Inorganic solid lithium ion conductors are potential candidates as replacement for conventional organic electrolytes for safety concerns. However, achieving a Li-ion conductivity comparable to that in existing liquid electrolytes (>1 mS cm–1) remains a challenge in solid-state electrolytes. One of the approaches for achieving a desirable conductivity is doping of various elements into the lattice framework. Our discussion on the structure and conductivity of crystalline Li-ion conductors includes description of NAtrium Super Ionic CONductor (NASICON)-type conductors, garnet-type conductors, perovskite-type conductors, and Lithium Super Ionic CONductor (LISICON)-type conductors. Moreover, we discuss various strategies currently used to enhance ionic conductivity, including theoretical approaches, ultimately optimizing the electrolyte/electrode interface and improving cell performance.

An efficient multi-doping strategy to enhance Li-ion conductivity in the garnet-An efficient multi-doping strategy to enhance Li-ion conductivity in the garnettype solid electrolyte Li7La3Zr2O12 type solid electrolyte Li7La3Zr2O12 Abstract Abstract Lithium-ion (Li + ) batteries suffer from problems caused by the chemical instability of their organic electrolytes. Solid-state electrolytes that exhibit high ionic conductivities and are stable to lithium metal are potential replacements for flammable organic electrolytes. Garnet-type Li 7 La 3 Zr 2 O 12 is a promising solid-state electrolyte for next-generation solid-state Li batteries. In this study, we prepared mono-, dual-, and ternary-doped lithium (Li) garnets by doping tantalum (Ta), tantalum-barium (Ta-Ba), and tantalum-barium-gallium (Ta-Ba-Ga) ions, along with an undoped Li 7 La 3 Zr 2 O 12 (LLZO) cubic garnet electrolyte, using a conventional solid-state reaction method. The effect of multi-ion doping on the Li + dynamics in the garnet-type LLZO was studied by combining joint Rietveld refinement against X-ray diffraction and high-resolution neutron powder diffraction analyses with the results of Raman spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and multinuclear magic angle spinning nuclear magnetic resonance. Our results revealed that Li + occupancy in the tetrahedrally coordinated site (24d) increased with increased multi-ion doping in LLZO, whereas Li + occupancy in the octahedrally coordinated site (96h) remained constant. Among the investigated compounds, the ternary-doped garnet structure Li 6.65 Ga 0.05 La 2.95 Ba 0.05 Zr 1.75 Ta 0.25 O 12 (LGLBZTO) exhibited the highest total ionic conductivity of 0.72 and 1.24 mS cm -1 at room temperature and 60 °C, respectively. Overall, our findings revealed that the dense microstructure and increased Li + occupancy in the tetrahedral-24d Li1 site played a key role in achieving the maximum room-temperature Li-ion conductivity in the ternary-doped LGLBZTO garnet, and that the prepared ternary-doped LGLBZTO was a potential solid electrolyte for Li-ion batteries without polymer adhesion. Disciplines DisciplinesEngineering | Physical Sciences and Mathematics ABSTRACT Lithium-ion (Li + ) batteries suffer from problems caused by the chemical instability of their organic electrolyte. Solid-state electrolytes that exhibit high ionic conductivities and stable to lithium metal are potential replacements for flammable organic electrolytes.Garnet-type Li7La3Zr2O12 is a promising solid-state electrolyte for next-generation solidstate Li batteries. In this study, we prepared mono-, dual-, and ternary-doped lithium (Li)

Li-ion batteries (LIBs) are a class of electrochemical energy storage devices widely adapted for their versatile use. Commercialized liquid electrolyte-based batteries are developing various issues like explosions, limited energy density, and leakage. All-solid-state batteries (ASSBs) with Li-ion-containing solid electrolytes (SEs) can be a solution to these shortcomings. However, assembling ASSBs is a challenge due to the high interfacial resistance between the electrodes and SEs. In the current Review, we addressed the rising concern over the interfacial deterioration leading to high charge-transfer resistance. A comprehensive discussion on the addition of buffer layers between the SE and electrodes is presented to improve interfacial stability. From polymer layers containing Li-salts with and without supporting fillers to amorphous oxides and metal coating, the interlayers ameliorate the ionic transport. Mutual compression and cosintering of SEs and electrodes can make a compact interface. Finally, the influence of morphology at the contacting surfaces is discussed.

Solid-state lithium-ion batteries are promising candidates for energy storage devices that meet the requirements to reduce CO2 emissions. NASICON-type solid-state electrolytes (SSE) are most promising materials as electrolytes for high-performance lithium ion batteries because of their good stability and high ionic conductivity. In this study, we successfully fabricate NASICON-based Li1.5Al0.5Ge1.5(PO4)3 lithium fast-ion conductors through melt-quenching with post-crystallization. The effect of crystallization temperature on the structure of LAGP and their ionic conductivity is systematically studied using Rietveld analysis of Synchrotron X-ray powder diffraction patterns, multinuclear magnetic resonance, and electrochemical analysis, revealing that the mobility of Li ion is dependent on crystallization temperature. The glass–ceramic LAGP annealed at 800 °C for 8 h exhibits the highest conductivity of 0.5 mS cm–1 at room temperature. Moreover, we report the viability of the prepared LAGP glass−ceramic as a solid electrolyte in Li-ion batteries without polymer adhesion. The cycling of Li/LAGP/LFP all-solid-state cell, provides a stable cycling lifetime of up to 50 cycles. This approach demonstrates that LAGP glass–ceramic can have good contact with the electrodes without interfacial layer and can deliver a reasonable discharge capacity after 50 cycles.

A new series of four-ring-fused π-conjugated anilido-benzoxazole boron difluoride (ABB) dyes were synthesized by employing an unsymmetrical bidentate ligand under a mild reaction condition. X-ray structural analysis demonstrated that the four-ring-fused π-conjugated skeleton is nearly coplanar, and almost orthogonal to the side anilido phenyl group with dihedral angles of 74-86°. The synthesized complexes exhibit very bright luminescence in solution (Φf = 0.45-0.96 in CH2Cl2) and in the solid-state (Φf = 0.07-0.37). These complexes show a larger Stokes shift (56-128 nm) than the well-known boron dipyrromethene dyes (8-12 nm, in most cases). The role of molecular packing patterns elucidated by the assistance of their X-ray crystal structures rationalizes the solid-state fluorescence. One of the tested compounds displayed aggregation induced emission (AIE). First-principle-based quantum-chemical studies were carried out on complexes . Time-dependent DFT (TD-DFT) calculations support the experimental results. The participation of the anilido phenyl moiety and the fluorine atoms was found to be negligible in the LUMO orbitals.