United States Patent (19) (11) 4,208,474 Jacobson et al. 45) Jun. 17, 1980 (54 CELL CONTAINING ALKALI METAL ANODE, CATHODE AND ALKALI OTHER PUBLICATIONS METAL-METALCHALCOGENEDE Hellstrom et al, Phase Relations and Charge Transport COMPOUND SOLD ELECTROLYTE in Ternary Aluminum Sulfides, Extended Abstracts, vol. 78-1, Electrochemical Soc., pp. 393-395, May 75) Inventors: Allan J. Jacobson, Princeton; 1978. Bernard G. Sibernagel, Scotch Plains, both of N.J. Primary Examiner-Donald L. Walton Attorney, Agent, or Firm-Kenneth P. Glynn 73) Assignee: Exxon Research & Engineering Co., Florham Park, N.J. 57 ABSTRACT A novel electrochemical cell is disclosed which con (21) Appl. No.: 974,021 tains an alkali metal anode, an electrolyte and a chalco genide cathode wherein the electrolyte is a solid com 22 Filed: Dec. 28, 1978 position containing an electrolytically active amount of 5ll int. Cl’............................................. HOM 6/18 one or more compounds having the formula: 52 U.S. C. ..................................... 429/191; 429/218 58 Field of Search ................................ 429/19, 218 56) References Cited wherein A is an alkali metal, wherein B is an element U.S. PATENT DOCUMENTS selected from the group consisting of boron and alumi 3,751,298 8/1973 Senderoff............................. 136/6 F num, wherein C is a chalcogen, wherein x and y are 3,791,867 2/1974 Broadhead et al. ................. 36/6 F each greater than zero and wherein x-3y=4. A pre 3,864,167 2/1975 Broadhead et al. ....... ... 136/6 LN 3,877,984 4/1975 Werth .................................. 136/6 F ferred compound is LiBS2. A preferred cell is one hav 3,925,098 12/1975 Saunders ....... ... 136/6 LF ing a lithium-containing anode, a titanium disulfide 3,988,164 10/1976 Liang et al. .......................... 429/191 cathode-active material cathode and the mentioned 4,066,824 la 1978 Rao ...................................... 429/191 electrolyte compound. 4,075,397 2/1978 Francis et al....................... 429/191 4,115,633 9/1978 Kasper et al......................... 429/191 34 Claims, 3 Drawing Figures U.S. Patent Jun. 17, 1980 Sheet 1 of 3 4,208,474 FIGURE OO 2OO 3OO TEMPERATURE (K) Jun. 17, 1980 Sheet 2 of 3 4,208,474 FIGURE 2 OO TEMPERATURE (K) U .S. Patent Jun. 17, 1980 Sheet 3 of 3 4,208,474 FIGURE 3 O O. OOO/T 4,208,474 1. 2 genide cathode, wherein the electrolyte is a solid com CELL CONTAINING ALKALI METAL ANODE, position containing an electrolytically active amount of CATHODE AND ALKALI one or more compounds having the formula: META-METAL-CHALCOGENDE COMPOUND SOLID ELECTROLYTE ABC2 (1) BACKGROUND OF THE INVENTION wherein A is an alkali metal, wherein B is an element 1. Field of the Invention selected from the group consisting of boron and alumi This invention relates to a novel electric current pro num, wherein C is chalcogen selected from the group ducing cell. More particularly, this invention relates to 10 consisting of sulfur, selenium, and tellurium, wherein x improvements in electric current producing cells hav and y are each numerical values greater than zero, and ing alkali metal-containing anodes, electrolytes and wherein x +3y=4. cathodes, wherein the electrolytes are solid materials. The present invention is more specifically directed to DETAILED DESCRIPTION OF THE electric current-producing cells having alkali metal 15 INVENTION containing anodes, solid electrolytes and cathodes con The novel electric current-producing cell of the pres taining one or more chalcogenides as the cathode-active ent invention is a solid state cell which contains an alkali material. metal anode, a chalcogenide cathode and a solid elec 2. Description of the Prior Art trolyte. By "solid state' is meant a cell from which There has been considerable interest in recent years 20 electric current may be drawn at temperatures below in developing high energy density batteries or voltaic the melting point of the electrolyte. cells. Among the systems being investigated are those The anode employed in the cell of the present inven employing nonaqueous liquid, fused or solid electro tion is, as mentioned, one which contains an alkali metal lytes, with lightweight metals, such as alkali metals, as as its anode-active material. Desirably, this anode-active anodes, and with cathodes containing metal chalcogen 25 material is sodium, potassium, lithium, or alloys contain ide compounds. Such systems are described, for exam ing these. It should be noted, therefore, that when the ple, in U.S. Pat. Nos. 3,988, 164; 3,925,098; 3,864,167 and specific alkali metals are recited herein with respect to 3,791,867. the anode, such recitations are meant to include alloys Various efforts have been made to develop new solid of such alkali metals. The anode-active material used in state electrolytes for secondary cell systems. Alkali 30 the anode of the present invention is preferably sodium metal-aluminum-chlorine and alkali metal-aluminum or lithium, and is most preferably lithium. These anode bromine compounds have been utilized in liquid and active materials may, for example, be in contact with molten state electrolyte systems (e.g., as described in other metal structures, e.g., nickel, copper or silver U.S. Pat. Nos. 3,877,984 and 3,751,298) and solid alkali screen, which serve as current collectors and are well metal-aluminum-halogen compound electrical conduc 35 tivity studies have been made. Recently issued U.S. Pat. known in the art. No. 4,066,824 to Rao et al. describes electrochemical The cathode used in the cell of the present invention cells having alkali metal anodes, metal chalcogenide may be any chalcogenide-containing cathode which cathodes, and solid electrolytes, these electrolytes being produces electric current when coupled with an alkali essentially one or more solid alkali metal aluminum metal anode and which will function using the specific tetrahalide compounds. solid electrolyte described herein. A useful chalcoge U.S. Pat. No. 4,115,633 describes cells with ABC nide-containing cathode for the cell of the present in solid electrolytes wherein A is a metallic atom with an vention is one which contains as its cathode-active ma atomic number no greater than 55, B is a group IIIA terial one or more chalcogenide compounds selected metallic atom, C is a group IVA atom, and x and y are 45 from the group. consisting of the sulfides, the selenies, such that the compound is essentially electrically neu and the tellurides of titanium, zirconium, hafnium, nio tral. This reference does not teach the use of boron as a bium, tantalum and vandium. In general, such chalco B-type atom, nor does it specifically teach the use of genides contain about 1.8 to about 3.2 atoms of the aluminum as a B-type atom, albeit aluminum is encom chalcogen per metal atom. Advantageously, these chal passed generically. The patent suggest gallium and in 50 cogenides are the sulfides, the selenides, and the tellu dium as effective B-type atoms and nowhere shows rides of one or more metals selected from the group examples or states specific use of any other B-type consisting of titanium, niobium, tantalum and vanadium. atoms. Further, the cathodes described therein are ele Preferred are the titanium chalcogenides. Among the mental or otherwise non-chalcogenide. Hellstrom et al., chalcogens employed in the chalcogenides used as the Electrochemical Society, Extended Abst., Vol. 78-1, 55 cathode active materials are, as mentioned, sulfur, sele pp. 393-5 (1978) describe the compounds LiAlS2, nium, and tellurium. Of these, sulfur and selenium are NaAl2, KAlS2, Na2S.(9-11)Al2S3, K2S.(9-11)Al2S3 and desired, and sulfur is preferred. Also, among the chalco LiAlsS8 and some ionic conductivity measurements, but genides, those which contain about 1.8 to about 2.1 now where suggest battery utility, much less batteries atoms of chalcogen per metal atom, commonly referred with chalcogenide cathodes. In summary, to date there 60 to as dichalcogenides, are preferred. has been no suggestion that the alkali metal-metal-chal Examples of cathode active materials which may be cogen compounds used in the present invention might useful, and which are selected from the above-men be useful in solid state electrolyte systems having alkali tioned chalcogenides, are titanium disulfide, zirconium metal anodes and chalcogenide cathodes. disulfide, hafnium disulfide, niobium triselenide, tanta 65 lum disulfide, tantalum trisulfide, vanadium disulfide, SUMMARY OF THE INVENTION vanadium diselenide, and vanadium ditelluride. Also A novel electrochemical cell is disclosed which con included are the chalcogenides having more than one of tains an alkali metal anode, an electrolyte and a chalco the mentioned metals, e.g., V0.25, Tio.75, S2.0. Other 4,208,474 3 possible chalcogenides such as iron vanadium sulfide, 1961). Analogous synthesis may be employed for many amorphous vanadium sulfides (e.g. amorphous V2S5), of the other compounds used in the electrolyte of the amorphous molybdenum sulfides (e.g. amorphous present invention as set forth above. MoS3) and the like are also included. In the alternative, the compounds of Formula (1) The cathode-active material used in the cathode of 5 the cells of the present invention, as mentioned, is pref. above may be prepared by direct reaction of the metal erably a chalcogenide selected from those described chalcogen compound with the alkali metal chalcogen above. However, it should be noted that the intercalata compound of the desired product. For example, B2S3 ble chalcogenides are preferred and these chalcogenies may be reacted with Li2S to yield LiBS2. An analogous are such that, in the discharged state they are interca 10 direct reaction technique may be used to prepare other lated and in the charged state they are intercalatable and compounds of the electrolytes used in the present inven contain no measurable intercalated species.