FIELD OF INVENTION
This invention relates to an improved process for producing an improved dry cell/chargeable battery.
PRIOR ART
Dry cell and chargeable battery are known to comprise of two metallic electrodes and a chemical electrolyte in dry or solution form. Electric current is generated following the chemical reactions involved. Dry cells involve the following reaction:
(Equation Removed)
and chargeable lead batteries involve the following :
(Equation Removed) Charge
In the former, the original integrity is lost gradually with corrosion of electrodes and contamination of electrolyte. In the latter, the charging cycle following a discharge is unable to restore the original integrity that gets accentuated with time. Depending on the charge capacity and the rate of consumption, each cell/battery has an expected life duration, with fall in performance parameters. Electrochemists contributed towards attaining maximum life through the use of additive chemicals in the electrolyte and appropriate coating/alloying of electrodes.
However, the known art is associated with several distinct disadvantages, which leads to reduction in the current capacity and limited life time of the cell/battery i.e. few months for dry cell and 2-3 years for chargeable battery. One of the disadvantages is that, the electrode coatings get chipped off with time due to poor adhesion of coating which dissolves in the electrolyte and contaminates the same. Another disadvantage is that, electrodes get corroded.
A technology of surface modification is known to have been provided, which employs ion-implantation and nano-particle materials to enhance adhesion, strength and restrict corrosion of metallic surface and coatings thereon. However, the same requires a costly accelerator.
OBJECT OF THE INVENTION
An object of the present invention is to propose an improved process for producing an improved dry cell/chargeable battery, which is cost effective and provides implantation over the entire surface of a sample in one go.
Another object of the present invention is to propose an improved process for producing an improved dry cell/chargeable battery, which facilitates treatment of a large number of samples with varying size/shape simultaneously unlike the accelerator based ion-implantation.
Still another object of the present invention is to propose an improved process for producing an improved dry cell/chargeable battery, which involves the use of nano-material technology so as to strengthen the coating paste within and its adhesion to the electrodes.
Further object of the present invention is to propose an improved process for producing an improved dry cell/chargeable battery, which results in enhanced adhesion, prevention of corrosion, increased hardness, controlled friction etc.
Still further object of the present invention is to propose an improved process for producing an improved dry cell/chargeable battery, which results in the formation of meta-stable phases in the sample, which leads to beneficial changes in the tribological properties of the sample.
Yet another object of the present invention is to propose an improved process for producing an improved dry cell/chargeable battery, which provides long-term integrity to the electrodes and their coatings, without affecting the chemical reactions involved in generating electric power.
Still another object of the present invention is to propose an improved process for producing an improved dry cell/chargeable battery, which involves monitoring and control of environmental parameters such as Temperature, Pressure, Humidity and Particulate density as and where considered necessary.
STATEMENT OF INVENTION
According to this invention there is provided an improved process for producing an improved dry cell/chargeable battery comprising steps of:-pretreatment of electrodes, -irradiation of the electrodes with ions using plasma ion implantation chamber, and coating of the irradiated electrodes with a paste of metal oxide.
DETAILED DESCRIPTION OF THE INVENTION
According to this invention, there is provided a process for producing an improved dry cell/chargeable battery comprising of irradiation of electrodes with ions such as Nitrogen using one of the treatments namely PI2 (Plasma Ion Implantation) and PI3 (Plasma Immersed Ion Implantation) In PI2, the sample is kept away from the plasma sheath while in PI3, it lies immersed within the plasma region. The former permits room temperature treatment with high acceleration. The latter involves a raised sample temperature and reduced acceleration. The higher temperature permits diffusion of implanted ions with in-depth concentration profile. The profile is Gaussian in nature for the PI2 type, as the concentration maxima corresponds to the mean range of ions of certain energy. Further, it suits substrates that may not tolerate elevated temperature. On the other hand, in the PI3 technique the applied bias pulse can be repeated at a higher rate, enabling a rise in the sample temperature. It causes diffusion of as-implanted ions resulting in a deeper doped concentration profile.
The treatment is carried out on a grid. Before being irradiated with ions, the electrodes are polished and kept in the bag containing inert gas so as to prevent the same from coming into contact of moisture, dust etc. Irradiation of the electrodes is carried out with ion dose of 1016-1018 ions and ion energy of 20-40 kev at a temperature of 15-40°C for a time period.
The time period depends on ion density in the plasma Ion Implantation chamber.
In case of PI3 (Plasma Immersed Ion Implantation) treatment, the irradiation of the electrodes is carried out with ion dose of 1016-1018 ions and ion energy of upto 250 kev at a temperature of 250-500°C for required time period, which is decided according to ion density in the Plasma Ion Implantation chamber.
The plasma may be generated using (i) a filament assisted DC arc, (ii) a radio frequency discharge or (iii) an electron cyclotron resonance (ECR) ion source using the specific gaseous/solid medium.
After irradiation with ions, the electrodes are coated with a paste prepared by mixing nano-particle based metal oxide in the range of 0.1-1.0% with normal metal oxide. The paste is prepared separately for the +ve and -ve electrode grids of the metal accumulator. The metal may be lead, lithium, cadmium etc. The admixture percentage in the coated oxide of chargeable batteries needs to vary according to the current/ power rating of the battery. The higher is the power rating, the higher is the thickness of the coating and vice-versa. However, the self-adhesion (within the/layer thickness) is required to be more enhanced for thicker layer.
In case of PI3 treatment, coated electrodes are subjected to the step of irradiation as it provides deeper penetration into the coated layer, possibly upto the interface with the electrodes. This is carried out only for chargeable batteries.
The specific advantages of PP process can be availed under strict technical personnel as it involves plasma ion implantation at varying temperature range within the effective plasma discharge region.
The process steps of the present invention are implemented before
curing, soaking, forming and drying and after casting. The present
invention provides physical technology, which is a better alternative to
the chemical additives currently used as
enhancers/preservers/optimizers in the manufacture of dry cells/chargeable batteries.
Further, the process of ion implantation offers unique possibilities for surface modification of materials such as enhanced adhesion, inhibiting corrosion, increased hardness, controlled friction, etc. Energetic ions on deposition in and near the surface results in the formation of meta-stable phases in the sample. Such a treatment thereby results in beneficial changes in the tribological properties of the sample
TEST RESULTS:
Battery manufacture involves handling of different processing steps in the manufacture. These are done by individual factory workers and the manufacture's specifications get implemented with individual variations. Further, the environmental conditions in battery manufacture are lacking. That is why, an individual piece of battery in a given batch as well as from different batches of the same manufacture may show useful life variations, say from 1 to 3 years.
The process steps of the present invention can therefore enhance the battery life in correspondence with the above stated variations and the net life enhancement lies in the range of 80-160 percent i.e. 1.6-3.2 times.
It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims:-

WE CLAIM:
1. An improved process for producing an improved dry
cell/chargeable battery comprising steps of:-
- pretreatment of electrodes,
- irradiation of the electrodes with ions using plasma ion implantation chamber, and
- coating of the irradiated electrodes with a paste of metal oxide.

2. An improved process as claimed in claim 1 wherein the irradiation of the electrodes is carried out with ion dose of 1016-1018 ions and ion energy of 20-40 kev at 15-40° C in case of PI2 (Plasma Ion Implantation) treatment in which the sample is kept away from Plasma sheath.
3. An improved process as claimed in claim 1 wherein the irradiation of the electrodes is carried out with ion dose of 1016-1018 ions and ion energy of upto 250 kev at 250-500°C in case of PI3 (Plasma Immersed Ion Implantation) treatment in which the sample lies immersed within plasma region.
4. An improved process as claimed in claim 1 wherein the paste of metal oxide comprises nanoparticle based metal oxide in an amount of 0.1-1.0%.
5. An improved process as claimed in claim 4 wherein the metal oxide is such as lead oxide, lithium oxide, cadmium oxide etc.
6. An improved process as claimed in claim 1 and 3 wherein the coated electrodes may be subjected to the step of irradiation in case of PI3 treatment.
7. An improved process as claimed in claim 6 wherein the further irradiation is carried out for chargeable batteries.
8. An improved process as claimed in any of the preceding claims wherein the ions are such as Nitrogen.
9. An improved process as claimed in any of the preceding claims wherein the pretreatment constitutes polishing of the electrodes followed by retention of the same in a bag containing inert gas before being subjected to the step of irradiation.
10. An improved process for producing an improved dry
cell/chargeable battery substantially as herein described.