LBL-20211 ~~\ Lawrence Berkeley Laboratory UNIVERSITY OF CALIFORNIA RE<...r::lv~r., LA'IfRENCE
APPLIED SCIENCE r·l LJ v 2u ·1sss
DIVISION LI& CHEMICAL AND OPTICAL PROPERTIES OF ELECTROCHROMIC NICKEL OXIDE FILMS C.M. L-ampert, T.R. Omstead, and P.C. Yu August 1985 TWO-WEEK LOAN COPY is is a Library Circulating Copy ~;~~ ch may be b.@f.~ed for two weeks. t•'·,.•. V:... -- };~~~- _.- ·'" ' --~·- APPLIED SCIENCE DIVISION Prepared for the U.S. Department of Energy under Contract DE-AC03-76SFC0098 DISCLAIMER This document was prepared as an account of work sponsored by the United States Government. While this document is believed to contain correct information, neither the United States Government nor any agency thereof, nor the Regents of the University of California, nor any of their employees, makes any warranty, express or implied, or assumes any legal responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by its trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or the Regents of the University of Califomia. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof or the Regents of the University of Califomia. LBL-20211 EEB-W 85-13 W/OM-202 Presented at the SPIE's 29th Annual International Technical Symposium on Optical and Electro-Optical Engineering, San Diego, CA, 18-23 August, 1985. 1 ... CHEMICAL AND OPTICAL PROPERTIES OF ELECTROCHROMIC NICKEL OXIDE FILMS C. M. Lampert, T.R. Omstead, and P .C. Yu Applied Science Division and Materials and Molecular Research Division Lawrence Berkeley Laboratory University of California Berkeley, California 94720 August 1985 This work was supported by the Assistant Secretary for Conservation and Renewable Energy, Office of Building Energy Research and Development, Build ing Systems Division of the U.S. Department of Energy under Contract No. DE AC03-76SF00098. Olemical and Optical Properties of Electrochrani.c Nickel Oxide Films C. M. Iairpert, T.R. anstead*, P. C. Yu Applied Science Division and Materials and Molecular Research Division, Lawrence Berkeley Laboratory, University of california, Berkeley, calif. 94720 U.S .A. Abstract 'lhin films of nickel oxid~nickel hydroxide are investigated to detennine electrochranic switching proper ties. Crystalline nickel oxide films are synthesized by electrochemical deposition and by arxxlization of nickel electrodes. Electrochemical deposition using nickel sulfat~based chemistry is used to deposit films directly on doped tin oxide-coated glass. Spectral solar transmittance is obtained for films switched in liquid cells containing a I Introduction 'lhe prcprrty of electrochranism. is very i.nportant to the develcprent of larg~area optical shutters and infornation displays, where switching speed is not a key CCt'lSideration. Fran a building energy efficiency viewpoint in regard to glazings, the ability to dynamically control the i.nccmi.ng solar radiation either in the visible or near-infrared spectral regions is very attractive. Also, electrochranism has importance to future autarotive and aerospace glazings. Electrochranism is known to occur in several transition-netal oxides. A fe.~ reviews on the subject detail the outccme of different investigations (1-4). Oliefly, tungsten oxide (~) and hydrated iridium oxide (IrOx'nH20) have been studied in~ detail. As for the other oxides, such as NiOOx'nH~ and MnOx'nH2o, very little is la1cwn atout their electrochranic properties (5). 'lhe characteristics ·of electrochrani.sm are rra.nifested by a reversible color change, usually switching fran an uncolored state to a colored one, as a result of an aJ_:plied electric current. Electrochranic rraterials exhibit both chemical and optical changes by dual ion and electron ejection or injection. As a result, color centers are fortred in the rraterial that produce optical adsorption in the visible wavelength region. Also, in certain cases, large changes in electrical ocnfuctivity can occur causing significant infrared reflectivity switching effects (6). Coloration of an electroc:hrani.c material can occur on either the cathodic or arxxiic cycle. Fbr nickel oxide, coloration occurs by chemical oxidation during anodization. A very i.nportant pro perty of electrochranic films is that they exhibit mixed ocnfuctivity, both electrcnic and ionic, in which ions can be. rapidly and reversibly inserted in step with injected or ejected electrons (7). As a rratter of exanple, it is i.nportant to detail the switching effect of the electrochranic layer in an actual solid-state device structure. Shaom in Figure 1 is the cross section of a typical solid-state device. AlthJugh other configurations exist, including liquid electrolytes in place of the ion conductor, this exanple serves to daronstrate the device call>lexity. In this fi~layer rrodel there is synmetry atout the ion conduc tor. lbth the electrochranic layer and ccunter-electrode (ion storage rredia) exhibit mixed ionic and elec tronic conduction. These layers are flanked by transparent conductors ·(SrlO:!:F, Cl or rn~3 :sn), which serve as electrical conduct.ors. The ionic conduct.or provides a rrediiill by which ions can be transported between the elect.rochrani.c layer to the CCI..Ult.er-electrode depending upon the polarity of the aJ_:plied potential. As a result, a reversible ionic reaction bet:loleen the electrochrani.c rraterial and ca.mter-electrode allows for the apprcpriate CFtical switching effect. Before the developnent of such a device, it is iitp;)rtant to fully characterize the electrochemical and optical properties of the electrochranic rraterial. In the follcwing experiments, nickel oxide film properties are determined by techniques of voltanmetry, sputter Auger spectros copy. x-ray photoelectron spectroscopy (XPS, ESCA.), and optical ~ . •Orrrently with Univ. of Minnesota, Dept. of Olemical Engineering and Material Science, Minneapolis, MN. 55455. Cross-Section of a Electrochromic Optical Shutter · Current Pulse HES, NIR - + 25 Nl (OH)2=NIOOH + H• + e· (A) (B) Transparent lon Conductor Conductor Transparent State Reflective or Opaque State 750 HES: High Energy Solar Radiation (O.~.n ,..m) NIR: Near Infrared Radiation (O.n-2 ,..m) Potential (mV) vs SHE lA: Infrared Radiation (2·100 ,..m) XBL 852-6957 Figure 1. Schematic cross section of an electro Figure .2. Cyclic voltanmetry of NiO/ Ni electrod~ chromic optical shutter. in 1M KOH solution after twelve cycles. Ex}?eri.mental Procedures In this study both net.allic nickel electrodes and transparent conductive oxide-ooated glass electrodes were used. 'lhe rret.al electrode was made fran a 1.59-mn nickel plate (0.999 p.~re). It was polished with sili con carbide paper (in sequence fran 180-600 grits) folla.led by 6-micra1 diai!DOO paste and finished by a series of alunina abrasives (in sequence fran 1 to 0.3 to 0.05 microns). Distilled water was used as a lubricant for polishing. To provide electrical cx:ntact, a nickel wire was spot welded at to the back of the electrode. By using a scanning potentiostat, Princet.al Applied :Research Model 362, a cx:ntrolled wavefunction was applied to the electrode. Electrooxidatiat was adlieved by using a sawtooth wavefunction alternating between -800 rrW and +1800 rrfoJ in a 1M KOH electrolyte. 'lhe wavefunctiat was nonitored by an oscillos~, and the voltage was rronitored by a !!Ult.ilreter. After several hours of cyclic oxidatiat of the electrode, visible opt ical switching was observed at the surface. 'lhe observed coloratiat was fran transparent (rret.allic) to bronze. Also, it was observed that the electrode, when rerroved fran the bath, could last a fe.t hours in the colored state with negligible fading. 'lhe second group of experiments was dale on fl"IX)I"ine doped tin oxide-coated glass. 'lhe tin oxide (SI"l02: F, Cl) ooating was produced by cx:nventional chemical vapor depositiat, involving hydrolysis of SnC4 and NH4F (8). 'lhis ooating had a sheet resistance of llO 0/sq., and a c:qJper wire was attached to the conductive coating with silver epoxy. 'lhe elect.rochemical working solutiat used to deposit the nickel oxide was a mixture of O.lM NiS04 .6H2o and O.lM Nli4Cti at 2J<>c. A platinun electrode served· as the counter-electrode. 'lhe applied potential was a sawtooth wavefunct.iat fran -275 rrW to +750 rrfoJ at 0.1 Hz frequency. 'lhe nickel hydroxide film fonred after three cycles. After rinsing in distilled water, the electrode was transferred to an:Jther electrolyte of 1M KOH. In this bath elect.roc:hranic !Jofi.t.ching oc:cured after at least twelve cycles at +200 rrW to +900 rrW (SHE). Depen:ling upon the exact cxnliticns of depositiat, the electrode could remain o.rt. of solutiat in its colored state for several haJ.rs before fading. nte electrode color ranged fran transparent to dark bronze. Other bath c:x:rtp)Siticns were experimented with before the former was developed. A bath cx:nsisting of O.IM NiS04 "6H2'J. O.IM NaAc, and O.OOIM KOH urder the same ccn:llticns made acceptable films but provided less uni fornri.ty in the deposit. Another bath cx:nsisted of 0.45M Ni(NJ3 ) "6H2'J, and 1. 75M Nacti. It provided good uni fornri.ty but lesser stability than the sulfate baths. Spectral transmittance rreasurerrents were made to investigate the cptical respcnse of the films. Spectral data were obtained at a Perkin Elmer Lmbia 9 spect.rqXlot.ar fran 2()()-3200 1"111. The chemical c:x:rtp)Sitiat of the ccnduct.ive electrode was analyzed with the Scanning Auger Microprobe, Phy . ·sical Electronics Inc., Model 590. A pri.nBry beam energy of 5 keV was used. 01emical depth profiles were obtained by usW -2- X-ray photoelectron spectroscopy (Physical Electronics Inc., fot:>del 548) was used to analyze the chemical states of the various elemental species. The spectrometer was calibrated so that the gold 4F712electron bind ing energy was at 83.8 eV, and adventitious carbon occured at 284.4 eV ± 0.1 ev. Magnesium x-ray radiation at 400 W was used as the excitation radiation. Results and Discussion ~is section is divided into two major parts. The first part concerns results on the nickel electrode. The second portion details studies on the nickel oxide/tin oxide/glass electrode. \) Nickel Electrode Study Electrochemical information was obtained by cyclic voltalmletry of the electrooxidized nickel electrode. '<.J The scanning potentiostat was used with a triangle potential from 0-800 mV (SHE) at 23°C The cell was IR com pensated, and the 1M KOH electrolyte was purified of oxygen by nitrogen gas saturation. In Figure 2, the results of this experiment are shown for sweep characteristics of 20 mV/sec after twelve cycles. The anodic peak (B) at 625 mV corresponds to-Ni(OH) 2 NiOOH + H+ + e-, and the cathodic peak (A) at 500 mV corresponds to NiOOH + W + e--> Ni (OH) 2• These reactions have been observed by various authors (9-14). The electrooxida tion sequence begins with nickel metal (Ni), which is electrooxidized by an anodic potential occurring at +500 mV (SHE) resulting in the formation of NiO or Ni (OH) 2 ruring this process the nickel surface has been transformed from Ni--> Ni(II). In the voltammogram shown in Figure 2, the first anodic peak (B) corresponds to electrooxidation of. Ni (II)--> Ni (III), forming a nickel oxyhydroxide phase such as fi-NiOOH. ~e next anodic peak corresponds to oxygen evolution (750- 775 mV). For the cathodic cycle, electroreduction of Ni(III) yields Ni(II), identified as NiO or Ni(OH) 2 These compounds can be further electroreduced to nickel only at high cathodic potentials. Sr------.------.------~ -Ni. ,,,...... , --0 I' ' ! .,I' ' ' ' ' ' ' ' ...... 0 0.5 -----1 1.5 Sputter Time (min) Figure 3. Auger sputter depth profile of NiO/ Ni of E'*VY (eV) its peal< to peal< intensities showing nickel a.OO oxy- , gen as a func;ion of depth fran the surface (sputter Figure 4a. Auger electron spectroscopy of NiO/ Ni rate is 1000 A/min for Ta:f>s) • electrode, as received. ?) .. , .. ~L---~---~--~---...--~---- ..~--~-- ...~~~--~ Ill .. .. Ill .... e..., (eV) EMrgy (eV) Figure 4b. Auger electron spectroscopy of NiO/ Ni Figure 4c. Auger electron spectroscopy of NiO/ Ni after 15 seconds of argon-ion sputtering. after 60 seconds of argon-ion sputtering. -3- :··-···-····--·-.. -····-···------··-···-···--Sn .... ! ·~ 2 F ,. 1- :r------<\\ lr.. (::::..·~-.i'' I \'--'\ \/ -~ 0 · I\~ s; ...:::, 0 200 400 600 800 1000 0 2 3 4 v SPUTTER TIME (nl\) Electron energy (eV) Figure Sa. Auger sputter depth profile of Si'l02:F, Cl/glass electrode of its peak to peak intensities Figure 5b. Auger electron spectroscopy for SnOi:F, showing uniformity in composition (sputter rate is Cl/glass electrode surface. 0 400 A/min for Ta2o5). •u c"' c ::l 0 ~ u e "2 0.5 •c .'::! co ~• E z0 Energy (eV) wavelength (nm) Figure 5c. X-ray photoelectron spectroscopy of tin Figure 6a. Norna! spectral visible transmittance of 3d electrons in Sn02:F, Cl, showing the characteris electroc:hranic NiO/S~: F, Cl/glass in bleached and tic binding energies. colored states: Tv (bleached) = 0. 77 and Tv (colored) = 0.21. oL · i 0,(0) I Ni (OH)2 = NiOOH + W + e ; r A i Cl u ' c ~ l L j e~ ' • ~ c ' ;=.. I i ~ \\ -; 1100 1300 1100 2300 2100 3200 .: •• : Wavelength (nm) ! -; -·~ Figure 6b. Nornal ~ral solar transmittance of ... TOO electrochran.ic NiO/Sn0 :F, Cl/glass in bleached and Potent'-! (mV) va. SHE - 2 - colored states: T5 (bleached) = o. 73, Tg (oolored)= 0.35, TNIR (bleached)= 0.72, and 'INIR (oolored) = Figure 7. Cyclic vol tammetry of NiO/Sn02:F, 0.55. Cl/glass electrode after twelve cycles. -4- The separation of the oxygen evolution potential fran the coloration (B) and bleaching (A) potentials, which ·is evident for nickel oxide, is an i.np:>rtant factor in the production of a practical solid-state optical switching device based on proton transfer. F\lrthernore, for coloration and bleaching of the electrode, only an instantaneous pulse of current is required for the reversible transfornation. Auger spectroscx:py and x-ray protoelectron spectroscx:py (XPS, ESCA) were used to obtain chemical infonna tion alxlut the electrode in the bleached (dehydrated) cx:ntition. A dlemical depth profile for oxygen and nickel was obtained by sequential argcn-ion sputtering and Auger electron analysis. These results are shewn in Figure 3. A full survey analysis is given for different ·depths into the film as sho.m in Figure 4a-c. Three general regions are noted in the oxide: (1) a surface layer containing a high concentration of oxygen and inplrities (Figure 4a), (2) a nickel oxide region (Figure 4b), and (3) a graded nickel-nickel oxide inter \) face (Figure 4c). The principle electronic transitions are N~ = 61, 102 eV, NiJ Transparent Tin Oxide Electrode Study Nickel oxide fil.ns were deposited onto doped tin-oxide coated glass electrodes. Since doped tin oxide was used in place of metallic nickel, it was :inportant to characterize this material. Using sputter Auger tech niques, a chemical analysis of this electroge was made. The sputter depth profile is shoom in Figure Sa. It was taken at a sp1tter rate of about 400 A/min. The Auger elemental survey for an as-received condition is depicted in Figure Sb. Fran these results, the principle CCI!pJSition was determined to be sne :F, Cl. The 2 Auger transitions were. <1 After electrochemical deposition of nickel oxide on the tin oxide substrate, solar and visible transmit tances were neasured using a spectrc:photaleer. CJloration was obtained by applying a one-volt pulse poten tial at 0.1 Hz. The film was rerroved fran the electrolyte and then rinsed in distilled water witb:lut effect ing coloration. ~tical spectra are shoom in Figures 6a and 6b for the visible and solar regions, respec tively. By integration with respect to the solar (11M2) (17) and photopic spectra (hunan eye visible response) (18), the folla.ring values were obtained for photopic transmittance and solar transmittance: Tp (bleached) = 0.77, Tp (colored) = 0.21, Ts (bleached) = 0.73, and Ts (colored) = 0.35. If the solar near-infrared is integrated separately (11M2), the values are TNIR (bleached)= 0.12 and TmR (colored)= o.ss. Also, the pro perties of the substrate coated with tin oxide were measured; they are Ts = 0. 74, Tp = 0.80, and TNIR = o. 11. Therefore in the bleached state, the nickel oxide only slightly alters the optical properties of the tin oxide-coated glass electrode. Volt.amretry was performed on the nickel oxide/tin oxide electrode under the san-e conditions as for the metal electrode. As depicted in Figure 7, the anodic peak occurs at 630 mJ and the cat:b:xtic peak occurs at 500 mJ. Oxygen evolution occurs at alxlut 750 mJ. This volt.arrmJgram is very similar to that noted for the oxidized nickel electrode and lacks the anodic sho.llder, thought to be caused by inplrities. Olemical analysis of the elect.rcde was detennined by Auger spectrosoopy and x-ray protoelectron spectros copy. An Auger depth profile is shown in Figure Sa. Here again near the surface is a highly oxidized inp.lr i ty region. This is followed by the nickel oxide regi.al and the interfacial region beO.Ieen nickel oxide and tin oxide. A survey Auger scan after 15 secaxls of sputtering is shown in Figure 8b. This survey details the nickel i.nplrities to be dllorine, carbon, and nitrogen. Argon was i.nplanted fran the sp1tter beam. 'It> further probe the nickel oxide dlemistry, x-ray protoelectron spectroscopy was enployed. Fran this study, the binding energy of the adventit.icus cartx:n ls .electron was noted at 284.7 ev. OJring calibration, adventitia.tS carbon ls occurred at 284.4 eN, so sanple charging ancunts to the energy difference. The shape and position of the nickel aro oxygen peaks are depicted in Figures 9 and 10, respectively. Q:::rlp!ritive bi.rrli.ng energies are shown in Table l. This data correlates well to 'known energies for NiO by other investigators (19-22), but there have been sare nickel electrode studies that i.nii.cate further c::arplexity for this reaction (23, 24) · The nickel hydroxides all fonn a layered structure where there are alternate layers of nickel and hydroxide ions. There exist two Fhase5, d and a for Ni(OH)2, and a and Y for NiCXE. These phases play an .intxJrtant role in the electro1e reaction and quite probably in the electrodlranic insertion of ar or: injection of ft". -5- Table I. XPS Bindi~ Energies for NiO and Ni Compounds* Material Ni2p312 Satellite Ni2p112 Satellite 2J.s- Ref. (ev)-- (ev)-- (eVJ 'Ibis 'w'Ork 854.7 860.7 872.7 878.7 530.5 NiO 854.3 861.5 529.7 19 NiO 854.4 529.5 20 NiO 855.0 861.1 873.0 879.8 21 ~' \ Ni(OH)2 856.4 862.2 531.5 19 '.I \o Ni (OH) 2 855.7 531.2 22 Ni 852.3 869.7 16 *A!l data adjusted for charging and differences in calibration. 7 6 5 .:Jt:ca &! 4 11.1 0 1!z .:Jt:- -sn '0 ca :. ----oNl Nl Energy (eV) Sputter Time (min) Figure Sa. Auger sputter depth profile of Figure Sb. Auger survey of NiO/ 51'10:!: F, Cl/glass Ni0/Sno2 :F, Cl/glass electrode of its peak to peak elect.rcx:le. intensities (sputter rate in TatJs = 1000 A/min). 1.0 1.0 N1 2p c"' 112 c"' :::l ::s 0 0 <.) <.) ,,!\ "0 Q) 0.5 al·o.5 ~ N (ij fa E E z0 \ z0 Multiplet Satellites ' 0 0 888 8 7 3 838.8 542 530.5 517.4 Energy (eV) Energy (eV) Figure 9. X-ray photoelectron spectroscopy of Figure 10. x-ray photoelectron spectroscopy of oxy nickel 2p electrons in NiO, showing the characteris gen is electron in NiO, showing the characteristic tic binding energies. binding energy. -6- Calclusial. As a result of these CCJ!i:>ined studies, it has been detennined that nickel oxide can exhibit favorable electrochrani.c switching properties for possible use for windcw glazings. By electrochenical techniques, nickel oxide can be groom on nickel el~es or deposited onto a oc:n:iuct.ive oxide such as sna2 : F, Cl on glass. '!be optical properties of a 500 A NiO/ S~:F, Cl/ glass electrode were Tp (bleached) = 0. 77 and Tp (colored) = 0.21, and Tg (bleached);:: 0.73 and Ts (colored) = 0.35. '!be electrochenical properties of both types of electrodes were detennined by cyclic volt.anm:!try. FOr both the metal and transparent electrode, the voltanmet.ry shewed the electrochranic switching reactioo. to be Ni(OH)2 <-> NiOOH + a++ e-. '!be chemistry of the electrodes has been detennined to be a hydrated fonn of NiO. ·Further research is clearly necessary, espe cially with regard to nickel oxide/ hydroxide fil.nB on transparent electrodes, which have not been studied in detail prior to this "WOrk. Cbntirued studies . utilizing electroo. microsc::xv.f and infrared spectroscopy is planned, in order to detennine the exact phases of nickel oxide/ hydroxide fil.nB. '!be authors wish to thank Dr. B. Beard, K. Gaugler, and Dr. s. Cogan (EIC Labs, NoniOCld, Mass.) for their help with ESCA analysis, scanning Auger microprobe, and electrochenistry, respectively. A special thanks goes to Steve Selkaori.tz, Prof. J. washblrn, and Dr. T. Sands (Bell Cbrporate Research Labs, Murray Hill, N.J.), for supporting this effort. 'Ibis "WOrk was performed at the Lawrence Berkeley Lalx>ratory, Materials and ~:).ec ular Research Division, I.D'lder a joint program with the Applied Science Divisioo.. '!be "WOrk was fi.D'lded by the Assistant Secretary for Cbnservatioo. and Renewable Energy, Office of Solar Heat Technologies, Passive and Hybrid Solar Energy Divisioo. of the Depart:ment of Energy I.D'lder a:mtract No. IE-Aa:>3-76SFOOQ98. References 1. I..anp:!rt, c. M., ''Electrochranic Materials and Devices for Energy Efficient Wi.ndcMs," Solar ~ Materials, Vol. 11, p.l, 1982. 2. Dautrerront-smith, w.c., "Transitioo. Metal Oxide Elect.rochranic Material and Displays: A Review," Displays, Vol. 4, p.3, 1982. 3. Clang, I. F., in Ncnemissive Electrcc:pt.ic Displays, I 4. Fangham, B. W. , and Crandall, R. S. , in Topics in Applied PhysiCS, Vol. 40, Pank.ove, J. I. , edit. , Springer-Verlag, Berlin, 1980. 5. Mcintyre, J. D., Peak W. F., and Scholartz, G. P., ''Electrochranism in HydroJs Nickel OXide Fil.nB," Elec tronic Materials Conference Abstract, D-4, 1979. 6. Goldner, R. B., et al., "High Near Infrared Reflectivity foobdulation with Polycrystalline Electrochranic \1103," Afplied l'hysics Letters, Vol-43, p. 1093, 1983. 7. Vashistita, P., Mundy, J. N. ,and Shency, G. K., Fast Ioo. Transport in Solids, North-fblland, Amsterdam, '!be Netherlands, 1979. 8. l..a!Tp:!rt, C. M., "Materials Olenistry and ~cal PI-operties of Transparent Conductive '!bin Films for SOlar Energy Utilizatioo.," Ind. En;;. Chern. Prcxl. Res. Dev., Vol. 21, p. 612, 1982. 9. Schrebler-Guzman, R. S., Vildle, J. R., and Arvia, A. J., "'llle Potentiodynami.c Behavior of Nickel in f) Potassiun Hydroxide SOlutioo.s," J. Aa>L Electrc:x:hem., Vol.B, p.·67, 1978 • .d 10. weininger, J. L., and Brei.ter, M. w., "Effect of crystal Structure oo. Ancd.ic Oxidatioo. of. Nickel," J. Electrochem. Soc., Vol. llO, p. 484, 1963. 11. weininger, J. L., and Breiter, M. w., "Hydrogen Evolutioo. ·and Surface OXidation of Nickel Electrodes in Alkaline Solutioo.s," J. Electrochem. Soc., VoL lll, p. 707, 1964. 12. MacArthur, D.M. , '"nle Hydrated Nickel Hydroxide Electrode Potential SWeep Experirrents I Of J. Electrochem Soc., Vol.ll7, p. 422, 1970 .. 13. Briggs, G. W. D., and Fleischmann, M., Trans. Faraday Soc., VoL 67, p. 2397, 1971. -7- 14. Schrebler-Guzman, R. s., Vilche, J. R., and Arvi.a, A. J.,"'lbe Kinetics and Mechanism of the Nickel Elec trodeiii, 'lbe Potentiodynami.c Response of Nickel Electrodes in Alkaline Solutioos in the Potential Region of Ni(OH)2 Fornation," corrosion Science, Vol. 18, p. 765, 1977. 15. Handtook of Auger Electron Spect:rosc:xJpY, Physical Elect.rati.cs Industries, Eden Prairie, MN., 1976. 16. wagner, C. D., Riggs, W. M., Davis, L. E., and fobllder, J. F., Handtx::dc of X-Ray Pl¥Jtoelectron Spectres ~· Physical Electronics Industries, Eden Prairie, MN., 1979. 17. Bird, R. E., and lillstran, R. L. "Additicnal So.lar Spectral Data," Solar Cells, Vol. 8, p. 85, 1983. 18. Barnes, F. A., edit., ICAElectro-Optics Handtx::dc, ICACorporation, Harrison, NJ., 1974. r- 19. Kim, K. s., Baiti.nger, w. E., M¥· J. w., and Winograd, N;, "ESCA Studies of Metal-Qxygen Surfaces using Argon and Oxygen Ion Bc:lttlardloont," J. Elect. Spect.. and Fel. Phenan., Vol. 5, p. 351, 1974. i.' 20. Kim, K. S., and Davis, R. E., "Electron Spectroscx:v.f of the Nickel-oxygen System," J. Elect. Spect.. and Fel. Phenan., Vol. 1, p. 251, 1972/73. 21. Matienzo, L. J., Yin, LD. I., Grim, S.D., and SWartz, Jr., W. E.," X-Ray Photoelectron Spectroscx:v.f of Nickel Ccltp:Junds," Inorg. Chern., Vol. 12, p. 2762, 1973. 22. Mcintyre, N. S., am.rery, T. E., Cl:xlk, M.G., and Q,ren, D., "X-Ray Photoelectron Spectrosoopic Study of the Aqueous OXidation of foobnel 400," J. Electroc:!lEm soc., VoL 123, p. 1164, 1976. 23. Bode, H., Del'lnelt, K., and Nitte, J. "Zur Kenntnis der Nickelhydroxidelelektrode- I Uber daS Nickel (II) Hydroxidhydrat," Electrodlim Acta., Vol. 11, p. 1074; 1966. 24. Oliva, P., et al., "Review of the Structure and the Electrodlemistry of Nickel Hydroxides and OXy Hydroxides," J. Pooler Sources., Vol.8, p. 229, 1982. -8- This report was done with support from the Department of Energy. Any conclusions or opinions expressed in this report represent solely those of the author(s) and not necessarily those of The Regents of the University of California, the Lawrence Berkeley Laboratory or the Department of Energy. Reference to a company or product name does not imply approval or recommendation of the product by the University of California or the U.S. Department of Energy to the exclusion of others that may be suitable. -1) (,. _..., ...~ ...... -·- LAWRENCE- BERKELEY LABORA TORY TECHNICAL INFORMATION DEPARTMENT UNIVERSITY OF CALIFORNIA BERKELEY, CALIFORNIA 94720