A novel state of the element manganese, first theorized in an article in a German language academic journal more than 90 years ago, has been confirmed by a group of scientists in the U.S. The discovery could lead to the development of high performance batteries, based on sodium-ion technology.
Scientists from California-based technology company, Natron Energy, formerly Alveo Energy, led the research, with key contributions also coming from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory and New York University.
The research, published in the journal Nature Communications, centers on an unconventional design for electrodes in a sodium-ion battery – supplied by Natron Energy. The battery’s anode is made from a blend of materials, including manganese, carbon and nitrogen; while the cathode utilizes copper, nitrogen, carbon and iron.
“The very interesting part here is that both electrodes are based on the chemistry of transition metals in the same type of materials,” explains Berkeley Lab Staff Scientist Wanli Yang. “Typically, in lithium-ion and sodium-ion batteries, the anode is more often carbon-based.”
In testing, the battery was able to deliver 90% of its total energy in a five minute discharge, and to retain 95% of its initial capacity after 1,000 cycles. According to Natron Energy CEO, Colin Wessells, the battery’s overall cost is competitive with lead-acid batteries, with a greatly reduced environmental footprint.
The battery’s performance is made possible by a newly discovered novel state of manganese in the anode. This state, where the element loses a single electron, is known as a ‘1-plus’ or ‘monovalent’ state. While unusual for manganese atoms, speculation that they could exist in this state dates all the way back to research first published in 1928.
Seeking to confirm its existence, the scientists turned to a newly built system at the Berkeley Lab’s Advanced Light Source. Named ‘in situ resonant inelastic X-ray scattering’ (RIXS), the tests immediately showed contrast in the electron’s behavior during charge and discharge cycles.
“A very clear contrast immediately shows up with RIXS,” Yang says. “We later realized that manganese 1-plus behaves very, very closely to the typical 2-plus state in other conventional spectroscopy,” which is why it had been difficult to detect for so many decades.
“The analysis of the RIXS results not only confirms the manganese 1-plus state; it also shows that the special circumstances giving rise to this state make it easier for electrons to travel in the material,” adds Andrew Wray of New York University. “This is likely why such an unusual battery electrode performs so well.”
Natron Energy’s Wessell states that commercial prototypes for the battery are already in beta testing, and that the company plans to promote the technology for grid-based storage applications, as well as emergency power and for powering heavy equipment.
Yang of the Berkeley Lab, meanwhile, states that this discovery could drive further innovation in the field of electrode materials. “The operation of a battery could drive the emergence of atypical chemical states that do not exist in our conventional thinking. This basic understanding could trigger other novel designs, and open our eyes beyond our conventional wisdom on electrode materials.”
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