ELECTRODEPOSITION

Plating the active material

voltage → film

Put a conductive pattern in a bath and apply a voltage. Metal oxides such as MnO₂ can plate directly from solution, and conducting polymers such as polyaniline or PEDOT form by electropolymerization of monomers. The film grows only on the conductive surface, and its thickness tracks the charge passed.

Grow only where the pattern is, and tune thickness by charge.

OTHER GROWTH ROUTES

Building the material on the electrode

Hydrothermal growth Heat a solution in a sealed vessel so nanostructures grow on a substrate

Chemical bath deposition Films precipitate onto a substrate from solution at mild temperature

CVD growth Nanotube forests or graphene grown directly on the current collector

Filtration and layer-by-layer Flakes stack up on a membrane, or alternately charged layers build up by dipping

Why it helps Direct growth gives binder-free electrodes with good electrical contact

Growing the material in place skips the binder entirely.

ELECTROSPINNING

Fibers from a high-voltage jet

jet → nanofibers

A high voltage pulls a polymer solution into a fine jet that dries into a mat of nanofibers, each just tens to hundreds of nanometers across. Heating the mat in stages, in air and then in inert gas, converts the polymer into carbon nanofibers that can serve as a self-standing, binder-free electrode.

Spin the polymer, then bake it into carbon.

MAKING FIBER DEVICES

Continuous processes for continuous devices

Wet spinning A graphene or nanotube dispersion is injected into a bath and solidifies into a fiber

Dip and coat A yarn or wire is pulled through electrode ink, layer by layer

Assemble Twist, wrap, or sheath the fibers with gel electrolyte between them

Textiles Dip-coat, dye, or print electrodes directly onto fabric

Fiber devices are made the way fibers are made: continuously.

UNIT 35 STUDY COMPLETE

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