Glass battery

The battery was invented by John B. Goodenough, inventor of the lithium cobalt oxide and lithium iron phosphate electrode materials used in the lithium-ion battery (Li-ion), and Maria H. Braga, an associate professor at the University of Porto[5] and a senior research fellow at Cockrell School of Engineering at The University of Texas.[1]

The paper describing the battery was published in Energy & Environmental Science in December 2016;[6] a number of follow-up works have also been published since.[7] Hydro-Québec is researching the battery for possible production.[8]

The battery, as reported in the original publication,[6] is constructed using an alkali metal (lithium or sodium foil) as the negative electrode (anode), and a mixture of carbon and a redox active component, as the positive electrode (cathode). The cathode mixture is coated onto copper foil. The redox active component is either sulfur, ferrocene, or manganese dioxide. The electrolyte is a highly conductive glass formed from lithium hydroxide and lithium chloride and doped with barium, allowing fast charging of the battery without the formation of metal dendrites.[2]

The publication states the battery operates during discharge by stripping the alkali metal from the anode and re-depositing it at the cathode, with the battery voltage determined by the redox active component and the capacity of the battery determined by the amount of the alkali metal anode. This operating mechanism is radically different from the insertion (intercalation) mechanism of most conventional Li-ion battery materials.

In 2018, a new version was described by most of the same authors in the Journal of the American Chemical Society, in which the cathode is coated with a special plasticiser solution to avoid interface cracking as different materials expand at different rates. Braga says the new battery has twice the energy density of conventional lithium ion batteries, and can be recharged 23,000 times.[15][16][17] Critics pointed out several extraordinary claims in the paper, such as a record-high relative dielectric constant; perhaps higher than any material recorded, and a raise in the capacitance of the battery over many charge cycles, rather than a decrease as is usually the case with all other battery technologies.[17][16] The paper was also not clear if the battery could hold its charge after it is unplugged, which would clarify whether it is really a new battery technology, or simply a capacitor.[17] Braga responded to critics, saying "Data is data, and we have similar data from many different cells, in four different instruments, different labs, glove box. And at the end of the day, the LEDs are lit for days with a very small amount of active material after having cycled for more than 23,000 times".[17][16]

Braga and Goodenough stated they expect the battery to have an energy density many times higher than current lithium-ion batteries, as well as an operating temperature range down to −20 °C (−4 °F); much lower than current solid-state batteries.[1][3][6] The electrolyte is also stated to have a wide electrochemical window.[18] The battery's design is safer than lithium-ion batteries, as the use of a flammable liquid electrolyte is avoided.[2] The battery can also be made using low-cost sodium instead of lithium.[2]

The authors claim the battery has a much shorter charging time than Li-ion batteries—in minutes rather than hours. The authors also state they tested the stability of the alkali metal/electrolyte interface over 1,200 charge cycles with low cell resistance;[1] the specification for Li-ion batteries is usually less than a thousand.[19][20]

• List of battery types