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When it comes to batteries, lots of factors impact things like capacity, efficiency, and longevity, one of which is the battery barrel effect. In the simplest of terms, this means that an energy storage system, such as a multicell battery, is only as powerful as its weakest component. Think of it as a barrel made out of different sized staves; if you pour water into it, it's going to start spilling once it rises past the shortest stave.

Before getting into specifics, it's worth understanding how single-cell and multicell batteries work. Each battery cell contains two electrodes — a positively charged cathode and a negatively charged anode — which are separated by a chemical material called electrolyte. Multicell batteries are made by stacking alternating electrodes, including separators between each one.

In single-cell batteries, capacity loss occurs due to long-term chemical changes caused by the interaction between the electrolyte and the electrodes.…