The incompatibility between the anode and the cathode chemistry limits the used of Mg as an anode. This issue may be addressed by separating the anolyte and the catholyte with a membrane that only allows for Mg2+ transport. Mg‐MOF‐74 thin films were used as the separator for this purpose. It was shown to meet the needs of low‐resistance, selective Mg2+ transport. The uniform MOF thin films supported on Au substrate with thicknesses down to ca. 202 nm showed an intrinsic resistance as low as 6.4 Ω cm2, with the normalized room‐temperature ionic conductivity of ca. 3.17×10−6 S cm−1. When synthesized directly onto a porous anodized aluminum oxide (AAO) support, the resulting films were used as a standalone membrane to permit stable, low‐overpotential Mg striping and plating for over 100 cycles at a current density of 0.05 mA cm−2. The film was effective in blocking solvent molecules and counterions from crossing over for extended period of time.

Polyoligomeric silsesquioxanes with eight (LiNSO2CF3) groups can be dissolved at very high loadings into tetraglyme, forming solvent-in-salt electrolytes, and stable colloids with increasing amount of tetraglyme. Li+ ions can migrate by diffusive or coordinated hopping motions. High tLi+ and conductivities are obtained.

Self-standing, high conductivity solid iongel electrolytes with good thermal stability (T d ∼ 200 °C), mechanical properties, and an anodic stability up to 5 V were prepared using the solvate ionic liquid [G4Li]+[TFSI]− in methyl cellulose (MC) with 90 wt % liquid. The excellent combination of high room temperature conductivity (σ > 10–4) and storage modulus (E′ ∼ 60 MPa) is due to the semicrystalline fibrillar network formed by the MC. The high anodic stability of 5 V for the iongel is attributed to the known 4.5 V stability of the [G4Li]+[TFSI]− and the −OH groups on MC, which hydrogen bond with any free G4 not in the [G4Li]+[TFSI]− complex, so that they are unavailable for oxidation. Li0/iongel/Li0 plating/stripping at low current densities is stable with low polarization, but at high current densities the polarization and cell impedance increase, which is due to mosaic lithium plating. Coin cells of Li0/iongel/LiFePO4 could be cycled at C/2 (1C = 170 mA h/g) for at least 100 cycles with 98–99% Coulombic efficiency and capacities of 125 mA h/g, comparable to that of the pure liquid [G4Li]+[TFSI]− cells.

Solid ion-gel separators for lithium or lithium ion batteries have been prepared with high lithium ion transference numbers (tLi+ = 0.36), high room temperature ionic conductivities (σ → 10−3 S cm−1), and moduli in the MPa range.

Soft solid electrolyte materials are promising alternative choices for conventional battery electrolytes. Here, we have synthesized, characterized and calculated structural, thermal and electrochemical properties of an adiponitrile-based lithium-ion electrolyte which combines the advantages of organic and ceramic materials. This solid material is (Adpn)2LiPF6, (Adpn = adiponitrile) wherein (Adpn)-based channels solvate Li + ions through weak C≡N---Li + contacts.The surface of the crystal is a liquid nanolayer that binds the grains so that ionically conductive pellets are easily formed without high pressure/temperature treatments, which self-heals if fractured and which provide liquid-like conduction paths through the grain boundaries. High conductivity (σ ~ 10 -4 S/cm) and high lithium-ion transference number (tLi + = 0.54) result from weak interactions between "hard" (charge-dense) Li + ions and "soft" (electronically polarizable) -C≡N, compared with the stronger interactions of previously reported "hard" ether oxygen contacts of polyethylene oxide (PEO) or glymes. The proposed mechanism of conduction is one in which Li + ion migration occurs preferentially along the low activation energy path at the co-crystal grain boundaries and within the interstitial regions between the co-crystals, with bulk conductivity comprising a smaller but extant contribution to the observed conductivity. (Adpn)2LiPF6(s) has a wide electrochemical stability window of 0 to 5 V. Li 0 /(Adpn)2LiPF6/LiFePO4 cells exhibit cycling for > 50 cycles at C/20, C/10, C/5 rates with capacities of 140 mAh-g -1 to 100 mAh-g -1 and Coulombic efficiencies ~ 99%, and mitigation of the deleterious reactions with Li metal due to the high ionic strength. LTO/(Adpn)2LiPF6/NMC622 full cells were cycled at C-rates of C/20 to 1C with Coulombic efficiencies > 96%, with no dendritic failure after 100 cycles. Novel MD approaches addressing multiple conduction pathways and PWDFT calculations offer insights into the molecular basis of the physical and conductivity properties.

No abstract

The solid electrolyte (ADN)2LiPF6 is described. The structure exhibits adiponitrile (ADN)-based channels based on XRD analysis, through which the -C≡N-solvated Li+ ions migrate. High conductivity (σ ~ 10-4 S/cm) and high lithium ion transference number (tLi+ = 0.54) results from weak interactions between “hard” (charge-dense) Li+ ions and “soft” (electronically polarizable) -C≡N, compared with the stronger interactions of previously reported “hard” ether oxygen contacts of polyethylene oxide (PEO) or glymes. The surface of the crystal is a liquid nanolayer that binds the grains so that ionically conductive pellets are easily formed without high pressure/temperature treatments. (ADN)2LiPF6(s) has a wide electrochemical stability window of 0 to 5 V. Li0/(ADN)2LiPF6/LiFePO4 half cells exhibit cycling for > 50 cycles at C/20, C/10, C/5 rates with capacities of 140 mAh-g-1 to 100 mAh-g-1 and efficiencies > 95%. MD simulations and PWDFT calculations offer insights into the molecular basis of the physical and conductivity properties.

The solid electrolyte (ADN)2LiPF6 is described. The structure exhibits adiponitrile (ADN)-based channels based on XRD analysis, through which the -C≡N-solvated Li + ions migrate. High conductivity (σ ~ 10 -4 S/cm) and high lithium ion transference number (tLi + = 0.54) results from weak interactions between "hard" (charge-dense) Li + ions and "soft" (electronically polarizable) -C≡N, compared with the stronger interactions of previously reported "hard" ether oxygen contacts of polyethylene oxide (PEO) or glymes. The surface of the crystal is a liquid nanolayer that binds the grains so that ionically conductive pellets are easily formed without high pressure/temperature treatments. (ADN)2LiPF6(s) has a wide electrochemical stability window of 0 to 5 V.Li 0 /(ADN)2LiPF6/LiFePO4 half cells exhibit cycling for > 50 cycles at C/20, C/10, C/5 rates with capacities of 140 mAh-g -1 to 100 mAh-g -1 and efficiencies > 95%. MD simulations and PWDFT calculations offer insights into the molecular basis of the physical and conductivity properties.