Advanced graphite additive for enhanced cycle-life of lead-acid batteries
AssigneeExide Technologies
InventorsSudhakar Jagannathan, Melchor Fernandez Garcia
Life of this patent
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Abstract
An Advanced Graphite, with a lower degree of ordered carbon domains and a surface area greater than ten times that of typical battery grade graphites, is used in negative active material (NAM) of valve-regulated lead-acid (VRLA) type Spiral wound 6V/25 Ah lead-acid batteries. A significant and unexpected cycle life was achieved for the Advanced Graphite mix, where the battery was able to cycle beyond 145,000 cycles above the failure voltage of 9V, in a non-stop, power-assist, cycle-life test. Batteries with Advanced Graphite also showed increased charge acceptance power and discharge power compared to control groups.
Claims10
An energy storage device, comprising:
- an electrode comprising lead;
- an electrode comprising lead dioxide;
- a separator between the electrode comprising lead and the electrode comprising lead dioxide;
- an aqueous solution electrolyte containing sulfuric acid;
- and
- a carbon-based additive comprising graphite having a specific surface area of approximately 100 to 900 m2/g, wherein the carbon-based additive is a disordered carbon additive in negative active material with (i) crystallinity of 60% or lower, (ii) degradation onset temperature of 650° C. or lower;
- and (iii) degradation temperature range of a minimum 170° C. or higher, and further wherein the carbon-based additive has (i) between about 20 and 40 percent microporous carbon particles of the total amount of carbon-based additive by weight;
- (ii) between about 60 and 70 percent mesoporous carbon particles of the total amount of carbon-based additive by weight;
- and (iii) between about 0 and 10 percent macroporous carbon particles of the total amount of carbon-based additive by weight.
Dependencies are inferred from the claim text.