ionics

Ionics is the branch of science that studies ions and ionic processes across phases such as gases, liquids, and solids. It covers how ions form, move, interact, and participate in chemical and physical transformations, including ionic conduction, electrochemical reactions, ion exchange, and transport through membranes. The term is often used in materials science and electrochemistry to describe systems designed to facilitate controlled ion movement.

Key subfields include solid-state ionics, which investigates ionic transport in solids such as ceramic and polymer electrolytes; electrochemistry, which studies redox processes and ion transfer at interfaces; polymer ionics and ionic liquids, which examine polymer electrolytes and room-temperature molten salts; and membrane ionics, focusing on ion-selective membranes for separation and energy applications.

Measurement and theory are central to ionics. Impedance spectroscopy is widely used to measure ionic conductivity; NMR and quasi-elastic neutron scattering probe ion dynamics; X-ray and electron microscopy reveal structure; computational modeling helps predict ion transport and design new materials.

Applications span energy storage and conversion, including batteries, fuel cells, supercapacitors, and solid-state electrolytes; water treatment and desalination, through electrodialysis and ion-exchange membranes; chemical sensing and catalysis; electroplating and metallurgy; and biotechnology where ion transport plays a critical role.

History traces the concept of ions to Svante Arrhenius in the late 19th century, which laid the foundations of electrochemistry. The term ionics has grown with advances in ionic conductors, ion exchange materials, ionic liquids, and solid electrolytes, shaping research across chemistry, physics, and materials science.