A lithium-ion cell stores energy by moving Li⁺ ions between two
host materials: graphite at the anode and a layered oxide at the
cathode. Charging drives ions (and their paired electrons, via the
external circuit) from cathode to anode against the cell's own
voltage; discharging lets them flow back down that gradient through
the electrolyte, doing useful work on the way.
flux ∝ C-rate × conductivity(T, electrolyte)
V_cell ≈ V_cathode − V_anode − I·R_internal
capacity(mAh) = ∫ I dt
- C-rate — how fast the cell is charged/discharged; 1C fully cycles capacity in one hour.
- Electrolyte conductivity — how freely ions cross the separator; low conductivity throttles flux and raises internal loss.
- Temperature — ion mobility falls sharply in the cold, raising internal resistance.
- Cathode material — NMC, LFP and LCO trade off voltage, capacity and thermal stability.