Materials chemistry

Lithium-ion, solid-state and lithium–sulfur batteries

Understand reversible lithium storage, cell voltage and capacity, and the materials and interfaces that limit liquid-electrolyte, solid-state, and lithium–sulfur batteries.

IntuitionA rechargeable chemical shuttle

During discharge, lithium moves from the negative electrode through an electrolyte to the positive electrode while electrons travel through the external circuit. Charging reverses the direction. The electrolyte carries ions but ideally blocks electrons, preventing an internal short circuit.

SchoolCell chemistry and capacity

A common graphite negative electrode stores lithium between carbon layers; layered transition-metal oxides or phosphates can serve as positive electrodes. The actual operating voltage depends on the difference in lithium chemical potential, not simply on the material names.

UndergraduateElectrochemical potential and interfaces

The open-circuit voltage is related to the Gibbs-energy change per transferred charge. In real cells, electrode potentials shift with composition and activity; the Nernst relation describes equilibrium trends. Under current, ohmic drop, charge-transfer kinetics, and mass transport create polarization and reduce terminal voltage.

AdvancedSolid electrolytes and lithium–sulfur chemistry

Solid electrolytes must combine useful Li⁺ conductivity with electronic insulation, chemical and electrochemical stability, and intimate contact to porous electrodes. Grain boundaries and interphases can dominate resistance. In Li–S cells, sulfur conversion involves soluble polysulfide intermediates in many liquid systems, giving high theoretical capacity but also shuttle and active-material loss.

ResearchResearch frontier