A damning critique of some of the half-truths the lithium-ion battery industry has disseminated in technical media and online is presented in the summer’s issue of Batteries and Energy Storage Technology Magazine.
Written by Dr Mike McDonagh (pictured), the publication’s technical editor, the article, entitled True Li-es, pours cold water on some of the general claims made by the industry that have made it the chemistry of choice for large-scale energy storage projects— vital for the widespread introduction of renewables.
McDonagh, a battery specialist with more than 30 years’ experience writes: “Performance data for lithium-ion batteries are based at the single cell level. This data very conveniently ignores the additional architecture required for safe operation in most installations and it is safety that manufacturers claim is their greatest concern.”
“Energy densities of current lithium-ion battery chemistries are given at around three to five times the gravimetric and volumetric energy density of lead-acid at cell level, which in part explains why the older technology has been all but ignored for this work,” McDonagh says.
“Factor in the connectors and spacing in a battery pack, the control and safety equipment, the battery management system, the fire control and cooling equipment which are required for the safe operation of larger lithium-ion batteries and the net result is that an installed working lithium-ion battery will have a working capacity less than one half its nameplate value,” says McDonagh.
In a practical operation, the advantage ratio of lithium-ion over lead-acid is reduced to around two times the energy density rather than the declared four to five times at cell level.
And the cost of lithium based storage systems is considerably higher as a consequence. The cost per kilowatt-hour of lithium-ion at cell level is up to five times that of lead-acid. According to forecasts, it is projected to fall sharply over the coming years. There is evidence, however, that these reductions are slowing down and perhaps leveling out.
The additional cost of safety equipment and the down rating of the lithium-ion usable energy range has the effect of increasing the cost per kWh. Because of this a lithium-ion cell that costs $300/kWh becomes inflated to $800/kWh at pack level and $1,200/kWh at system level.
“When you take into account environmental cost and safety, on top of the performance issues, the lithium-ion case over lead-acid doesn’t stack up anything like as well as manufacturers would have you believe. You need to look very carefully at their numbers. Lead-acid is a safe sound and, sadly, overlooked technology that’s 150 years young and completely recyclable.”
McDonagh’s full article is available to paid subscribers. Go to http://bit.ly/2ucENKd