Anode and Cathode in Electrochemical Cells
– The first electrochemical battery, called the Voltaic cell, was invented by Alessandro Volta and consisted of copper and zinc electrodes separated by brine-soaked paper disks.
– The Daniell cell, invented by John Frederic Daniell, was the first practical battery and also used the zinc-copper electrode combination.
– Anodes are the electrodes through which conventional current enters from the electrical circuit into the non-metallic part of the cell.
– Cathodes are the electrodes through which conventional current flows from the electrical circuit into the non-metallic part of the cell.
– The anode has a negative charge, and the cathode has a positive charge.
– The term ‘anode’ was coined by William Whewell at Michael Faraday’s request and comes from the Greek words meaning ‘upwards’ and ‘a way.’
– The anode is the electrode where the oxidation reaction takes place, and electrons flow away from it.
– Conventional current flows towards the anode.
– The charge of the anode is negative.
– The electrons entering the anode come from the oxidation reaction.
– The term ‘cathode’ was also coined by William Whewell and comes from the Greek words meaning ‘downwards’ and ‘a way.’
– The cathode is the positive electrode where the reduction reaction takes place, and electrons are absorbed by the oxidizing agent.
– Conventional current flows from the electrical circuit through the cathode.
– The cathode has a positive charge.
– The cathode is the opposite of the anode.
Primary and Secondary Cells
– Primary cells are batteries designed to be used once and then discarded.
– The electrochemical reactions in primary cells are not reversible.
– An example of a primary cell is the alkaline battery used in flashlights.
– Primary cells have specific half-reactions at the anode and cathode.
– Recharging primary cells is not recommended due to safety concerns.
– Secondary cells are rechargeable batteries.
– The lead-acid battery, invented in 1859 by Gaston Planté, was the first rechargeable battery.
– Other commonly used rechargeable batteries include nickel-cadmium, nickel-metal hydride, and lithium-ion.
– Secondary cells can be recharged multiple times.
– The cathode and anode materials determine the properties and performance of secondary cells.
Efficiency and Electrode Properties
– Electrodes used in electrochemical cells must be conductive materials.
– Materials like metals, semiconductors, graphite, or conductive polymers can be used as electrodes.
– Electrodes often consist of a combination of materials with specific tasks.
– Important properties of electrodes include electrical resistivity, specific heat capacity, electrode potential, and hardness.
– The efficiency of electrochemical cells is determined by properties such as self-discharge time, discharge voltage, and cycle performance.
– Surface topology of the electrode affects efficiency.
– Contact resistance can reduce electrode efficiency.
– Designing the electrode to minimize contact resistance improves efficiency.
– Efficient electrode design is important for overall battery performance.
– Surface effects play a crucial role in electrode performance.
Electrode Manufacturing and Structure
– Electrode production involves various steps.
– Constituents of the electrode are mixed into a solvent.
– The mixture includes active electrode particles, binder, and conductive agent.
– The mixture is called electrode slurry.
– The slurry is coated onto a conductor and dried to the required thickness.
– The internal structure of the electrode determines final efficiency.
– Clustering of active material and conductive agent affects performance.
– Even distribution of the conductive agent optimizes electrode conductivity.
– Adherence of the electrode to current collectors prevents dissolution.
– Density of the active material should be balanced with other components.
Anodes and Cathodes in Lithium-ion Batteries
– Lithium-ion batteries are popular and widely used.
– Li-ion batteries can act as galvanic or electrolytic cells.
– Li-ion batteries use lithium ions as solute in the electrolyte.
– Anodes and cathodes are integral parts of Li-ion batteries.
– Research focuses on increasing efficiency, safety, and reducing costs.
– Cathodes in Li-ion batteries consist of intercalated lithium compounds.
– Cobalt-based compounds have advantages but also drawbacks.
– Manganese-based compounds have advantages but tend to dissolve.
– Research aims to find cheaper and longer-lasting materials.
– Cathode choice depends on battery application.
– Anodes in Li-ion batteries are either carbon-based or made of lithium titanate.
– Graphite anodes are commonly used due to price and energy density.
– Dendrite growth is a safety issue with graphite anodes.
– Silicon anodes have high capacity but face issues with expansion.
– Metallic lithium anodes offer high specific capacity but are unstable. Source: https://en.wikipedia.org/wiki/Electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). Electrodes are essential parts of batteries that can consist of a variety of materials depending on the type of battery.
The electrophore, invented by Johan Wilcke, was an early version of an electrode used to study static electricity.
