Dry cell battery

A dry-cell battery construction includes a zinc electrode and a graphite electrode. An external electrolyte of a raw paste material from vegetal origin contacts the zinc electrode. The external electrolyte is preferably raw paste material of the fruit of the carica papaya. The filler material which contacts the graphite electrode contains carbon black. The carbon black may be acetylene black, but can be carbon black of other types, preferably petroleum black, but also oven black or the like, including carbon black produced from natural gas.

FIELD OF THE INVENTION 
This invention relates to a dry cell which includes carbon black, 
preferably petroleum black, and urine as constituents of the depolarizing 
mixture or internal electrolyte which is positioned about its carbon 
electrode, this internal electrolyte being placed within a zinc capsule 
whose interior surface, in turn, is homogeneously covered by an organic 
electrolyte, principally composed of the fruit carica papaya, and acting 
as external electrolyte. 
BACKGROUND OF THE INVENTION 
The dry-cell construction Leclanche devised by 1868 affords the basic 
principle on which the present time dry or primary batteries are 
constructed. According to Leclanche's construction, a carbon plate or rod 
was encircled by a mixture of powdered carbon and manganese dioxide, with 
an amount of 10-20 weight percent ammonium chloride solution. Manganese 
chloride was sometimes added. As the battery case, zinc sheet was used. 
A 1.5 volt changing tension was obtained. From such value the tension 
slowly dropped off, with an actual average value being from 1.2 to 1.3. 
During its inactive condition, the original tension was nearly wholly 
regained, the battery being so particularly useful for intermittent 
action. 
The general chemical reaction involved is now expressed as follows: 
EQU Zn+2NH.sub.4 Cl+2MnO.sub.2 .fwdarw.Cl.sub.2 Zn.2NH.sub.3 +H.sub.2 
O+Mn.sub.2 O.sub.3 
Dr. Carl Gassner in 1888 improved the Leclanche cell, originating the first 
dry-cell battery. The improved battery was comprised of a zinc case, 
acting as both the battery anode and its container. A gel-like electrolyte 
was put up within such container and a carbon rod, encircled by 
depolarizing mixture, was located at the center thereof. This is the basic 
construction followed at the present for manufacturing commercial dry 
batteries, of any model, which are currently used to generate low-voltage 
electric power. 
Broadly, the electrolyte heretofore used for dry batteries has consisted of 
a gel-like body containing therein about 20 weight percent ammonium 
chloride and 9 weight percent zinc chloride, arranged between the battery 
anode and cathode. Such gelly paste usually comprises a mixture of the 
electrolyte substance and corn starch and wheat meal. Synthetic materials 
affording improved electrical properties and longer shelf life, such as 
methylcellulose, Cellosolve and the like, are also used. 
It is well known that during the discharging process the battery 
electrolyte changes in composition. In the layer adjacent the zinc 
electrode the pH value changes from about 5.7 to about 3.8 (thus becoming 
more acidic) while in the innermost region the pH of the mixture changes 
from about 5.8 to 11 (more alkaline). 
Dry batteries comprising the aforecited conventional electrolyte, generally 
show a steady slow rate characteristic of discharge, until reaching the 
1-volt final tension, when discharging at 20.degree. C. The electrical 
tension of the battery continuously decreases as it discharges. The rated 
capacity depends upon, therefore, the intended final tension. For 
comparison purposes, when testing commercial Size D batteries, at a 4 ohms 
load, the results set forth in the following Table I are obtained, for 
different final tensions. 
TABLE I 
______________________________________ 
Final Time Watts- 
Voltage Hrs. Ah Hr. Wh/kg. 
______________________________________ 
1.4 0 0 0 0 
1.2 0.25 0.244 0.317 0.31 
1.0 2.35 0.681 0.792 8.27 
0.9 3.50 0.955 1.04 10.87 
0.8 5.50 0.37 1.37 14.33 
______________________________________ 
Another kind of electrolyte uses 20 weight percent caustic soda, in which 
the zinc goes into reaction to form sodium zincate, the hydrogen released 
being absorbed at the carbon surface by the atmospheric oxygen occluded 
within the electrolyte, thus spending air at a rate above 1 liter in one 
hour. In order to decrease the hydroxyl ion consumption, calcium 
hydroxide, which is scarcely soluble, is added to the electrolyte, thereby 
forming soluble calcium zincate being so reclaimed the sodium hydroxide. 
The electrolyte in this latter kind of dry batter is held in place by 
adding thereto corn starch paste. Preferably, the miniature 5.5 
ampere-hour dry batteries are so constructed. 
Also, the electrolyte may be comprised of 35-40 weight percent potassium 
hydroxide saturated with sodium zincate, supported on alpha-cellulose. 
The aforecited prior art batteries have a rather short life as contrasted 
to that one attainable in the batteries according to the invention as 
disclosed in the above-mentioned U.S. patent application Ser. No. 657,293 
and 446,900. 
It is known to provide, as the depolarizing mixtures in conventional dry 
cells, a mixture which includes manganese dioxide, graphite, roasted coke, 
acetylene black, ammonium chloride, zinc chloride and other less important 
constituents. It is believed that acetylene black, as opposed to other 
types of carbon black, has been used because of its relatively superior 
low resistance and superior absorption characteristics. The use of other 
types of carbon black has not proved feasible in the construction of 
commercial dry cell batteries. 
While it has been proposed, as known from U.S. Pat. No. 215,899, to use 
urine as an electrolyte (excitant) in Galvanic batteries, it has not 
heretofore been known to use urine in a dry cell to reduce its internal 
resistance and to increase the absorption of carbon black. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a dry cell battery 
which contains a depolarizing mixture or internal electrolyte which need 
not include acetylene black. 
It is another object of the present invention to provide a dry cell battery 
which includes a depolarizing mixture or internal electrolyte containing a 
carbon black other than acetylene black, preferably petroleum black. 
It is a further object of the present invention to provide a dry cell 
battery which includes acetylene black and has an extended life and 
improved characteristics, using as external electrolyte one made up of an 
organic substance such as carica papaya. 
It is an additional object of the present invention to provide a 
depolarizing mixture suitable for use in dry cell batteries. 
The foregoing objects are achieved, in accordance with the present 
invention, by providing a dry cell battery having among the constituents 
of its depolarizing mixture or internal electrolyte carbon black and 
urine. 
The carbon black, in accordance with the present invention, is preferably 
petroleum black, but may also be oven black or the like, as well as 
acetylene black. 
Applicants have discovered that if, in a dry battery comprising an anode 
and a cathode separated from one another by means of a permeable web, such 
as absorbent paper, a raw paste material from vegetal origin, especially 
paste material of fruit of the carica papaya, is used as the battery 
external electrolyte according to this invention, surprisingly a longer 
lasting actual duration of discharge is attained, with such discharge 
occurring at a more steady rate, as contrasted to the whole performance of 
the prior art batteries. This type of battery is further improved by using 
as constituents of its depolarized mixture urine and carbon black which 
gives far greater power of absorption. 
The mayor barrier heretofore to the substitution of lower varieties of 
carbon black, such as petroleum black, for acetylene black in dry cells is 
believed to lay in that these are too porous and insufficiently absorbent, 
and consequently not apt for use in the internal electrolyte. Applicants 
have found that, by mixing manganese dioxide, graphite, ammonium chloride 
plus urine, petroleum blacks and the like have their power of absorption 
greatly enhanced, making such blacks roughly equal to that of acetylene 
black. The substances of the mixture are believed to be absorbed in such a 
manner that they compact the groups of molecules of the petroleum blacks 
and the like, making these blacks more conductive and usable in the 
manufacture of dry cells similar as to voltage, amperage, durability and 
use to those made with acetylene black. 
Absorption has been found by applicants to be substantially and equally 
high when the depolarizing mixture consists of, on the one hand, acetylene 
black, graphite, ammonium chloride, and manganese dioxide as is 
conventional, and on the other hand, petroleum black, graphite, ammonium 
chloride, manganese dioxide plus urine in accordance with the present 
invention. 
Hence, by treatment with urine in the depolarizing mixture, petroleum 
blacks and the like are made to have absorption characteristics similar to 
those of acetylene black. These results are optimum within the dry cell 
makeup if the paste of a fruit, preferably carica papaya, gelled with any 
known gel-former (starch, etc.) and dried with a drying agent such as 
wheat meal, coffee, etc., is used as the external electrolyte, thereby 
producing a dry cell of 1.5 volts and up to 6 amperes with equal or 
greater effectiveness than the Leclanche type cells. 
An electrolyte which may be used in a dry cell battery accoding to the 
present invention is comprised of raw paste material of vegetal origin, in 
particular of raw paste of fruit of the carica papaya (Carica papaya). By 
the term "raw material of vegetal origin" used throughout this 
description, raw pulp of fruits of plants and pulp of tree stalks is 
meant. If desired, such paste material may contain compounded therein, 
natural or synthetic neutral agents, such as yucca starch, corn starch, 
wheat meal, alpha-cellulose, and the like as gel-formers. Particularly 
suitable for forming the electrolyte is the paste obtained from the fruit 
of any kind of the varieties of the carica papaya (Carica papaya). This 
fruit is commonly known as the papaya. The dry battery embodying the 
electrolyte of papaya squash shows a steady tension drop rate, rather than 
the jerking-wise drop from one tension level to another lower one, as in 
the case with the prior art batteries.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The fruit paste of papaya or other fruit may be formed by liquefying the 
fruit and thoroughly mixing therewith the starch. The mixture is heated to 
about 80.degree. C. with continuous stirring. When the paste has dried to 
some extent, adjuvants may be added. For example, wheat meal may be added 
as drying agent thereto and heated to keep the mixture boiling at 
100.degree. C. until a thick and sticky gel is formed which may suitably 
be adhered to the interior surface of the battery shell. 
The pulp of fruits is comprised of a number of organic compounds, varying 
as to amount and class, depending on the subject fruit. Among such organic 
compounds there are organic acids, carbohydrates and proteins comprised of 
high-weight molecules. Without attempting to be limited to any particular 
explicative theory, it may be postulated that such high-weight molecules, 
probably on hydrolysis occurring in the electrolytic process performed in 
the dry battery, undergo structural changes of not well known nature, but 
that as a result they split into lower molecules which are capable of 
chelation with the metallic ions afforded to the system by the zinc metal, 
the manganese dioxide and those metals in trace amounts found as 
impurities in the cell container. 
It is known that the metal chelated forms are apparently more soluble than 
the salts of their own metals and that, therefore, they will form a bridge 
of continuous solubilization, thus permanently acting as electrolytes for 
the dry battery comprising raw paste of fruits of plants. The mechanism of 
the process performed is not well known at the present, but its actual 
improved effectiveness is brought out by means of the following 
illustrative, non-limitative example. 
EXAMPLE 
To 7.60 g. of paste formed from the fruit of the carica papaya there is 
added as gel-formers 0.95 g. of yucca starch and 1.45 g. of wheat meal or 
coffee as drying agent with thorough mixing. The so-prepared mixture was 
gently heated at about 80.degree. C. for 25 minutes using a water bath. 
About 10 g. of the above mixture were coated on the inner side wall of a 
zinc container weighing 18 g. A graphite rod weighing 4 g. was located at 
the center of the container provided on its bottom with an insulating 
cardboard disk. The rod was encircled by 34.4 g. of depolarizing mixture 
or internal electrolyte and this was wrapped with a thin web of absorbent 
paper. The above filler and depolarizing mixture was taken from the mix 
comprised of: carbon black from petroleum 17.8 g.; MnO.sub.2 8.9 g.; urine 
7.7 g. and ammonium chloride 3.5 g. 
A test was devised for comparing the performance of the dry battery of this 
invention against the prior art batteries. Commercial Size D dry batteries 
and dry batteries prepared as described in the above Example, having the 
same weight, were used. One commercial battery was applied to drive a 
first toy electrical locomotive. At the same time one battery according to 
the invention was used to drive a second toy electrical locomotive of the 
same weight as the first one. In both instances, the tracks were closed 
trackways having the same length and shape, arranged at the same 
horizontal plane. When some time lapsed the first locomotive stopped as 
its associated battery becomes weak enough. In contraposition, the dry 
cell battery of the present invention continued to drive the associated 
toy locomotive. 
Among the fruits of plants applicants have found suitable in different 
degrees to constitute an electrolyte which may be used in some embodiments 
of the present invention are included pineapple, papaya, citrics and the 
like. Suitable materials are also tubers, for instance, yucca (Manihot 
utilissima) and tree parts, such as pine bark. The papaya has been shown 
to be by far the most suitable fruit. 
Applicants have noted that the fruits of the following plants have also 
shown, to a limited degree, some promise of providing paste material 
having an electrolytic nature: Mandarin orange (Citrus madurensis); orange 
(Citrus aurantium); bergamot (Citrus bergamia); grapefruit (Citrus 
deevmana); pineapple (Ananas sativus); pear (Pirus communis); plum (Prunus 
domestica); cusard apple (Anona muricata); guava (Psidium guajava); 
tamarind (Tamarindus indicia); Indian mango (Magnifera indica); melon 
(Cucumis melo); tomato (Lycopersicum esculentum); Cucurbit (Passiflora 
specierum); eggplant (Solanum melongenea); lulo (Datura stramonium); 
pumpkin (Adenostyles albiferous); and potato (Solanum tuberosum). 
The preferred proportions to form a suitable electrolyte paste are as 
follows, expressed in weight percent: 
______________________________________ 
Fruit of the carica papcya 
69.3-84.7% 
Starch 8.1-9.9% 
Wheat meal 12.6-15.4% 
______________________________________ 
and especially fruit of the papaw tree 77%, starch 9% and wheat meal 14%. 
It should be understood, however, that the important consideration is that 
the jelly-like mass formed by such substances be compact and adhesive, 
especially when the substance is to be used in a dry battery according to 
some embodiments of the present invention. On the other hand, it should be 
noted that the two gel-forming elements--starch and wheat meal--could be 
theoretically eliminated altogether and the papaya component could 
increase to 100%. 
In the present battery a depolarizing filler or internal electrolyte 
comprising carbon black of many types or acetylene black is used along 
with the electrolyte comprising the raw paste of vegetal origin, 
preferably paste of fruit of the carica papaya. As is usually done in the 
manufacture of dry batteries, zinc chloride and/or manganese chloride may 
be used. One kind of carbon black used is Sterling V.RTM. manufactured by 
Cabot Corp. This carbon black has a surface area of 30 m.sup.2 /g, 
particle size of 108 millimicrons and a volatile content of 1%, fixed 
carbon 99% and pH of 7.5. The electrical resistivity of this kind of 
carbon is low, its density is of about 41 kg/m.sup.3. These properties 
altogether improve the shelf life, and upon mixing with urine, develop a 
power of absorption equal to that of acetylene black, as measured by the 
DBP test. 
The depolarizing mixture range proportions, in one aspect of the present 
invention, are as follows: 
______________________________________ 
Weight Percent 
______________________________________ 
Carbon black 35-70% 
Manganese dioxide 5-40% 
Urine 33.3% 
______________________________________ 
A specific example of a depolarizing mixture according to the present 
invention, within the ranges set out above, found to be preferred is 
constituted by carbon black 44.4%, urine 33.3% and manganese dioxide 
22.2%, by weight. 
The depolarizing mixture may include paste of fruit of carica papaya which 
increases the absorption. In this instance, the range of the mixture 
proportions are substantially as follows: 
______________________________________ 
Weight percent 
______________________________________ 
Carbon black (either) 
petroleum black or 
acetylene black) 35-70% 
Manganese dioxide 35-40% 
Carica papaya fruit paste 
10-12.5% 
Urine 10% 
______________________________________ 
A specific example of a preferred depolarizing mixture, which includes 
Carica papaya fruit paste, according to the present invention within the 
ranges set out above is constituted by carbon black from petroleum 
preferably 51.6%, manganese dioxide 25.9%, Carica papaya fruit paste 12.5% 
and urine 10%, by weight. 
As stated above, urine is a necessary constituent of the depolarizing 
mixture or internal electrolyte according to the present invention. The 
urine may be of either human or animal origin. Non-limiting examples of 
the composition of human urine can be seen in Greyton, Basic Human 
Physiology: Normal Functions and Mechanisms of Disease, page 280, Table 
24-1, W. B. Sanders Company, Philadelphia (1971) and Winton and Baylis, 
Human Physiology, page 250, Table 9.1, 5th Col., Little, Brown and 
Company, Boston (1962). 
In the constructions of applicants battery the carbon electrode may be 
located at the center thereof encircled by a filler having therein the 
depolarizing mixture or internal electrolyte. Surrounding each filler is 
the permeable web and surrounding such web and contacting the zinc 
electrode, there is arranged the electrolyte comprised of the raw paste of 
fruit of the carica papaya having therein a suitable gel forming material. 
As shown in the drawing FIGURE, an exemplary dry cell battery according to 
the present invention includes a cylindrical, external tubular electrode 
10 of zinc which is positioned coaxially with a solid cylindrical, 
electrode 14 of graphite. A permeable web 12, which may be made of 
newsprint, or the like, is positioned between the zinc electrode 10 and 
the graphite electrode 11, it being positioned more closely to the zinc 
electrode 10. An electrical insulating disk 13 or the like is positioned 
beneath the electrodes 10 and 11. A star bottom washer 11 is fixed to the 
electrode 10 in contact with the disk 13. 
An external electrolyte 15 comprised essentially of a raw paste material of 
fruit of the carica papaya or other pastes of vegetable origin, is 
provided between the zinc electrode 10 and the web 12. The electrolyte 15 
desirably contains a gel forming amount of suitable gel forming material 
to make it compact and adhesive. The gel forming material may be starch 
and wheat meal, as stated above. In weight percentages, the starch is 
desirably present in the range of from 8.1% to 9.9%, the wheat meal is 
present in the range of from 12.6% to 15.4%, and the fruit of the carica 
papaya is present in the range of from 69.3% to 84.7%. A particularly 
effective battery is obtained by providing that the fruit of the carica 
papaya constitutes 77%, the starch constitutes 9% and the wheat meal 
constitutes 4% of the electrolyte by weight. 
A depolarizing mixture or internal electrolyte 16 is provided between the 
web 12 and the graphite electrode 11. This depolarizing mixture 16 
according to the present invention is composed of a novel mixture. The 
depolarizing mixture 16 is constituted by a mixture of the materials in 
the weight proportions set out above. The depolarizing mixture 16 may 
include, as mentioned above, raw paste of the fruit of the carica papaya. 
The urine effects a reduction in the internal resistivity of the 
depolarizing mixture by causing the manganese dioxide and the graphite to 
be absorbed by the carbon black from petroleum, allowing the substitution 
of ordinary carbon black for acetylene black as absorption capacity of the 
two become approximately equal. When acetylene black is used with urine, 
the characteristics of the battery are improved over the characteristics 
without the presence of urine. The carbon black may be in any of its 
forms, preferably petroleum black, but also oven black, thermal black from 
natural gas and coke black. Coke black has been found to be the least 
desirable of the available carbon blacks and is not recommended over the 
other carbon blacks for use in commercial batteries. It is believed that 
impurities in coke black detract from its function as an ingredient of a 
depolarizing mixture, at least in its ordinary commercially available 
form. Both the urine and the paste of fruit of the papaw tree augment the 
current and result in good voltage regulation. The urine causes the carbon 
black to absorb the other components of the internal electrolyte, thus 
substituting for the use of acetylene black other varieties of carbon 
black. 
A gas-storing, expansion space 17 is provided between a conventional pitch 
seat 18 which extends between the graphite electrode 11 and the zinc 
electrode 10, as is conventional in dry battery construction. The battery 
can be provided with a steel jacket and bottom, if desired, or some other 
housing of conventional construction, the insulating disk 13 serving, in 
this case, to insulate the graphite electrode 11 from the steel bottom. 
The star bottom washer 14 need not be present in this alternate variant. 
The top of the graphite electrode 11 is provided with a brass cap 19 to 
facilitate making electrical connections. The electrode 10 of zinc serves 
both as a container and as a terminal connection of the battery. 
Dry cell batteries constructed in accordance with the present invention 
exhibit high durability and long life, comparing favorably with 
present-day commercial batteries. Batteries constructed in accordance with 
the present invention provide an output of about six (6) amperes and a 
voltage of 1.5 volts. 
Using standard procedures of the International Standards Organization, two 
dry cell batteries constructed in accordance with the present invention 
were tested by placing them in standard resistance load circuits. Both 
batteries were of standard size D and contained a depolarizing mixture 
according to the present invention. One of the batteries contained a 
conventional electrolyte; the other contained an electrolyte composed of 
raw paste material of fruit of the carica papaya. The results are set out 
below in Table II. 
TABLE II 
______________________________________ 
Test Circuits With Conven- With Paste Material 
Conditions tional Electrolyte 
Electrolyte 
______________________________________ 
2.25 ohms, continuous 
Cutting point 0.65 volts 
700 minutes 800 minutes 
25 ohms, 4 hrs. every 
25 hours 
Cutting point 1.1 volts 
100 hours 140 hours 
Cutting point 9.9 volts 
90 hours 110 hours 
Watts-hours 7.36 hours 8.36 hours 
8 ohms, 4 hrs. every 
24 hours 
Cutting point 1.1 volts 
16 hours 20 hours 
Cutting point 0.9 volts 
39 hours 46 hours 
Watts-hour 2.25 9.25 hours 
______________________________________ 
As can be seen from Table II, batteries made in accordance with the present 
invention have excellent energy storing capacity and good terminal voltage 
characteristics under load. 
Each of the aforementioned types of batteries incorporating a depolarizing 
mixture according to the present invention maintained their shapes and 
retained their electrolytes under load for considerable periods. The 
battery provided with conventional external electrolyte did not exhibit 
gushing or spillage or became deformed under 2.25 ohm continuous or 
discontinuous load until the elapse of 70 days. The battery provided with 
the paste material of fruit of the carica papaya did not become deformed 
or exhibit gushing or spillage under the same conditions until the elapse 
of 90 days. One can conclude that batteries made in accordance with the 
present invention have significant lifetimes and are practical under load 
conditions. 
Batteries constructed similarly to those of the present invention, 
substituting for the urine component in the depolarizing mixture, an 
electrolytic solution of the Ringer type, a solution well known in the 
medical arts, indicated that currents and voltages of such batteries 
declined rapidly relative to the batteries containing urine and carbon 
black as constituents of the depolarizer mixture. In particular, it was 
noted that an electrolyte solution of the Ringer type gave an initial 
voltage of 0.8 volts and a current 25 milliamperes. Using 30% of this 
solution with 60% carbon black and manganese dioxide, as a depolarizing 
mixture in a battery with a conventional external electrolyte comprising 
ammonium chloride, zinc chloride and a gel former, resulted in an initial 
voltage of 1.0 volts and a curent of 500 milliamperes. The voltage and 
current of these batteries, however, declined rapidly in comparison to 
batteries constructed with a depolarizing mixture in accordance with the 
present invention. 
Using the same depolarizing mixture set out above, including Ringer 
solution, but substituting a paste of fruit of the carica papaya for the 
conventional external electrolyte, a battery resulted having an initial 
voltage of 1.3 volts, a current of 1.0 amps and a somewhat longer life, 
but again the voltage and current fell quickly in comparison to similar 
batteries using the depolarizing mixture of the present invention. 
In a similar experiment 30% by weight paste of other organic substances, 
such as guava, apples, pineapple, tomato or the like, were added to a 
urine-free depolarizing mixture containing approximately 60% carbon black 
and 10% manganese dioxide, by weight. When this mixture was used in a 
battery having a conventional external electrolyte, an initial voltage of 
1.3 volts with current in the range of from 1.1 to 1.5 amperes were 
obtained. If papaya in a gelatinous form is substituted for the 
conventional external electrolyte and used with these depolarizing 
mixtures, initial voltage 1.4 volts and initial currents of from 1.0-1.8 
amperes were obtained. Cells so constructed exhibited better results than 
those using a solution of the Ringer type as set out above; nevertheless, 
life of these somewhat better batteries was still short in comparison to 
batteries of the present invention. 
It can thus be seen that the use of urine in the depolarizing mixture gives 
unexpectedly superior results than other electrolytes. 
It is to be understood that the various mixtures mentioned above which can 
form the depolarizing mixture according to the present invention, can in 
one preferred aspect of the invention, be pressed under pressure into 
shaped bodies, such as a web which can be formed into a spiral. These 
bodies shaped under pressure provide a somewhat increased current capacity 
for the depolarizing mixture when used in a battery, as compared to the 
same mixture which has not been subjected to pressure. 
It is to be appreciated that the described and illustrated embodiments of 
the present invention have been set out by way of example, not by way of 
limitation. Other embodiments and numerous variants are possible within 
the spirit and scope of the present invention, its scope being defined in 
the appended claims.