DOE OSTI · 2588302
Machinable, high‐conductivity NaSICON through mitigation of humidity effects during solid‐state synthesis
Abstract
The Na + super ion conductor (NaSICON, Na 1+x Zr 2 Si x P 3-x O 12 ) is a solid electrolyte well-known for fast, selective Na + transport at low temperatures, uniquely enabling sodium-based batteries. Producing high-quality NaSICON from solid-state methods, especially when cost-effective, potentially hygroscopic precursors are used, is not trivial. To understand and eliminate the influence of humidity during processing, a scheme was developed to reproducibly yield a high Na + conductivity (3.75 mS/cm at 25°C, 81.7 mS/cm at 150°C), high density (97%), and machinable NaSICON without the use of binders, sintering aids, or dopants. Controlled humidity studies over 20%–50% RH coupled with thermal, structural, and electrical analysis reveal that calcination temperatures < 1000°C leave NaSICON processing susceptible to water absorption at > 20% RH due to the presence of hygroscopic Na 3 PO 4 and Na 2 CO 3 during shaping, pressing, and sintering. Water absorption results in NaSICON with lower densities, machinability, and Na+ conductivity, due to impaired intergranular Na+ transport. At the other extreme, fully converting precursor to the NaSICON phase at 1230°C before pressing and sintering leads to poor conductivity and density. By calcining at 1000°C, excellent quality NaSICON may be produced under a range of laboratory environments, enabling low-cost production of high-conductivity, machinable NaSICON necessary the ever-growing energy storage market.
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Peretti, Amanda Sheree [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)] (ORCID:0009000187863137), Spoerke, Erik David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)] (ORCID:0000000322862560), Ureña, Michael Earl [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)] (ORCID:0009000252120197), Dyer, Isaac D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)] (ORCID:0009000669844297), Salinas, Perla Arely [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)], Rodriguez, Mark. Andrew [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)] (ORCID:0000000269405044), Mantos, Philip Stewart [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)], Williard, John Newsom [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)], Small, Leo Joseph [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)] (ORCID:0000000304046287). 2025-09-04. Machinable, high‐conductivity NaSICON through mitigation of humidity effects during solid‐state synthesis. https://doi.org/10.1111/jace.70195
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