Mr. Andrea Sanvito, Founder and CEO of the Company Triatech s.r.l., provides useful insights on the different types of lithium batteries, as well as an overview of the evolution of the market over the last ten years.
There is no doubt that lithium batteries represent the main innovation in the field of energy storage solutions. In this regard, some questions arise spontaneously. Are all lithium batteries the same? And how much do they cost?
In this article we will try to answer these two questions together with Mr. Andrea Sanvito, Founder and CEO of the Company Triatech s.r.l.
Currently, when generally mentioning “lithium batteries”, indeed we indicate 6 different types, depending on the materials used to manufacture the electrodes, also known as “anode” and “cathode”. Depending on the different combination of some metals, there are the following categories:
lithium cobalt (LiCoO2)
lithium manganese (LiMn2O4)
lithium iron phosphate (LiFePO4)
lithium nickel cobalt aluminum (LiNiCoAlO2)
lithium nickel manganese cobalt (LiNiMn-CoO2)
lithium titanate (Li4Ti5O12)
These different types differ in properties and characteristics, depending on the composition of the internal structure, with reference to the specific power (Watt / Kg), energy density (Wh / kg or liters), thermal stability, cycling, performance and, finally, the cost profile and expected useful life.
"In general, all lithium-ion batteries have undergone a rapid evolution in recent years, which has led to a significant improvement in product performance, especially in terms of reliability and durability, thanks to a better industrial design of the cells and a more efficient assembly system of the same - explains Mr. Sanvito -. The most recent battery packs, following these technical-production changes, guarantee lower internal resistance and a better management of operating temperatures, with a consequent reduction in overheating phenomena and, ultimately, an increase in the expected useful life ".
Mr. Andrea Sanvito,Triatech Founder and CEO
A recent study, published in January 2020 by the Swiss Research Institute MDPI (www.mdpi.com), analyzed the behaviour of some cells, manufactured with different chemistries, in applications for photovoltaic use, whose usage profiles are not very unlike those of forklifts. The study compared the degradation rate of the accumulators, in relation to variables such as the distribution of consumption during the day, the frequency and the recharging profile, the types of site in which the system was installed, the size of the system itself, always with an operating temperature between 35 ° C and 45 ° C.
"The degree of obsolescence of the batteries is mainly a function of the time factor (which affects the temperature and state of charge during the stand-by phases) and of the cycling, also associated with the temperature, and defined by the number, duration and depth of discharge cycles – Mr. Sanvito specifies -. During the tests carried out, it was observed how cyclic use affects, in terms of expected useful life, more on NMC (nickel-manganese-cobalt) cells than LPF (iron phosphate) cells. The latter have a better resistance to cycling, especially when it comes to small battery packs, intended for small photovoltaic systems for domestic use. This explains the widespread use, now a consolidated standard, of lithium iron phosphate (LPF) cells in the field of renewable energies".
With reference to the charge profile and site location, which affects daily irradiation, no significant correlation was found with respect to the obsolescence rate, with homogeneous behaviours between LFP and NMC. In summary, based on the simulations carried out, the cases analyzed show that the new generation batteries, both LFP and NMC, subjected to operating conditions in a temperature range between 35 ° C and 45 ° C, have an effective duration of no less than 10 years. Incidentally, this is a useful life perfectly compatible with the break-even point of a photovoltaic system, which varies between 8 and 12 years depending on the country and its tariff system.
Resuming the comparison of the different types of cells, in terms of characteristics, it is worthwhile reporting that the energy density, expressed in the Wh / Kg ratio, is higher in the combinations lithium nickel cobalt aluminum (NCA), followed by lithium nickel manganese cobalt (NMC) and lithium manganese, not surprisingly widely used for the production of battery packs for the automotive sector. In terms of safety, though having all the new generation cells reached high standards, the lithium iron phosphate (LFP), lithium titanate and lithium nickel manganese cobalt (NMC) solutions are more stable.
But how much do lithium-Ion batteries cost?
"Certainly, more than the traditional lead-acid ones, since their cost is higher in a ratio of 3 to 5 times, depending on the types and solutions selected - continues Mr. Sanvito -. Against a greater expense, lithium batteries however, they guarantee performance far superior to those of lead.
Just remember that a new generation lithium battery for automotive use is completely recharged in about 30 minutes, while a lead-acid cell takes no less than 8 hours, just as lithium is characterized by the total absence of maintenance and gaseous emissions".
The good news is that the cost of lithium has dropped very significantly and drastically over the past 10 years, thanks to standardization, increasing economies of scale and more efficient use of materials. If in 2010 the average cost of an NMC-type bag cell was $ 400 per kWh, in 2020 it was about $ 120 per kWh and a further drop is expected to be around $ 100 over the next 5 years. There is also a drop in the cost of battery packs, although in this case some less easily compressible expense items affect, such as assembly, wiring, control electronics. Between 2019 and 2020 it has gone from an average cost of 165 dollars to 150 dollars, and a value of just under 120 dollars is expected for 2025.
"Under the growing pressure of electric mobility, renewable energy, and thanks to growing economies of scale, it is not difficult to predict that lithium batteries will soon take over in almost all applications - concludes Mr. Sanvito -, in some cases going to replace traditional batteries, in others to expand the number of installations with accumulators, in one market, that of batteries, which grew on average by 8% per year in the period 2016 - 2019 and is expected to increase by the same amount until 2030 ".