Lithium Ion rechargeable batteries compare favourably to other types of battery but all have advantages and disadvantages. Li-ion technology has many good characteristics for use in modern applications.
Lead acid batteries have traditionally been used in (combustion engine) vehicles because they are relatively inexpensive and can source large currents (for starting). The down-side is that they are quite heavy, and contain sulphuric acid and so not great for portable applications. The technology has advanced and newer lead-acid batteries overcome the liquid acid in the more advanced AGM batteries which are maintenance free, smaller, but more expensive and slower to charge.
For portable applications, NiCd and NiMH batteries were popular, inexpensive and readily available. They are still used in many applications. These required some care during use to ensure they were charged and discharged properly otherwise they can quickly lose performance because of the “memory” effect.
Lithium Ion cells are small and comparatively light compared to other chemistries. They are higher voltage than other chemistries (3.7V typically). They are available in different shapes and so can be made to suit a particular application (e.g. smartphone or watch) and are also widely available in industry standard cylindrical shape. They can be joined together to build bigger, higher capacity and higher voltage batteries.
The problem with Lithium Ion chemistry is that, in a way, it is too good. They are capable of sourcing high currents very quickly and in doing so can get hot. If uncontrolled they can get very hot. This can lead to the build up of gas inside the cell which is vented when the build up of temperature gets out of control. It’s not hard to achieve: there are plenty of videos on Youtube of people putting a bare cell in their pocket, it shorts out through their keys or loose change and then sets their pants on fire. To compound this, the cell produces oxygen when it’s out of control, which is really good if you want a fire, but less good for your pants if they are on fire.
For this reason all lithium batteries should come with a protection PCB that will tame the battery and prevent this sort of reaction. More on this in a future article. So lithium ion, because of its wide availability, small size, high power-density and relatively low cost has become the go-to cell for many portable applications. Like all batteries, they are meant to provide power and need to be treated with respect.