I
`
`Umted States Patent [191
`Babjak et al.
`
`[11] Patent Number:
`[45] Date of Patent:
`
`.
`
`4,957,543
`Sep. 18, 1990
`
`OTHER PUBLICATIONS
`Nickel-Jun. 1988, Nickel Foam Metal Continues to
`Find New Applications Beyond Reach of Most Metals, Dr.
`Gen-ichi Nakazawa.
`Journal of Applied Electrochemistry-Oct. 21, 1987,
`Flow-Through and Flow-By Porous Electrodes of Nickel
`Foam, I. Material Characterization, S. Langlois & F.
`Cosmet
`Non-Nuclear Energy Technology, Jun. 1981, Develop
`men; of Gas Phase Metalh-zed Plaques for Electrodes of
`Storage Batten-es’ in Particular for Nickel Oxide E1ec_
`trodes, R. Linkohr and H. Schladitz, Rpt. #= BMFT-F
`B_T 31453‘
`Primary Examiner—Melvyn J. ‘Andrews
`Attorney, Agent, or Firm-Francis J. Mulligan, J11;
`Edward A. Steen; Blake T. Biederman
`
`[57]
`
`-
`
`-
`
`ABSTRACT
`'
`
`-
`
`The lnve‘mim Pmvldes a mck‘?‘ f°am an‘! ‘? meth°d °f
`forming a mckel foam for a n1ckel contaimng battery.
`A“ °P°n'°°11 f°am structure is Placed in a nickel “81'
`bonyl 888 containing Structure The foam Structure is
`heated to a temperature at which nickel carbonyl de
`composes. Nickel from the nickel carbonyl gas decom
`poses on the foam structure to form a nickel plated foam
`structure. The nickel plated foam structure is then sin‘
`tend leavmg an °p°n'°°u mckel netwmk t° f°rm the
`nickel foam. The open-cells of the nickel foam comprise
`substantially hollow wires having a substantially uni
`form transverse cross-section. The nickel foam is fur
`ther characterized by the conductivity through the
`nickel foam multiplied by a factor of 3.4 being equal to
`or greater than the theoretical conductivity of nickel.
`
`~
`
`-
`
`9 Claims, 6 Drawing Sheets
`
`0D 0F F0
`I
`1
`54
`[75] Inventors:
`
`G NI
`
`FOAM
`.
`
`S
`
`1 m o
`
`lmssauga’
`
`[73] Assignee: Inco Limited, Toronto, Canada
`
`[21] Appl‘ No‘: 368’193
`[22] Filed:
`Jun. 16, 1989
`
`[51] Int. CL5 ...... .1 ................. .. C228 5/20; B22F 1/00
`[52] US. CL .................................... .. 148/13; 428/614;
`429/235; 75/",15
`[58] Field of Search .......................... .. 75/20 F; 419/2;
`428/614; 429/235
`
`[56]
`
`References Cited
`U.S_ PATENT DQCUMENTS
`
`2,986,115 5/1961 Toulmin, Jr. ....................... .. 118/48
`3,075,494 1/ 1963 Toulmin, Jr. . . . . .
`. . . .. 118/495
`
`3,111,396 11/1963 131111 ................... .. 75/20 F
`3 160 517 12/1964 Jenkin
`117/93 3
`31213527 10/1965 Jenkin I:
`1:: 118/495
`3,769,086 10/1973 Schladitz . . . . . .
`. . . . .. 117/228
`3,877,987 4/1975 Gutjahr et a1.
`136/29
`3,900,646 8/1975 Clyde .................. ..
`427/55
`4,25l,603 2/1981 Matsumoto et al. ..
`429/94
`1,2231%;
`L'Fkwltz et al
`4,761,323 8/1988 Muhlratzer et al. .............. .. 428/198
`
`,
`
`,
`
`1bsees ............... ..
`
`.
`
`FOREIGN PATENT DOCUMENTS
`101681 8/1983
`151064 8/1985
`128543 11/1978
`17977 2/1979
`123942 8/ l982
`263974 11/1987
`
`European Pat. Off. .
`European Pat. Off. .
`Japan .
`Japan .
`Japan .
`Japan .
`
`36
`
`R.J. Reynolds Vapor
`IPR2016-01268
`R.J. Reynolds Vapor v. Fontem
`Exhibit 1030-00001
`
`

`

`US. Patent Sep. 18,1990
`
`Sheet 1 of6
`
`4,957,543
`
`FIG. 1
`
`R.J. Reynolds Vapor Exhibit 1030-00002
`
`

`

`US. Patent Sep.18,1990
`
`Sheet 2 of6 '
`
`4,957,543
`
`FIG. 3
`
`R.J. Reynolds Vapor Exhibit 1030-00003
`
`

`

`US. Patent Sep. 18,1990
`
`Sheet 3 0f 6
`
`4,957,543
`
`FIG.4
`
`FIG. 5
`
`R.J. Reynolds Vapor Exhibit 1030-00004
`
`

`

`US. Patent Sep. 18, 1990
`
`Sheet 4 of 6
`
`4,957,543
`
`FIG.6
`
`R.J. Reynolds Vapor Exhibit 1030-00005
`
`

`

`US. Patent Sep. 18, 1990
`
`Sheet 5 of 6
`
`4,957,543 ~
`
`FIG. 7.’ _
`
`m
`
`E 2500 X\
`‘f
`l
`
`x
`
`2000
`
`>
`
`'
`
`\
`
`:
`
`‘ 1500
`
`8
`
`E 2
`f- 1000
`U
`
`a
`g 500
`U
`
`x '
`
`F \
`‘
`
`I
`
`\4‘
`
`c94
`
`95
`
`S7
`96
`FOAM POROSITY (°/<,)
`
`98
`
`99
`
`X~NICKEL FOAM OF THE INVENTION
`I-ELECTROCHEMICAL NICKEL FOAM
`-— l/3 THEORETICAL CONDUCTIVITY
`
`R.J. Reynolds Vapor Exhibit 1030-00006
`
`

`

`US. Patent Sep. 13, 1990
`
`Sheet 6 of 6
`
`4,957,543
`
`FIG.8
`
`5
`
`£4
`E
`
`V
`
`I
`p:
`
`‘z’ u
`
`[I
`'
`‘"2
`
`3
`
`6
`z‘
`LLI'
`‘..
`
`C
`95
`
`Xil
`
`I
`
`T
`
`X
`
`Xi‘
`
`X
`
`x
`
`A
`
`X
`
`97.5
`97
`95.5 96 96.5
`POROSITY (°/,)
`
`96 98.5
`
`X-NICKEL FOAM OF THE INVENTION
`(23.6 CELLS PER LINEAR CM)
`A-NICKEL. FOAM OF THE INVENTION
`(31.5 CELLS PER LINEAR CM)
`I-ELECTROCHEMICAL NICKEL FOAM
`
`R.J. Reynolds Vapor Exhibit 1030-00007
`
`

`

`1
`
`METHOD OF FORMING NICKEL FOAM
`
`15
`
`20
`
`25
`
`4,957,543
`2
`It is an object of this invention to produce a nickel
`foam having improved conductivity.
`It is a further object of this invention to produce a
`nickel foam having improved mechanical properties at
`higher porosity levels.
`It is a further object of this invention to produce a
`nickel foam having a smaller pore size and more uni
`form structure for improved battery performance.
`It is a further object of this invention to provide an
`effective method of forming nickel foams with the
`above improved properties.
`SUMMARY OF THE INVENTION
`The invention provides a method of forming nickel
`foam. An open-cell foam structure of thermally decom
`posable material is placed in an atmosphere containing
`nickel carbonyl gas. The foam structure is heated to a
`temperature at which the nickel carbonyl gas decom
`poses. Nickel from the nickel carbonyl gas is decom
`posed on the foam structure to form a nickel plated
`foam structure. The nickel plated foam structure is then
`sintered to remove the foam structure from the nickel
`plated foam structure leaving an isotropic, open-cell
`network of interconnected nickel wires to form the
`nickel foam.
`In addition, the invention provides a battery plaque of
`interconnected open-pore cells. The open-pore cells are
`comprised of substantially hollow nickel wires having a
`substantially uniform cross-section. Conductivity
`through the nickel structure is characterized by actual
`conductivity across the reticulated nickel network mul
`tiplied by a factor of 3.4 being about equal to or greater
`than the theoretical conductivity of nickel.
`
`The invention relates to the ?eld of nickel foams.
`More particularly, the invention relates to nickel foam
`battery plaques having improved conductivity, poros
`ity, foam cell size, capacity to hold active mass, strength
`and a method for producing the improved battery
`plaques.
`BACKGROUND OF THE INVENTION AND
`PROBLEM
`Battery plaques have conventionally been formed by
`sintering nickel powder onto a coated steel plate. Poros
`ities achieved in the sintered plaque have been generally
`. limited to porosities in the 80% range. These 80% range
`porosities, in turn, limit the amount of active mass that
`may be held in the plaque which limits the battery ca
`pacity. Low porosity and decreased capacity for hold
`ing active mass has long been a problem limiting the
`battery performance.
`Nickel plaques having increased porosity for batteries
`have been experimentally formed by chemical vapor
`deposition of nickel carbonyl on carbon felt. The bat
`tery plaques were formed by depositing nickel onto a
`carbon felt substrate and using the nickel coated felt
`substrate to support active mass. There are several
`problems with the carbon felt process. First, carbon felt
`is relatively expensive for the manufacture of batteries;
`second, the cell size of felt structures varies widely
`within the felt itself and is difficult to control for ?~
`brous, felt-type structures; third, the carbon felt sub
`strate remains in the battery; and fourth, the process
`was not satisfactory for polymer coated felts. Previous
`35
`experimental attempts at chemical vapor deposition of
`polymer ?bers for batteries produced a product having
`an inferior nickel coating having inferior mechanical
`stability which was unsuitable for battery plaques.
`Recently, in an attempt to overcome the low porosity
`problem, nickel battery plaques have been produced by
`an alternative electrochemical method (Matsamoto US.
`Pat. No. 4,251,603). Nickel is electroplated onto a poly
`urethane foam and sintered to form nickel foam. Before
`plating may be conducted, polyurethane foam is made
`45
`conductive by immersion of the foam into a colloidal
`graphite dispersion and drying the foam. This nickel
`foam has increased porosity for increasing the amount
`of active mass battery plaques can support.
`Nickel foam, formed by electrochemical technique,
`has been produced by Sumitomo Electric Industries
`under the name CELMET TM and by SORAPEC
`under the name METAPORE TM . The CELMET TM
`nickel foam has a highly irregular surface when magni
`lied about 100 times. The electrical conductivity of the
`electrodeposited nickel foam is lower than the expected
`conductivity as a function of porosity due to the intrin
`sic structure of the electroplated nickel layer. The
`poorer conductivity e?'ects battery output, recharging
`rates and battery overheating during recharging.
`Additionally, electrochemically plated nickel foam
`had less than ideal mechanical properties at high porosi
`ties. These lower mechanical properties at higher poros
`ities limit the amount of active mass that may be reliably
`used in a battery without premature battery failure. A
`65
`battery plaque formed with electrochemical nickel
`foam having too high a porosity would cause the plaque
`to have weak mechanical properties.
`
`30
`
`DESCRIPTION OF THE DRAWING
`FIG. 1 is a scanning electron microscope (SEM) >
`photomicrograph of a transverse cross-section of a
`nickel carbonyl plated foam magni?ed 30 times;
`FIG. 2 is a SEM photomicrograph of the cell struc
`ture of electrochemically deposited nickel foam at l50
`times magni?cation;
`FIG. 3 is a SEM photomicrograph of a cross-section
`of electrochemically deposited nickel foam at 150 times
`magni?cation;
`FIG. 4 is a SEM photomicrograph of the cell struc
`ture of nickel carbonyl deposited nickel foam at 150
`times magni?cation;
`FIG. 5 is a SEM photomicrograph of a cross-section
`of nickel carbonyl deposited nickel foam at 150 times
`magni?cation;
`FIG. 6 is a schematic drawing of an apparatus for
`producing nickel foam by decomposing nickel carbonyl
`onto foam and sintering the coated foam;
`FIG. 7 is a graph of conductivity versus porosity for
`electrochemically plated nickel foam and the nickel
`foam of the invention; and
`FIG. 8 is a graph of ultimate tensile strength versus
`porosity for electrochemically plated nickel foam and
`the nickel foam of the invention.
`_
`
`PARTICULAR DESCRIPTION OF THE
`INVENTION
`Referring to FIG. 1, the reticulated open-cell struc
`ture of the invention is continuous and uniform. The
`uniform structure is a result of decomposition of nickel
`carbonyl vapor onto a reticulated or open-cell foam.
`The nickel coated foam is then sintered to “burn off’
`the enclosed foam, leaving an isotropic network of open
`
`50
`
`55
`
`R.J. Reynolds Vapor Exhibit 1030-00008
`
`

`

`4,957,543
`3
`'
`nickel cells known as nickel foam. It has been discov
`ered that battery plaques formed by the method of the
`invention have superior properties over battery plaques
`formed by sintering and electrochemical techniques.
`Theoretically, energy requirements for nickel foam
`produced by chemical vapor deposition are less than the
`energy requirements for electrochemical deposition of
`nickel.
`Improvements of the invention are dramatically illus
`trated by comparing electrochemically deposited nickel
`foam of FIGS. 2 and 3 to nickel foam of the invention of
`FIGS. 4 and 5. FIG. 2 illustrates an irregular, bumpy,
`nodular deposit of nickel. These nodules of nickel and
`especially weaker points connecting the nodules, are
`suspected to create areas of inef?cient electrical con
`ductivity which increase the internal resistance of the
`battery plaque. Additionally, FIG. 3 illustrates actual
`discontinuities or holes within the nickel conductor
`wire of the nickel foam. These holes and especially
`weak points connecting the nodules, are also suspected
`of causing inef?cient conductivity in battery plaques.
`Additionally, it is believed that this irregular shape of
`the electrochemical deposit contributes to mechanical
`weakness of the nickel foam. By contrast, FIGS. 4 and
`5 illustrate a-continuous smooth uniform deposit with
`out any visible holes. The nickel carbonyl deposit of the
`invention has been proven to have unexpectedly im
`proved qualities. The nickel carbonyl deposited nickel
`foam has both improved conductivity and improved
`mechanical properties. This improved conductivity and
`improved mechanical properties should facilitate a sig
`ni?cant improvement in battery performance by lower
`ing internal battery resistance, and increasing the
`amount of active mass a plaque will hold in a battery
`without mechanical failure.
`Referring to FIG. 6, the apparatus set up for coating
`foam with nickel carbonyl initially appears to be fairly
`simple. A carbon monoxide supply 10 feeds carbon
`monoxide gas to nickel carbonyl (N i(CO)4) supply auto
`clave l2. Ni(CO)4 gas in nickel carbonyl supply auto
`clave is maintained at a desired temperature from about
`10° C. to about 38° C. Feed gas concentration resulting
`from pick~up of nickel carbonyl in carbon monoxide
`ranges from about 20 to about 90 percent nickel car
`bonyl by volume and from about 10 to about 80 percent
`carbon monoxide by volume. Ni(CO)4 gas from auto
`clave 12 enters the coating chamber 14. Optionally, HZS
`gas or another catalyst may be added to the coating
`chamber 14 to promote nickel plating.
`The coating chamber 14 is supplied with continuous
`strips of foam 15. The foam 15 utilized may be any
`reticulated or open-pore foam. The reticulated foam
`may be polyurethane, polystyrene, polyvinylchloride,
`polyethelene, polyiocyanurates, polyphenols or poly
`propylene. Preferably, reticulated polyurethane foam is
`supplied to the coating chamber. Polyurethane has
`proven effective despite having a melting temperature
`only slightly higher than the decomposition tempera
`ture of nickel carbonyl. Polyvinylchloride foam would
`be the least desirable, because of problems of treating
`exhaust gases formed during the sintering step.
`The chamber 14 is horizontally mounted, having two
`windows 16 and 18 constructed of Te?on TM polymer,
`Pyrex TM glass or quartz. The windows 16 and 18 form
`essentially infrared radiation transparent windows for
`allowing radiation to enter the coating chamber 14 from
`infrared sources 20 and 22 having parabolic re?ector.
`The infrared radiation penetrates the windows 16 and
`
`4
`18 to selectively heat the foam 15 to a temperature at
`which nickel carbonyl decomposes without heating the
`chamber or gases inside the chamber to a temperature at
`which Ni(CO)4 decomposes. The nickel carbonyl de
`composes on the foam 15 to form a substantially uni
`form deposit. Other alternative means for heating the
`foam 15 include induction heating and resistance heat
`ing of foams having or treated to have at least partial
`electrical conductivity.
`Polyurethane foam has infrared absorption peaks
`between 3.0 and 3.7 pm with a very strong absorption at
`5.7 pm. Nickel carbonyl has a strong absorption be
`tween 4.8 and 4.9 pm and carbon monoxide has a strong
`absorption between 4.5 and 4.8 pm. This closeness in
`absorption peaks can cause problems in selectively heat
`ing foam in coating chamber 14. The problem is sponta
`neous decomposition of the Ni(CO)4 in chamber 14
`without plating nickel on the foam 15 to form nickel
`plated foam 23. Heating potential of radiators 20 and 22
`is controlled by a variable voltage regulator when radi
`ators 20 and 22 are electrically powered. The voltage is
`adjusted to a voltage at which the radiators emit most
`energy at wavelengths below 2.5 pm. When polyure
`thane foam is used, the radiation must also not overheat
`the polyurethane. Intensity of infrared radiators 20 and
`22 at the windows 16 and 18 has been about 1 watt per
`square centimeter. If the polyurethane is overheated it
`will decompose in the coating chamber 14. Wave
`lengths below 2.5 pm also effectively heat the nickel
`plated foam 23, since the nickel continues to decompose
`onto the nickel of nickel plated foam 23 without any
`signi?cant decrease in decomposition rate. If available,
`use can be made of radiation filters external of chamber
`14 which selectively absorb radiation of 4.5 to 4.9 pm
`wavelength.
`Polyurethane foam is ?rst coated with a material for
`absorption of infrared radiation that is weakly absorbed
`by nickel carbonyl and carbon monoxide, such as car
`bon black, before it enters the coating chamber 14.
`Alternatively, pigments may be incorporated directly
`into the foam itself to promote absorption of infrared
`radiation. Grey colored polyurethane foam has been
`successfully coated, however if the foam is too light in
`color, the foam is not effectively heated with infrared
`sources 20 and 22. Infrared sources 20 and 22 then sup
`ply infrared radiation with wavelengths primarily
`below 2.5 pm. Preferably, the infrared radiation is sup
`plied at wavelengths primarily below 2.0 pm. This
`range of wavelengths effectively heats the foam 15
`without causing any spontaneous decomposition of the
`nickel carbonyl gas. Nickel carbonyl decomposes uni
`formly on the carbon black coated foam l5 plating ?rst
`from the center of the foam 15. Coating chamber 14 is
`horizontally mounted. There is a Ni(CO)4 concentra
`tion gradient in the coating chamber 14. For this reason,
`the top and bottom infrared sources 20 and 22 may be
`adjusted to different settings to correct for any Ni(CO)4
`concentration gradients by heating one side of foam 15
`slightly hotter than the other. Also, it is important to
`avoid any uneven gas ?ow patterns of concentrated
`nickel carbonyl. These uneven gas flow patterns will
`also tend to deposit heavier in some areas. Alterna
`tively, the coating chamber 14 may be positioned verti
`cally. Vertical mounting of coating chamber 14 should
`facilitate a more uniform gas distribution on both sides
`of the foam 15.
`The nickel plated foam 23 is then transported to the
`furnace 24. Furnace 24 may be either openly connected
`
`65
`
`5
`
`35
`
`45
`
`R.J. Reynolds Vapor Exhibit 1030-00009
`
`

`

`4,957,543
`6
`5
`travel between the active mass and the battery plaque,
`to combustion chamber 14 for continuous operations, as
`but allows nickel hydroxide to be pushed freely into the
`illustrated, or be separately attached for batch-type
`plaque. If the size of the cells decreases substantially
`operations. The furnace 24 is maintained in a reducing
`condition with hydrogen gas. The furnace 24 may be of
`more, it could be difficult to squeeze nickel hydroxide
`particles into the plaque since the size of nickel hydrox
`any known type such as resistance, induction, or any
`suitable externally heated, fuel-type furnaces. Furnace
`ide particles is typically on the order of about 10 pm.
`24 is supplied with a reducing gas 26 such as hydrogen
`A battery plaque having a cell size between 400 and
`gas to prevent oxidation of nickel foam 27. The nickel
`20 pm may be created by either plating a compressed
`plated foam 17 is heated to a temperature between 850°
`foam having a very small cell size or by simply rolling
`C. and 900' C. in furnace 24. The polyurethane decom
`a nickel foam of larger size to reduce the cell size. The
`poses, leaving a reticulated network of substantially
`preferred method of producing the cells is to directly
`hollow nickel wires or nickel foam 27. The gases result
`coat foam having a small cell size such as compressed
`ing from evaporation of the polyurethane foam escape
`polyurethane foam. The rolling of nickel foam is a sim
`from the network of wire. A portion of the foam 15 may
`ple way to decrease cell size, however, in rolling nickel
`remain within the nickel foam 27. However, it is pre
`foam, cell size is decreased at the expense of porosity.
`ferred that the foam 15 is completely removed. The
`Additionally, rolling of battery plaques will not deform
`gases are believed to escape through small, unseen holes
`in a completely uniform manner causing disparities in
`in the network or perhaps the gases escape partially by
`the shape and size of cells across the battery plaque. The
`diffusion. When foam 15 is plated using HZS gas cata
`process of the invention avoids the need to roll nickel
`lyst, sulfur deposited in the nickel during this step is
`foam to decrease cell size.
`effectively removed from the nickel foam 27 in the
`To test conductivity of the samples, copper clamps
`furnace 24. Nickel foam 27 may shrink during anneal
`were attached to opposing ends of rectangular nickel
`ing, however, nickel'foam 27 having a porosity less than
`foam samples. Conductivity along the length of the
`96 percent does not shrink appreciably when heated at
`foam was calculated by the formula:
`850‘ C. In addition, the nickel foam 27 at temperatures
`between 850° C. and 900° C. anneals, greatly improving
`the mechanical properties of nickel foam 27. After an
`nealing, nickel foam 27 may be rolled on a collection
`spool 28. Nickel foam 27 from the collection spool 28
`may be rolled to desired thickness and cut to size for
`forming battery plaques. If desired, nickel foam 27 may
`be ?rst annealed under oxidizing conditions and then
`under reducing conditions. This sequence may be neces
`sary when using a more stable polymeric substrate.
`Tension between collection spool 28 and supply
`spool 29 may be used to stretch cells of foam 15. Collec
`tion spool 28 is pulled at a constant rate by a direct
`current motor (Experimental rates have pulled foam 15
`at rates between 50 and 100 cm/hr). Nickel foam 27
`formed from stretched foam 15 will have elongated
`cells and tend to have anisotropic properties. These
`anisotropic properties may be used to increase strength
`or conductivity in a preferred direction.
`In the illustrated con?guration of the invention, ex
`haust gases from the coating chamber 14 travel ?rst to
`a condenser autoclave 30 maintained by dry ice at —- 80°
`C. to condense and freeze nickel carbonyl. Exhaust
`gases then pass on to a high temperature secondary
`decomposer 32 maintained at 280° C. to further remove
`remaining Ni(CO)4. Exhaust gases from the secondary
`decomposer 32 are then burned with burner 34 to insure
`complete removal of the Ni(CO)4. Also, nitrogen from
`nitrogen supply 36 is supplied at a positive pressure to
`the entrance of foam 15 and exit of nickel foam 27 to
`insure Ni(CO)4 does not leak from the system. A nitro
`gen gas purge is also connected to the furnace exit to
`prevent the escape of hydrogen gas. Exhaust gases from
`the furnace are released through exit 38. '
`Cell size of the battery plaque is controlled initially
`by the cell size of the foam. A foam of greater cell size
`than the-?nal cell is required to compensate for shrink
`age during heating of the foam and annealing of the
`nickel foam. Preferentially, the average distance across
`open-pore cells of the battery plaque is between 4-00 pm
`and 20 pm. More preferentially, the average distance
`65
`across the open-pore cell is between 100 pm and 60 pm.
`The smaller cell size increases surface area of the bat
`tery plaque and decreases the distance that electrons
`
`where
`if: Nickel foam conductivity
`V=measured voltage in volts
`w=sample width in cm
`t==sample thickness in cm
`l=distance between probes
`I= current in amperes
`Cell size of the battery plaque is controlled initially
`by the cell size of the foam. A foam of greater cell size
`than the ?nal cell is required to compensate for shrink
`age during heating of the foam. Table 1 below provides
`a summary of conductivity comparing electrochemical
`nickel foams to nickel foams of the invention of various
`porosities.
`
`20
`
`25
`
`4-0
`
`45
`
`55
`
`TABLE 1
`The conductivity of the nickel foam of the invention
`as a function of porosity (Samples l-l3) was substan
`tially greater than the electrochemically deposited
`CELMET TM product of Sumitomo (Samples 14-18).
`The data from Table 1 are illustrated in FIG. 7, where
`the electrochemical nickel foam has a signi?cantly
`lower conductivity than'nickel foam of the invention at
`a similar porosity. This increased performance satis?ed
`the conductivity of a model having one third of its wires
`conducting in the x, y and z directions, unlike nickel
`foam formed from electrochemically deposited foam.
`Conductivity of the nickel foam of the invention was
`found to satisfy the equation:
`
`vf(3)
`"M = (1 - P)
`
`where
`iN,-=acceptecl conductivity of bulk nickel
`if= apparent conductivity of nickel foam
`P=porosity of nickel foam
`This relationship is satis?ed by the nickel foam pro
`duced by the method of this invention. In calculation of
`
`R.J. Reynolds Vapor Exhibit 1030-00010
`
`

`

`4,957,543
`8
`7
`theoretical conductivity of nickel foam of the invention,
`tween clamps) and a variable thickness which varied
`the accepted value of 1.46><105 ohm—l cm”1 was used
`with the samples. The samples were 1 cm wide in the
`for 0w,- (CRC Hand book of Chemistry and Physics 68"l
`neck (4.6 cm in length) and tapered at each end over a
`Edition). A factor of 3.4 multiplied by the theoretical
`length of 1.6 cm to 2.0 cm in width. This standardized
`conductivity and corrected for porosity satis?es the
`sample was a modi?cation of ASTM D 412-83 Die C
`used for rubber testing. This standard was modi?ed by
`experimental data of the nickel foam of the invention. A
`factor of 3.2 satis?es most nickel foams of the invention.
`increasing the width at the neck of the sample to 1.0 cm.
`The plotted factor of 3 appears to effectively predict the
`The samples were pulled at a constant rate of 0.13
`relationship between porosity and conductivity for the
`mm/sec until the sample fractured. Only samples in
`which the sample fractured in the neck region were
`nickel foam of the invention.
`10
`TABLE 1
`NICKEL FOAM CONDUCTIVITY
`
`THEORETICAL 1/ 3
`SAMPLE LENGTH WIDTH THICKNESS MASS DENSITY POROSITY CONDUCTIVITY CONDUCTIVITY
`NUMBER
`(cm)
`(cm)
`(cm)
`(g)
`(g/cmz)
`(%)
`(1/ Ohm-cm)
`(1/ Ohm-cm)
`1
`5
`l
`0.15
`0.5055
`0.481
`94.59
`2528.2
`2636.1
`2
`5
`1
`0.15
`0.1723
`0.177
`98.01
`898.0
`967.6
`3
`5
`1
`0.15
`0.4112
`0.397
`95.54
`2352.4
`2175.4
`4
`5
`1
`0.15
`0.1471
`0.140
`98.43
`756.1
`767.1
`5
`5
`l
`0.15
`0.2863
`0.252
`97.16
`1394.4
`1382.4
`6
`5
`1.15
`0.15
`0.1445
`0.129
`98.55
`856.0
`705.7
`7
`5
`l
`0.15
`0.2597
`0.247
`97.22
`1265.7
`1354.3
`8
`5
`1
`0.19
`0.1498
`0.149
`98.33
`730.7
`814.5
`9
`5
`1.05
`0.17
`0.2816
`0.222
`97.50
`1328.5
`1216.7
`10
`5
`l
`0.08
`0.2621
`0.468
`94.74
`2624.0
`2562.8
`11
`1.6
`1.45
`0.145
`0.1209
`0.290
`96.74
`1593.1
`1590.2
`12
`4.7
`2.1
`0.125
`0.4473
`0.339
`96.19
`1810.7
`1855.0
`13
`4.7
`2.05
`0.145
`0.5262
`0.351
`96.06
`1726.5
`1919.4
`14
`5
`l
`0.15
`0.5072
`0.483
`94.57
`2045.3
`2645.0
`15
`5
`1.1
`0.16
`0.503
`0.403
`95.48
`1336.3
`2204.1
`16
`5
`1.08
`0.16
`0.48
`0.408
`95.41
`1345.0
`2236.8
`17
`4.7
`2.18
`0.16
`0.7231
`0.411
`95.39
`1686.9
`2247.8
`18
`4.7
`2.12
`0.16
`0.6951
`0.408
`95.42
`1942.7
`2230.8
`
`CELMET TM and METAPORE TM products require
`a factor of 4, which demonstrates their relatively high
`resistance. The factor of 4 for CELMET TM was deter
`mined by the experimented data of TABLE 1 and the
`factor of 4 for METAPORE TM was published in S.
`Langlois and F. Coeuret, Flow-through and ?ow-by pa
`raus electrodes of nickel foam. I. Material characteriza
`tion., 19 Journal of Applied Electrochemistry 43, 43-50
`(1989). Increasing conductivity of the nickel foam of the
`invention lowers the internal resistance of the battery
`plaque. The lower resistance contributes to allowing
`
`accepted as being valid. The data for the tests was as
`follows:
`
`35
`
`TABLE 2
`Sample numbers 1-12 correspond to nickel foam
`produced by the process of the invention. Sample num
`bers l2 and 13 correspond to electrochemically pro
`duced CELMET TM nickel foams. Referring to FIG. 8,
`a graph of Table 2, it is readily apparent that nickel
`foam of the invention has improved mechanical proper
`ties.
`
`TABLE 2
`ULTIMATE TENSILE STRENGTH
`
`Pores
`per
`Sample Linear Thickness
`Number (cm)
`(mrn)
`1
`31.5
`0.5
`2
`23.6
`1.1
`3
`23.6
`1.05
`4
`23.6
`1.2
`5
`23.6
`1.35
`6
`23.6
`1.2
`7
`23.6
`1.15
`8
`31.5
`1.9
`9
`31.5
`1.95
`10
`31.5
`1.95
`11
`31.5
`1.65
`12
`23.6
`1.63
`13
`23.6
`1.6
`
`_
`
`Mass
`(g)
`0.2534
`0.6253
`0.4759
`0.4668
`0.5461
`0.3426
`0.3659
`0.6775
`0.6982
`0.6147
`0.426
`0.9436
`0.949
`
`Porosity
`(%)
`96.538
`96.117
`96.904
`97.343
`97.237
`98.050
`97.827
`97.564
`97.554
`97.847
`98.237
`95.499
`95.388
`
`Densit
`(g/cm )
`0.308
`0.346
`0.276
`0.236
`0.246
`0.174
`0.193
`0.217
`0.218
`0.192
`0.157
`0.401
`0.410
`
`Initial
`Apparent
`Cross
`Section
`(mmz)
`5
`11
`10.5
`12
`13.5
`12
`11.5
`19
`19.5
`19.5
`16.5
`16.3
`16
`
`Fracture
`Strength
`(N)
`13.13
`28.67
`14.03
`14.92
`22.27
`11.67
`13.2
`25.28
`28.2
`34.14
`20.55
`27.9
`28.55
`
`Stress at
`Fracture
`(N/cm2)
`262.6
`260.6
`133.6
`124.3
`165.0
`97.3
`114.8
`133.1
`144.6
`175.1
`124.5
`171.2
`178.4
`
`Stress at
`Fracture
`(MPa)
`2.63
`2.61
`1.34
`1.24
`1.65
`0.97
`1.15
`1.33’
`1.45
`1.75
`1.25
`1.71
`1.78
`
`quicker recharging rates and lowering battery over
`heating during recharging.
`The tensile strength of nickel foam of the invention
`also was superior to that of electrochemically produced
`nickel foam. A die was used to cut samples of nickel
`foam to standard dimensions. The samples were dum
`bell shaped, having a total length of 11 cm (8 cm be
`
`65
`
`These mechanical properties are important because
`battery plaques are wound to ?t within a battery hous
`ing. A battery plaque must have suf?cient strength to be
`deformed and continue to hold an active mass such as a
`paste containing nickel hydroxide particles. Nickel
`foam from electrochemical nickel foam had an ultimate
`
`R.J. Reynolds Vapor Exhibit 1030-00011
`
`

`

`10
`
`9
`tensile strength of 1.754 MPa with a porosity of about
`95.5 percent. The ultimate tensile strength of pure
`nickel bars is about 317 MPa. However, sample from
`the method of the invention had similar strengths with
`porosities as high as nearly 98 percent. This increase in
`mechanical properties allows a higher amount of active
`mass to be reliably held by the battery plaque having the
`same strength as the electrochemical nickel foam. The
`tensile strength of nickel foam of the invention cor
`rected for porosity and multiplied by a factor between 4
`and 6 was equal to or greater than 317 MPa. The tensile
`strength of nickel foam of the invention appears to be
`characterized by a factor of about 5.
`The method of the invention provides an extremely
`?exible method of producing nickel foam having signi?
`cantly improved properties for use as battery plaques.
`The invention has produced nickel foams with porosi
`ties as high as 99 percent. The method of the invention
`also facilitates the production of nickel of increased
`thickness, such as foams 10 cm thick or more. The in
`vention has the ability to produce foams having pore
`sizes as low as 20 pm. As shown in FIG. 7 and 8, con
`ductivity‘ and tensile strength also are greatly improved
`with the invention. The nickel foam of the invention
`provides the above advantages over electrochemical
`nickel foam. These advantages indicate that nickel foam
`of the invention should signi?cantly improve both bat-,
`tery plaque and battery performance. The nickel foam
`of the invention may also be used for other applications,
`such as high temperature ?lters.
`While in accordance with the provisions of the stat
`ute, there is illustrated and described herein speci?c
`embodiments of the invention. Those skilled in the art
`will understand that changes may be made in the form
`of the invention covered by the claims and that certain
`features of the invention may sometimes be used to
`advantage without a corresponding use of the other
`features.
`The embodiments of the invention in which an exclu
`sive property or privilege is claimed are defined as
`follows:
`1. A method of forming a nickel foam comprising:
`
`4,957,543
`10
`placing an open-cell thermally decomposable foam
`structure in an atmosphere containing nickel car
`bonyl gas,
`heating said foam structure to a temperature at which
`said nickel carbonyl gas decomposes,
`decomposing nickel from said nickel carbonyl gas on
`said foam structure to form a nickel plated foam
`structure, and
`‘
`sintering said nickel plated foam structure to ther
`mally decompose and remove said foam structure
`from said nickel plated foam structure leaving an
`open-cell nickel network of interconnected nickel
`wires to form said nickel foam.
`2. The method of claim 1 additionally including the
`step of annealing said nickel foam to improve mechani
`cal properties of said nickel foam.
`3. The method of claim 1 wherein