Reaction mechanism studies towards effective fabrication of lithium-rich anti-perovskites Li3OX (X= Cl, Br)

Abstract

Lithium-rich Anti-perovskites (LiRAPs), with general formula Li 3 OX (X = Cl, Br), recently reported as superionic conductors with 3-dimensional Li + migrating channels, are emerging as promising candidates for solid electrolytes in all-solid-state lithium-ion batteries (LIBs). However, great challenges remain in the fabrication of pure LiRAPs due to difficulties such as low yield, impurity phases, thermodynamic instabilities, and moisture-sensitivity. In this work, we thoroughly studied the formation mechanism of Li 3 OCl and Li 3 OBr using various solid state reaction routes. Different experimental strategies were developed to improve the syntheses, namely for the purposes of phase stability, phase purity, and large-scale production. One feasible method is to use the strong reducing agents Li metal or LiH to eliminate the OH species. The results show that LiH is more effective than Li metal, mainly due to negatively charged Hand reaction uniformity. The other successful method employs a solid diffusion approach using Li 2 O and LiX as the starting reagents, thereby avoiding OH entirely; ball milling of reagents under Ar atmosphere was utilized to decrease initial grain size and increase the reaction rate. Fourier transform infrared spectroscopy (FTIR), thermal analyses and first-principles calculations were performed to give indications on the reaction pathway.

Promises, Challenges, and Recent Progress of Inorganic Solid‐State Electrolytes for All‐Solid‐State Lithium Batteries

“…Zhang et al demonstrated that Li vacancies and anion sublattice disorder are the driving forces for Li‐ion diffusion in antiperovskites by using ab initio molecular dynamics (MD) simulations, as shown in Figure d . The crystalline structure of antiperovskites can be manipulated quite easily by chemical substitution, for example, introducing Br − anions at the dodecahedral site to replace Cl − anions . It can induce high ion conductivity because of the rational optimization of the Cl–Br ratio.…”

Elucidating lithium-ion and proton dynamics in anti-perovskite solid electrolytes

“…[7][8][9][10][11] Although the high Li-ion conductivities of Li-rich antiperovskite materials have been known for decades, 12,13 it is only recently that significant interest has been generated for solid electrolyte applications. [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] Zhao and Daemen 14 reported high ionic conductivities (410 À3 S cm À1 at room temperature) and low activation energies (0.18-0.26 eV) for Li 3 OX-based compositions, where X = Cl or Br. However, subsequent reports have noted reduced Li-ion conductivities and increased activation barriers for these materials.…”

Iron Phosphate Coated Flexible Carbon Nanotube Fabric as a Multifunctional Cathode for Na‐Ion Batteries

“…Most solution‐based techniques fail to allow for thin conformal coatings of CNT fibers by active materials . Because the electron charge transfer from the conducting material to an insulator is typically effective on the distances of less than 5 nm, formation of highly conformal and thin coating onto every single CNT fiber of a composite material plays a crucial role in providing higher power densities. Fortunately, vapor deposition techniques, such as atomic layer deposition and CVD, are adept at creating conformal surface coatings made of active materials …”