Title of Invention

A NOVEL GELLED-ELECTROLYTE-AGM-HYBRID-VRLA BATTERY

Abstract

Disclosed herein is a novel gelled-electrolyte-AGM-hybrid-VRLA battery with a recombinant catalyst. The said catalyst is a hydrogen and oxygen recombinant catalyst filled in its vent plug. Such a battery has good high-rate discharge performance, moderate energy-density, good float-service life, and is also cost effective as it allows flexibility in design and materials. In the gelled-electrolyte-AGM-hybrid-VRLA battery of this invention, the hydrogen and oxygen recombination efficiency is near 100% and the said battery is nearly free from electrolyte stratification and thermal runaway.

Full Text

This invention relates to a novel gelled-electrolyte-Absorbent glass mat (AGM)-hybrid-Valve-Regulated lead/Acid (VRLA) Battery with a novel Recombinant catalyst. It is known that considerable research has been done in improving the performance and cycle life capability of sealed Maintenance-Free-Valve-Regulated Lead-Acid Batteries. These batteries are one type of Lead-Acid Batteries. Industrial Lead-Acid battery systems are of two types, namely Low Maintenance and Valve Regulated. Both these conventional Lead-Acid Battery Systems have certain limitations in cycle-Hfe service especially at high ambient temperature operations under Indian conditions. Gelled-electrolj^e (GEL) VRLA batteries are able to overcome the drawbacks of the above systems and have gained wide acceptance in Remote Area Power Supply (RAPS). However, this system has its limitations with respect to high-rate discharge performance. Hybrid AGM-GEL-systems still do not address the problem of negative plate discharge. This invention relates to the use of a recombinant catalyst along with a Hybrid-AGM-GELVRLA system. Such a construction, we claim, overcomes the drawbacks of the above-mentioned systems without compromising on any of their advantages. The important characteristics of the secondary or rechargeable batteries are that the charge and discharge - the transformation of electrical energy to chemical energy and back again to electrical energy - should proceed nearly reversibly, should be energy efficient, and should have minimal physical changes that can limit the battery's cycle life. Chemical action, which may cause deterioration of the battery's components, loss of Ufe, or loss of energy, should be absent, and the cell should possess the usual desired characteristics such as high specific energy, low resistance, and good performance over a wide temperature range. These requirements limit the number of materials that can be successfully employed in a rechargeable battery system. The lead-acid battery system has many of these characteristics. The charge/discharge processes are essentially reversible, the system does not suffer from deleterious chemical action, and, while its energy density may not be as high as desired, the lead-acid battery can perform reliably over a wide temperature range. A key factor in its popularity and dominant position is its combination of relatively low-cost with good performance and cycle-hfe characteristics. The lead-acid battery is one of the most successful electrochemical systems ever developed, and no other battery is yet able to compete with the lead-acid batteries on cost groimds, albeit based on other chemistries are rapidly catching up. In the past, although lead-acid battery designs have been optimized in several different ways, there are still certain new challenges facing the lead-acid battery designers as additional failure modes have become evident in various use modes. », The main types of Lead-Acid batteries used in industrial applications are flooded Low 1 Maintenance Lead Acid (LMLA) Batteries, and Valve Regulated Lead Acid (VRLA) Batteries. Conventional lead-acid batteries manufactured using low antimony alloys are plagued with the problem of electrolyte loss due to the low gassing over potential of the alloy; these batteries require periodic maintenance and top-up. To reduce the periodicity of maintenance required, the free volume in LMLA batteries is increased to hold greater volume of electrolyte. These batteries have good high-rate discharge performance, thermal management, float and cyclic service performance; these batteries however have poor energy densities, and are prone to sulphataion/stratification due to the large electrolyte volume. yRLA (AGM) batteries overcome the problems of maintenance completely. These batteries have good high-rate discharge performance and energy density; they are however prone to r thermal runaway in float service due to increase of float current due to negative plate discharge. Also, their performance, when subjected to elevated temperatures, deep discharges and prolonged Partial State of Charge (PSOC) operation, is poor. VRLA (GEL) type batteries offer excellent high-temperature performance. These batteries have a better performance in float and cyclic service due to better thermal management and greater resistance when subjected to elevated temperatures, deep discharges and prolonged Partial State of Charge (PSOC) operation. However, they have a poor high-rate discharge performance and moderate energy density as compared with AGM-type VRLA batteries; also the problem of negative plate discharge is not addressed. Hybrid (AGM-GEL) VRLA batteries offer the advantageous traits of both the above types of batteries, i.e. good high rate discharge performance, energy density, thermal management and prolonged Partial State of Charge (PSOC) cycle-life performance, without most of their accompanying limitations. However, they do not address the problem of negative-plate discharge in float service. This problem can only be addressed by the introduction of a Recombinant catalyst to aid extemal recombination of Hydrogen and Oxygen thereby i reducing the chances of negative plate discharge. 5 Accordingly, it is an object of the present invention to provide a novel gelled-electrolyte-AGM-hybrid-VRLA battery with recombinant catalyst. A further object of the present invention is to provide a novel gelled-electrolyte-AGM-hybrid-VRLA battery with a vent plug containing catalyst with hydrogen and oxygen recombination efficiency near 100%. Yet another object of the present invention is to provide a VRLA battery nearly free from electrolyte stratification and thermal runaway. r ^s invention thus provides a novel gelled-electrolyte-AGM-hybrid-VRLA Battery with Recombinant catalyst comprising: i I a. A container housing, b. A plurality of AGM-VRLA cells having the required positive and negative plates, the said cells being filled with sulphuric acid to facilitate electrolyte soaking, c. A gelled electrolyte obtained by ultrasonic mixing of aqueous sulphuric acid with colloidal silica, and d. A vent plug filled with a recombinant catalyst such as 2 at. % ceria-supported platinxmi catalyst. Proposed Solution 2V/40AH AGM-VRLA cells were assembled by stacking three positive plates each of HAH ^d four negative plates each of 12AH. Positive and negative plates in these cells were Separated by placing 2mm AGM separator obtained from Nippon Sheet Glass Co., Japan. The cells were connected to their respective lugs prior to placing them in a polypropylene container. The cells were filled with the required amount of 5M aqueous sulphuric acid and were kept for about 2 hours to facilitate electrolyte soaking. 12V/40AH monobloc AGM-VRLA batteries were assembled by connecting six 2V/40AH cells in series by group burning. c prhe batteries were filled with the required amount of gelled electrolyte obtained by ultrasonically mixing 5M aqueous sulphuric acid with 5.5 wt. % colloidal silica procured from Eka Chemicals, Sweden. The gelled-electrolyte-AGM-hybrid-VRLA cells thus assembled were kept for about 24 hours for the gel to form fully and settle. As the gel stiffens, it shrinks and leads to formation of numerous micro-fine cracks. It is noteworthy that, gelled-electrolyte-AGM-hybrid-VRLA cells were dry formed prior to gel filling. The vent plug of the batteries were filled with a required amoimt of 2 at. % ceria-supported platinum catalyst to promote recombination of evolved hydrogen and oxygen gases as water, which is retumed to various cell compartments of the batteries. The battery is shown schematically in Figure 1 of the accompanying drawing. A techno-economic rating of VRLA, gelled-electrolyte VRLA, and gelled-electrolyte -AGM-hybrid-VRLA batteries is presented in Table 1, which uses the following scale: Poor / High as -1, Moderate as 0, good as +1, and excellent as +2. From the comparison presented in Table 1, it is clear that the gelled-electrolyte-AGM-hybrid-VRLA battery of this invention in combination with a 2 at. % ceria-supported platinum recombinant catalyst has a clear edge over its other counterpart. Such a battery has good high-rate discharge performance, moderate energy-density, good float-service life, and is also cost effective as it allows flexibility in design and materials. In the gelled-electrolyte-AGM-hybrid-VRLA battery of this invention, the hydrogen and oxygen recombination efficiency is near 100% and the said battery is nearly free from plectrolyte stratification and thermal runaway. Jhe present invention will now be described with reference to the accompanying drawing, ^tvherein: Figure 1 is an example model illustrating the details of lead-acid battery in an embodiment of the present invention. The battery is shown containing plates 110 and 120, absorbent glass mat 130, thixotropic gel 140, catalyst vent-plug 150 and container 160. Each component is described below. Each of plates 110 and 120 may contain multiple units of plate formed depending on the amount of energy to be stored and delivered at a desired battery voltage. Plates 110 and 120 may be formed in a known way, for example, by applying lead oxide paste followed by curing. One of the two plates 110 and 120 may be implemented as positive plate and negative plate in a known way. Electrolj^e may also be applied between a plurality of plates 110 and 120 in a known way. The separator absorbent glass mat 130 separates plates 110 and 120 from each other. A thixotropoic gel 140, fills the air gaps present in the battery container. Catalyst vent-plug 150 containing a hydrogen-oxygen recombinant catalyst may be fixed to reduce the water loss in a known way. Container 160 generally needs to be made with a strong, leak-proof, and corrosion resistant material. Thus, the various aspects of the present invention enable lead-acid batteries with long cycle-life. benefits of the present invention No Maintenance, i.e. water topping-up. Good High discharge performance. High charge efficiency better than LMLA but on par with VRLA (AGM). High Energy density. Good float service life. Greater resistance to High temperature operation (due to better thermal management). Greater resistance to prolonged PSOC operation. Good deep discharge recovery. Good cycle service life. Low cost due to greater flexibility for selection of materials. Boundary conditions under which the invention works effectively Based on the results of the elaborate tests carried out on the product. Lead-acid batteries of the present invention work effectively for the following applications. Solar Photo-Voltaic Systems Uninterrupted Power Supply Systems Electric Vehicles References Apateanu L, HoUenkamp AF and Koop MJ 1993 J.Power Sources 46 239. Brendt D 2001 J.Power Sources 100 29. Dell R M and Rand D A J 2002 Understanding batteries (Cambridge, UK: Royal Society of Chemistry. Guo Y, Wu J, Song L, Perrin M, Doering H and Garche J 2001 J.Electrochem. Soc. 148 A1287 Haring P and Giess H 2003 J.Power Sources 116 257. Higashimoto K, Miura A, Hayakawa T and Komaki A 1989 Prog. Batteries & Solar Cells 8 268 Lambert D W H, Greenwood P H J and Reed M C 2002 J.Power Sources 107 173. Linden D and Reddy T B (eds) 2002 Handbook of batteries (NY: McGraw-Hill) 3"* ed. May G J and Lenain P 1992 J.Power Sources 40 187. Nakayama Y, Nagayasu T, Kishimoto K and Kasai Y 1991. Yuasa Jiho 71 46 Newnham R H and Baldsing WGA 1996 J.Power Sources 59 137 Newnham R H and Baldsing WGA 1997 J.Power Sources 66 27 Richter J 1993 J.Power Sources 42 231 Shimpo M, Nakashima h, Sasabe S and Kasia Y 1990 Yuasa Jiho 68 26 Strebe J, Reichman B, Mahato b and Bullock K R 1990 J. Power Sources 31 43 Sunu W G and Burrows B R 1981 J.Electrochem. Soc 128 1405 Takahashi K, Sagawa T and Tsubota M 1985 GSNews 44 8 Tuphom H 1992 J.Power Sources 40 47 We Claim: 1. A gelled-electrolyte-AGM-hybrid-VRLA Battery with Recombinant catalyst comprising: a. A container housing; b. A plurality of AGM-VRLA cells having the required positive and negative plates, the said cells being filled with sulphiiric acid to facilitate electrolyte soaking; c. A gelled electrolyte obtained by ultrasonic mixing of aqueous sulphuric acid with colloidal silica; and d. A vent plug filled with a recombinant catalyst such as 2 at. % ceria-supported platinum catalyst. ^ 2. A gelled-electrolyte-AGM-hybrid VRLA Battery as claimed in claim 1, wherein the positive and negative plates are separated by placing 2mm AGM separator. 3. A gelled-electrolyte-AGM-hybrid VRLA Battery as claimed is claim 1, wherein the container hoixsing is a polypropylene container. 4. A gelled-electrolyte-AGM-hybrid VRLA Battery as claimed in claim 1, wherein the gelled electrolyte used is an ultrasonic mixer obtained by mixing 5M aqueous sulphuric acid with 5.5 wt. % colloidal silica. 5. A gelled-electrolyte-AGM-hybrid as claimed in claim 1, wherein the cells are dry formed prior to gel filling.

Documents:

228-che-2004-abstract.pdf

228-che-2004-claims duplicate.pdf

228-che-2004-claims original.pdf

228-che-2004-correspondnece-others.pdf

228-che-2004-correspondnece-po.pdf

228-che-2004-description(complete) duplicate.pdf

228-che-2004-description(complete) original.pdf

228-che-2004-drawings.pdf

228-che-2004-form 1.pdf

228-che-2004-form 19.pdf

228-che-2004-form 26.pdf

228-che-2004-form 3.pdf