013 at negative electrode A is 1M 1..1PF6 with ethylene carbonate (EC)/dimethyl carbonate (DNIC)/diethyl carbonate (DEC)(1:1:1 vol%)+3.5wt% vinylene carbonate (VC).
The OE at negative electrode B is lM LiP1=-6 with ethylene carbonate (EC)/dimethyl carbonate (DIVIC)/diethyl carbonate (DEC)(1:1:1 vol%)+3.5wt% fluoroethylene carbonate (FEC).
Details of the amount of various constituents in the electrolyte of the batteries (Samples 1 to 21) are provided in Figure 9 4 0 The resulting batteries are tested with the Neware Battery Performance Test System, being charged and discharged at 0.2C-rate The It-off condition: The battery is considered to he invalid when the charge and discharge cycle capacity drops below 80% of the original capacity.
Based on the findings in Figure 9, it is concluded that the addition of a second stabilizer (PYRNESI or PYRNIT SI to an electrolyte mixture of OE, PYR1sPF6 and first -23 -stabilizer (PYR14BOB or PYR:40DFB) in a battery further improves the cycle life of that battery when compared to the battery with only a first stabilizer as an additive to the electrolyte.
With reference to Figure 9: In Sample 1, the electrolyte comprises OE. PYRIsPF(., PYRI4BOB, and PYRI4TESI.
The OE: BY Bit11FG: !Wilt's:410B: RitTES ratio is 79-ityt%: 1 ts-yid?, ;c5w111r.: 1-tve.-1). The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 789 and that of Negative B electrode is 210.
In Sample 2, the electrolyte comprises OE, PYRI5PF6,PYR1.4ODFB, and PYRI4TESI.
The OE: PYRitPFO:PYR.,,ODFS: PY R F S I ratio is 119=xt1/0:15-wt?.1):5%-t412: I writ). The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 801 and that of Negative B electrode is 201.
In Sample 3, the electrolyte comprises OE, PYR15PF6, PYR14BOB and PYR.14FSI. the OE: PYR1s:PF61.1)YR.14BOB:PYR J41; SI rink, is 79WC431 1 5 Wil? 70:5VINI 12'4%, The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 537 and that of Negative B electrode is 215, In Sample 4, the electrolyte comprises 01E, PYR uPFr., PVT?. 140DFB and PYRrilFSI.
The OE: PYR.15PF61"-{R14ODES:PYRHFS1 ratio is 79,,,,,a%:15'vt%:5wt%: 1 wrl8. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 521 and that of Negative B electrode is 228.
In Sample 5, the electrolyte comprises 0112PYRI PftPYRriBOB and PYRE iIFSI. The OE: PVT< rt:PF6:PYR OB:PYRI r IF SI ratio is 84ixt%:10-wt(18:5\ytn.:8:1'tert%. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 1321 and that of Negative B electrode is 241.
In Sample 6, the electrolyte comprises OE, PYR;sPF6, BYThrODTB and PYRHTESI.
'The OE: PYR.JsPF6:PYR.140DEB:pyR14TFSI ratio is 84wt%:10wC/0:5tvt.':1y411i,. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 1318 and that of Negative B electrode is 238.
In Sample 7, the electrolyte comprises OE, PYRI5PF6. PYR:4BOB and PYRLiFSI. The OE: PYR sit Fei:PYRI 41308 PYRt4F SI ratio is 84 tyt%:10-tvC/0:5wtt'o.1\yr%. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 759 and that of Negative B electrode is 253.
In Sample S. the electrolyte comprises OE, PYR.15PF6, PYRNOTWEi arid PYRHFST.
rile OE: PYRI5P1:6:PYR00DFB:PYRABSI ratio is 84wt%:15wi1l/0:5w-Nciwt%. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 773 and that of Negative B electrode is 257, -24 -In Sample 9, the electrolyte comprises GE, PYRiiiiPTio, PVIZi43OB and PVT-Z.1411'Si. The OF.: PYRiii,P176:PYRI4BOB:PYR11TliTS1 ratio is Fi2wt111):10sivt%:5wt1110:3iisit%. The number of cliarge and discharge life cycle of Negative A elect de in the resulting battery is 1433 and that of Negative B electrode is 253 hi Sample 10, the electrolyte comprises OE, PYRi,PF6, PVIZE4ODEB and PYRi4TEST The OE: MT,: sPFG:PYRitODEB:PYRstiTIESI ratio is 82siiit%:10w011):5'vt?"031A4%. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 1437 and that of Negative B electrode is 240.
111 Sample ii, the electrolyte comprises OE, PYRiirPIE6, PYRE4BOB and PYP,Thif.ST. The OE: PYRI5PF6iPYRI4BOB:PYRI/FSI ratio is 82s011/0:10wt%:3wt'110:3',\4%. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 785 and that of Negative B electrode is 262.
In Sample 12, the electrolyte comprises OE, PYR:5PFii, PilThrODFB and PYRIZSI. The OR P VitiiiP1161/1\11& ilODEB:PYR.iiiiiSI ratio is 82wit%ilOwl%*5-iiivt%liiist%. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 792 and that of Negative B electrode is 279.
In Sample Ii, the electrolyte comprises GE, PYRiiiP116, PYRI/BOB and PYRI4TES11. The OE: PYR sPhiiPYR i4BOB: PYR JP'S' ratio is 93% 5.?*iii 1-sivt%: Twt11i. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 1345 and that of Negative B electrode is 299 In Sample 14, the electrolyte comprises the OF: PYRiirPF6:PYR,10DFB:PYRI4TIPSI ratio is 93%:5%: wt%. The number of etiarge and discharge life cycle of Negative A electrode in the resulting battery is 1372 and that of Negative B electrode is 305.
In Sample IS, the electrolyte comprises the OE: PYRii5PF6:PYRi4BOB:PYRI4FSI ratio is 93%:51'./bi1iiivt%i1tivt%. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 910 and that of Negative B electrode is 310.
In Sample 16, the electrolyte comprises OE., PYRisPF6, PYRi4ODFB and PYRHFSI.
The GE: PYR141F6:13YRHODFB:PYRI4i:S1 ratio is 93111i:5%:11749.iii: The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 920 and that of Negative B electrode is 326.
in Sample 17, the electrolyte comprises OF., PYRii;PF6. PYRI/BOB and PYRI4TFSI. The GE: PYR15i1F6iPYRHBOB:PYRIi1iiTS1 ratio is 91%:5?b:lwi.?.1-2:3wCiii. The number of charge and discharge cycle cif Negative A electrode in the resulting battery is 1537 and that ofNegative B electrode is 306 In Sample.he electrolyte comprises OE, PYRoPF6,PYRi4ODFIB and PYRiiiif ESL 1sPF6:1731i7R1.ODFB:PYRHTFSI ratio is 91'1i":517iiiilwit%:3iwt?..1s. The The OE: -25 -number of charge and discharge life cycle of Negative electrode in the resulting battery is 1587 and that of Negative B electrode is 32 In Sample 19, the electrolyte comprises OR WY RitlIF6, PYRHBOB and PYR141:SI. The OR IPYRITIF6:PYRitI30.13::PYRHE'S1 ratio is 91%:5%:1 wt°/:,,3wt.EI'Ir The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 915 and that of Negative B electrode is $54.
Tri Sample 20, the electrolyte comprises OE, PYRI5PF6, IFY7RItODFB and PVRI4FSI.
The OF: PYlItt5PFG,PYR.1400FB:PA'R14ESi ratio is 91%,5%: wi24:3-tv12.7h. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 908 and that of Negative B electrode is $69.
In Sample 21, which is a control, the electrolyte comprises only 100weii) OR The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 2163 and that of Negative B electrode is 511 :Ft is reasonable to conclude that the addition of a second stabilizer PYRi bisrtriftuoromethane)sulfonimide (TEST) or PYR.n.{-bis(fluorosulfonypimide (17S1) to the electrolyte of a battery 'vith GE+ PYRIRPF6 where R. ---2 to 10 and PYRip. boron
-
based first stabilizer will result in further int pro:, em eni of the cycle life of that battery when compared to the battery with only a first stabilizer added to the electrolyte..
Battery performance test performed on batteries with electrolytes thatVt.( first second and third stabilizers.
With refer to Figure 10: Battery performance test with the Neware Battery Performance'lest System.
The battery contains a positive electrode, a negative electrode, a. separator and an electrolyte.
The positive electrode comprises 90 wt% LiFe.PO4+ 5 wt% Super P+ 5 wit% PVD.F. The negative electrode comprises MCNIB 92 wt%t-Super P 5 wt%1-3 wfb PVDF.
The separator comprises ceramic coated polypropylene separator with a thickness of 20 The electrolyte comprises an organic electrolyte (0E) comprises I NI LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), an ionic liquid (IL) comprises PYR.16Ph" PYRHBOB, PYIttaTFSI at 10:1:4 wt% and a third stabilizer.
The battery is charged and discharged -26 -Charge and discharge at 0 2C-rate The Cut-off condition: The battery is considered to be invalid when the charge and discharge cycle capacity drops below 80% of the original capacity.
Different batteries with different amounts of third stabilizer are tested and the results are provided in Figure 10 A self-extinguishing test is also performed. 1,2. , of the electrolyte is dropped on a 47 mm glass fiber membrane having a thickness of 0.5 mm. Ignition timing test. The restins are listed in Figure 10 as well.
The results Show that the addition of the third stabilizer can most effectively improve the cycle life of the battery, while ensuring the safety of the battery The third stabilizer can be ally of the four additives as listed below: Ethoxy(pentafluoro) cyclotriphosphazene (PFPN) is added in an amount of 0.5 to 10 wt.% of the electrolyte, and a more preferred embodiment is 0.5 to 2.9% of the electrolyte.; Ethylhexyl Diphen hate (171-1DP) is added in ati amount of 1 5 to 5 wt.% of the electrolyte., Hexaphenotcycyclotriphosphazene (HPCP) is added in an amount of 0.5 to 5% by weight of the electrolyte; and 10-(2,5-dihydroxypherty1) -10-hydro-9-oxa-10-phosphaphenanthrene-10-oxidation (DOPO-HQ) is added less than 1.5 wt.?../0 of the electrolyte.
With reference to Figure 10: In Sample 1, the electrolyte comprises the Oh. IL and PFPN. The OE:IL ratio is 85 wt. %.15 wt. 14:.. The OE -1-PYRI6PF6, PYR14BOB, PYRI4TFSI (II..).' PFPN ratio is 99.50wa%:0.50wt%. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 1674 and the self-extinguishing time is less than 6 second per gram.
hi Sample 2, the electrolyte comprises the OE. IL and PFPN. The 0:Elt, ratio is 85 wt.
%.15 Vilt, °'/C:. The OE -1-PYRI6PF6, PYR14BOB, PYRRITFSI (IL): PFPN ratio is 9Swt%:2wt%. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 2291 and the self-extinguishing time is less than 6 second per gram.
In Sample 3.. the electrolyte comprises the OE. IL and PFPN. The OEtIL ratio is 85 wt.
%:15 wtt. The OE -1-PYRI6PF6, PYIt14BOB, PYR14TFSI (IL;: PFPN ratio is 97.50,-mt%:2.50wtt-1-. The number of charge and discharge life cycle of Negative A electrode in the resultina battery is 2308 and the seiftextinauishing time is less than 6 -27 -second ocr gram In Sample 4, the electrolyte comprises the OE. IL and PFPN. The OE:IE ratio is 85 wt. %:15 wt. %. The OF ± PYR16PF6, PYRHBOB, PYRHTFSI (IL): PFPN ratio is 97.10wt%:2.90wt?'i, The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 2315 and the self-extinguishing time is less than 6 second per gram.
In Samples, the electrolyte comprises the OE, IL and PFPN. The OE:IL ratio is 85 wt.
%:15 wt. %. The OF PYR16PF6, PYRHBOB, PYRHTFSI (I 1.).....PFPN ratio is 97wt%:3wl%. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 2330 and the self-extinguishing time is less than 6 second per gra Ill In Sample 6, the electrolyte comprises the OF, IL and PFPN. The 0- ratio is 85 wt.
%:15 wt. %. The OE 4i PYR16PF6, PYRHBOB, PYRHTFSI (IL: PFPN ratio is (95wt%:5wt%). The number of charge and discharge life cycle of Negative A electrode in the resulting battery is '2392 and the self-extinguishing time is less than 6 second per gram.
In Sample the electrolyte comprises the OE, IL and PFPN. The OEJL ratio is 85 wt. %:15 wt. %. The OE ± PYR16PF6, PYRHBOB, PYRHTFSI (IL): PFPN ratio is 90wt%:10w-tN. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 2432 and the self-extinguishing time is less than 6 second per Gram.
in Samp e 8, the e eetrolyte comprises the O1?, IL and EHDP. The O'E:TL ratio is 85 wt. %:15 wt. %. The OF PYRIGPF6, PYRHBOB, PYRHTFSI (IL): JEHDP ratio is 99.50wl%:0.50w1%. The number of charge and discharge life cycle of Negative A. electrode in the resulting battery is 1637 and the self-extinguishing time is less than 6 second per gram.
In Sample 9, the electrolyte comprises the OE: IL and EHDP. The ratio is 85 wt.
%:15 wt. %. The OE ± PYROF6, PYRHBOB, PYRI4TFSI (fL)::.EHDP ratio is 98w1,,/;:2s,/,d,%. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 1943 and the self-extinguishing time is less than 6 second per gram.
In Sample 10, the electrolyte comprises the OE. IT and El-1E3P. The OE:IL ratio is 85 wt %A5 wt. 'N. The OE PYRI6PF6, PYRI4BOB, PYRI4TFSI (IL)::EI-IDP ratio is (96.50wt(!//b,:3.50wt/%). The number of charge and discharge life cycle of Negative A electrode in the resulting battery, is n5S and the self -extinguishing time is less than 6 second per gram.
iii Sample he electrolyte comprises the OF, IL and EHDP. The OEIL ratio is 85 wt. %:15 wt. The OE + PYRi6PF6, PYRHBOB, PYRHTFSI (11.,):EHDP ratio is 95.50wt%:4.50wt%. The nurriber of charge and discharge life cycle of Negative A -28 -electrode in the resulting battery is 2158 and the ielfextinguishing time is less than b second per gram.
In Sample 12, the electrolyte comprises the OE. IL and EHDP. The OE:IL ratio is 85 wt. %1 5 wt. %. The OE + PYR16PF6, PYRI4BOB, PYRI4TFSI OEM:HOP ratio is 95s,vt%:5wt%. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 2153 and the sealexti ngni shing time is less than 6 second per grain.
In Sample 13, the electrolyte comprises the OE, IL and HPCP. The OE:11. ratio is 85 wt. %:15 wi %. The GE + PYR16PF6, PYR14130B, PYR14TFSI (IL):HPCP ratio is 99.50w6:0.50wt%. The number of chari:ie and discharge life cycle of Negative A electrode in the resulting battery is 1484 and the self-extinguishing time is less than 6 second per gram.
In Sample 14, the electrolyte comprises the OF, IL and HPCP. The OF:IL ratio is 85 wt. %:15 wt ?AL The GEr PYR16PF6, PYR14130B, PYR14TFSI (IL):ffPCP ratio is 98w1%:2-wt%. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 1599 and the self-extinguishing time is less than 6 second per gram.
In Sample IS, the electrolyte comprises the OE, 1L and HPCP. The OE:11, ratio is s. wt. %,15 wt. //^. The GE + PYR16PF6, PYR14BOB, PYR14TFSI (IL):HPCP ratio is 96.50w1,%3.50wt%. The number of charge and discharge life cycle of Negative A elect -ode in the resulting battery is 1932 and the self -extinguishing nme is less flian 6 second per gram.
In Sample 16, the electrolyte comprises the OE. IL and HPCP. The OE:IL ratio is 85 wt. %:15 wt. (N^. The GE + PYR16PF6, PYRiaBOB, PYR14TFSI (II..):HPCP ratio is 95.50w-t%:4.50wt%. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 1908 and the self-extinguishing time is less than 6 second per gram.
In Sample 17, the electrolyte comprises the GE. IL and HPCP. The OE:IL ratio is 85 wt. %: 15 wt. The GE + PYR16PF6, PYRI4BOB, PYRI4TFSI (IL):.[IPCP ratio is 95-syte/0:5vcit%. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 1956 and the self -extinguishing, time is less than 6 second per In Sample 18, the electrolyte comprises the GE, EL and DOP0-11Q. The OE:IL ratio is wt ?if:15 wt. %. The OF, + PYR16PF6, PYRI4BOB, PYRI4TFS1(11.):D0130-HO ratio is 99.5wt%:0.5wi%. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 1957 and the self-extinguishing time is less than 6 second per gram In Sample 19, the electrolyte comprises the GE, IL and DOPO-HQ. The GETI.. ratio is 85 wt. V0:15 wt. 2,6. The OF +PYRI6PF6, PYRI4BOB, PYRI4TF SI (LL):DOPO-HQ ratio -29 -is 98.50 wr.i:1.5.0yvt%. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 2084 and the self-extinguishing time is less than 6 second per gram.
In Sample 20, which is a control, the electrolyte comprises only OE. The number of charge and discharge life cycle of Negative A electrode in the resulting battery is 2163 and the self-extinguishing rime is about $5 second per gram.
hi Sample 21, which is a control, the electrolyte comprises OE and IL, DEIT, ratio is 85wt14:15wezi, The number of charge and discharge life cycle of Negative A electrode in die resultiitg battery is 1396 and the self-extinguishing time is less than 6 second per gram.
The addition of the third stabilizer renders the battery commercially useful as far as charging and discharging life cycles is concerned. However the side reactions as shown in Figure 3 to 6 require attention. The addition of the flame retardant is necessary but brings about the unwanted side reaction. These side reactions are inhibited by the addition of the first and second stabilizers. The addition of the first and second stabilizers not only improves the charging and discharging life cycles but also to avoid 2 0 the side reactions.
In Figure 12, there is shown a cyclic voltammetry graph for a battery in which the electrolyte contains no PYRiRPF6 but organic electrolyte (OE) comprises 1M LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DNIC)/diethyl carbonate (DEC) (at 1: 1: vol%) and 3.5wt% vinylene carbonate (VC). There is no side reaction (redox reaction). This is confirmed by the experiment resulting in the findings in the table of Figure 11. Upon the addition of PYRRPF6, where R = any one of 2 to 1 0, side reactions are detected as shown detailed in Figure 3.
One or more stabilizers are added with the intension to inhibit the side reaction as a result of the addition of PYR1RPF6, where R = any one of 2 to 10.
Referring to Figure 11, the side reaction peak test is performed using a three-electrode test method measured by Autoiab 302N electrochemical workstation.
The working electrode is a Negative A electrode comprising MCM13 92 wt1110-Super P wt%+3 wt% PVDF.
The reference electrode comprises lithium metal.
The counter electrode comprises lithium metal.
The scan range is 0-2.5V and the scan rate is 1 mV/s.
Sample 1 in Figure 11 is a control in which the electrolyte contains no PYRIRPF6 but organic electrolyte (OE) comprises I MI ILiPF5 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3 Swt% vinylene carbonate (VC).. There is no side reaction after testing as shown in the cyclic voltammetry graph of Figure 12. -3 -
Sample 2 in Figure 11 includes 85wt% of OE, lOwt% of PYRI6PF6 and a first stabilizer 5wt?io of PYR1413E4 in the electrolyte. Side reaction is found after testing as shown in the cyclic voltammetry graph of Figure 13.
Sample 3 in Figure 11 includes 80wt% of OE, 15wt% of PYRI6PF6 and a first stabilizer 5wt% of PYRHODFB in the electrolyte No Side reaction is found after testing as shown in the cyclic voltammetry graph of Figure 14 Sample 4 in Figure 11 includes 80wt% of OE, 15wt% of PYRI6PF6 and a first stabilizer 5wt% of PYRI4BOB in the electrolyte. No Side reaction is found after testing as shown in the cyclic voltammetry graph of Figure 15.
Sample 5 in Figure 11 includes 85wt% of OE, lOwt% of PYR16PF6 and a second stabilizer 5wt% of PYR14FSI in the electrolyte. Side reaction is found after testing as 13 shown in the cyclic voltammetry graph of Figure 16.
Sample 6 in Figure 11 includes 85wt% of OE, lOwt°,1) of PYR16PF6 and a second stabilizer 5web of PYRNTF SI in the electrolyte. Side reaction is found after testing as shown in the cyclic voltammetry graph of Figure 17.
Sample 7 in Figure 11 includes 80wt% of OE, 14wt% of PYR16PF6, lwt%PYRHBOB as a first stabilizer and a second stabilizer 5wt% of PYRitTFSI in the electrolyte. No side reaction is found after testing as shown in the cyclic voltammetry graph of Figure 18 Sample 8 in Figure 11 includes 80wt% of OE, 9wt% of PYR16PF6, lwt%PYRI4BOB as a first stabilizer and a second stabilizer lOwt% of PYRutTFSI in the electrolyte. No side reaction is found after testing as shown in the cyclic voltammetry graph of Figure 19.
As noted in Sample 2, the first stabilizer-PYRmborom-based ionic liquid and the anion ofBb do not contribute to the inhibition ()Ulm side reaction peak. As shown in Samples and 6, when there is only a second stabilizer being used with PYR16PF61.e. without a first stabilizer: no inhibition of the side reaction peak is observed. When the first stabilizer is used without a second stabilizer, it seems to be slightly more effective than the use of second stabilizer without a first stabilizer as can be seen from the results of Samples 3 and 4 in comparison with Samples 5 and 6.
Example
Battery performance tests performed on batteries of the invention with electrolytes that contain a first, a second and a third stabilizer The organic solvent 1M LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC) is mixed with PYRIGPF6 as the flame retardant, PYRI4B013 as the first stabilizer; PYRIATSI as the second stabilizer to form a main solvent of the electrolyte. The main solvent is tested with different amount of third stabilizer selected from a group consisting of PFPN, EHDP,131PCP and DOPO-HQ.
jibe resulting battery is tested with the Neware Battery Performance lest System.
Battery performance test with reference to Figure 20: The batter contains a positive electrode, a negative electrode, a separator and an electrolyte_ The positive electrode comprises a composition of 90 wata LiFeP01+ 5 wil), Super P+ 1 0 5 wt% PV BE The negative A electrode comprises a composition of MCI'y B 92 wt%-i-Super P wt% PV011.
The separator comprises of ceramic coated polypropylene separator with a thickness of urn.
The electrolyte comprises the OE, PYR16PF6 as the flame retardant, PVIt11B0113 as the first stabilizer, l?'llfTR[4TEISI as the second stabilizer and a third stabilizer as detailed in 2 0 Figure 20.
The resulting battery is charged and discharged at 0.2C--rate Tile cut-off condition is when the battery is judged to be invalid i.e.when the charge and discharge cycle capacity drops below 80 ii of the original capacity Self-extinguishing test is performed by dropping 1.2 g of the electrolyte on a 47 ram glass fiber membrane having a thickness of 0.5 nun, The self-extinguishing time is recorded.
With reference to Figure 20 In Sample I. the electrolyte comprises organic electrolyte (OF) jNII,IPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYRI6PF6, PYRriBOB, PYR6ITFSI at 1:0.5: lwt% and PFPN as a third stabilizer at 2.0wt%. The number of charge and discharge life cycle of electrode A in the resulting battery is 2013 and the self-extinguishing time is less than 12 second per gram.
In Sample 2, the electrolyte comprises organic electrolyte (OF) 1M LiPF6 with ethylene 4 0 carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYRI6PF6, PY1214130B, PYRIJFSI at 1:0.5:1wt% and PFPN a third stabilizer at 2.5wt%. The number of charge and discharge life cycle of electrode A in the resulting battery is 2089 and the self-extinguishing time is less than 8 second per gram.
In Sample 3, the electrolyte comprises organic electrolyte (OE) 1M I.I.PF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) -3 -and 3.5wf,va vinylene carbonate (VC), PYRI6PF6, PYR14BOB, PYRNITSI at 1:0.5:1 wt% and PFPI\La third stabilizer at 2.9wt%. The number of charge and discharge life cycle of electrode A in the resulting battery is 2149 and the self-extinguishing time is less than 8 second per grant.
In Sample 4, the electrolyte comprises organic electrolyte (OE) 1M L1PF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYR16PF6, PYRNBOB, PYR14ITS1 at 1:0.5:1 wt% and PFPN_a third stabilizer at 3.0wt%. The number of charge and discharge life cycle of electrode A in the resulting batten is 7315 and the self-extinguishing time is less than 6 second per gram.
In Sample 5, the electrolyte comprises organic electrolyte (OE) IM tiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYR16PF6, PYR14130B, PYR11TFS1 at 1:0.5:1 wt% and PFPNLa third stabilizer at 4wt%. The number of charge and discharge life cycle of electrode A in the resulting battery is 2317 and the self-extinguishing time is less than 6 second per gram.
In Sample 6, the electrolyte comprises organic electrolyte (OF) 1M: I.11T6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5weia vinylene carbonate (VC), PYR16PF6, PYR14130B, PYR14TFS1 at 1:0.5:1 wt% and PFPN.,"a third stabilizer at 5w1%. The number of charge and discharge life cycle of electrode.A. in the resulting battery is 2340 and We self-extinguishing time is less than 6 second per gram.
In Sample 7, the electrolyte comprises organic electrolyte (OF) 1\4 LiPf26 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYR16PF6, PYR14130B, PYRI4TFSI at 1:0.5:1 wt% and PFPI\La third stabilizer at 10wt%. The number of charge and discharge life cycle of electrode A in the resulting battery is 2452 and the self-extinguishing time is less than 6 second per grant, hi Sample 8, the electrolyte comprises organic electrolyte(0E) 11M LIPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PY1116PF6, PYR14130B, PYRNITSI at 1:0.5:1 wt% and EHDP as a third stabilizer at 4.50wt%. 'The nuinber of charge, and di sc,harge life cycle of electrode A in the resulting battery is 2173 and the self-extinguishing time is less than 7 second per gram.
In Sample 9, the electrolyte comprises organic electrolyte (OE) I M LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYRI6PF6, PYRI4BOB, PYRNITSI at 1:0.5:1 wt% and EHDP as a third stabilizer at 5wt%. The number of charge and discharge life cycle of electrode A in the resulting battery is 2188 and the self-extinguishing time is less than 6 second per grant.
-33 -In Sample 10, the electrolyte comprises organic electrolyte (OF) 1M LIPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYR16PF6, PYR14130B, PYR14ITS1 at 1:0.5:1 wt% and HPCP as a third stabilizer at 4.50wt%. The number of charge and discharge life cycle of electrode A in the resulting battery is 2098 and the self-extinguishing time is less than 6 second per gram.
in Sample 11, the electrolyte comprises organic electrolyte (0E) iM 1,11iF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYRI6PF6, PYRI4BOB, PYRI1TTS1 at 1:0.5:1 wt% and EIPCP as a third stabilizer at 5wt%. The number of charge and discharge life cycle of electrode A in the resulting battery is 2134 and the self-extinguishing time is less than 6 second per gram.
in Sample 12, the electrolyte comprises organic electrolyte (DE) IM LiPlio with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt9/i) vinylene carbonate (VC), PYR16PF6, PYR14BOB, PYR14TESI at 1:0.5:1 wt% and DOPO-HQ as a third stabilizer at 1.50wt.%. The number of charge and discharge life cycle of electrode A in the resulting battery is 2102 and the se F- 2 0 extinguishing dine is less than 10 second per grain.
In Sample H. it is a control, the electrolyte comprises organic electrolyte (OF) !NI:TATO with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt%vinylene carbonate (VC). The number of charge and discharge life cycle of electrode A electrode in the resulting battery is 2163 and the self-extinguishing dine is 35 second per gram.
in Sample 14; it is a control, the electrolyte comprises organic electrolyte (OE) 1M LiPl'o with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC) and PYL6PF6, PYRABOB, PYRI4TF SI at 1:0.5:1 wt%. 'The number of charge and discharge life cycle of electrode A in the resulting battery is 1873 and the self-extinguishing time is less than 25 second per grant Examul e 2 Battery performance tests performed on batteries of the invention with electrolytes that contain a first., a second and a third stabilizer The organic electrolyte (OE) comprises 1 M LiPF6 with ethylene carbonate (EC)/di methyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC) is mixed with PYR16PF6 as the flame retardant, PYR14ODFB as the first stabilizer. PYRIJIHS1 as the second stabilizer to form a main solvent of the electrolyte, The n ai n solvent is tested wth different amount of third stabilizer sel ected from a group consisting of PFPN, EHDP, HPCP and DOPO-HQ.
The resulting battery is tested with the Neware Battery Performance Test System. -3 -
Battery perfbrrnanee test with reference to Figure 21: The battery contains a posttjve electrode, electrode, a separator and an electrolyte Inc positive electrode comprises a composition of 90 wt% UFO + 5 1.7,4% Sup P± 5 wt% PVDF.
1 0 The negative electrode comprises a composition of MCMB 92 tik " +Super P 5 wt%+3 wt(Vo PVD13 The separator comprises of ceramic coated polypropylene separator wi a tbi' ess 20 um.
The electrolyte comprises the;OE), PYRI6PF6 as the flame retardant, PYRHODFB as the first stabilizer, MM..: al, SI as the second stabilizer and a third stabilizer as detailed in Figure 21.
2 0 The resulting battery is charged and discharged at 0.2C-rat oat-off condition is when the battery is judged to be inytilid i.e, when the charge and discharge cycle capacity drops below 80% of the original capacity.
Sell-extinguishing test is performed by dropping 1.2 g of the electrolyte on a47 mm glass fiber membrane having a thickness of 0.5 inm The self-extinguishing time is recorded.
With reference to Figure 21 In Sample I. the electrolyte comprises organic electrolyte (OE) IMIDE; with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYRI6PF6, PYRNODFB, PYRHTFSI at 1:0.5: lwt% and PFPN as a third stabilizer at 2.5wt%. The number of charge and discharge life cycle of electrode A in the resulting battery is 2078 and the self- 3 5 extinguishing time is less than 8 second per gram.
In Sample 2, the electrolyte comprises organic electrolyte (OE) 1M LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYRI6PF6, PYRI4ODFB, PYRI3TFSI at 4 0 1: 0.5: lwt% and PFPN a third stabilizer at 2.9wf1/0. The number of charge and discharge life cycle of electrode A in the resulting battery is 2102 and the self-extinguishing time is less than 8 second per gram.
In Sample 3, the electrolyte col n pri E! S organic electrolyte (GE) 1 M LiPE5 with ethylene 4 5 carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol?:/0) and 3.5wt% vinylene carbonate (VC), PYR16PF6, PYRI4ODFB, PYRHTFSI at 1:0.5:1 wt% and PFPN,a third stabilizer at 3.0wt%. The number of charge and discharge life -3 -cycle of electrode A electrode in the resulting battery is 2311 and the self-extinguishing time is less than 6 second per gram.
In Sample 4, the electrolyte comprises organic electrolyte (OE) Ni Liffa with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYRR,PH" PYRI4ODFB, PYRHTF SI at 1:0.5:1 wt% and PFPN_a third stabilizer at 4wt9/i). 'The number of charge ancl discharge life cycle of electrode A in the resulting battery is 2315 and the self-extinguishing time is less than 6 second Der gram.
In Sample 5" the electrolyte comprises organic electrolyte (OE) 1M LiPT6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYRI6PF6, PY11140DFB, PYRHTF SI at 1:0.5:1 wt% and PFPN_a third stabilizer at 5wt%. The number of charge and discharge life cycle of electrode A in the resulting battery is 2338 and the self-extinguishing time is less than 6 second per gram.
In Sample 6, the electrolyte comprises organic electrolyte (GE) 114 L1PF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYR16PF6, PYRI4ODFB, PYRHTFSI at 1:0.5:1 wt% and PFPI\La third stabilizer at lOwt%. The number of charge and discharge life cycle of electrode A in the resulting battery is 2433 and the self-extinguishing time is less than 6 second per gram.
In Sample?, the electrolyte comprises organic electrolyte (OE) 114 LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYRI6PF6, PYRI4ODFB, PYRHTF ST at 1:0.5:1 wt% and EHDP as a third stabilizer at 4.50wt?i'r). The number of charge and di scharg,e life cycle of electrode A in the resulting battery is 2149 and the self-extinguishing time is less than 7 second per gram.
In Sample 8, the electrolyte comprises organic electrolyte (OF) IM LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYR16PF6, PYRI40DFB, PYRHTF SI at 1:0.5:1 wt% and EHDP as a third stabilizer at 5wt%. The number of Charge and discharge life cycle of electrode A electrode in the resulting battery is 2176 and the self-extinguishing time is less than 6 second per gram.
In Sample 9, the electrolyte comprises organic electrolyte (OE) 1M LiP176 with ethylene 4 0 carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYR16PF6, PYRI4ODFB, PYR13TFS1 at 1:0.5:1 wt% and HPCP as a third stabilizer at 4.50wt%. The number of charge and discharge life cycle of electrode A in the resulting battery is 2055 and the self-extinguishing time is less than 6 second per gyam In Sample 10: the electrolyte comprises organic electrolyte (0E) 114 LiPT6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 -3 -vol%) and 3.5we/0 vinylene carbonate (VC), PY121613F6, PY11140DFB, PYRDTFSI at 1:0.5:1 wt% and HPCP as a third stabilizer at 5wt%. The number of charge and discharge life cycle of electrode A in the resulting battery is 2122 and the self-extinguishing time is less than 6 second per gram.
In Sample 11, the electrolyte comprises organic electrolyte (OE) TM LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYR16PF6, PYRprODFB, PYR13TFS1 at wt% and DOPO-HQ as a third stabilizer at 1.50wt%. The number of charge and discharge life cycle of electrode A in the resulting battery is 2095 and the self-extinguishing time is less than 10 second per grant.
In Sanyle 13, it is a control, the electrolyte comprises organic electrolyte (0E) :I Ni UPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC). The number of charge and discharge life cycle of electrode A in the resulting battery is 2163 and the self-extinguishing time is 35 second per gram.
In Sample 14, it is a control, the electrolyte comprises organic electrolyte (OE) 1 Ni LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC) and PYRI6PF6, PYR..mODEB, PYRBTESI at 1:0.5:1 wt%. The number of charge and discharge life cycle of electrode A in the resulting battery is 1824 and the self-extinguishing time is less than 25 second per grain.
Example 3
Battery performance tests performed on batteries of the invention with electrolytes that contain a first, a second and a third stabilizer The organic solvent (OF) comprises 1 NI,HP/116 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC) is mixed with PYR16PF6 as the flame retardant:, PYRii0DFS as the first stabilizer, .1n1R0TFSI. as the second stabilizer to form a main solvent of the electrolyte. The main solvent is tested with different amount of third stabilizer selected from a group consisting of PFPN, EIMP, HPCP and DOPO-HQ.
The resultina t with the Neware Battery Performance Test System.
Battery performance test with reference to Figure 27 The battery contains a positive electrode, a ive electrode, a separator and an electrolyte The positive electrode comprises a composition of 90 /1.i LiFel?04+ 5 wt% Super.1-H wt% PVITh. -3 -
The negative A electrode comprises a composition of MCMB 92 -04%1-Super P 5 'yt%-t3 wt% PVDF.
The separator comprises of ceramic coated polypropylene separator with a thickness of 5 20 um.
The electrolyte comprises the OE, PYR16PF6 as the flame retardant, i'''Yrii34.40DFB as the first stabilizer, PYR13TFS1 as the second stabilizer and a third stabilizer as detailed in Figure 22.
The resulting battery is charged and discharged at 0.2 C-rate. The cut-off condition is when the battery is Mdged to be invalid i.e. when the charge and discharge cycle capacity drops below 80% of the original capacity.
Self-extinguishing test is performed by dropping 1.2 g of the electrolyte on a 47 rum glass fiber membrane having a thickness of 0,5 mm, The self-extinguishing time is recorded.
With reference to Figure 22 In Sample 1, the electrolyte comprises organic electrolyte 0E1 I Ni L1PF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYRI6PF6, PYRI4ODFB, PYRHTFSI at 10:1:4wt9/0 and PFPN as a third stabilizer at 2.50wt%. The number of charge and discharge life cycle of electrode A in the resulting battery is 2251 and the self-extinguishing time is less than 6 second per gram.
In Sample 2, the electrolyte comprises organic electrolyte (OF) I M LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5yvt% vinylene carbonate (VC), PYRI6PF6, PYRI4ODFB, PYRHTFSI at 10:1:4wt% and PFPN a third stabilizer at 2.90wt%. The number of charge and discharge life cycle of electrode A in the resulting battery is 2294 and the self-extinguishing time is less than 6 second per gram.
In Sample 3, the electrolyte comprises organic electrolyte (OE) 1M L1PF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYR16PF6, PYRmODFB, PYR43TESI at 10:1:4wt% and PFPN.a third stabilizer at 3wt%. The number of charge and discharge 'e cycle of electrode A in the resulting battery is 2315 and the self-extinguishing time is less than 6 second per gram.
In Sample 4, the electrolyte comprises organic electrolyte (OE) IN1 LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYRI6PF6, PYRI4ODFB, PYRHTEST at 10:1:4wt9/0 and PFPN a third stabilizer at 5wt%. The number of charge and discharge life evcle of electrode A in the resulting battery is 2337 and the self-extinguishing time is less than 6 second per gram.
In Sample 5, the electrolyte comprises organic electrolyte (OE) IM IL1PF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYRI6PF6, PYRmODFB, PYRI3TFSI at 10:1:4wt% and PFPNIA third stabilizer at lOwt%. The number of charge and discharge life cycle of electitde A in the resulting battery is 1356 and the self-extinguishing time is less than 6 second per gram.
Tn Saniple 6, the electrolyte comprises organic electrolyte (OE) I M IAPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5vvt% vinylene carbonate (VC), PYRI6PF6, PYRI4ODFB, PYRI3TESI at 10:1:4wt% and EHDP as a third stabilizer at 3.50wt%. The number of charge and discharge life cycle of electrode A in the resulting battery is 2043 and the self-extinguishing time is less than 6 second per gram.
In Sample 7, the electrolyte comprises organic electrolyte (OE) I M LIPT6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYRIGPF6, PYRI4ODFB, PYRHTFSI at 10:1:4wt% and EHDP as a third stabilizer at 4.50wt%. The number of charge and discharge life c),,cle of electrode A in the resulting battery is 2098 and the self-extinguishing time k less than 6 second per gram.
in Sample 8, the electrolyte comprises organic electrolyte (0E) 1M iIi156 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vole/o) and 3.5wt% vinylene carbonate (VC), PYRI6PF6, PYRmODFB, PYR13TFS1 at 10:1:4wt% and EHDP as a third stabilizer at 5wt% hemlinber of charge and discharge life cycle of electrode A electrode in the resulting battery is 2156 and the self-extinguishing time is less than 6 second per gram.
In Sample 9, the electrolyte comprises organic electrolyte (OE) 1M LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PY1116PF6, PYRNODFB, PYIIHTFSI at 10:1:4wt94,' and HPCP as a third stabilizer at 3.50wt%. The number of charge and discharge life cycle of electrode A in the resulting battery is 1894 and the se f-extinguishing time is less than 6 second per gram.
In Sample ID. the electrolyte comprises organic electrolyte (OE) M LiliE6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYRI6PF6, PY11140DFB, PYRDTFSI at 10:1:4wt% and HPCP as a third stabilizer at 4.50wt%. The number of charge and discharge life cycle of electrode A in the resulting battery is 1902 and the se f-extinguishing time is less than 6 second per gram.
in Sample Ii, the electrolyte comprises organic electrolyte (OF) IM LiPF6 with ethylene carbonate (EC)/dimethyl carbonate (DMC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYRI5PF6, PYR14ODFB, PYR13TFSI at 10:1:4wt% and HPCP as a third stabilizer at 5wt%. The number of charge and discharge -3 -life cycle of electrode A in the resulting battery is 1941 and the self-extinguishing time is less than 6 second per gram, In Sample 12, the electrolyte comprises organic electrolyte (DE) 1M LIPP6 with ethylene carbonate (EC)/dimethyl carbonate (DIVIC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC), PYRH,Ph" PYRI4ODFB, PYR13TFSI at 10:1:4w/194 and DOPO-HQ as a third stabilizer at 1.50wt%. The number of charge and discharge life cycle of electrode A in the resulting battery is 2096 and the selfexti ngui shing time is less Man 6 second per gram.
In Sample 13 ills a control:, the electrolyte comprises organic electrolyte (OE) 1M LiP1F6 with ethylene carbonate (EC)/dimethyl carbonate (DNIC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC). The number of charge and discharge life cycle of electrode A in the resulting battery is 2163 and the self-extinguishing time is 35 second per gram.
In Sample; it is a control, the electrolyte comprises organic electrolyte (OE) IM LiPIT6 with ethylene carbonate (EC)/dimethyl carbonate (DNIC)/diethyl carbonate (DEC) (at 1:1:1 vol%) and 3.5wt% vinylene carbonate (VC) and PYR15PF6, PVRAODFB, PYRI3TESI at 10:1 Awt%. The number of charge and discharge life cycle of electrode A in the resulting battery. is 1361 and the self-extinguishing time is less than 6 second per gram, Examples I and 2 are the most cost effective embodiments of the invention while Example 3 is the embodiment that has the best performance.
The invention has been given by way of example only, and various other modifications of and/or alterations to the described embodiment may be made by persons skilled in the art without departing from the scope of the invention as specified in the appended claims.

Claims (34)

  1. -40 -CLAIMSI. An electrolyte for a lithium-ion battery comprising: a lithium salt, a non-aqueous organic solvent which includes a carbonate-based solvent, a flame retardant, a film former and a stabilizing medium, wherein the flame retardant comprises PYRIRPF6 (N-Methyl-N-alkylpyn-olidinium Hexafluorophosphate Salt) at the amount of 1 to 15 wt. % of the electrolyte.
  2. 2. The electrolyte as claimed in claim I, wherein R in PYR1RPF6 indicates the number of carbon atoms in the alkyl side chains, in which R is selected from any one of 2 to 10.
  3. 3. The electrolyte as claimed in claim 2, wherein the PYR1RPF6 has a melting point greater than 200 °C.
  4. 4. The electrolyte as claimed in claim 3, wherein the R is 2, 5 or 6.
  5. 5. The electrolyte as claimed in claim 1, wherein the stabilizing medium includes first and second stabilizer.
  6. 6 The electrolyte as claimed in claim 5, wherein the first stabilizer comprises an ionic liquid with PYRin-cation and a boron-based anion other than BF4-
  7. 7 The electrolyte as claimed in claim 6, wherein R is 2, 3, 4, 5 or 6
  8. S. The electrolyte as claimed in claim 7, wherein the boron-based anion is selected from a group consisting of bis(xoalateborate) (BOB), difluoro(oxalate)borate (ODFB) and bi s(m an del ato)borate(BMB).
  9. 9. The electrolyte as claimed in claim 5, wherein the second stabilizer comprises an ionic liquid with PYR1R11cation.
  10. 10. The electrolyte as claimed in claim 9, wherein R is 3 or 4.
  11. 11. The electrolyte as claimed in claim 10, wherein the second stabilizer comprises an ionic liquid with an anion selected from a group consisting of TESL and ESL.
  12. 12. The electrolyte as claimed in claim 6, wherein the amount of the first stabilizer is between 0 to 5 wt. % of the electrolyte.H.
  13. The electrolyte as claimed in claim 9, wherein the amount of the second stabilizer is between 0 to 10 wt (110 of the electrolyte.
  14. 14 The electrolyte as claimed in claim 5 further comprising a third stabilizer,
  15. 15. The electrolyte as claimed in claim 14, wherein the third stabilizer is selected from a group consisting of Ethoxy(pentafluoro) cyclotriphosphazene (PFPN), Ethylhexyl -41 -Diphenyl Phosphate (EITDP), Hexaphenoxycyclotriphosphazene (FIPCP) and 1042,5-dihydroxypheny1)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxidation (DOPOH Q).
  16. 16. The electrolyte as claimed in claim 15, wherein the amount of PFPN is between 0.5 to 10 wt. % of the electrolyte.
  17. 17. The electrolyte as claimed in claim 15, wherein the amount of EHDP is between 0.5 to 5 wt. % of the electrolyte. 10
  18. 18. The electrolyte as claimed in claim 15, wherein the amount of ELPCP is between 0.5 to 5 wt. % of the electrolyte.
  19. 19. The electrolyte as claimed in claim 15, wherein the amount of DOPO-HQ is less than or equal to 1.5 wt. % of the electrolyte.
  20. 20. The electrolyte as claimed in claim 16, wherein the amount of PFPN is 0.5 to 2.9 wt. % of the electrolyte.
  21. 21. The electrolyte as claimed in claim 1, wherein the non-aqueous organic solvent comprises carbonate-based organic solvents.
  22. 22. The electrolyte as claimed in claim 21, wherein the carbonate-based organic solvents is selected from a group consisting of ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), Propylene carbonate (PC), dimethyl carbonate (D1V1C) and a mixture thereof
  23. 23. The electrolyte as claimed in claim 1, wherein the film former is selected from a group consisting of vinylene carbonate (VC) and fluoroethylene carbonate (FEC)
  24. 24. The electrolyte as claimed in claim 1 wherein the lithium salt comprises lithium hexafluorophosphate (LiPF6).
  25. 25. An electrolyte for a lithium-ion battery comprising: a lithium salt, a non-aqueous organic solvent which includes a carbonate-based solvent, a flame retardant, a film former and a stabilizing medium, wherein the flame retardant comprises PYRIRPF6 (N-Methyl-N-alkylpyrrolidinium Hexatluorophosphate Salt), the stabilizing medium includes first, second and third 4 0 stabilizers.
  26. 26. The electrolyte as claimed in claim 25, wherein the lithium salt comprises LiPF6; the carbonate-based organic solvents is selected from a group consisting of ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), Propylene carbonate (PC), dimethyl carbonate (DIVIC) and a mixture thereof; the film former is selected from a group consisting of vinylene carbonate (VC) and fluoroethylene carbonate (FEC); the PYRIRPF6 indicates the number of carbon atoms in the alkyl side -42 -chains, in which R is selected from any one of 2 to 10, the first stabilizer is selected from a group consisting of bis(xoalateborate (BOB), difluoro(oxalate)borate (ODF13-) and bis(mandelato)borate(BMW), the second stabilizer comprises an ionic liquid with an anion selected from a group consisting of TFSI-and FSI-; and the third stabilizer is selected from a group consisting of Ethoxy(pentafluoro) cyclotriphosphazene (PFPN), Ethylhexyl Diphenyl Phosphate (EHDP), Hexaphenoxycyclotriphosphazene (HPCP) and 10-(2,5-dihydroxypheny1) -10-hydro-9-oxa-10-phosphaphenanthrene-10-oxidation(DOPO-HQ).
  27. 27. The electrolyte as claimed in claimed in claim 26, wherein the flame retardant is PYRI6PF6, the first stabilizer is PYRNBOB, the second stabilizer is PYRNTFSI at a ratio of 1:0.5:1 wt %.
  28. 28. The electrolyte as claimed in claimed in claim 26, wherein the flame retardant is PYR15PF6; the first stabilizer is PYR14ODEB; the second stabilizer is PYRI3TFSI at a ratio of 1:0.5:1 wt %.
  29. 29. The electrolyte as claimed in claimed in claim 26, wherein the flame retardant is PYR16PF6; the first stabilizer is PYRI4ODFB; the second stabilizer is PYREATFSI at a ratio of 10:1:4 wt
  30. 30. The electrolyte as claimed in claim 26, wherein the carbonate-based organic solvent comprises EC, DMC and DEC at 1:1:1 vol% and the film former comprises 3.5wt % of VC.
  31. 31. A battery comprising: a positive electrode, a negative electrode, a separator, and an electrolyte as claimed in any one of claims 1 to 30.
  32. 32. The battery as claimed in claim 31, wherein the positive electrode comprises LiFePO4.
  33. 33. The battery as claimed in claim 31, wherein the negative electrode is formed from a material selected from a group consisting of carbon and carbon/silicon (SiC).
  34. 34. The battery as claimed in claim 31, wherein the separator is a composite film formed from a material selected from a group consisting of Polypropylene (PP), Polyethylene 4 0 (PE), ceramic, glass fiber and a combination thereof
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