Basic Working Principle of Lithium-ion Batteries

Lithium-ion batteries achieve the conversion between electrical energy and chemical energy through the reversible migration of lithium ions between the positive and negative electrodes. During charging, lithium ions are released from the positive electrode material (e.g., LiCoO₂) and travel through the electrolyte. They pass through the separator and embed into the graphite structure of the negative electrode, while electrons flow via the external circuit to store energy. During discharge, lithium ions de-intercalate from the negative electrode and return to the positive electrode. The electron flow powers external devices, releasing energy. Internally, lithium-ion batteries mainly consist of four components: the positive electrode material, negative electrode material, electrolyte, and separator. The electrolyte acts as a medium for lithium-ion transport, and the separator prevents short circuits by keeping the positive and negative electrodes apart while allowing ion passage.