Additives for electrolytes in Li-ions batteries

Abstract

Method of improving the performance and safety of a Li-ion battery. The method includes using a nitrile-based small organic compound of general formula I, V or IX outlined in the application in association with the electrolyte of the battery. An electrolyte including a nitrile-based small organic compound. A battery including the electrolyte.

Claims

1. A lithium-ion battery comprising a nitrile-based organic compound in association with an electrolyte of the battery, wherein the compound has a general formula IV outlined below ##STR00037## wherein: X is C or N; Ri are each independently selected from the group consisting of H, alkyl, cycloalkyl, alkene, alkyne, aryl and alkylaryl, alkoxy, thioalkoxy, OH, SH, NH.sub.2, a halogen atom, a halogeno alkyl, a halogeno alkoxy, a halogeno thioalkoxy, a cyano alkyl, a cyano alkene, a cyano alkyne, CN, NO.sub.2, SO.sub.2, COOH and acyloxycarbonyl; and when Ri is H, m is 5 and when Ri is not H, m is an integer from 0 to 5.

2. The battery according to claim 1, wherein the compound has a general formula B outlined below ##STR00038## wherein: X is C and R.sub.3 is H; or X is N; and R.sub.1 to R.sub.5 are each independently selected from the group consisting of H, alkyl, cycloalkyl, alkene, alkyne, aryl and alkylaryl, alkoxy, thioalkoxy, OH, SH, NH.sub.2, a halogen atom, a halogeno alkyl, a halogeno alkoxy, a halogeno thioalkoxy, a cyano alkyl, a cyano alkene, a cyano alkyne, CN, NO.sub.2, SO.sub.2, COOH and acyloxycarbonyl.

3. The battery according to claim 1, wherein the compound is B1, B2, B3, B4, B5, B6, B7 or B8 outlined below ##STR00039## ##STR00040##

4. A method of improving the performance and safety of a Li-ion battery, comprising adding a nitrile-based organic compound of claim 1 to an electrolyte of the battery.

5. The battery according to claim 1, wherein the nitrile-based organic compound is added to the electrolyte as an additive in an amount ranging from about 0.01 to about 5.0% wt.

6. The battery according to claim 1, wherein a cathode of the Li-ion battery comprises a lithium-containing material.

7. The battery according to claim 6, wherein capacity or reversibility of the battery are improved.

8. The battery according to claim 1, wherein a cathode of the Li-ion battery comprises one or more of a lithium oxide, olivine, lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium nickel oxide (LNO), or a nickel manganese cobalt oxide (NMC).

9. An electrolyte comprising a nitrile-based organic compound of a general formula IV outlined below ##STR00041## wherein: X is C or N; Ri are each independently selected from the group consisting of H, alkyl, cycloalkyl, alkene, alkyne, aryl and alkylaryl, alkoxy, thioalkoxy, OH, SH, NH.sub.2, a halogen atom, a halogeno alkyl, a halogeno alkoxy, a halogeno thioalkoxy, a cyano alkyl, a cyano alkene, a cyano alkyne, CN, NO.sub.2, SO.sub.2, COOH and acyloxycarbonyl; and when Ri is H, m is 5 and when Ri is not H, m is an integer from 0 to 5.

10. A battery comprising the electrolyte as defined in claim 9.

11. The electrolyte of claim 9, wherein the compound is B1, B2, B3, B5, B6, B7 or B8 outlined below ##STR00042## ##STR00043##

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the appended drawings:

(2) FIG. 1: Cycling data of LMFP-LTO battery (PC/EMC/DMC (4/3/3)+1M LiPF.sub.6+0.1 wt % additive according to the invention (a compounds of Serie A)) versus Reference after 300 cycles at 45? C.

(3) FIG. 2: Static capacity (0.05C) of LMFP-LTO battery (PC/EMC/DMC (4/3/3)+1M LiPF.sub.6+0.1 wt % additive according to the invention (a compound of Serie A)) versus Reference at 45? C.

(4) FIG. 3: Nyquist plots of LMFP-LTO battery (PC/EMC/DMC (4/3/3)+1M LiPF.sub.6+0.1 wt % additive according to the invention (a compound of Serie A)) versus Reference, at 0 and 100 cycles.

(5) FIG. 4: Cycling data of LMFP-LTO battery (PC/EMC/DMC (4/3/3)+1M LiPF.sub.6+0.5 wt % additive according to the invention (a compounds of Serie B)) versus Reference after 300 cycles at 45? C.

(6) FIG. 5: Static capacity (0.05C) of LMFP-LTO battery (PC/EMC/DMC (4/3/3)+1M LiPF.sub.6+0.5 wt % additive according to the invention (a compound of Serie B)) versus Reference at 45? C.

(7) FIG. 6: Nyquist plots of LMFP-LTO battery (PC/EMC/DMC (4/3/3)+1M LiPF.sub.6+0.5 wt % additive according to the invention (a compound of Serie B)) versus Reference, at 0 and 200 cycles.

(8) FIG. 7: Cycling data of LMFP-LTO battery (PC/EMC/DMC (4/3/3)+1M LiPF.sub.6+0.5 wt % additive according to the invention (a compounds of Serie C)) versus Reference after 300 cycles at 45? C.

(9) FIG. 8: Static capacity (0.05C) of LMFP-LTO battery (PC/EMC/DMC (4/3/3)+1M LiPF.sub.6+0.5 wt % additive according to the invention (a compound of Serie C)) versus Reference at 45? C.

(10) FIG. 9: Nyquist plots of LMFP-LTO battery (PC/EMC/DMC (4/3/3)+1M LiPF.sub.6+0.5 wt % additive according to the invention (a compound of Serie C)) versus Reference, at 0 and 100 cycles.

(11) FIG. 10: Cycling data of LMFP-LTO battery (PC/EMC/DMC (4/3/3)+1M LiPF.sub.6+0.5 wt % additive according to the invention (a compounds of Serie D)) versus Reference after 100 cycles at 45? C.

(12) FIG. 11: Static capacity (0.05C) of LMFP-LTO battery (PC/EMC/DMC (4/3/3)+1M LiPF.sub.6+0.5 wt % additive according to the invention (a compound of Serie D)) versus Reference at 45? C.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(13) Before the present invention is further described, it is to be understood that the invention is not limited to the particular embodiments described below, as variations of these embodiments may be made and still fall within the scope of the appended claims. It is also to be understood that the terminology employed is for the purpose of describing particular embodiments, and is not intended to be limiting. Instead, the scope of the present invention will be established by the appended claims.

(14) In order to provide a clear and consistent understanding of the terms used in the present specification, a number of definitions are provided below. Moreover, unless defined otherwise, all technical and scientific terms as used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure pertains.

(15) The use of the word a or an when used in conjunction with the term comprising in the claims and/or the specification may mean one, but it is also consistent with the meaning of one or more, at least one, and one or more than one. Similarly, the word another may mean at least a second or more.

(16) As used in this specification and claim(s), the words comprising (and any form of comprising, such as comprise and comprises), having (and any form of having, such as have and has), including (and any form of including, such as include and includes) or containing (and any form of containing, such as contain and contains), are inclusive or open-ended and do not exclude additional, unrecited elements or process steps.

(17) As used herein when referring to numerical values or percentages, the term about includes variations due to the methods used to determine the values or percentages, statistical variance and human error. Moreover, each numerical parameter in this application should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

(18) Term alkyl or alk as used herein, represents a monovalent group derived from a straight or branched chain saturated hydrocarbon comprising, unless otherwise specified, from 1 to 15 carbon atoms and is exemplified by methyl, ethyl, n- and iso-propyl, n-, sec-, iso- and tert-butyl, neopentyl and the like and may be optionally substituted with one, two, three or, in the case of alkyl groups comprising two carbons or more, four substituents.

(19) The term alkoxy or alkyloxy as used interchangeably herein, represents an alkyl group attached to the parent molecular group through an oxygen atom.

(20) The term alkylthio or thioalkoxy as used interchangeably herein, represents an alkyl group attached to the parent molecular group through a sulfur atom.

(21) The term alkylene as used herein, represents a saturated divalent hydrocarbon group derived from a straight or branched chain saturated hydrocarbon by the removal of two hydrogen atoms, and is exemplified by methylene, ethylene, isopropylene and the like.

(22) The term alkenyl as used herein, represents monovalent straight or branched chain groups of, unless otherwise specified, from 2 to 15 carbons, such as, for example, 2 to 6 carbon atoms or 2 to 4 carbon atoms, containing one or more carbon-carbon double bonds and is exemplified by ethenyl, 1-propenyl, 2-propenyl, 2-methyl-1-propenyl, 1-butenyl, 2-butenyl and the like and may be optionally substituted with one, two, three or four substituents.

(23) The term alkynyl as used herein, represents monovalent straight or branched chain groups of from two to six carbon atoms comprising a carbon-carbon triple bond and is exemplified by ethynyl, 1-propynyl, and the like and may be optionally substituted with one, two, three or four substituents.

(24) The term cycloalkyl as used herein, represents a monovalent saturated or unsaturated non-aromatic cyclic hydrocarbon group of three to eight carbon atoms, unless otherwise specified, and is exemplified by cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, bicyclo[2.2.1]heptyl and the like.

(25) The term halogen or halo as used interchangeably herein, represents F, Cl, Br and

(26) The term heteroatom, as used herein, is understood as being oxygen, sulfur or nitrogen.

(27) The inventors have designed and prepared an additive for use in association with the electrolyte in a Li-ion battery. The additive of the invention is an organic compound as described herein below and which comprises at least one nitrile group. Also, the organic compound is compatible with the electrolyte as well as other components of the battery.

(28) More specifically, the additive of the invention for use in association with the electrolyte is a nitrile-based organic compound as described herein and having general formulae I-XI, A, B, C and D depicted below.

(29) ##STR00022## ##STR00023## ##STR00024##

(30) Such organic compounds are exemplified by compounds defined in Table 1 below, namely, Compounds A1-A4, B1-68, C1-C2 and D1.

(31) TABLE-US-00001 TABLE 1 Organic compounds according to the invention (Series A, B, C and D) R.sub.1 R.sub.2 R.sub.3 R.sub.4 R.sub.5 X n Cycle A A1 H H OMe OMe H 0.1% 300 A2 F F F F F 0.1% 300 A3 F F CN F F 0.1% 300 A4 CN H CN CN H 0.1% 300 B B1 H H OMe OMe H C 0.5% 300 B2 F F F F F C 0.5% 200 B3 H H NO.sub.2 H NO.sub.2 C 0.5% poor results B4 H H CF.sub.3 H NO.sub.2 C 0.5% 300 B5 H H CF.sub.3 H H C 0.5% 300 B6 H H CN H H C 0.5% 300 B7 H H NO.sub.2 H H C 0.5% poor results B8 H H H H H N 0.5% 300 C C1 0 0.5% 300 C2 1 0.5% 300 D D1 0.5% 300 A B C D1

(32) The present invention is illustrated in further details by the following non-limiting examples.

Nitrile-Based Organic Compounds for Use as Additive in Association with Li-Ion Electrolytes

Example 1General Procedure for the Preparation of the Compounds

(33) To a solution of aldehyde (1 eq.) in 15 mL of chloroform are added, molonodinitrile (1.5 eq.) and few drops of triethylamine. The mixture is refluxed one night under nitrogen. After return to room temperature, dichloromethane is added, and the solution is washed twice with water and dried over MgSO.sub.4. After solvent removal, the residue is chromatographed (silica gel/dichloromethane) to give a solid.

Example 2Compound B1

(34) ##STR00029##

(35) Bright yellow solid (70%). NMR .sup.1H (400 MHz, CDCl.sub.3) ?: 7.69 (d, 1H, J=4 Hz); 7.64 (s, 1H); 7.38 (dd, 1H, J=4 Hz, J=12 Hz); 6.95 (d, 1H, J=12 Hz); 3.99 (s, 3H); 3.93 (s, 3H).

Example 3Compound B2

(36) ##STR00030##

(37) Yellow solid (40%). NMR .sup.1H (400 MHz, CDCl.sub.3) ?: 7.77 (s, 1H). NMR .sup.19F (400 MHz, CDCl.sub.3) ?: ?132.55 (s, 2H); ?143.68 (s, 1H); ?158.50 (s, 1H).

Example 4Compound B3

(38) ##STR00031##

(39) White solid. NMR .sup.1H (400 MHz, CDCl.sub.3) ?: 8.60 (d, 1H, J=4 Hz); 8.25 (dd, 1H, J=4 Hz, J=12 Hz); 8.18 (s, 1H); 8.15 (d, 1H, J=12 Hz).

Example 5Compound B4

(40) ##STR00032##

(41) Bright yellow solid. NMR .sup.1H (400 MHz, CDCl.sub.3) ?: 8.12 (d, 1H, J=4 Hz); 8.03 (s, 1H); 7.67 (dd, 1H, J=4 Hz, J=12 Hz). NMR .sup.19F (400 MHz, CDCl.sub.3) ?: ?63.65 (s, 3F).

Example 6Compound B5

(42) ##STR00033##

(43) White solid. NMR .sup.1H (400 MHz, CDCl.sub.3) ?: 8.02 (d, 2H, J=12 Hz); 7.83 (d, 2H, J=8 Hz); 7.80 (s, 1H). NMR .sup.19F (400 MHz, CDCl.sub.3) ?: ?63.48 (s, 3F).

Example 7Compound B6

(44) ##STR00034##

(45) White solid. NMR .sup.1H (400 MHz, CDCl.sub.3) ?: 7.99 (d, 2H, J=8 Hz); 7.83 (d, 2H, J=8 Hz); 7.74 (s, 1H).

Example 8Compound B7

(46) ##STR00035##

(47) Pale orange solid. NMR .sup.1H (400 MHz, CDCl.sub.3) ?: 8.39 (d, 2H, J=12 Hz); 8.07 (d, 2H, J=8 Hz); 7.88 (s, 1H).

Example 9Compound B8

(48) ##STR00036##

(49) Pink solid. NMR .sup.1H (400 MHz, CDCl.sub.3) ?: 8.89 (d, 2H, J=12 Hz); 7.81 (s, 2H); 7.68 (d, 2H, J=8 Hz).

(50) Compounds of the Series A and C and Compound D1 are commercially available and were used as received.

(51) Referring to the figures, FIGS. 1-3 outline results obtained using compounds of the Serie A; FIGS. 4-6 outline results obtained using compounds of the Serie B; FIGS. 7-9 outline results obtained using compounds of the Serie C; and FIGS. 10-11 outline results obtained using compounds of the Serie D. It should be noted that Reference batteries as well as batteries according to the invention, do not contain vinylene carbonate (VC), which explains the poor stability after 300 cycles. Nonetheless as can be seen, batteries comprising the additive according to the invention present a far better stability.

(52) As can be seen in FIG. 2, use of 0.1 wt % of compound A1 or A4 allows for improvement of the battery capacity as well as a better reversibility. Moreover, a global decrease of the battery resistance is noted (FIG. 3).

(53) FIG. 5 shows results obtained for compounds B1 and B4. Use of 0.5 wt % of the additive allows for an improvement of the battery capacity. A global decrease of the battery resistance is noted (FIG. 6).

(54) FIG. 7 shows results obtained for compounds C1 and C2. Use of 0.5 wt % of the additive yields a good stability after 300 cycles at 45? C. As can be seen in FIG. 8, better results are obtained for compound C1 (shorter carbon chain).

(55) FIG. 10 shows results obtained for compound D1. As can be seen in FIG. 11, use of 0.5 wt % of compound D1 allows for improvement of the battery capacity as well as a better reversibility.

(56) As will be understood by a skilled person, the additive for use in association with the electrolyte are adapted to be compatible with the components of the battery including the electrolyte and the cathode active material.

(57) The invention is described in relation to lithium manganese iron phosphate (LMFP)lithium titanium oxide (LTO) batteries. As will be understood by a skilled person, other lithium-ion batterie types may also be used. In other words, any battery wherein the cathode active material comprises a lithium-containing material may be used. Such lithium-containing material may be lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium nickel oxide (LNO) and the like including olivines, lithium oxides, nickel manganese cobalt oxide (N M C).

(58) Also, as will be understood by a skilled person, the anode material may be of any suitable type, such as for example lithium alloys, Si, SiOx, graphite and carbon mixtures, titanates, lithium titanates.

(59) The scope of the claims should not be limited by the preferred embodiments set forth in the examples but should be given the broadest interpretation consistent with the description as a whole.

(60) The present description refers to a number of documents, the content of which is herein incorporated by reference in their entirety.

REFERENCES

(61) 1. Rohan R. et al. J. Phys. Chem. C (2016), 120 (12), 6450-6458. 2. Kim Y.-S. et al. ACS Appl. Mater. Interfaces (2014), 6 (11), 8913-8920. 3. Pohl B. et al. J. Electrochem. Soc. (2015), 162 (3), A460-A464.