[1]UNITED STATES PATENT OFFICE.@ JOHN -iVI. PETERSON, OF DA@WSON, A!INNESOTA. PROCESS FOR FORTILING SECONDARI 7-BATTERY 3?LATES. 1,375,317. Specifica'cion of Letters Patent. Patented Apr. 19, No Drawing. Application filed September 18, 1918. Serial No. 254,614. l'o cill,tvhog?i, it ma.y colt,-ern: B-1 it kiioavn that 1, JOIIN M. PETE@RSON, a ei-'C;zen )f the United St,,ites of Americi 7 resic@,ing ,it Dai@,son, in ttie county o'L L,,ic qui Pai-le ancl St,,tte of Minnesota, hive invented @@eAv aii(i usef Li! Inii)rovemeiits ill Processes TOr L '@'orming Secoi@claryB,,tttery Plates, of the 'ollov@,,ing is ,t specification. .L S'Lora(,o battery pl,,ttes ire oi- two types, 10 'Llie F,,i,-Lire type aiad tlio Pl,,tnt'e type. The u I ,)resen@' 'r-.Yention is directed ,tt the la+ter z Lype, ,ii,-! its principal purpose is to 'rovicle p a lieiv aii(I iiovel process -elor -l'orming tl-ie pl@,lte @o ti,@at tii opIL-'Imui-ii mty @,e obtai-necl 15 iii tli,,, m,,ttter of the meeli-,tnical strength o'L t'ite Dlate ancl the ,Lctive mal@-erial proclueed 't'hercon. Orio-in,,tllv PI,-,-Tit6 plates were form,.-d by 51 ',Zisem@lino'them in sets and sLibject'iDg 20 he,,tvy --,heets of le,@td to ,t chargincr clirrent Nvhen in ,t stilf-Liric ,teid sol-Lition. The cell ttilis formed was @@lien clisch,,trged and slibsequently recharged in tjae opposite direetion, being clischarged and recharged 25 in the origin,,il clirection' By repeated el-iargings, and disch,,trgings and reversals the surfoces of the plaq'es were so thoroughly att,,Lckecl by the oxygen ,ts to corrode or oxidize its s-Lirftee. 'Cells formecl in this 30 map-iier -while very durtble gave a very lo-w efficiency in ampere ho-Lirs per polind o.'L le,,td due. to tl-ie f ,ict that the s-Lirf aces of the plate, were pl,,tin ,tncl only ,tllo-wed It Small - ,LmoLint of tetive m,,iteri,,il to be corrodecl or oxidizecl 35 from the s-Lirf,,tee. I-lowever the Nery greqt (lisaclv,,int,,tge o-l' this process was that it reqi.iii,ecl a very large anaount of electric current anci several months' time to produce and - w,qs therefore not a commercially practical 40 one. This tedio-Lis ,i-nd expeiisive process Of fc)i-ming h,,is been su-oorsecled by ,t pickliiio, tre-.ttment ol' the hetvy pure leacl pl,,ttes. The pl,,,.tes are first immersed in ,tpproxi45 m-,itely a fifty . per cent. sollit ion of ,tqueous nitric acid for a prescribed lenath of titne monia ,tfter which they are treated wiih am ancl baked in an ove-n at high temper,,ttlire the pickling b,,tth being, of co-Lirse, to re5o d-Lice the plates to ,t poro-Lis or spono;y state. It matters not bow c,,trefully or with what skill the pick@ing operation is perform,-d, it is next to impossible to completely remove ever ic .y p,,irt' le of the pickling ,teid or 55 er,,Ldicate its deleterious effects ancl, where but i little remains, the pl@Lte is attacked by it with the resullu- th,,tt t'ne life of t'lle piite is gre,,ttly shor'u-ened. Thus the picl-ili-iit pi:ocess of foi-miiio, plites of which the above is b-Lit one of M,,tiiy used while short- 60 ening the operatioii, lias the clis,,tdvant,,tge of 1 some o4L@ tli's le',Id attticking teid ill ti-le plates with the rec,,Lilt th use the In plttes rapidly corrode with the result that they are soon eate:n away -,tnd hive to be re- 65 placed. in the present inventioii it is plirposed to spin, roll cut, or cist the usual Plant6 plttes or prepare them iii iny otlier m,,iiiner whereby a maxim-Lim sui@@' be obt,,tined, 70 L,,,.ce area may the se plttes hiving sui@.cient strpngtli to me et the -vLrio-Lis -,Yarping or bending sti @esses to which they wolild be subjecteot by reason of the thickness Itnd solidit3, of the plates in carrying out the Plant@, idet 75 o-I provicling a su-fficient body of lead to c,,i rry on t forming process of active m,@tteri,,t l is the oriai--R,,tl active material is o@rtdual ly clisintegr,.tted and los'L from the plltes. Th e pl,,ttes are then given a coatino, of 80 mi nium or red le-,td (Pb,04) or ox'Lcl-Piterall y pain,-ecl-af4Ler which they @tre IlloN'Ve(l to dty. When dry the plttes Lire re,@tdy for for mi@.ig and Ire il)-ereupon iinmel-,sed in an ele ctrolyte-preferably an aqueous Sol-Lition 85 o'i sulfuric acicl-and stibjeefed to ,t chargirg c-Lirrent when fie red leid or oxid on tios e pli,,tes constittiting the tiriodo is peroxidi zed 'ormino- lead peroxid (PbO,). At the same time 11 '@-lie red le,,td oii the cathode 90 is reclticecl-first 'U-o I lower oxid and then to sl)on,-y met@,)Ilic leid. The re le-,Ld thus ,tcts ts the initi,,tl ,ictive mat eri,,tl and, ,is the cell of which the plates are parts is used, this initial active m,,tte- 95 rial 'Ltlls away from the plates as is uii,tv oid,@ible in the operetion of the cell, but slo wly onouuh to -Dej,jp-it the ele-,trolyte to ,itt, -.ck and o-,@,-icliz@ the p-Lire lead benelth, ti-iLis mtinttining the Plftnt6 icti6n of cre,,tt@t oo ;,iA g active ma-@,ei-ia,l in progression with the op erc ttive wastage of such materi,,tl, within the limits oi '@,he q7Ligntity of pure lead - v@,hich forms the body of the pltte. Not having been disintegr,,tted by a pickling acid, 105 the pure lead is found to be -,resh when the ele ctrolvte extends its ,tction to the surfaces of the plates Linderlying the initi,,tl active ri mat 6 'al. The structure of the plates is liot )ve akened by the application of the red lead 110
