“We’re delighted to be part of this project,” says UC San Diego Professor Shyue Ping Ong, “and apply our group’s latest advances in AI and machine learning for materials science to gain critical new insights into the synthesis and performance of these emerging materials.”
“We’re delighted to be part of this project and apply our group’s latest advances in AI and machine learning for materials science to gain critical new insights into the synthesis and performance of these emerging materials,” said Shyue Ping Ong, professor in the Aiiso Yufeng Li Family Department of Chemical and Nano Engineering at the UC San Diego Jacobs School of Engineering.
A paper from the laboratories of Meng and Ong, published recently in Joule, helps rectify that problem. Their research raises the benchmark for sodium-based all-solid-state batteries, demonstrating thick cathodes that retain performance at room temperature down to subzero conditions.
The research helps put sodium on a more equal playing field with lithium for electrochemical performance, said co-first author Sam Oh of the A*STAR Institute of Materials Research and Engineering in Singapore, a visiting scholar at Meng’s Laboratory for Energy Storage and Conversion at UChicago and UC San Diego during the research. Also co-first author of the research was Zihan Yu, a chemical engineering Ph.D. student in the Ong lab at UC San Diego.
How they accomplished that goal represents an advance in pure science.
“The breakthrough that we have is that we are actually stabilizing a metastable structure that has not been reported,” Oh said. “This metastable structure of sodium hydridoborate has a very high ionic conductivity, at least one order of magnitude higher than the one reported in the literature, and three to four orders of magnitude higher than the precursor itself.”
Established technique, new field
The team heated a metastable form of sodium hydridoborate up to the point it starts to crystalize, then rapidly cooled it to kinetically stabilize the crystal structure. It’s a well-established technique, but one that has not previously been applied to solid electrolytes, Oh said.
That familiarity could, down the road, help turn this lab innovation into a real-world product.
“Since this technique is established, we are better able to scale up in future,” Oh said. “If you are proposing something new or if there’s a need to change or establish processes, then industry will be more reluctant to accept it.”
Pairing that metastable phase with an O3-type cathode that has been coated with a chloride-based solid electrolyte can create thick, high-areal-loading cathodes that puts this new design beyond previous sodium batteries. Unlike design strategies with a thin cathode, this thick cathode would pack less of the inactive materials and more cathode “meat.”
“The thicker the cathode is, the theoretical energy density of the battery – the amount of energy being held within a specific area – improves,” Oh said.
The current research advances sodium as a viable alternative for batteries, a vital step to combat the rarity and environmental damage of lithium. It’s one of many steps ahead.
“It’s still a long journey, but what we have done with this research will help open up this opportunity,” Oh said.
Citation: “Metastable sodium closo-hydridoborates for all-solid-state batteries with thick cathodes,” Oh et al. Joule, Sept. 16, 2025. DOI: 10.1016/j.joule.2025.102130
This article was adapted from a post by Paul Dailing from UChicago PME.
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