USOO8722005B1 (12) United States Patent (10) Patent No.: US 8,722,005 B1 POShusta et al. (45) Date of Patent: May 13, 2014 (54) SYNTHESIS OF HYDROGEN (58) Field of Classification Search BIS(FLUOROSULFONYL)IMIDE USPC ................ 423/386,388,467:564/82:568/35 See application file for complete search history. (71) Applicants: Joseph Carl Poshusta, Broomfield, CO (US); Jerry Lynn Martin, Superior, CO (56) References Cited (US); Rajendra P. Singh, Broomfield, CO (US) U.S. PATENT DOCUMENTS Inventors: 7,253,317 B2 8, 2007 Cernik et al. (72) Joseph Carl Poshusta, Broomfield, CO 7.919,629 B2 4/2011 Michot (US); Jerry Lynn Martin, Superior, CO 8,134,027 B2 3/2012 Okumura et al. (US); Rajendra P. Singh, Broomfield, 8,377,406 B1 2/2013 Singh et al. CO (US) 2011/0178306 A1* 7, 2011 Michot ......................... 548.101 2012/0041233 A1 2/2012 Sato et al. (73) Assignee: Boulder Ionics Corporation, Arvada, CO (US) * cited by examiner Primary Examiner — Anthony J Zimmer (*) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 Assistant Examiner — Justin Bova U.S.C. 154(b) by 0 days. (74) Attorney, Agent, or Firm — Don D. Cha; Hamilton DeSanctis & Cha, LLP Appl. No.: (21) 13/951,973 (57) ABSTRACT (22) Filed: Jul. 26, 2013 The invention provides a method for producing hydrogen bis(fluorosulfonyl)imide (HFSI) by reacting hydrogen bis (51) Int. C. (halosulfonyl)imide (HXSI) with hydrogen fluoride, where COIB 2/086 (2006.01) each X is independently a nonfluoro-halide, such as Cl, Br, or C07C303/00 (2006.01) I. (52) U.S. C. USPC ..... - - - - - - - - - - - - - - - - - - - - - - - - - - - 423/386; 564/82:568/35 20 Claims, 2 Drawing Sheets : *.... 3-...-- : . * {3:3:32:3: S 3:5:::::: U.S. Patent May 13, 2014 Sheet 1 of 2 US 8,722,005 B1 Sixxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx S. IGIRI[]©IAI ~*~ zzzzzzzzzzzzzzzzzzzzzzz,3% $$4 U.S. Patent May 13, 2014 Sheet 2 of 2 US 8,722,005 B1 xxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx ZGIRI[15)IH US 8,722,005 B1 1. 2 SYNTHESIS OF HYDROGEN degradation product. More significantly, the inventor con BIS(FLUOROSULFONYL)IMIDE cludes that “... the synthesis of HFSI with HF is not satis factory.” (Emphasis added). FIELD OF THE INVENTION Accordingly, there is a need for a relatively safe and/or simple method for producing a high yield of hydrogen bis The present invention relates to a method for producing (fluorosulfonyl)imide. hydrogen bis(fluorosulfonyl)imide (HFSI) from hydrogen bis (halosulfonyl)imide (HXSI) using hydrogen fluoride, where SUMMARY OF THE INVENTION X is a nonfluoro-halide. 10 As stated above, U.S. Pat. No. 7,919,629, discloses that the BACKGROUND OF THE INVENTION reaction between HCSI and HF is not a satisfactory method to produce HFSI. The bis(fluorosulfonyl)imide anion (FSI) is useful in vari Surprisingly and unexpectedly, in contrast to U.S. Pat. No. ous applications including electrolytes in electrochemical 7.919,629, the present inventors have found that under appro devices such as batteries and capacitors. The present inven 15 priate conditions, a high yield, e.g., at least 80% yield, of tion is directed at the synthesis of hydrogen bis(fluorosulfo HFSI can be obtained using HF and hydrogen bis(halosulfo nyl)imide (HFSI), which is a useful intermediate for salts and nyl)imide (HXSI, where each X is independently a non-fluo ionic liquids containing this anion. rohalide such as Cl, Br, or I). One particular aspect of the Hydrogen bis(fluorosulfonyl)imide, its corresponding invention provides a method for producing a high yield of salts and ionic liquids comprising the FSI anion have been hydrogen bis(fluorosulfonyl)imide (HFSI) from hydrogen bis shown to be useful in a wide variety of applications including, (halosulfonyl)imide (HXSI) using hydrogen fluoride. It was but not limited to, as electrolytes in lithium ion batteries and discovered by the present inventors that HFSI yield of at least ultracapacitors. Hydrogen bis(fluorosulfonyl)imide is a rela 80%, typically at least 95%, often at least 98% and more often tively strong acid and forms various stable metal salts. The 25 at least 99% can be achieved using HF. In the formula above, lithium salt of bis(fluorosulfonyl)imide (i.e., LiFSI) has X in HXSI is a nonfluorohalide, e.g., each X is independently shown to be particularly useful in batteries and ultracapaci Cl, Br, or I, often X is C1. tOrS. Despite the advantages of compounds containing the FSI BRIEF DESCRIPTION OF THE DRAWINGS anion, the corresponding salts and ionic liquids thereof, no 30 large scale commercial production exists. While many pro FIG. 1 is a schematic illustration of one particular embodi cesses for producing HFSI are known, each of the known ment of a continuous stirred-tank reactor (“CSTR) for HFSI methods for synthesizing HFSI has disadvantages. For synthesis with distillation and recycle. example, one method for synthesizing HFSI uses urea FIG. 2 is a schematic illustration of one particular embodi (NHCONH) and fluorosulfonic acid (FSOH). One of the 35 ment of a continuous HFSI production reactor system. major disadvantages for this process is the toxicity and cor rosiveness of fluorosulfonic acid. Moreover, it is difficult to DETAILED DESCRIPTION OF THE INVENTION control this reaction due to local overheating during the addi tion of fluorosulfonic acid to the reaction mixture. This diffi Synthesis of HFSI has been demonstrated by multiple culty in controlling the reaction results in an unpredictable 40 routes including in a commonly assigned U.S. Pat. No. 8,377, yield of the desired product. 406, which discloses inter alia fluorination of hydrogen bis Another method for synthesizing HFSI involves fluorinat (chlorosulfonyl)imide (HCSI) using bismuth trifluoride. ing bis(chlorosulfonyl)-imide (i.e., HCSI) with arsenic trif As discussed above, attempts by others to produce HFSI luoride (AsF). In this reaction, HCSI is treated with AsF. from HCSI using anhydrous HF resulted in a relatively low Arsenic trifluoride is toxic and because it has a high vapor 45 yields and impure products. See, for example, U.S. Pat. No. pressure, it is particularly difficult to handle on an industrial 7.919,629, issued to Michot. In fact, U.S. Pat. No. 7,919,629 scale. A typical reaction uses 1:8.6 ratio of HCSI to AsF. This unequivocally states that “the synthesis of HFSI with HF is means a large excess of highly dangerous arsenic trifluoride is not satisfactory.” Col. 36, line 67. The best yield obtained in used. U.S. Pat. No. 7,919,629 was 55% at 130° C. for 2 hours. See HFSI can also be prepared by the fluorination of HCSI with 50 Table on Col. 36, lines 50-60. antimony trifluoride (SbF). The antimony trichloride Surprisingly and unexpectedly, under proper conditions byproduct of this reaction has both high solubility in HFSI the present inventors were able to achieve a substantially and a very similar boiling point, making it very difficult to higher yield of HFSI by reacting a hydrogen bis(halosulfo separate from the desired product. The product of this reac nyl)imide (HXSI, where each X is independently a nonfluo tion is also typically contaminated with chloride, which ren 55 rohalide such as Cl, Br, or I) with hydrogen fluoride. As used ders the product unsuitable for electrochemical applications. herein, when describing a chemical reaction, the terms “treat One of the simplest reactions for producing HFSI is to react ing”, “contacting and “reacting are used interchangeably hydrogen bis(halosulfonyl)imide (HXSI) with hydrogen herein, and refer to adding or mixing two or more reagents fluoride, where X is a nonfluoro-halide. However, this reac under appropriate conditions to produce the indicated and/or tion has been reported to produce a relatively poor yield and 60 the desired product. It should be appreciated that the reaction involved reacting HCSI with excess anhydrous HF at high which produces the indicated and/or the desired product may temperature. See, for example, U.S. Pat. No. 7,919,629. In not necessarily result directly from the combination of two particular, Example 10 of U.S. Pat. No. 7,919,629 discloses reagents which were initially added, i.e., there may be one or reacting HCSI with anhydrous HF at various temperatures. more intermediates which are produced in the mixture which The best yield was 55% at 130° C. for 2 hours. Some reaction 65 ultimately leads to the formation of the indicated and/or the was observed after 12 hours at 30 and 50° C. (<10% yield). desired product. In fact, using methods disclosed herein, the The inventor of this patent observed fluorosulfonic acid as a desired HFSI can be produced from HXSI and HF in at least US 8,722,005 B1 3 4 80% yield, typically at least 95% yield, often at least 98% added is more than 1 equivalent, often at least 1.5 equivalent, yield, and more often at least 99% yield. more often at least 2 equivalents, and still more often at least In some embodiments, the reaction also produces HX. In 2.5 equivalents. some instances, the step of reacting HXSI with HF also com The reaction temperature for methods of the invention is at prises removing HX that is produced in the reaction. Typi least that of the boiling point of HX that is produced. In this cally, the boiling point of HX is lower than that of HF added. manner. HX that is produced can be easily removed from the Therefore, HX can be removed by simple distillation or reaction mixture by distillation or evaporation. Since the boil evaporation. Any HF that may evaporate or distill during the ing point of HF is higher than HX, any HF that is also evapo process of removing HX can be condensed and returned back rated or distilled can be condensed back into the reaction 10 mixture by using a condenser of appropriate temperature.