Lead, nickel, lithium… The different types of batteries that power our daily lives have characteristics that are as varied as they are nebulous for the average person. It is likely that you have already read the mention “lithium-ion” on the back of your phone without really understanding what it was about… In this article, we will explain what is hidden under the hood of your batteries!
First of all, it is important to remember that each technology has specific needs: storage, power, cost, size, recharge time… For example, you won’t need the same battery to power a smartphone, a Tesla or a golf cart. This brings us to the key concept of “energy density“. What is it? Energy density is the energy that can be stored in a battery for a given weight. Lead, nickel and lithium have different energy densities.
The lead battery is not new: in fact, the first lead accumulators appeared in the middle of the 19th century! Made of a lead-acid mixture, it supplies electricity to most gasoline and diesel vehicles. Inexpensive, the lead-acid battery is only slightly affected by the memory effect, i.e. it does not lose energy capacity after a succession of partial recharges. It also has a good life span.
However, the lead battery has a low energy density, which explains its high weight. Moreover, the lead battery does not support partial charges very well, and fears deep discharge, i.e. when the battery is discharged below the critical threshold of 20%. Finally, the power of the lead-acid battery will decrease in cold weather; this is why your vehicle may have already been stranded in sub-zero temperatures.
Invented at the end of the 19th century and first marketed in the 1950s, nickel batteries come in two main compositions: nickel-cadmium (Ni-Cd) and nickel-metal hydride (Ni-MH). Your rechargeable remote control or camera batteries are probably nickel-based. Nickel-cadmium and nickel-metal hydride batteries are very similar, but you should know that cadmium has been banned in Europe since 2016 due to its toxicity. The use of nickel-cadmium is today only used in security systems (alarms) or medical equipment.
The nickel-metal hydride battery, which is less polluting, has gradually replaced its cadmium cousin, especially since it has a better energy density. Nickel batteries have the advantage of being lighter than lead-acid batteries and can withstand much higher positive and negative temperatures. As for the memory effect, nickel-cadmium batteries must be completely discharged before recharging in order to preserve their energy capacity. This memory effect is reduced on nickel-metal hydride models, which on the other hand undergo a more pronounced self-discharge phenomenon, i.e. they lose a few percent of their charge each month even though they are inactive (this phenomenon is due to parasitic chemical reactions).
Li-ion, Li-Po… Names that you may be familiar with. Lithium is a component embedded in most of the electronic devices you use every day, and for good reason: the energy density of lithium is excellent. In other words, you can store more energy in a smaller volume. The different types of batteries are various, but the most common are lithium-ion (Li-ion), lithium-polymer (Li-Po) and lithium-iron phosphate (LiFePO4).
Although similar, the difference between these three technologies lies largely in their stability. Conventional lithium-ion is known to be the least stable technology because of the risk of explosion or ignition in case of overcharging, high temperatures, shocks or exposure of the component to open air. This is the reason why airlines systematically prohibit external batteries in checked luggage.
While lithium polymer has improved stability, it is really lithium iron phosphate that holds the gold medal for stability and safety. It is also the latter technology that allows the greatest number of charge/discharge cycles, which gives it a much longer life than other batteries in any category.