JP2014049286A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery capable of dramatically improving reliability and performance of a battery by suppressing generation of gas and deterioration in discharge capacity even when a battery in a charged state is exposed under a high-temperature environment.SOLUTION: A nonaqueous electrolyte secondary battery includes: a positive electrode 1 including a positive electrode active material in which a compound comprising zirconium and a fluorine element is attached on a surface of a lithium transition metal composite oxide; a negative electrode 2; and a nonaqueous electrolyte containing methyl 3,3,3-trifluoropropanoate(FMP).

Description

  The present invention relates to a non-aqueous electrolyte secondary battery.

In recent years, mobile information terminals such as mobile phones, notebook computers, and smart phones have been rapidly reduced in size and weight, and batteries as driving power sources are required to have higher capacities. A non-aqueous electrolyte secondary battery that performs charge / discharge by moving lithium ions between the positive and negative electrodes along with charge / discharge has a high energy density and a high capacity. Widely used as a drive power source.
Here, the mobile information terminal has a tendency to further increase power consumption with enhancement of functions such as a video playback function and a game function, and further increase in capacity and improvement in cycle characteristics are strongly desired.

From such a viewpoint, the following proposals have been made.
(1) By covering the surface of the positive electrode active material with AlF ₃ , ZnF ₂ or LiF, the influence of the acid generated near the positive electrode active material is reduced, and the reactivity between the positive electrode active material and the electrolyte is suppressed. Proposal for improving cycle characteristics by doing (Patent Document 1 below).
(2) A proposal that uses a fluorinated carboxylic acid ester as an electrolyte and suppresses a voltage drop during charge storage at 4.2 V (Patent Document 2 below).

Special table 2008-536285 JP 2010-62132 A

  With the transition of mobile information terminals and the like as described above, laminate type batteries and square type batteries have come to be used more frequently than cylindrical type batteries. Compared to the cylindrical battery, the outer package is flexible. For this reason, when a positive electrode active material and electrolyte solution react and gas is generated and the internal pressure of a battery becomes high by this, an exterior body becomes easy to change. As a result, the battery swells, and there is a risk of damaging the components of the equipment in which the battery is used. In particular, in a small device such as the above-described smartphone, such a problem is likely to occur because the space in which the battery is arranged is significantly limited. Therefore, it is necessary to suppress the generation of gas in the battery and to prevent the battery from expanding even when used under any conditions. However, in the proposals shown in the above (1) and (2), since a large amount of gas is generated when the battery is stored at a high temperature, the above problem cannot be solved sufficiently. In addition, since the positive electrode active material deteriorates when the gas is generated, there is a problem that the capacity of the battery is reduced.

  The non-aqueous electrolyte secondary battery of the present invention contains a positive electrode including a positive electrode active material in which a compound containing a fluorine element is attached to the surface of a lithium transition metal composite oxide, a negative electrode, and a carboxylic acid ester containing fluorine. And a non-aqueous electrolyte.

  According to the present invention, even when a charged battery is exposed to a high temperature environment, there is an excellent effect that gas generation and a decrease in discharge capacity can be suppressed.

The front view of the nonaqueous electrolyte secondary battery which concerns on embodiment of this invention. FIG. 2 is a cross-sectional view taken along line AA in FIG.

  Hereinafter, the nonaqueous electrolyte secondary battery and the like according to the present invention will be described below. In addition, the nonaqueous electrolyte secondary battery in this invention is not limited to what was shown to the following form, In the range which does not change the summary, it can change suitably and can implement.

[Production of positive electrode]
(Preparation of coating solution for spraying on the surface of lithium cobaltate)
After mixing 4.8 g of ammonium zirconium carbonate (13% solution, converted to ZrO ₂ ) and 0.76 g of ammonium fluoride, distilled water was added to dilute to 75 ml to prepare a coating solution.
(Coating on lithium cobaltate)
The coating solution was sprayed onto the lithium cobalt oxide using a spray method while stirring 500 g of lithium cobalt oxide in which 0.5 mol% of Al and Mg were dissolved in a TK Hibismix. Next, the lithium cobalt oxide sprayed with the coating solution was dried at 120 ° C. for 2 hours and then heat-treated at 300 ° C. for 7 hours. As a result, a positive electrode active material in which zirconium fluoride (hereinafter sometimes referred to as Zr fluoride) was adhered to the surface of lithium cobaltate was obtained.

(Preparation of positive electrode slurry)
First, NMP (N-methyl-2-) in which carbon black (acetylene black having an average particle size of 40 nm) powder as a positive electrode conductive agent and polyvinylidene fluoride (PVdF) as a positive electrode binder are dispersed in the positive electrode active material. A pyrrolidone) solution was mixed to prepare a positive electrode mixture slurry. At this time, the ratio of the positive electrode active material, the positive electrode conductive agent, and the positive electrode binder was 95: 2.5: 2.5 by mass ratio. Next, after apply | coating the said positive mix slurry on both surfaces of the positive electrode collector which consists of aluminum foils, it dried at 120 degreeC and further rolled with the rolling roller. This obtained the positive electrode by which the positive mix layer was formed on both surfaces of the said positive electrode collector. In addition, the packing density of the positive electrode active material in this positive electrode was 3.70 g / cm ³ . Content of the said Zr fluoride was 0.0934 mass% with respect to the said lithium cobaltate in conversion of a zirconium element.

(Production of negative electrode)
First, artificial graphite as a negative electrode active material, CMC (carboxymethylcellulose sodium) as a dispersant, and SBR (styrene-butadiene rubber) as a binder in an aqueous solution at a mass ratio of 98: 1: 1. The mixture was mixed to prepare a negative electrode mixture slurry. Next, this negative electrode mixture slurry was uniformly applied to both surfaces of a negative electrode current collector made of copper foil, dried, and further rolled with a rolling roller. This obtained the negative electrode in which the negative mix layer was formed on both surfaces of the negative electrode collector. The packing density of the negative electrode active material in this negative electrode was 1.60 g / cm ³ .

(Preparation of non-aqueous electrolyte)
One lithium hexafluorophosphate (LiPF ₆ ) is mixed with a mixed solvent in which fluoroethylene carbonate (FEC) and methyl 3,3,3-trifluoropropionate (FMP) are mixed at a volume ratio of 2: 8. A non-aqueous electrolyte was prepared by dissolving to a concentration of 0.0 mol / liter.

[Production of battery]
A current collecting tab was attached to each of the positive and negative electrodes, a separator was disposed between the two electrodes and wound in a spiral shape, and then the winding core was pulled out to produce a spiral electrode body. Next, the spiral electrode body was crushed to obtain a flat electrode body. Thereafter, the flat electrode body and the non-aqueous electrolyte solution were placed in an aluminum laminate outer package to produce a non-aqueous electrolyte secondary battery having the structure shown in FIGS. The size of the nonaqueous electrolyte secondary battery is 3.6 mm × 35 mm × 62 mm, and the discharge capacity when the nonaqueous electrolyte secondary battery is charged to 4.40V and discharged to 2.75V. Was 750 mAh.

  Here, as shown in FIGS. 1 and 2, the specific structure of the non-aqueous electrolyte secondary battery 11 is such that a positive electrode 1 and a negative electrode 2 are disposed to face each other with a separator 3 therebetween. 2 and the separator 3 are impregnated with a non-aqueous electrolyte. The positive electrode 1 and the negative electrode 2 are connected to a positive electrode current collector tab 4 and a negative electrode current collector tab 5, respectively, and have a structure capable of charging and discharging as a secondary battery. In addition, the electrode body 9 is arrange | positioned in the storage space of the aluminum laminate exterior body 6 provided with the closing part 7 by which the periphery was heat-sealed. In the figure, reference numeral 8 denotes a spare chamber for minimizing the influence of the gas generated by the decomposition of the electrolytic solution on the charge / discharge.

(Example)
A battery was produced in the same manner as in the embodiment for carrying out the invention.
The battery thus produced is hereinafter referred to as battery A.

(Comparative Example 1)
A battery was fabricated in the same manner as in the above example except that a positive electrode active material having no Zr fluoride adhered to the surface of lithium cobaltate was used.
The battery thus produced is hereinafter referred to as battery Z1.

(Comparative Example 2)
A battery was fabricated in the same manner as in the above example, except that the compound attached to the surface of lithium cobaltate was replaced with Zr fluoride instead of zirconium oxide (hereinafter sometimes referred to as Zr oxide). . Specifically, when the compound was attached to the surface of lithium cobaltate, a positive electrode active material was prepared by spraying only ammonium zirconium carbonate without adding a fluorine source.
The battery thus produced is hereinafter referred to as battery Z2.

(Comparative Example 3)
A battery was fabricated in the same manner as in the above example, except that a mixture of FEC and MEC (methyl ethyl carbonate) at a volume ratio of 3: 7 was used as the mixed solvent of the electrolytic solution.
The battery thus produced is hereinafter referred to as battery Z3.

(Comparative Example 4)
A battery was fabricated in the same manner as in Comparative Example 1 except that a mixed solvent of FEC and MEC was used at a volume ratio of 3: 7.
The battery thus produced is hereinafter referred to as battery Z4.

(Comparative Example 5)
A battery was produced in the same manner as in Comparative Example 2 except that a mixed solvent of FEC and MEC was used in a volume ratio of 3: 7.
The battery thus produced is hereinafter referred to as battery Z5.

(Experiment)
Using the batteries A and Z1 to Z5, charging / discharging and the like were carried out by the following method, and high temperature continuous charging characteristics (battery expansion due to gas generation, capacity remaining rate) were examined. Show. Moreover, since the BET specific surface area of the positive electrode active material used for the batteries A and Z1 to Z5 was measured, the results are also shown in Table 1. It should be noted that the amount of battery swelling due to gas generation in Table 1 (hereinafter sometimes simply referred to as the amount of battery swelling) is expressed as an index when the amount of battery swelling of battery A is 100.

-Charging / discharging conditions before a continuous charge test After carrying out constant current charge until the battery voltage was set to 4.40 V at a current of 1.0 It (750 mA), the current was (1/20) It ( The battery was charged until it reached 37.5 mA). Next, after resting for 10 minutes, constant current discharge was performed at a current of 1.0 It (750 mA) until the battery voltage reached 2.75V. And the discharge capacity was measured at the time of this discharge, and this was made into the discharge capacity before a continuous charge test.

-Charge conditions at the time of a continuous charge test After performing charge / discharge once on the said charge / discharge conditions, it was left to stand in a 60 degreeC thermostat for 1 hour. Next, under a 60 ° C. environment, the battery was charged with a constant current of 1.0 It (750 mA) until the battery voltage reached 4.40 V, and then charged with a constant voltage of 4.40 V. At this time, the total charging time in an environment of 60 ° C. was set to 60 hours.

-Measurement after continuous charge test Each battery was taken out from a 60 degreeC thermostat, and the battery swelling amount (thickness increase amount) in a preliminary | backup room was measured.
Further, after measuring the amount of battery swelling, the battery was cooled to room temperature. Then, discharge was performed at room temperature under the same conditions as the discharge conditions before the continuous charge test, and the first discharge capacity after the continuous charge test was measured. And the capacity | capacitance residual rate shown to following (1) Formula was computed.
Capacity remaining rate (%) = (first discharge capacity after continuous charge test / discharge capacity before continuous charge test) × 100 (1)

  As shown in Table 1, it is recognized that the battery A has a smaller amount of battery swelling and a higher capacity remaining rate than the batteries Z1 to Z5. When examining in more detail, when batteries A, Z1, and Z2 containing FMP in the non-aqueous electrolyte are compared, the battery A in which Zr fluoride is adhered to the lithium cobaltate surface has nothing adhered to the lithium cobaltate surface. Compared with the battery Z1 without, the battery swell amount is small and the capacity remaining rate is high. However, it can be seen that the battery Z2 having the Zr oxide adhered to the lithium cobaltate surface has a larger amount of battery swelling and a lower capacity remaining rate than the battery Z1. On the other hand, when batteries Z3 to Z5 containing MEC in the non-aqueous electrolyte are compared, the batteries Z3 and Z5 in which Zr fluoride or Zr oxide adheres to the lithium cobaltate surface have nothing attached to the lithium cobaltate surface. It can be seen that the battery swell amount is small and the capacity remaining rate is high compared to the battery Z4 without. Such a result is considered to be due to the following reasons.

  At the time of charging / discharging, the negative electrode and the electrolytic solution containing fluorine react, and the fluorine-containing decomposition product generated by the reaction moves to the positive electrode and reacts with the positive electrode active material. By this reaction, gas is generated or the positive electrode is deteriorated. In this case, the battery Z2 having the Zr oxide adhered to the lithium cobaltate surface has a surface area of the oxide in the positive electrode active material (lithium cobaltate and Zr oxide compared to the battery Z1 having nothing adhered to the lithium cobaltate surface. And the sum of the surface areas). As a result, in the battery Z2, the reaction between the decomposition product generated on the negative electrode and the positive electrode active material is promoted compared to the battery Z1. Note that the positive electrode active material of the battery Z2 has an increased surface area of the oxide as compared with the positive electrode active material of the battery Z1, when the BET specific surface areas of both positive electrode active materials are compared. On the other hand, in the battery A in which the Zr fluoride is adhered to the lithium cobalt oxide surface, the surface area of the oxide in the positive electrode active material is reduced as compared with the battery Z1. This is because the exposed area of lithium cobaltate is reduced because Zr fluoride is attached to a part of the surface of lithium cobaltate. And since the decomposition product produced | generated on the negative electrode does not react easily with Zr fluoride, the reaction active area in the positive electrode active material surface becomes small, the amount of gas generation decreases, and deterioration of the positive electrode active material does not occur. It is suppressed.

  On the other hand, in spite of the same phenomenon occurring in the batteries Z3 to Z5, not only the battery Z3 having the Zr fluoride adhered to the lithium cobaltate surface but also the battery Z5 having the Zr oxide adhered to the lithium cobaltate surface. Also, the battery swelling amount is small and the capacity remaining rate is high as compared with the battery Z4 in which nothing adheres to the lithium cobalt oxide surface. This is because FMP contained in the electrolytes of batteries A, Z1, and Z2 has excellent oxidation resistance and is difficult to decompose on the lithium cobaltate surface, whereas it is contained in the electrolytes of batteries Z3 to Z5. Since MEC is inferior in oxidation resistance, it is easily decomposed on the lithium cobalt oxide surface. In addition, the amount of MEC that decomposes on the surface of lithium cobaltate is much larger than the amount of decomposition products generated on the negative electrode that decompose on the surface of lithium cobaltate. Therefore, not only when Zr fluoride is attached to the surface of lithium cobaltate but also when Zr oxide is attached, the exposed area of lithium cobaltate is reduced. Even in the case of Z5, it is considered that gas generation is reduced as compared with the battery Z4. However, as described above, since the amount of MEC decomposed on the surface of lithium cobalt oxide is extremely large, the batteries Z3 to Z5 generate much more gas than the batteries A, Z1, and Z2, and the battery swell is significantly increased. In addition, since the positive electrode is also significantly deteriorated, the capacity retention rate is greatly reduced.

(Other matters)
(1) Examples of the compound comprising zirconium and a fluorine element used in the present invention include zirconium difluoride (ZrF ₂ ), zirconium trifluoride (ZrF ₃ ), zirconium tetrafluoride (ZrF ₄ ), and the like. Moreover, O and OH may be contained in a part of these compounds composed of zirconium and a fluorine element.

(2) It is necessary that the compound comprising zirconium and fluorine adheres to the surface of the lithium transition metal composite oxide. Thus, if the compound adheres to the surface of the lithium transition metal composite oxide, the compound is difficult to peel off from the lithium transition metal composite oxide, so that the effects of the present invention can be sufficiently exerted.
Here, as a method of adhering a compound composed of zirconium and fluorine to the surface of the lithium transition metal composite oxide, a solution containing zirconium and fluorine is mixed with the lithium transition metal composite oxide while stirring the lithium transition metal composite oxide. It can be carried out by spraying on objects. Since it can implement by such a simple method, it can suppress that the manufacturing cost of a battery rises.

(3) As lithium transition metal composite oxide used in the present invention, in addition to the above lithium cobaltate, nickel-cobalt-lithium manganate, nickel-cobalt-aluminum lithium, nickel-lithium cobaltate, nickel-lithium manganate Well-known materials such as lithium and transition metal oxides such as lithium nickelate and lithium manganate, and olivic acid compounds such as iron and manganese can be used.

(4) The amount of the compound consisting of zirconium and fluorine present on the surface of the lithium transition metal composite oxide is 0.01% by mass or more and 0.50% by mass with respect to the lithium-containing transition metal oxide in terms of zirconium element. The following is preferable. When the amount is less than 0.01% by mass, the amount of the compound composed of zirconium and fluorine is so small that the effect of the addition of the compound may not be sufficiently exerted. On the other hand, when the amount exceeds 0.50% by mass, the lithium The surface of the transition metal composite oxide may be excessively covered with a compound that is not directly involved in the charge / discharge reaction, and the discharge performance may be reduced.

(5) The lithium transition metal composite oxide may be contained in grain boundaries in addition to a solid solution of substances such as Al, Mg, Ti, and Zr. In addition to the compound composed of zirconium and fluorine, compounds such as Al, Mg, Ti, and Zr may be attached to the surface of the lithium transition metal composite oxide. This is because even if these compounds are attached, contact between the electrolytic solution and the lithium transition metal composite oxide can be suppressed.

(6) As carboxylic acid ester containing fluorine, in addition to the above methyl 3,3,3-trifluoropropionate, trifluoro compounds such as 2,2,2-trifluoroethyl acetate (CH ₃ COOCH ₂ F ₃ ) In addition, CHF ₂ COOCH ₃ , CHF ₂ COOC ₂ H ₅ , CH ₃ CF ₂ COOCH _3, etc. —COO— is partially or entirely substituted with F on the left and right of —COO— such as a methyl group, an ethyl group, or a propyl group. Things can be used.

(7) As the solvent of the nonaqueous electrolytic solution used in addition to the carboxylic acid ester containing fluorine (the solvent that reacts with the negative electrode during charge and discharge), the following solvents can be used. For example, cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, chain carbonates such as dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, propionic acid Compounds containing esters such as ethyl and γ-butyrolactone, compounds containing sulfone groups such as propane sultone, 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 1,2-dioxane, 1,4 -Compounds containing ethers such as dioxane and 2-methyltetrahydrofuran, butyronitrile, valeronitrile, n-heptanenitrile, succinonitrile, glutaronitrile, adiponitrile, pimeronite Le, 1,2,3-propanetriol-carbonitrile, 1,3,5-pentanetricarboxylic carbonitrile compounds containing nitrile such as nitrile or can be used compounds comprising an amide such as dimethylformamide. In particular, a solvent in which a part of these H is substituted with F is preferably used. Further, these can be used alone or in combination, and a solvent in which a cyclic carbonate and a chain carbonate are combined, and a solvent in which a compound containing a small amount of nitrile or an ether is further combined with these is preferable. .

Furthermore, as a solute used in the non-aqueous electrolyte, a known lithium salt that is conventionally used in a non-aqueous electrolyte secondary battery can be used. As such a lithium salt, a lithium salt containing one or more elements among P, B, F, O, S, N, and Cl can be used. Specifically, LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (FSO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), Lithium salts such as LiC (C ₂ F ₅ SO ₂ ) ₃ , LiAsF ₆ , LiClO ₄ and mixtures thereof can be used. In particular, LiPF ₆ is preferably used in order to enhance the high rate charge / discharge characteristics and durability of the nonaqueous electrolyte secondary battery.

As the solute, a lithium salt having an oxalato complex as an anion can also be used. As a lithium salt having this oxalato complex as an anion, in addition to LiBOB [lithium-bisoxalate borate], a lithium salt having an anion in which C ₂ O ₄ ²⁻ is coordinated to the central atom, for example, Li [M (C ₂ O ₄ ) _x R _y ] (wherein M is a transition metal, an element selected from groups IIIb, IVb, and Vb of the periodic table, R is selected from a halogen, an alkyl group, and a halogen-substituted alkyl group) Group, x is a positive integer, and y is 0 or a positive integer). Specifically, there are Li [B (C ₂ O ₄ ) F ₂ ], Li [P (C ₂ O ₄ ) F ₄ ], Li [P (C ₂ O ₄ ) ₂ F ₂ ], and the like. However, it is most preferable to use LiBOB in order to form a stable film on the surface of the negative electrode even in a high temperature environment.
In addition, the said solute may be used not only independently but in mixture of 2 or more types. Further, the concentration of the solute is not particularly limited, but is preferably 0.8 to 1.7 mol per liter of the electrolytic solution. Furthermore, in applications that require discharge with a large electric current, the concentration of the solute is desirably 1.0 to 1.6 mol per liter of the electrolyte.

(8) As the negative electrode used in the present invention, a conventionally used negative electrode can be used, and in particular, a carbon material capable of occluding and releasing lithium, a metal capable of forming an alloy with lithium, or an alloy containing the metal Compounds.
As the carbon material, natural graphite, non-graphitizable carbon, graphite such as artificial graphite, coke, etc. can be used, and examples of the alloy compound include those containing at least one metal that can be alloyed with lithium. . In particular, silicon or tin is preferable as an element capable of forming an alloy with lithium, and silicon oxide, tin oxide, or the like in which these are combined with oxygen can also be used. Moreover, what mixed the said carbon material and the compound of silicon or tin can be used.
In addition to the above, although the energy density is lowered, a negative electrode material having a higher charge / discharge potential than lithium carbon such as lithium titanate can be used.

(9) At the interface between the positive electrode and the separator or at the interface between the negative electrode and the separator, a layer made of an inorganic filler that has been conventionally used can be formed. As the filler, it is possible to use oxides or phosphate compounds using titanium, aluminum, silicon, magnesium, etc., which have been used conventionally, or those whose surfaces are treated with hydroxide or the like. .
The filler layer can be formed by directly applying a filler-containing slurry to a positive electrode, a negative electrode, or a separator, or by attaching a sheet formed of a filler to the positive electrode, the negative electrode, or the separator. it can.

(10) As the separator used in the present invention, conventionally used separators can be used. Specifically, not only a separator made of polyethylene, but also a material in which a layer made of polypropylene is formed on the surface of a polyethylene layer, or a material in which a resin such as an aramid resin is applied to the surface of a polyethylene separator is used. Also good.

(11) As the exterior body used in the present invention, an easily deformable one such as an aluminum can, a stainless steel can, etc. can be used in addition to an aluminum laminate. In order to reduce the weight of the battery, it is preferable to use an aluminum laminate or an aluminum can as the outer package. Moreover, since the exterior body is easily deformed when the thickness of the exterior body is 0.5 mm or less, the present invention is useful.

  The present invention can be expected to be deployed in, for example, driving power sources for mobile information terminals such as mobile phones, notebook computers, and smartphones, high power driving power sources such as electric vehicles, HEVs, and power tools, and power sources related to power storage.

1: Positive electrode 2: Negative electrode 3: Separator 4: Positive electrode current collecting tab 5: Negative electrode current collecting tab 6: Aluminum laminate outer package

Claims (6)

A positive electrode including a positive electrode active material in which a compound containing a fluorine element is attached to a surface of a lithium transition metal composite oxide;
A negative electrode,
A non-aqueous electrolyte containing a carboxylic acid ester containing fluorine;
A non-aqueous electrolyte secondary battery comprising:   The non-aqueous electrolyte secondary battery according to claim 1, wherein the non-aqueous electrolyte is composed of a cyclic carbonate and a carboxylic acid ester containing fluorine.   The nonaqueous electrolyte secondary battery according to claim 1 or 2, wherein the compound containing a fluorine element contains at least one element selected from the group consisting of Zr, W, Al, and a rare earth.   The nonaqueous electrolyte secondary battery according to claim 3, wherein the compound containing fluorine element contains at least one element selected from rare earth elements.   The nonaqueous electrolyte secondary battery according to claim 4, wherein the compound containing fluorine element contains at least one element selected from the group consisting of neodymium, samarium, and erbium.   The nonaqueous electrolyte secondary battery according to any one of claims 1 to 5, wherein the fluorine-containing carboxylic acid ester is methyl 3,3,3-trifluoropropionate (FMP).

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