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2h ago

MIT’s CIET Model Recasts Lithium-Ion Intercalation for Faster, More Durable Batteries

Published in Science, the study attributes rate control to simultaneous ion–electron transfer, highlighting electrolytes as a practical lever.

electric car lithium battery pack
Lithium intercalation is the process by which lithium ions insert themselves into the solid electrode of a lithium-ion battery. MIT researchers have shown that as lithium ions (green) move from an electrolyte solution (right) to a cobalt oxide electrode (left), electrons also move into the electrode and reduce the cobalt (gray atoms with gold halo).

Overview

  • Systematic measurements using short voltage bursts across more than 50 electrolyte–electrode pairs found intercalation rates far lower than prior reports and inconsistent with Butler–Volmer predictions.
  • The Coupled Ion–Electron Transfer mechanism holds that lithium inserts only as an accompanying electron reduces the host, making the electron-transfer step the true rate controller.
  • Experimental data validated CIET’s mathematical framework for materials including NMC used in electric vehicles and LCO used in consumer electronics.
  • Altering electrolyte composition, including swapping anions, tuned kinetics and lowered the energy barrier for coupled ion–electron transfer.
  • The work, led by MIT with senior authors Yang Shao-Horn and Martin Bazant, was published in Science and funded by Shell and the Toyota Research Institute through the D3BATT Center.