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Carbon-coated NaTi 2 (PO 4 ) 3 was successfully synthesized via a rapid microwave-assisted method and was found to have promising electrochemical function in a neutral pH Na 2 SO 4 aqueous electrolyte. The effects of various processing parameters, including precursor ball mill time, microwave irradiation parameters, and graphite precursor concentration, on the physical and electrochemical properties of the synthesized NaTi 2 (PO 4 ) 3 . To further study electrochemical performance, a full test cell consisting of NaTi 2 (PO 4 ) 3 /1 M Na 2 SO 4 /Na 0.44 MnO 2 was assembled. The highest discharge specific capacity obtained for this material was 85 mAh/g. These results indicate that, with an appropriate amount of graphite included in the precursor mix, microwave-synthesized NaTi 2 (PO 4 ) 3 is a promising sodium-ion functional anode material that can be produced using an extremely appealing low-cost manufacturing process.

Solvent-free single-ion polymer electrolytes with high conductivity have historically been prepared in the form of block copolymer or polymer blends. In this work, single-ion homopolymer electrolytes consisting of poly­(poly­(ethylene oxide) methacrylate lithium sulfonyl­(tri­fluoro­methyl­sulfonyl)­imide), poly­(PEOMA-TFSI–Li+), were prepared for the first time by photoinduced metal-free atom-transfer radical polymerization. The PEO-based macromonomer PEOMA-TFSI–Li+ was synthesized via click chemistry, copper-catalyzed alkyne–azide cycloaddition. Because of the conductive, amorphous PEO phase in which the lithium ions are located, these polymers showed improved ionic conductivity (10–5–10–4 S/cm at 90 °C) and high transference number (0.97–0.99). A continued lithium plating–stripping experiment was performed at current density ≥0.1 mA/cm2 over 300 cycles at 90 °C. The potential dendrite-suppressing capability of the polymer with such high transference number was also estimated by employing a kinetic model using the measured transport and transference properties to study the current density at the dendrite tip. The analysis indicates that the synthesized polymers could have a high propensity to suppress dendrite growth.

A composite anode comprising blended NASICON‐structured NaTi2(PO4)3 and activated carbon has been implemented in an aqueous electrolyte electrochemical energy storage device. A simple solid‐state synthetic route based on low‐cost precursors was used to produce the NaTi2(PO4)3, and thick (>1 mm) freestanding electrodes were fabricated with a range of activated carbon mass fractions. Electrochemical analyses showed the efficacy and stability of this composite anode combination in a functional paradigm where both Na+ and Li+ cations can participate in the charge storage reactions. Use of this composite anode in concert with a λ‐MnO2‐based cathode results in an energy storage device that is low cost, robust, and of sufficient energy density to be implemented in stationary applications. Data from large‐format units that contain many cells in series indicate that string‐level self‐balancing occurs, an effect that can be relied on for making cycle‐stable high‐voltage strings of cells.

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Aqueous alkali -ion batteries offer an economical method for large-scale energy storage demanded by current sources of renewable energy. Although NASICON-type NaTi 2 (PO 4 ) 3 is an attractive anode material with high capacity and a low redox potential allowing for high voltage cells, it suffers from considerable capacity fade when cycled slowly and deeply. In this work polypyrrole has been introduced as a coating for NaTi 2 (PO 4 ) 3 through a high-energy ballmilling process. When an excessive coating was applied, no redox reactions from the NaTi 2 (PO 4 ) 3 were visible due to the poor Na + diffusion through the polypyrrole. However, the as-coated composites containing 5 wt% polypyrrole showed much better capacity retention compared to the uncoated material, retaining 57% of the initial discharge capacity after 50 cycles compared to the uncoated material, which retained only 10% of the initial discharge capacity. It is concluded that coating NaTi 2 (PO 4 ) 3 with conducting polymers can be an effective strategy for promoting battery lifetime. Large-scale energy storage is needed for the deployment of gridtied and distributed renewable energy sources such as solar installations and wind farms, which rely on power generation that is inherently intermittent. For this kind of storage, the single most important performance attribute is the amortized cost of stored electricity over the life of the energy storage device; as such long life and robustness through thousands of use cycles are critical attributes.1,2 As such, we have sought to develop low cost, easy to manufacture battery chemistries that are composed of benign materials and have the necessary long-term stability. Neutral pH aqueous based battery systems are well suited for this purpose. The higher conductivity of aqueous electrolytes allows for thicker electrodes, low cost electrolyte salts such as Li 2 SO 4 and Na 2 SO 4 can be used in place of LiPF 6 , and nonwoven cellulose separators can be used in place of more expensive porous polyolefins. ,9-11,15,19-27 as anode materials. While a significant amount of research has been carried out on the failure mechanism of cathode materials, little has been done to elucidate the anode material role in battery failure in aqueous electrolytes. Furthermore, there are some cathode systems that have exhibited many thousands of stable cycles without loss in function, 8,28 while materials at useful anode potentials tend to lose function rapidly. 23,29 Of particular interest are the sodium super ionic conductor (NA-SICON) titanium phosphates due to their high ionic conductivities, relative low cost of production, and chemical stability. 11,24,25 In particular, NaTi 2 (PO 4 ) 3 with a theoretical capacity of 133 mAh/g and the ability to replace lithium salts with sodium equivalents should offer a cost-effective alternative to the lithium equivalent. However, this material commonly exhibits significant capacity fade, especially when cycled deeply/slowly, and the phenomena responsible for this loss in function remains p...

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