High Li⁺ and Mg²⁺ Conductivity in a Cu-Azolate Metal–Organic Framework

Abstract

A Cu-azolate metal-organic framework uptakes stoichiometric loadings of Group 1 and 2 metal halides, demonstrating efficient reversible release and reincorporation of immobilized anions within the framework. Ion pairing interactions lead to anion-dependent Li + and Mg 2+ transport in Cu 4 (ttpm) 2 •0.6CuCl 2 , whose high surface area affords a high density of uniformly distributed mobile metal cations and halide binding sites. The ability to systematically tune the ionic conductivity yields a solid electrolyte with a Mg 2+ ion conductivity rivaling the best materials reported to date. This MOF is one of the first in a promising class of frameworks that introduces the opportunity to control the identity, geometry, and distribution of the cation hopping sites, offering a versatile template for application-directed design of solid electrolytes. ASSOCIATED CONTENT Supporting Information. Materials and Methods. Weight percentages of M n+ ions in the electrolytes. 1 H NMR spectra of MOF-MX n /PC. [110] reflection of Cu[(Cu 4 Cl)(ttpm) 2 ] 2 •CuCl 2. Electrolyte potential windows of MOF-LiX. SEM-EDS. I-V curve of Cu 4 (ttpm) 2 •0.6CuCl 2. Variable temperature EIS spectra of MOF-MX n. Li + transference number data of MOF-LiX. Li redox CVs with MOF-LiX. Arrhenius data of MOF-AlCl 3. The Supporting Information is available free of charge on the ACS Publications website.

Designing a Multifunctional Separator for High‐Performance Li–S Batteries at Elevated Temperature

“…Using a ceramic layer composing of porous Al 2 O 3 nanoparticles instead of Li@Nafion layer, a stable Li plating/tripping process with a low average overpotential (≈49 mV) was achieved (Figure S5b, Supporting Information). The effective inhibition of lithium dendrites growth is attributed to the uniform porosity of the Al 2 O 3 nanoparticles (Figure S6, Supporting Information), which can aid in regulating homogeneous Li ions flux, realizing a stable Li plating/stripping process . As a result, integrating both Li@Nafion layer and Al 2 O 3 layer on the two sides of PEP membrane, the LNPA‐cell maintains a stable overpotential even after an ultralong duration of cycle over 1000 h (Figure d).…”

“…Furthermore, the potential of LNPA for practical applications was further evaluated at a high current density of 5 mA cm −2 (2.5 mA h cm −2 ). A slight fluctuation was observed from the initial several cycles, generally because the symmetric cell plated/stripped at such a high rate needs an activation process 16b,17. The overpotential gradually became stable and maintained at ≈96 mV.…”

Recent Development of Mg Ion Solid Electrolyte

“…MIT-20 was attractive for its feature of immobilizing anions by the Cu(II) metal center, allowing the favorably free migration of cations within the one-dimensional pores. Later in 2019, Miner from Dinca's group continued their work on the tunable solid electrolyte of MOF (Miner et al, 2019). The MOF was Cu 4 (ttpm) 2 •0.6CuCl 2 , possessing high surface area with plenty of Cu(II) cations to bound halide anions.…”

Practical energy densities, cost, and technical challenges for magnesium‐sulfur batteries

“…[79][80][81] At present, one of the key challenges in obtaining a suitable solid-state magnesium-based electrolyte lies in the ionic conductivity at room temperature (around 1 mS cm −1 ). 79 However, with few exceptions, [82][83][84] the low room-temperature ionic conductivities are the upmost challenge hampering the application of solid-state electrolytes (SSEs). Henceforth, the development of an appropriate SSE is highly desired for Mg/S batteries.…”