By Helen Gavaghan.
The 2019 Nobel Prize in chemistry was awarded to John B Goodenough (b. 1922), M. Stanley Whittingham (b. 1941) and Akira Yoshino (b. 1948). Among them they have developed the lithium chemistry needed for lightweight rechargeable lithium batteries, such as those in mobile phones. For a battery to work electrons must flow from anode (negative) to cathode (positive). Anode and cathode are separated by a solvent (electrolyte) or solid substance able to accept ions. Electron flow from anode to cathode enables energy to be extracted during the process to do work. There must be a virtuous circle of ions and electrons moving from anode to cathode and back. For rechargable batteries, an external power source is needed to maintain that virtuous circle during recharging. That is where the chemistry of lithium becomes interesting. Lithium has three electrons, one of which is available for chemical bonding or providing an electron for conductance. That electron is both lithium's strength in a battery and its weakness. The electron makes lithium highly reactive. The need when lithium batteries were first being developed was to find a chemical means of combining lithium with other substances such that its reactivity was tamed, while its electro-potential was maintained. And that had to be accomplished while keeping the light weight of lithium. It is the lightest metal, making lithium more attractive than lead as a battery component. That is the applied chemical magic which Goodenough, Whittingham and Yoshino performed, and which led them to their Nobel prize in chemistry today. They found materials accepting of lithium in anode, electrolyte and cathode, and chemical combinations through different types of bonding arrangements that made lithium batteries safe, with reaction kinetics which can sustain a continuing cycle of reversible reactions.
*Published first online at 21.30 BST, 9th October, 2019 for issue four 2019.