A novel NaSn intermetallic improves critical electrochemical interfaces between molten sodium and NaSICON ceramic electrolyte at low temperatures (110 °C).

A major risk factor for colon cancer growth and progression is chronic inflammation. We have shown that the MAPK-activated protein kinase 2 (MK2) pathway is critical for colon tumor growth in colitis-associated and spontaneous colon cancer models. This pathway is known to regulate expression of the tumor-promoting cytokines, IL-1, IL-6, and TNF-α. However, little is known about the ability of MK2 to regulate chemokine production. This is the first study to demonstrate this pathway also regulates the chemokines, MCP-1, Mip-1α, and Mip-2α (MMM). We show that these chemokines induce tumor cell growth and invasion in vitro and that MK2 inhibition suppresses tumor cell production of chemokines and reverses the resulting pro-tumorigenic effects. Addition of MMM to colon tumors in vivo significantly enhances tumor growth in control tumors and restores tumor growth in the presence of MK2 inhibition. We also demonstrate that MK2 signaling is critical for chemokine expression and macrophage influx to the colon tumor microenvironment. MK2 signaling in macrophages was essential for inflammatory cytokine/chemokine production, whereas MK2−/− macrophages or MK2 inhibition suppressed cytokine expression. We show that addition of bone marrow-derived macrophages to the tumor microenvironment enhances tumor growth in control tumors and restores tumor growth in tumors treated with MK2 inhibitors, while addition of MK2−/− macrophages had no effect. This is the first study to demonstrate the critical role of the MK2 pathway in chemokine production, macrophage influx, macrophage function, and tumor growth.

Low-temperature molten sodium batteries show remarkable promise as the kind of low-cost, large-scale, reliable energy storage technology which is key to enabling a sustainable, safe, and resilient electric grid. Here, we describe a combination of cathode chemistry and engineered interfaces needed to reduce the molten sodium battery operating temperature from ∼300 °C to near 100 °C. This approach involves the development of a fully molten, inorganic sodium battery comprising a sodium anode, a NaSICON (Na 3 Zr 2 Si 2 PO 12 ) solid electrolyte separator, and a sodium iodide/aluminum bromide liquid catholyte operated at 110 °C. Battery performance is greatly improved by the application of a Sn coating on the anode-facing side of the NaSICON electrolyte and by the activation of a carbon felt current collector, together enabling the low-temperature molten sodium battery to achieve 200 cycles at 110 °C. The advancement of the low operating temperature molten sodium battery shows promise as a low-cost, large-scale energy storage system.

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Low-temperature molten sodium batteries comprising molten sodium anodes, a NaSICON solid-state separator, and molten halide salt catholytes offer promise as low-cost, earth-abundant energy storage technologies. The emergence of a specific, high-voltage, sodium iodide (NaI)-based catholyte chemistry has prompted the evaluation of chemical and electrochemical properties of the molten salts, particularly at critical interfaces with high-performance NaSICON separators. Herein, batteries operated at 110 °C with NaI-AlCl3-based catholytes of differing Lewis acidities were evaluated. Batteries with >50 mol % AlCl3 (acidic catholytes) experienced a linear decline in energy efficiency during cycling, whereas batteries with >50 mol % NaI (basic catholytes) maintained >95% energy efficiency for 50 cycles (>80 days) at 2.5 mA cm–2. A three-electrode cell was developed, enabling identification of the NaSICON–catholyte interface as the source of increased battery impedance. Complementary physical and chemical characterization of the NaSICON exposed to acidic and basic catholytes showed no changes in crystallinity, bulk morphology, or bulk chemical composition, but surface sensitive X-ray photoelectron spectroscopy (XPS), however, revealed subtle changes in local NaSICON surface chemistry. In addition, Raman spectroscopy indicated that stably performing basic catholytes lack the dimer species Al2Cl6I– present in acidic catholytes. Select thermodynamic and formal charge assessments suggest that preferential interactions between these acidic dimeric species and the NaSICON surface may be responsible for the observed increases in electrochemical impedance and degraded battery performance. These results indicate that maintaining a Lewis basic catholyte avoids such potentially deleterious interactions, enabling efficient and stable battery cycling.