Flame Retardants For Lithium Batteries

Abstract

This invention provides nonaqueous electrolyte solutions for lithium batteries which contain one or more brominated flame retardants. The nonaqueous electrolyte solutions comprise a) a liquid electrolyte medium; b) a lithium-containing salt; and c) at least one brominated flame retardant. The brominated flame retardant is present in the electrolyte solution in a flame retardant amount.

Claims

1. A nonaqueous electrolyte solution for a lithium battery, which solution comprises i) a liquid electrolyte medium; ii) a lithium-containing salt; and iii) a flame retardant amount of A) tribromoethylene or tribromoneopentyl alcohol, wherein the flame retardant amount is more than 4 wt % relative to the total weight of the solution for tribromoethylene and wherein the flame retardant amount is more than 10 wt % relative to the total weight of the solution for tribromoneopentyl alcohol; or B) a flame retardant mixture of a) 1,2-dibromoethane and tribromoethylene in a weight ratio of about 0.75:1 to about 3:1, or b) tribromoethylene and 2-phenoxy-2,4,4,6,6-pentafluoro-1,3,5,2λ5,4λ5,6λ5triazatriphosphinine in a weight ratio of 0.75:1 to about 2.25:1.

2. (canceled)

3. A solution as in claim 1 wherein iii) is tribromoethylene or tribromoneopentyl alcohol, and wherein the flame retardant amount is more than 15 wt % relative to the total weight of the solution; or a flame retardant mixture, and is 1,2-dibromoethane and tribromoethylene, wherein the flame retardant amount is about 6 wt % or more relative to the total weight of the solution; or tribromoethylene and 2-phenoxy-2,4,4,6,6-pentafluoro-1,3,5,2λ5,4λ5,6λ5triazatriphosphinine, and wherein the flame retardant amount is about 4 wt % or more relative to the total weight of the solution; or a flame retardant mixture is 1,2-dibromoethane and tribromoethylene, and wherein the flame retardant amount is about 20 wt % or more relative to the total weight of the solution.

4-5. (canceled)

6. A solution as in claim 1 which also comprises 2-phenoxy-2,4,4,6,6-pentafluoro-1,3,5,2λ5,4λ5,6λ5triazatriphosphinine, wherein the brominated flame retardant is tribromoethylene, wherein the weight ratio of tribromoethylene to 2-phenoxy-2,4,4,6,6-pentafluoro-1,3,5,2λ5,4λ5,6λ5triazatriphosphinine is about 0.75:1 to about 2:1, and the flame retardant amount is about 4 wt % or more flame retardant molecules relative to the total weight of the nonaqueous electrolyte solution.

7. A solution as in claim 1 wherein the liquid electrolyte medium is ethylene carbonate, ethyl methyl carbonate, or a mixture thereof, and/or wherein the lithium-containing salt is lithium hexafluorophosphate or lithium bis(oxalato)borate.

8. A solution as in claim 1 wherein iii) is tribromoethylene or tribromoneopentyl alcohol, and wherein the solution also comprises iv) at least one electrochemical additive selected from: a) unsaturated cyclic carbonates containing three to about six carbon atoms, b) fluorine-containing saturated cyclic carbonates containing three to about five carbon atoms and one to about four fluorine atoms, c) tris(trihydrocarbylsilyl) phosphites containing three to about nine carbon atoms, d) trihydrocarbyl phosphates containing three to about twelve carbon atoms, e) cyclic sultones containing three to about eight carbon atoms, f) saturated cyclic hydrocarbyl sulfites having a 5-membered or 6-membered ring and containing two to about six carbon atoms, g) saturated cyclic hydrocarbyl sulfates having a 5-membered or 6-membered ring and containing two to about six carbon atoms, h) cyclic dioxadithio polyoxide compounds having a 6-membered, 7-membered, or 8-membered ring and containing two to about six carbon atoms, i) another lithium-containing salt, and j) mixtures of any two or more of the foregoing.

9. A solution as in claim 8 wherein the electrochemical additive is selected from: a) unsaturated cyclic carbonates containing three to about four carbon atoms, b) fluorine-containing saturated cyclic carbonates containing three to about four carbon atoms and one to about two fluorine atoms, c) tris(trihydrocarbylsilyl) phosphites containing three to about six carbon atoms, d) trihydrocarbyl phosphates containing three to about nine carbon atoms, e) cyclic sultones containing three to about four carbon atoms, f) saturated cyclic hydrocarbyl sulfites having a 5-membered ring and containing two to about four carbon atoms, g) saturated cyclic hydrocarbyl sulfates having a 5-membered ring and containing two to about four carbon atoms, h) cyclic dioxadithio polyoxide compounds having a 6-membered or 7-membered ring and containing two to about four carbon atoms, i) another lithium-containing salt, and j) mixtures of any two or more of the foregoing.

10. A solution as in claim 8 wherein the electrochemical additive is selected from: a) an unsaturated cyclic carbonate in an amount of about 0.5 wt % to about 12 wt %, relative to the total weight of the nonaqueous electrolyte solution, b) a fluorine-containing saturated cyclic carbonate in an amount of about 0.5 wt % to about 15 wt %, relative to the total weight of the nonaqueous electrolyte solution, c) a tris(trihydrocarbylsilyl) phosphite in an amount of about 0.1 wt % to about 5 wt %, relative to the total weight of the nonaqueous electrolyte solution, d) a trihydrocarbyl phosphate in an amount of about 0.5 wt % to about 5 wt %, relative to the total weight of the nonaqueous electrolyte solution, e) a cyclic sultone in an amount of about 0.25 wt % to about 5 wt %, relative to the total weight of the nonaqueous electrolyte solution, f) a saturated cyclic hydrocarbyl sulfite in an amount of about 0.5 wt % to about 5 wt %, relative to the total weight of the nonaqueous electrolyte solution, g) a saturated cyclic hydrocarbyl sulfate in an amount of about 0.25 wt % to about 5 wt %, relative to the total weight of the nonaqueous electrolyte solution, h) a cyclic dioxadithio polyoxide compound in an amount of about 0.5 wt % to about 5 wt %, relative to the total weight of the nonaqueous electrolyte solution, i) another lithium-containing salt in an amount of about 0.5 wt % to about 5 wt %, relative to the total weight of the nonaqueous electrolyte solution, and j) mixtures of any two or more of the foregoing.

11. A solution as in claim 8 wherein the electrochemical additive is a saturated cyclic hydrocarbyl sulfate, a cyclic sultone, a tris(trihydrocarbylsilyl) phosphite, or another lithium-containing salt; or a saturated cyclic hydrocarbyl sulfate in an amount of about 1 wt % to about 4 wt %, a cyclic sultone in an amount of about 0.5 wt % to about 4 wt %, a tris(trihydrocarbylsilyl) phosphite in an amount of about 0.2 wt % to about 3 wt %, or another lithium-containing salt in an amount of about 1 wt % to about 4 wt %, each relative to the total weight of the nonaqueous electrolyte solution; or vinylene carbonate, 1,3,2-dioxathiolane 2,2-dioxide, 1,3-propene sultone, 1,3-propane sultone, tris(trimethylsilyl)phosphite, or lithium bis(oxalato)borate.

12-13. (canceled)

14. A solution as in claim 11 wherein each electrochemical additive is not used with other electrochemical additives.

15. A solution as in claim 8 wherein the electrochemical additive is selected from vinylene carbonate, 4-fluoro-ethylene carbonate, tris(trimethylsilyl)phosphite, triallyl phosphate, 1-propane-1,3-sultone, 1-propene-1,3-sultone, 1,3,2-dioxathiolane 2-oxide, 1,3,2-dioxathiolane 2,2-dioxide, 1,5,2,4-dioxadithiane 2,2,4,4-tetroxide, lithium bis(oxalato)borate, and mixtures of any two or more of these.

16. A solution as in claim 15 wherein the electrochemical additive is selected from: vinylene carbonate in an amount of about 0.5 wt % to about 3 wt %, relative to the total weight of the nonaqueous electrolyte solution; vinylene carbonate in an amount of about 8 wt % to about 11 wt %, relative to the total weight of the nonaqueous electrolyte solution; 4-fluoro-ethylene carbonate in an amount of about 0.5 wt % to about 15 wt %, relative to the total weight of the nonaqueous electrolyte solution; tris(trimethylsilyl)phosphite in an amount of about 0.2 wt % to about 3 wt %, relative to the total weight of the nonaqueous electrolyte solution; triallyl phosphate in an amount of about 1 wt % to about 5 wt %, relative to the total weight of the nonaqueous electrolyte solution; 1,3-propane sultone or 1,3-propene sultone in an amount of about 0.5 wt % to about 4 wt %, relative to the total weight of the nonaqueous electrolyte solution; 1,3,2-dioxathiolane 2-oxide in an amount of about 1 wt % to about 4 wt %, relative to the total weight of the nonaqueous electrolyte solution; 1,3,2-dioxathiolane 2,2-dioxide in an amount of about 1 wt % to about 4 wt %, relative to the total weight of the nonaqueous electrolyte solution; 1,5,2,4-dioxadithiane 2,2,4,4-tetroxide in an amount of about 1 wt % to about 4 wt %, relative to the total weight of the nonaqueous electrolyte solution; lithium bis(oxalato)borate in an amount of about 1 wt % to about 4 wt %, relative to the total weight of the nonaqueous electrolyte solution; and mixtures of any two or more of these.

17. A solution as in claim 15 wherein the electrochemical additive is selected from vinylene carbonate, 1-propane-1,3-sultone, 1-propene-1,3-sultone, 1,3,2-dioxathiolane 2,2-dioxide, tris(trimethylsilyl)phosphite, and lithium bis(oxalato)borate; or selected from 1-propane-1,3-sultone in an amount of about 0.5 wt to about 4 wt %, 1-propene-1,3-sultone in an amount of about 0.5 wt % to about 4 wt %, 1,3,2-dioxathiolane 2,2-dioxide, in an amount of about 1 wt % to about 4 wt %, and lithium bis(oxalato)borate in an amount of about 1 wt % to about 4 wt %, each relative to the total weight of the nonaqueous electrolyte solution.

18. (canceled)

19. A solution as in claim 17 wherein each electrochemical additive is not used with other electrochemical additives.

20. A nonaqueous lithium battery comprising a positive electrode, a negative electrode, and the nonaqueous electrolyte solution as in claim 1.

21. A process for producing a nonaqueous electrolyte solution for a lithium battery, which process comprises combining components comprising: i) a liquid electrolyte medium; ii) a lithium-containing salt; and iii) a flame retardant amount of A) tribromoethylene or tribromoneopentyl alcohol, wherein the flame retardant amount is more than 4 wt % relative to the total weight of the solution for tribromoethylene and wherein the flame retardant amount is more than 10 wt % relative to the total weight of the solution for tribromoneopentyl alcohol; or B) a flame retardant mixture of a) 1,2-dibromoethane and tribromoethylene in a weight ratio of about 0.75:1 to about 3:1, or b) tribromoethylene and 2-phenoxy-2,4,4,6,6-pentafluoro-1,3,5,2λ5,4λ5,6λ5triazatriphosphinine in a weight ratio of 0.75:1 to about 2.25:1.

22. A process as in claim 21 wherein iii) is tribromoethylene or tribromoneopentyl alcohol, and the components also comprise iv) at least one electrochemical additive selected from: a) unsaturated cyclic carbonates containing three to about six carbon atoms, b) fluorine-containing saturated cyclic carbonates containing three to about five carbon atoms and one to about four fluorine atoms, c) tris(trihydrocarbylsilyl) phosphites containing three to about nine carbon atoms, d) trihydrocarbyl phosphates containing three to about twelve carbon atoms, e) cyclic sultones containing three to about eight carbon atoms, f) saturated cyclic hydrocarbyl sulfites having a 5-membered or 6-membered ring and containing two to about six carbon atoms, g) saturated cyclic hydrocarbyl sulfates having a 5-membered or 6-membered ring and containing two to about six carbon atoms, h) cyclic dioxadithio polyoxide compounds having a 6-membered, 7-membered, or 8-membered ring and containing two to about six carbon atoms, i) another lithium-containing salt, and j) mixtures of any two or more of the foregoing.

23. A process as in claim 22 wherein the electrochemical additive is selected from vinylene carbonate, 4-fluoro-ethylene carbonate, tris(trimethylsilyl)phosphite, triallyl phosphate, 1-propane-1,3-sultone, 1-propene-1,3-sultone, 1,3,2-dioxathiolane 2-oxide, 1,3,2-dioxathiolane 2,2-dioxide, 1,5,2,4-dioxadithiane 2,2,4,4-tetroxide, lithium bis(oxalato)borate, and mixtures of any two or more of these.

24. (canceled)

25. A process as in claim 21 wherein iii) is tribromoethylene or tribromoneopentyl alcohol, and wherein the flame retardant amount is more than 15 wt % relative to the total weight of the solution; or a flame retardant mixture, and is 1,2-dibromoethane and tribromoethylene, wherein the flame retardant amount is about 6 wt % or more relative to the total weight of the solution; or tribromoethylene and 2-phenoxy-2,4,4,6,6-pentafluoro-1,3,5,2λ5,4λ5,6λ5triazatriphosphinine, and wherein the flame retardant amount is about 4 wt % or more relative to the total weight of the solution; or a flame retardant mixture which is 1,2-dibromoethane and tribromoethylene, and wherein the flame retardant amount is about 20 wt % or more relative to the total weight of the solution.

26-27. (canceled)

28. A process as in claim 21 wherein the liquid electrolyte medium is ethylene carbonate, ethyl methyl carbonate, or a mixture thereof, and/or wherein the lithium-containing salt is lithium hexafluorophosphate or lithium bis(oxalato)borate.

Description

EXAMPLE 1

[0065] Several nonaqueous electrolyte solutions containing either tribromoethylene or tribromoneopentyl alcohol, prepared as described above, were subjected to the modified UL-94 test described above. Results are summarized in Table 1 below; as noted above, the reported numbers are an average value from three runs.

TABLE-US-00001 TABLE 1 Flame Flame retardant Bromine Time to retardant wt % in soln. wt % in soln. Result extinguish Tribromo- 20 18.1 flame  5 s ethylene retardant 10 9.1 flame 16 s retardant 8 7.2 flame 24 s retardant 6 5.4 flame 37 s retardant 4 3.6 fail — Tribromo- 30 22.2 flame — neopentyl retardant alcohol 25 18.5 flame — retardant 10 7.4 fail —

EXAMPLE 2

[0066] Several nonaqueous electrolyte solutions containing mixtures of brominated flame retardants, prepared as described above, were subjected to the modified UL-94 test described above. Results are summarized in Table 2 below; as noted above, the reported numbers are an average value from three runs.

TABLE-US-00002 TABLE 2 Flame retardants A:B Flame retardant Bromine Time to (boiling point) (wt.) wt % in soln. wt % in soln. Result extinguish A. 1,2-Dibromoethane (132° C.) 1:1 6 5.3 flame 25 s B. Tribromoethylene (163° C.) retard. A. 1,2-Dibromoethane (132° C.) 7:3 20 17.4 flame 11 s B. Tribromoethylene (163° C.) retard. A. Tribromoethylene (163° C.)* 1:1 4 3.7 fail — B. Bromoform (150° C.) *Comparative run.

EXAMPLE 3

[0067] Several nonaqueous electrolyte solutions containing mixtures of flame retardants, prepared as described above, were subjected to the modified UL-94 test described above. Results are summarized in Table 3 below; as noted above, the reported numbers are an average value from three runs.

TABLE-US-00003 TABLE 3 Flame retardants A:B Flame retardant Bromine Time to (boiling point) (wt.) wt % in soln. wt % in soln. Result extinguish A. Tribromoethylene (163° C.) 1:1 4 1.8 flame 23 s B. Hishicolin ® O (194° C.) retard. A. Tribromoethylene (163° C.).sup.1 7:3 4 2.5 self-exting. 71 s B. Hishicolin ® O (194° C.).sup.2 Hishicolin ® O (194° C.)*.sup.1, 2 — 6 — flame 38 s retard. — 4 — self-exting. 1 min 17 s — 2 — fail — .sup.1Comparative runs. .sup.2Hishicolin ® O is 2-phenoxy-2,4,4,6,6-pentafluoro-1,3,5,2λ5,4λ5,6λ5triazatriphosphinine (Nippon Chemical Co.).

EXAMPLE 4

[0068] Tests of some nonaqueous electrolyte solutions containing brominated flame retardants in coin cells were also carried out. Coin cells were assembled using nonaqueous electrolyte solutions containing the desired amount of flame retardant. The coin cells were then subjected to electrochemical cycling of CCCV charging to 4.2 V at C/5, with a current cutoff of C/50 in the CV portion, and CC discharge at C/5 to 3.0 V.

[0069] One sample was a nonaqueous electrolyte solution without a flame retardant, and contained 1.2 M LiPF.sub.6 in ethylene carbonate/ethyl methyl carbonate (wt ratio 3:7). The rest of the samples contained the desired amount of flame retardant in the electrolyte solution; some solutions also contained an additive in addition to the flame retardant. Results are summarized in Table 4 below; the error range in the Coulombic efficiencies is about ±0.5% to about ±1.0%. Results reported in Table 4 are averages from multiple cells; “multiple cells” usually means two or three cells.

TABLE-US-00004 TABLE 4 Flame Coulombic efficiency Chemical name retardant Additive Bromine 1st 10th (boiling point) in soln. in soln. in soln. cycle cycle Electrolyte soln.* 0 0 0 81.8% 99.6% Tribromoethylene (163° C.) + 8 wt % 10 wt % 7.2 wt % 32.1%   94% vinylene carbonate (162° C.) Tribromoethylene (163° C.) + 8 wt % 10 wt % 7.2 wt % 8.7% 53.8% 4-fluoro-ethylene carbonate (212° C.) *Comparative run.

EXAMPLE 5

[0070] Additional flammability testing of nonaqueous electrolyte solutions was performed at Sandia National Laboratories. In these thermal abuse tests, a closer approximation was made to the conditions under which electrolytes in abuse conditions need to exhibit non-flammable properties, in particular a cell that is venting in combination with an ignition source. The tests were conducted by filling an 18650-sized battery cell with approximately 5 mL of the nonaqueous electrolyte solution, crimping the cell with a typical cell header assembly, and heating the electrolyte-containing cell at a fixed rate of 5° C./min with a spark-wire ignition source at a fixed position roughly 2 inches above the cell header. At about 200° C., the battery cell began venting, the hot electrolyte solution became aerosolized, and was exposed to the spark-wire ignition source. Each sample was monitored for ignition; non-ignition was considered to pass the test, while ignition of the sample failed the test.

[0071] One sample was a nonaqueous electrolyte solution without a flame retardant, and contained 1.2 M LiPF.sub.6 in ethylene carbonate/ethyl methyl carbonate (wt ratio 3:7). The rest of the samples contained the desired amount of flame retardant in the electrolyte solution. Results are summarized in Table 5 below.

TABLE-US-00005 TABLE 5 Flame retardant Bromine Chemical Name wt % in soln. wt % in soln. Result Tribromoethylene 30 27.2 Pass Tribromoethylene 10 9.1 Pass Hishicolin ® O.sup.1,2 10 0 Pass Tribromoethylene 8 7.2 Pass Tribromoethylene 6 5.4 Fail Tribromoethylene 4 3.6 Fail Tribromoneopentyl alcohol 4 2.96 Fail Hishicolin ® O.sup.1,2 4 0 Fail Electrolyte soln..sup.1 0 0 Fail .sup.1Comparative run. .sup.22-phenoxy-2,4,4,6,6-pentafluoro-1,3,5,2λ5,4λ5,6λ5triazatriphosphinine (Hishicolin ® O, Nippon Chemical Co.).

[0072] Additional embodiments include, without limitation:

[0073] A. A nonaqueous electrolyte solution for a lithium battery, which solution comprises [0074] a) a liquid electrolyte medium; [0075] b) a lithium-containing salt; and [0076] c) a brominated flame retardant, in a flame retardant amount, wherein the brominated flame retardant is selected from tribromoethylene and tribromoneopentyl alcohol.

[0077] B. A solution as in A wherein the flame retardant amount is more than 4 wt % relative to the total weight of the solution, and wherein the brominated flame retardant is tribromoethylene.

[0078] C. A solution as in A wherein the flame retardant amount is more than 6 wt % relative to the total weight of the solution, and wherein the brominated flame retardant is tribromoethylene.

[0079] D. A solution as in A wherein the flame retardant amount is more than 8 wt % relative to the total weight of the solution, and wherein the brominated flame retardant is tribromoethylene.

[0080] E. A solution as in Claim 1 wherein the flame retardant amount is about 8 wt % to about 10 wt % relative to the total weight of the solution, and wherein the brominated flame retardant is tribromoethylene.

[0081] F. A solution as in A wherein the flame retardant amount is more than 10 wt % relative to the total weight of the solution, and wherein the brominated flame retardant is tribromoethylene.

[0082] G. A solution as in A wherein the flame retardant amount is more than 10 wt % relative to the total weight of the solution, and wherein the brominated flame retardant is tribromoneopentyl alcohol.

[0083] H. A solution as in A wherein the flame retardant amount is more than 15 wt % relative to the total weight of the solution.

[0084] I. A solution as in any of A-H wherein the liquid electrolyte medium is ethylene carbonate, ethyl methyl carbonate, or a mixture thereof, and/or wherein the lithium-containing salt is lithium hexafluorophosphate or lithium bis(oxalato)borate.

[0085] J. A nonaqueous lithium battery comprising a positive electrode, a negative electrode, and the nonaqueous electrolyte solution as in any of A-I.

[0086] K. A process for producing a nonaqueous electrolyte solution for a lithium battery, which process comprises combining components comprising: [0087] a) a liquid electrolyte medium; [0088] b) a lithium-containing salt; and [0089] c) a brominated flame retardant, in a flame retardant amount, wherein the brominated flame retardant is selected from tribromoethylene and tribromoneopentyl alcohol.

[0090] L. A process as in K wherein the flame retardant amount is more than 4 wt % relative to the total weight of the solution, and wherein the brominated flame retardant is tribromoethylene.

[0091] M. A process as in K wherein the flame retardant amount is more than 6 wt % relative to the total weight of the solution, and wherein the brominated flame retardant is tribromoethylene.

[0092] N. A process as in K wherein the flame retardant amount is more than 8 wt % relative to the total weight of the solution, and wherein the brominated flame retardant is tribromoethylene.

[0093] O. A process as in K wherein the flame retardant amount is about 8 wt % to about 10 wt % relative to the total weight of the solution, and wherein the brominated flame retardant is tribromoethylene.

[0094] P. A process as in K wherein the flame retardant amount is more than 10 wt % relative to the total weight of the solution, and wherein the brominated flame retardant is tribromoneopentyl alcohol.

[0095] Q. A process as in K wherein the liquid electrolyte medium is ethylene carbonate, ethyl methyl carbonate, or a mixture thereof, and/or wherein the lithium-containing salt is lithium hexafluorophosphate or lithium bis(oxalato)borate.

[0096] R. A process as in any of K-Q wherein the liquid electrolyte medium is ethylene carbonate, ethyl methyl carbonate, or a mixture thereof, and/or wherein the lithium-containing salt is lithium hexafluorophosphate or lithium bis(oxalato)borate.

[0097] Components referred to by chemical name or formula anywhere in the specification or claims hereof, whether referred to in the singular or plural, are identified as they exist prior to coming into contact with another substance referred to by chemical name or chemical type (e.g., another component, a solvent, or etc.). It matters not what chemical changes, transformations and/or reactions, if any, take place in the resulting mixture or solution as such changes, transformations, and/or reactions are the natural result of bringing the specified components together under the conditions called for pursuant to this disclosure. Thus the components are identified as ingredients to be brought together in connection with performing a desired operation or in forming a desired composition. Also, even though the claims hereinafter may refer to substances, components and/or ingredients in the present tense (“comprises”, “is”, etc.), the reference is to the substance, component or ingredient as it existed at the time just before it was first contacted, blended or mixed with one or more other substances, components and/or ingredients in accordance with the present disclosure. The fact that a substance, component or ingredient may have lost its original identity through a chemical reaction or transformation during the course of contacting, blending or mixing operations, if conducted in accordance with this disclosure and with ordinary skill of a chemist, is thus of no practical concern.

[0098] The invention may comprise, consist, or consist essentially of the materials and/or procedures recited herein.

[0099] As used herein, the term “about” modifying the quantity of an ingredient in the compositions of the invention or employed in the methods of the invention refers to variation in the numerical quantity that can occur, for example, through typical measuring and liquid handling procedures used for making concentrates or use solutions in the real world; through inadvertent error in these procedures; through differences in the manufacture, source, or purity of the ingredients employed to make the compositions or carry out the methods; and the like. The term about also encompasses amounts that differ due to different equilibrium conditions for a composition resulting from a particular initial mixture. Whether or not modified by the term “about”, the claims include equivalents to the quantities.

[0100] Except as may be expressly otherwise indicated, the article “a” or “an” if and as used herein is not intended to limit, and should not be construed as limiting, the description or a claim to a single element to which the article refers. Rather, the article “a” or “an” if and as used herein is intended to cover one or more such elements, unless the text expressly indicates otherwise.

[0101] This invention is susceptible to considerable variation in its practice. Therefore the foregoing description is not intended to limit, and should not be construed as limiting, the invention to the particular exemplifications presented hereinabove.