Inside the case are electrodes including cathodes and anodes where chemical reactions occur. Copper cathodes produced using this method are also described as electrolytic copper. The cell consists of two parallel cathodes with a fixed anode in the middle. Cold cathodes may also emit electrons by photoelectric emission. MWNTs are used in lithium ion batteries cathodes. These usually had directly heated thoriated filament cathodes that glowed like light bulbs. All have 1.25 volt DC filaments and directly heated cathodes. The gold ions are removed from solution at steel wool cathodes from electrowinning. Transition metal sulfies are considered promising candidates for magnesium ion battery cathodes. Addition of bismuth to caesium enhances the quantum yield of caesium cathodes. Their lifetimes tend to be longer than those of oxide cathodes. A few extreme examples of sputtering have even resulted in complete disintegration of Nixie-tube cathodes. The temperature required for modern oxide-coated cathodes is around . This means that insertion of one is equivalent to three ions in conventional intercalation cathodes. In general, this is seen for many lithium ion battery cathodes.