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FIELD OF INVENTION
This invention relates to batteries, and more particularly to an Electrode manufacturing method of Valve Regulated Lead Acid batteries to make VRLA Monobloc batteries for Electric 2 -3 wheeler application. This is achieved by providing textured / knurling / serrated surface by passing electrodes through a special set of rollers, mechanically / hydraulically pressurized against each other or by pressing with a press with pressure control, which is an innovative idea in making high performance electrodes for lead acid battery.
OBJECTIVE OF INVENTION
The objective of the invention is to manufacture Valve Regulated Lead Acid batteries with increased surface area of both positive and negative electrodes and to improve energy density and discharge characteristics.
One of the objectives of the invention is to manufacture lead acid battery electrodes that have a high percentage utilization of active material while maintaining strong / hard non- porous property, thereby increasing deep cycling capability and cyclic life.
Another objective of the invention is to provide a battery electrode that has increased active material packing density, which minimizes positive grid oxidation.
Another objective of the invention is to explore the processes / methods to increase the active material surface area without increasing the basic electrode dimensions, i.e., the battery dimensions are unaltered.
Another objective of the invention is to get a flat discharge profile with minimum voltage drop and extended discharge durations. This will be beneficial to Electric & Hybrid, two and three wheeled vehicle applications, by providing a uniform constant power discharge over and extended durations. This will result in more mileage per charge.
Further objectives and advantages of the invention will be brought out in the following portions. The detailed description is for the purpose of disclosing preferred embodiments of the invention, without placing limitations thereon.
BACKGROUND OF INVENTION
A lead-acid storage batteiy remains the battery of choice for traditional use such as starting an automobile, providing emergency lighting, power for an electric vehicle or as a storage buffer for a solar-electric system. Such batteries may be charged periodically by a generator, driven by an engine, or by some other source of electrical energy.
The electrical energy requirement and cycling demands that are placed on modern Electric & Hybrid vehicles in particular are greater than ever before. This results in a reduction in the service life of the battery among other factors,
Another consequence of changes in volume in the active material is the loss of adhesion of the corrosion layer with the grid, leading to the shedding of active materials. Over a period of time the active materials may completely disintegrate with grid members, leading to high internal resistance which will result in a dead cell and loss of battery life.
The aforementioned problems are seen in battery designs utilizing very thin electrodes, to reduce the overall weight of the battery, for use in aircraft, electric cars and the like. While thinner lightweight electrodes reduce the weight of the battery, the structure of the cell electrodes may not be sufficiently strong to prevent structural failure during the normal use of the battery.
A need therefore exists for a lead-acid battery that will maintain strong and stable electrode structures during multiple charging cycles, provide a high reaction surface area as well as an increased electronic conductivity of the active materials, that can be easily and inexpensively fabricated. The present invention satisfies those needs, as well as others, and overcomes the deficiencies as compared to flat smooth surface electrodes.
Applications like Electric & Hybrid, two and three wheeled vehicles require High Rate Discharge for moderate discharge durations of about 2 hours. The battery is cycled continuously.
BRIEF SUMMARY OF INVENTION
The present invention provides the methodology for manufacturing battery electrodes, which are hard non-porous, with high packing density and more surface area. This is achieved by passing the electrodes after flash drying through a specially designed roller setup or pressing with a press with pressured control.
The setup is made up of two rollers, which are spring loaded sufficiently to create the serrated surface on electrode with proper thickness control. These rollers are made up of stainless steel material and coated with special rubber coating, which will have resistance to acid and anti sticking property with paste. The hardness of rubber material / coating is maintained between 70 -90 Shore A and Serrations are created on the rubber coating.
The present invention provides the method of manufacturing a battery electrode with a hard compressed and serrated surface that has improved surface area in the order of approximately 25 - 30%, as compared to a smooth surface electrode.
The improved active material packing density is about 10 - 15%. The serrated surface will improve current density / unit area. The increased active material packing results in low internal resistance, which increases charge acceptance and low positive active material shedding.
The serrated surface will provide a very high surface area for the chemical and electrochemical reactions that take place during charge and discharge. The skeletal structure also allows a substantial increase in the utilization of the active material over the prior method / process. In addition, the positive grid oxidization is minimized due to the improved bonding of active material with the grid surface.
Thereby in accordance with the present invention, the improved surface area of the electrode will improve energy density, because of the higher packing density of active material. This method of making electrodes will increase high rate discharge, low positive active material shedding. This will contribute in high rate discharge performance and long cycling life for the battery.
The highly desirable feature for electric bike battery application is to provide a maintenance-free battery capable of enduring repeated deep discharge cycles without any significant loss from the capacity obtained in the initial cycles.
Batteries constructed according to the present invention are expected to have a high rate discharge and deep discharge and an extended service life
DETAILED DESCRIPTION OF THE INVENTION
The Valve Regulated Lead Acid Monobloc Battery consists mainly of the following components, which are described in detail with the help of accompanying drawings Figure 1, Figure 2, Figure 3 and Figure 4.
The Valve Regulated Monobloc Lead Acid batteries are manufactured with 6 cells internally connected in series in a single container made of high strength, impact resistant ABS / Polypropylene container. The cell consists of group of positive electrodes and negative electrodes connected in parallel and separated by absorptive glass mat separator, which will keep electrolyte in immobilized condition.
The grids are made on Gravity casting machines / continuous casting machines.
The paste is prepared using fully automatic paste mixers, which takes care of 4BS formation in paste. Then the paste is applied on grids using belt / belt less pasting machine.
This is the common process to manufacture flat-pasted electrode lead acid batteries by using belt / belt less pasting machines. The pastes formed from mixing, depends on the ratio of materials, the mixing rate and the temperature.
The material contains powder mixtures of lead sulfate, and basic lead sulfates such as Pb0PbS04 (monobasic lead sulfate), 3PbO PbS04.H.20 (tribasic lead sulfate), and 4PbO
PbS04. (Tetra basic lead sulfate).
To prevent sticking of the electrodes, the positive and negative electrodes are surface dried in an oven prior to stacking them on the skids. To improve the active material/grid contact and the mechanical strength of the active material, the electrodes are passed through a specially designed roller setup attached to machine, which results in increase in the serrated surface, active material packing density and improved surface area. The serrated electrode picture is shown in figure 1.
The pasted electrodes will be cured at 70- 100 °C for 24 hrs and then dried. The preferable Temperature of curing is about 80°C.
The measurements of surface area for typical electrode as shown in Table 1

Table 1: Surface area Comparison Between smooth and serrated electrode The cured and dried electrodes are assembled together by joining positive and negative in stacks, and then put into container and lid are fixed using glue and or heat-sealed. The sealed battery will be filled with Electrolyte (with additives sodium sulfate) using a vacuum- filling machine.
The batteries are then subjected to routine acceptance tests to verify their confirmation to specification. The batteries are selected randomly to subject life cycle test thereon. The practical testing on Electric Bike of motor ratings are 500 - 600 watts and payload capacity is 70 kg maximum.
The charge acceptance tests conducted with battery grids are made with Pb-Sb-Cd / Pb-Sn- - Ag lead alloy which has a similar performance with the above-invented electrode manufacturing method. The effects of the tests are plotted in the figure 2.
With high packing density of the active material, an advantage in the increased discharge duration with a less voltage drop is seen, the increased discharge duration is 15%. The outcomes are shown in figure 3.
The cyclic life test is conducted in well-established in-house Centralized Testing Facility. The specification of the test is derived in such a way that will simulate the actual conditions of the electric vehicle requirements. The effects are plotted in Figure 4.
Further analyses are in progress with conductive fillers in addition to serrated surface, to improve the performance of the batteries for Electric bike and Hybrid Electric Vehicle HEV)too.
Similarly additions of additives to electrolyte to minimize hard sulfate formation to improve the electronic conductivity are being analyzed.

CLAIMS
We claim
1. A lead acid battery comprising a stack of high performance positive and negative electrodes grouped independently and separated by a separator, put into sealed plastic jar and filled with an electrolyte.
2. Battery as claimed in claim 1 are being manufactured using the special set up along with mechanical / hydraulic pressurized system to make high performance battery electrode.
3. A process of making the electrode in cliaml, wherein the electrode has an improved surface area in the range of 20-40% when compared to flat smooth electrode manufactured by conventional method.
4. The electrode as claimed in claim 2, wherein the electrode has an increased by a packing density of active materials in the range of 10-35%.
5. The electrode as claimed in claim 2, wherein the electrode has an improved conductance due to the good adhesion between grid members and active material, which will reduce the internal resistance of the battery.
6. The electrode as claimed in claim 2, wherein the battery made with this electrodes has an improved acid availability at the surface of the electrode because of the textured / knurling / serrations on the surface.
7. The electrodes as claimed in claim 2, with more surface area of 20 - 45 % has an improved high rate discharge capability.
8. The electrodes as claimed in claim 4, with high packing density of active material have advantages of increased discharge duration with a less voltage drop, which results in increased discharge duration by 15%.
9. The electrodes made of claim 5, battery is capable of cyclic life from 100-120 (with conventional flat smooth surface of electrode) is increased to 280-350 cycles.
10. The electrodes made of claim 2; along with top-up of gel (fumed silica / colloidal silica along with sulphuric acid) has an advantage of increased discharge duration of about 5%. This enhances the resistance over thermal runaway.
11. The electrodes made of claim 2, electrodes made using the Pb-Sb-Cd / Pb-Ca-Sn- Ag / Pb-Ca-Sn lead alloy shows improved performance than flat smooth surface electrode.