Over the last decade, lithium-ion batteries (LIBs) have seen a meteoric rise in deployment. They are preferred in consumer electronics, in electric vehicles (EVs), and for grid support. In 2018, the LIB market size of USD 40 billion was already seven per cent greater than lead-acid batteries. Annual deployment grew to 195 GWh in 2019 from a paltry 60 GWh five years prior.1 In this article we discuss the reasons behind the rapidly growing popularity of LIBs.
The most apparent difference between LIBs and other established technologies is the energy density. Lithium is the lightest metal and possesses a high electrochemical potential which allows LIBs to have extremely high energy densities; much higher than nickel-cadmium (Ni-Cd), nickel-metal hydride (NiMH) and lead-acid (Pb-Acid) batteries.2 This makes LIBs ideal for applications such as mobile phones or EVs, where excess weight is a liability.
The long cycle life of LIBs has further enhanced their popularity. Products that contain these batteries can reach the end of their product life without requiring a battery change. Also, the current higher costs of lithium-ion – with respect to lead-acid, for instance – can be significantly offset by the much longer cycle life of the battery. A lead-acid battery may have to be replaced several times over the lifespan of the product.
LIBs are essentially zero maintenance, without the need for intermittent charging and discharging required to prolong the battery’s life. The self-discharge of the battery is minimal, and it doesn’t need a topping charge to maintain its original state-of-charge (SOC). LIBs don’t show the battery memory effect common in NiMH and Ni-Cd batteries, which causes a loss of capacity when partially charged and discharged repeatedly.3
A single type of lithium-ion cell (the functional unit that makes up a battery), such as a cylindrical 21700 cell, can be used in a torch4 brought together into a EV battery pack, or even be used in a large grid-connected energy storage installation5. This versatility allows manufacturers to greatly scale production of specific cell architectures, bringing prices of lithium-ion batteries down considerably.