Enhanced room-temperature Na+ ionic conductivity in Na4.92_{4.92}Y0.92_{0.92}Zr0.08_{0.08}Si4_{4}O12_{12}

Developing cost-effective and reliable solid-state sodium batteries with superior performance is crucial for stationary energy storage. A key component in facilitating their application is a solid-state electrolyte with high conductivity and stability. Herein, we employed aliovalent cation substitution to enhance ionic conductivity while preserving the crystal structure. Optimized substitution of Y3+ with Zr4+ in Na5YSi4O12 introduced Na+ ​ion vacancies, resulting in high bulk and total conductivities of up to 6.5 and 3.3 ​mS ​cm−1, respectively, at room temperature with the composition Na4.92Y0.92Zr0.08Si4O12 (NYZS). NYZS shows exceptional electrochemical stability (up to 10 ​V vs. Na+/Na), favorable interfacial compatibility with Na, and an excellent critical current density of 2.4 ​mA ​cm−2. The enhanced conductivity of Na+ ​ions in NYZS was elucidated using solid-state nuclear magnetic resonance techniques and theoretical simulations, revealing two migration routes facilitated by the synergistic effect of increased Na+ ​ion vacancies and improved chemical environment due to Zr4+ substitution. NYZS extends the list of suitable solid-state electrolytes and enables the facile synthesis of stable, low-cost Na+ ion silicate electrolytes

Neutron Diffraction Analysis of NASICON-type Li 1+x_{1+ x} Al x_{x} Ti 2−x_{2- x} P 3_{3} O 12_{12}

Powder neutron diffraction analysis was carried out on a sample of Li1+xAlxTi2–xP3O12 at two temperatures, 10 K and 300 K. After heat treatment the material contained small amounts of LiTiOPO4 as impurity. Refinement of the neutron diffraction data confirmed that the main phase crystallized with a NASICON structure. No structural change was observed at low temperature. Al atoms randomly substituted Ti atoms, and additional Li atoms occupied a second site in the crystal structure. A detailed analysis of the diffraction data, including the inspection of Fourier difference maps, indicated that these excess Li+ ions occupied a 6a site within the ion conduction channels of the NASICON-type structure instead of the formerly reported 18e or 36f sites

Synthesis and Characterization of the Ternary Telluroargentate K 4_{4}[Ag 18_{18} Te 11_{11} ]

The ternary potassium telluroargentate(I), K4[Ag18Te11], was prepared by solvothermal synthesis in ethylenediamine at 160 °C. It crystallizes in the cubic space group Fmequation imagem (no. 225) with the cell parameter a = 18.6589(6) Å. The crystal structure can be described as a [Ag18Te11]4– three-dimensional anionic framework with the voids accommodating potassium cations. Chemical bonding analysis reveals polar covalent Ag–Te bonds and considerable Ag–Ag interactions, which support the complex anionic character of the structure. The compound is thermally stable up to 450 °C in an inert atmosphere

Conductivity, microstructure and mechanical properties of tape-cast LATP with LiF and SiO2 additives

LATP sheets with LiF and SiO2 addition prepared by tape casting as electrolytes for solid-state batteries were characterized regarding conductivity, microstructure and mechanical properties aiming towards an optimized composition. The use of additives permitted a lowering of the sintering temperature. Rietveld analyses of the samples with additives revealed a phase mixture of NaSICON modifications crystallizing with rhombohedral and orthorhombic symmetry as a superstructure with space group Pbca. It seems that LiF acts as a sintering additive but also as a mineralizer for the superstructure of LATP. As general trend, higher LiF to SiO2 ratios led to lower porosities and higher values of elastic modulus and hardness determined by indentation testing, but the presence of the orthorhombic LATP leads to a decrease of the ionic conductivity. Micro-pillar testing was used to assess the crack growth behavior revealing weak grain boundaries