Battery cells as told by a slide, oranges and a chocolate aero
I would hazard a guess that if challenged in a pub, most automotive engineers would not be able to tell you how an electric battery for an EV actually works. They would probably be able to tell you about the battery pack and how it powers the electric motor. They may well describe the battery management system which monitors the health status of the battery cells within the battery pack (though this may not constitute pub appropriate conversation), and I suspect there may even be a few mumbled words about electrons and cobalt whilst they desperately try to recall their GCSE physics.
Until recently, I would count myself within this cohort of automotive professionals. That was until Karandeep Bhogal (who I should disclose is my husband) joined battery material company Nexeon, and our dinner time conversations required some sly wikipedia-ing on my part. Nexeon, like StoreDot and Sila Nanotechnologies are developing silicon based anodes for batteries. I shall attempt to explain why that is significant armed with my new fangled knowledge.
Electro-chemists and material scientists, look away now before I offend you with my terrible (and immensely unscientific) analogy.
Firstly, battery packs are made of battery cells. For an idea of scale, the standard range Tesla Model 3 has 2,976 battery cells arranged in 96 groups of 31. These cells are where the magic happens — i.e. where energy is stored and extracted in order to make the electric vehicle go.
Whether the cells are charging, or discharging to release energy when in use, both states involve moving atoms and electrons from one place to another -in the case of battery cells, from the cathode to the anode. Consider the image below. Here the orange represents an atom of Lithium with the peel representing an electron.
When the battery is empty (i.e. has fully discharged), all of the lithium atoms and their electrons are in the cathode — the oranges plus their peel are in the cathode crate.