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How sodium-ion batteries work
Sodium-ion cells turn chemical potential into electrical current by shuttling Na⁺ ions through an electrolyte while electrons take the useful route through an external circuit.
Inside the cell
The cathode is the sodium reservoir when the cell is discharged. During charging it releases sodium ions. The electrolyte conducts those ions, the separator blocks direct electrical contact, and a porous hard-carbon anode stores the arriving sodium. Aluminium or copper foils collect current from the coated electrodes.
Manufacturers assemble coated foils into stacked pouch cells or wound cylindrical and prismatic cells, add electrolyte, seal the case and run formation cycles. Pack makers then add busbars, fuses, temperature sensing, contactors and a battery-management system.
Why hard carbon is common
Graphite, the standard lithium-ion anode, does not readily host sodium in ordinary carbonate electrolytes. Disordered hard carbon provides larger sites and pores. Its first-cycle efficiency, pore structure and behaviour at low state of charge are therefore central engineering problems.
Voltage, power and control
Cell voltage depends on the electrode pair, so “sodium-ion voltage” is not one number. A battery-management system must use limits written for the particular cells. Treating an unfamiliar sodium pack as a drop-in lithium replacement without confirmed inverter or charger compatibility is unsafe and can invalidate a warranty.
Questions answered
Can I charge one with a lithium charger?
Only when the battery or cell maker explicitly approves that charge profile. Similar-looking nominal voltages do not prove compatibility.
What is formation?
The first controlled charge and discharge cycles that establish interfaces inside a new cell and help determine its usable performance.
Sources
- Strong performance — Faradion, checked 10 November 2026.
- Sodium-ion cell design research call — The Faraday Institution, June 2026.
Sources last checked 10 November 2026. Product availability can change.