A chemical reaction split in two and made to pay its electrons through a wire, run on the page: why a cell has its voltage, how fast its reactions go and how ions move; the cells people have built, from the lemon to lithium-ion; the models that predict a cell from the inside; how batteries age and why they sometimes burn; the packs, management systems and chargers that make cells into products; phones, cars and grids; fuel cells, electrolysers, corrosion and recycling. Pick electrodes, sweep a potential, age a cell for ten years and balance a pack — every number computed by the page.
Every curve and number on these pages is computed by the page or cited with its source; your progress stays in this browser. Never open, puncture, heat, short or rebuild a battery: nothing here asks you to. A swallowed button cell or a battery fire is an emergency. The course gives no engineering, legal, medical or investment advice and names no battery brand. Not affiliated with or endorsed by any organisation, manufacturer, publisher or author mentioned here.