ANALYSIS OF STATE OF THE ART TECHNOLOGY FOR LEAD ACID AND LITHIUM-ION BATTERIES

ANALYSIS OF STATE OF THE ART TECHNOLOGY FOR LEAD ACID AND LITHIUM-ION BATTERIES
–J Varney April 16, 2009

Lead acid battery banks, even with state of the art improvements, these units appear to embody the following limitations and of course disadvantages:

[a] they are heavy in nature [because of plate material] and thus have a relatively poor “specific energy” rating in comparison with ultracapacitors. The claimed “specific energy” is, as an absolute maximum, 50 wh/kg and the battery weight for a 100KWH storage rating is 2000 kgs [4400 lbs]
[b] they utilize a hazardous electrolyte which can seriously burn and needs processing prior to legal disposal.
[c] they utilize dangerous and most toxic electrodes which have also serious obstacles to a legal disposal
[d] any manufacturing plant would represent a multi-layered environmental challenge to the owner and his endeavors to get the necessary operating permits.
[e] even with relatively high voltage and short charging time capability, their maximum number of discharge cycles [before becoming dysfunctional] is orders of magnitude less than that of ultracapacitor banks.
At this point the advantages awarded to the ultracapacitor are so profound as to make the lead acid battery a non starter in the dawn of the electric vehicle era.

Lithium-ion battery banks although much progress has been made in this technology and the compactness, weight and “specific energy” ratings are better than lead acid units. The claimed specific energy is, as an absolute maximum, 135 wh/kg and the battery weight for a 100KWH storage rating is 741 kgs [1630 lbs]. They have exhibited serious instability characteristics that at this time constitute a considerable hazard to the vehicle occupants and must be thoroughly engineered out of this otherwise attractive product. However its energy storage potential is still considerably less than that heralded for the ultracapacitor and again the maximum discharge cycled are of a much lower order of magnitude than that of the ultracapacitor unit. Perhaps a final disadvantage of the lithium-ion battery is that under mass production conditions it is expected to be more costly than its ultracapacitor competitor.

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