Anodes and Cathodes in Electrochemical Cells
- Anodes and cathodes are essential components of electrochemical cells.
- The first electrochemical battery was invented by Alessandro Volta and called the Voltaic cell.
- The practical battery, known as the Daniell cell, was invented by John Frederic Daniell in 1839.
- Electrochemical cells use two electrodes, anodes and cathodes, to facilitate chemical reactions.
- Anodes are the electrodes through which the conventional current enters the electrochemical cell.
- Cathodes are the electrodes through which the conventional current exits the electrochemical cell.
- The charge of the anode is negative, while the charge of the cathode is positive.
- At the anode, oxidation reactions occur, resulting in the release of electrons.
- At the cathode, reduction reactions occur, where electrons are absorbed.
- The flow of electrons and conventional current determines the direction of electrical flow in the cell.
Primary and Secondary Cells
- Primary cells are designed for single-use and cannot be recharged.
- Alkaline batteries, such as those used in flashlights, are examples of primary cells.
- The electrochemical reactions in primary cells are irreversible.
- Primary cells include zinc–carbon, zinc–chloride, and lithium iron disulfide batteries.
- Recharging primary cells is not recommended due to safety concerns.
- Secondary cells are rechargeable and can be reused multiple times.
- The lead–acid battery, invented by Gaston Planté, was the first rechargeable battery.
- Lead dioxide and solid lead are used as the cathode and anode in lead-acid batteries.
- Other commonly used rechargeable batteries include nickel–cadmium, nickel–metal hydride, and lithium-ion batteries.
- Lithium-ion batteries are widely used in various applications due to their efficiency and performance.
Electrode Efficiency and Properties
- Electrode materials should be conductive to be used as electrodes.
- Conductive materials like metals, semiconductors, graphite, and 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 like self-discharge time, discharge voltage, and cycle performance.
- The values of electrode properties vary depending on the material used.
- Commonly used electrode materials include lithium (Li) and manganese (Mn).
- The cost of the electrode material is also an important factor for technological applications.
- Electrode properties play a significant role in determining the performance of electrochemical cells.
Manufacturing and Structure of Electrodes
- Electrode production involves multiple steps.
- Constituents of the electrode are mixed into a solvent.
- Common components of the mixture include active electrode particles, binder, and conductive agent.
- The mixture is known as an 'electrode slurry'.
- The slurry is coated onto a conductor and dried to the required thickness.
- Internal structure determines the final efficiency of the electrode.
- Clustering of active material and conductive agent affects performance.
- Even distribution of conductive agent optimizes electrode conductivity.
- Adherence of the electrode to current collectors prevents dissolution.
- Density of active material should be balanced with other components.
Electrodes in Lithium-ion Batteries
- Li-ion batteries use electrodes.
- Li-ion batteries are rechargeable and can act as galvanic or electrolytic cells.
- Lithium ions are dissolved in an organic solvent in the electrolyte.
- Li-ion batteries have various applications, such as mobile phones and electric cars.
- Research aims to improve efficiency, safety, and cost of Li-ion battery electrodes.
- Cathodes in Li-ion batteries consist of intercalated lithium compounds.
- Cobalt and manganese are commonly used elements in cathode compounds.
- Cobalt-based compounds have advantages such as high specific heat capacity and voltage.
- Manganese-based compounds have lower cost but tend to dissolve over time.
- Research focuses on finding new materials for cheaper and longer-lasting cathodes.
- Anodes in Li-ion batteries are carbon-based or made of lithium titanate.
- Graphite anodes are widely used due to their price, longevity, and energy density.
- Graphite anodes can experience dendrite growth and pose safety risks.
- Silicon anodes have high capacity but suffer from volumetric expansion issues.
- Metallic lithium is another candidate for anodes, offering high capacity but stability challenges.
Note: Some content may overlap across the groups, but this organization should help consolidate similar concepts.
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.
