text: the invention is based on the observation that excellent electrolytic loading results are obtained for nickel electrodes by first anodically dissolving nickel from a conducting nickel structure using an anodic electrical pulse and then precipitating the dissolved nickel using a cathodic electrical pulse . this was done in an electrolytic solution containing ions believed to reduce the protective nature of surface films on the nickel metal ( believed to be an oxide layer ) to permit dissolution of the nickel metal . the process can be carried out on any nickel structure useful for nickel electrodes in battery cells but is most conveniently carried out on nickel plaques conventionally used for nickel electrodes . such electrodes are useful in a wide variety of battery cells including nickel - hydrogen cells , nickel - cadmium cells , nickel - zinc cells , and nickel - iron cells . also included in the invention are batteries with one or more cells as described above ( i . e ., with nickel electrodes made in accordance with the invention ). a large variety of conducting nickel structures may be used in the practice of the invention . the structure should contain significant amounts of nickel , say 30 or 50 or 90 percent nickel by weight . also , it is preferred that the conducting nickel structure be porous ( preferably porosities of from 60 - 90 percent porosity ) so that a high surface area of nickel is exposed for conversion and preferably the porous nickel plaques should be nearly pure nickel ( at least 99 percent by weight ). as stated above , the electrolytic solution should contain sufficient electrolyte for a conductivity of at least 0 . 001 mho - cm and a substance which promotes anodic dissolution of nickel . various salts might be added to improve conductivity . preferred for the composition of the electrolytic solution is an aqueous solution containing a halide ion , preferably bromide or chloride with chloride most preferred . although any convenient cation can be used in the electrolytic solution , generally an alkali - metal ion ( potassium , sodium , etc .) is most convenient . more than one cation and / or anion may be used . concentration of halide ion may vary over large limits consistent with the minimum conductivity of the solution set forth above and possible precipitation of the salt in the nickel plaque . a typical range is from 0 . 01 molar to saturation or just below saturation , with the range from 0 . 1 to 2 molar preferred . most preferred , especially for kcl is from 0 . 2 to 1 . 2 molar . generally , the process is not extremely sensitive to ph particularly in the range from slightly acidic ( 6 . 0 ) to slightly basic ( 8 . 0 ). inside the plaque , nickel that has been anodically dissolved during the anodic part of the cycle is precipitated during the cathodic part of the cycle due to an increase in the concentration of oh - ions . an important part of the conversion process is repeated cycling of the electrode potentials so as to expose the nickel plaque alternately to anodic and cathodic potentials . for convenience , these varying potentials are often spoken of as anodic and cathodic pulses but the exact nature of the potential variation is not of particular importance as long as the nickel plaque is exposed to anodic and cathodic potentials . indeed , the plaque need not be connected to a power supply . for example , putting the plaque in close proximity to one or more electrodes may be sufficient and in some cases may be preferred . the frequency of the cycling may vary over large limits . typical values are in the range from 0 . 01 to 100 hz with 0 . 1 to 10 preferred and 0 . 2 to 2 . 0 most preferred . total cycles may vary over large limits and depend on the type of conducting nickel structure used as well as other variables . total cycles between 400 and 4000 are typical . both too few cycles and too many cycles tend to reduce discharge capacity from maximum values . the anodic pulses are used to dissolve some of the nickel from the plaque ( believed to be divalent nickel ) and the cathodic pulse to precipitate the dissolved nickel as the active material . it is believed that the precipitate is in the form of nickel hydroxide . the potentials of the various pulses may vary over large limits provided the anodic potential is sufficient to dissolve the nickel and the cathodic pulse is sufficient to precipitate the dissolved nickel . generally , an anodic potential more positive than 0 . 1 volts on the hydrogen scale ( nhe ) is used and a cathodic potential more negative than 0 . 0 volts ( nhe ) is used . more positive anodic potentials and more negative cathodic potentials may be used to increase rate , current , etc . the impregnation process is usually monitored by observing the current passing in each direction . the exact waveform of the potential is not generally of importance . a sinusoidal variation is often convenient but a square wave is often more convenient for monitoring the impregnation process . various other waveforms including asymmetric waveforms are also useful . the ratio of anodic to cathodic charge in a given cycle may vary between 10 and 0 . 1 . a number of experiments were carried to demonstrate the usefulness of the impregnation procedure . a variety of counter - electrodes may be used ( graphite , titanium , platinum , stainless steel , etc .) but in these experiments graphite was used . the plaque was an eagle pitcher ni sintered on a wire mesh support with overall thickness of 0 . 030 inches and an exposed area of one centimeter squared . the plaque was electrically connected to a conventional galvonostat ( model 371 eg and g ) was used together with a square waveform generator . after cycling , the electrodes were washed in distilled water and charged and discharged in 30 percent koh at 2 ma / cm 2 ( foil electrodes ) or 250 ma / cm 2 ( ep - sinter ) capacities were calculated on discharge to ˜ 0 . 0 v ( nhe ). the reference electrode was a cathodically charged pd / pdh x wire or a standard calomel electrode . the results of some of these experiments are summarized in table i . ______________________________________summary of electrolytic loading experiments peak dischargesolution freq . curr . total capacitycomp . ( hz ) ( ma ) cycles ( coulombs ) ______________________________________1 . 0 m kcl 1 . 0 + 500 500 16 . 5 - 2501 . 0 m kcl 1 . 0 + 500 1000 19 . 0 - 2501 . 0 m kcl 1 . 0 + 500 500 7 . 5 - 1751 . 0 m kcl 1 . 0 + 500 500 24 . 5 - 3251 . 0 m kcl 1 . 0 + 500 500 33 - 5001 . 0 m kcl 1 . 0 + 500 500 26 - 6001 . 0 m kcl 1 . 0 + 650 1000 22 . 5 - 3251 . 0 m kcl 1 . 0 + 750 500 21 . 0 - 3751 . 0 m kcl 1 . 0 ± 225 1111 31 . 01 . 0 m kcl 1 . 0 ± 300 833 34 . 51 . 0 m kcl 1 . 0 ± 375 667 33 . 01 . 0 m kcl 1 . 0 ± 425 588 33 . 51 . 0 m kcl 1 . 0 ± 375 434 29 . 51 . 0 m kcl 1 . 0 ± 300 1600 491 . 0 m kcl 1 . 0 + 300 1600 37 - 2001 . 0 m kcl 1 . 0 ± 300 2400 64 . 51 . 0 m kcl 1 . 0 ± 300 3200 691 . 0 m kcl 1 . 0 ± 225 4400 681 . 0 m kcl 1 . 0 ± 400 2500 691 . 0 m kcl 1 . 0 ± 400 1400 611 . 0 m kcl 1 . 0 ± 400 1600 611 . 0 m kcl 1 . 0 ± 500 1000 571 . 0 m kcl 1 . 0 ± 500 1200 621 . 0 m kcl 1 . 0 ± 500 1400 631 . 0 m kcl 0 . 5 ± 150 1200 51 . 51 . 0 m kcl 0 . 5 ± 150 1400 581 . 0 m kcl 0 . 5 ± 150 1600 641 . 0 m kcl 0 . 5 ± 150 1600 671 . 0 m kcl 0 . 5 ± 150 1800 751 . 0 m kcl 0 . 5 ± 150 2000 70 . 51 . 0 m kcl 0 . 5 ± 150 2000 761 . 0 m kcl 0 . 5 ± 150 3200 72 . 50 . 2 m kcl 0 . 5 ± 150 2000 371 . 0 m kcl 0 . 5 ± 100 2000 541 . 0 m kcl 0 . 5 ± 100 2500 641 . 0 m kcl 0 . 5 ± 100 3000 681 . 0 m kcl 0 . 5 ± 200 800 501 . 0 m kcl 0 . 5 ± 200 975 551 . 0 m kcl 0 . 5 ± 200 1000 591 . 0 m kcl 0 . 5 ± 200 1200 75 . 51 . 0 m kcl 0 . 5 ± 200 1400 701 . 0 m kcl 0 . 5 ± 200 1600 781 . 0 m kcl 0 . 5 ± 250 700 521 . 0 m kcl 0 . 5 ± 250 800 601 . 0 m kcl 0 . 5 ± 250 900 671 . 0 m kcl 0 . 5 ± 250 1000 711 . 0 m kcl 0 . 5 ± 250 1000 651 . 0 m kcl 0 . 25 ± 75 1600 66 . 51 . 0 m kcl 0 . 25 ± 75 3200 82 . 51 . 0 m kcl 0 . 25 ± 100 1600 83 . 51 . 0 m kcl 0 . 25 ± 125 800 62 . 51 . 0 m kcl 0 . 25 ± 125 1000 721 . 0 m kcl 0 . 25 ± 125 1200 811 . 0 m kcl 0 . 25 ± 125 1600 131 . 0 m kcl 0 . 25 ± 150 700 62 . 51 . 0 m kcl 0 . 25 ± 150 800 721 . 0 m kcl 0 . 25 ± 150 900 301 . 0 m kcl 0 . 25 ± 175 600 671 . 0 m kcl 0 . 25 ± 200 400 511 . 0 m kbr 0 . 25 ± 125 1000 491 . 0 m kbr 0 . 25 ± 125 1400 551 . 0 m kbr 0 . 25 ± 175 1200 801 . 0 m kbr 0 . 25 ± 225 600 601 . 0 m kbr 0 . 25 ± 225 800 781 . 0 m kbr 0 . 25 ± 225 1000 761 . 0 m kbr 0 . 25 ± 275 600 731 . 0 m kbr 0 . 5 ± 200 1600 381 . 0 m kbr 0 . 5 ± 250 1000 65______________________________________ as can be seen from table i , excellent nickel impregnation capacities can be obtained using the inventive process . both asymmetric and symmetric waveforms may be used but symmetric waveforms yield greater capacities under conditions of these experiments . lower frequencies ( 0 . 25 hz ) also seem to yield higher capacities but the dependence is not strong and other conditions ( i . e ., frequency , electrolyte , concentration , etc .) might affect that conclusion . a sinusoidal variation is often convenient but a square wave is often more convenient for monitoring the impregnation process . various other waveforms are also useful . a particularly convenient way of carrying out the impregnation process is illustrated in fig1 . fig1 shows an apparatus 10 useful for the impregnation of nickel plaques by a contactless process . it is made up of a container 11 filled with electrolytic solution and equipped with two inert electrodes ( generally made of an inert metal such as platinum , platinized titanium , etc .). the potential of these electrodes 13 and 14 is varied from anodic to cathodic by use of a varying source of current 15 ( generally a galvanostat with waveform generator ). the nickel plaque 16 to be impregnated is located between the two electrodes 13 and 14 . the varying potentials on the electrodes produce varying potentials on the plaque to be impregnated so as to produce anodic dissolution of the nickel followed by cathodic production of hydroxyl ions to precipitate the dissolved nickel . fig2 shows several components of a typical alkaline battery 20 , namely cadmium battery . the negative electrode 21 is a cadmium electrode . the positive electrode 22 is a nickel electrode made by impregnation in accordance with the invention . also shown are separators between electrodes used to electrically insulate the negative electrode from the positive electrode . here the separators are made from micro - porous polymeric material . a multiplicity of such positive electrodes and negative electrodes may be assembled so as to make up a completed battery . the electrolyte in this particular battery is a 30 percent by weight koh in water . in fabricating such a battery the individual electrodes are usually formed ( electrolytically cycling the electrodes several times ) and then assembled in the discharged condition . on charging , the battery becomes ready for use .