Solid-Electrolyte-Free O3-Li_xTiS₂ Cathode for High-Energy-Density All-Solid-State Lithium-Metal Batteries

Abstract

Composites made of high-capacity and highpotential LiNi x Mn y Co 1−x−y O 2 (NMC) lamellar transition-metal oxides and S-based ionic conductors are primarily used as positive electrodes in all-solid-state batteries (ASSBs). However, NMC coatings are necessary to prevent the chemical reactivity of oxygen and sulfur at the expense of some penalty in capacity and in ionic conduction. To overcome these problems, the current trend is to move to S-based positive electrodes, which exhibit higher electronic and ionic conductivities and no S−O reactivity. Herein we succeed in preparing highly divided O3-Li x TiS 2 powders by ball milling, which can be used as a positive electrode free of the electrochemically dead solid electrolyte (SE) in ASSBs that shows energy densities of more than 350 Wh/kg and stable cycling under low pressures down to 1 bar. These enhanced performances were rationalized by 7 Li NMR measurements that revealed a decrease in the site-to-site activation energy barrier with increasing ballmilling time. This finding, based on diffusion considerations associated with particle size reduction, can be generalized to other 3D metal sulfides and provides insights on the benefits of using a SE-free and C-free design relying on highly divided Li-containing sulfides to boost energy densities in ASSBs. KEYWORDS: all-solid-state lithium batteries, lithiated titanium disulfide, O3-Li x TiS 2 , low pressure, SE-free cathode, chalcogenides

Effect of the Nature of Both Cation and Anion Substitution on the Structural Symmetry of Li‐Rich 3d‐Metal Chalcogenide Electrodes

“…[13][14][15][16] To avoid this coating step, while minimizing the S-O interface reaction, our group and others have demonstrated the feasibility of using a Li-rich sulfide as part of the positive electrode or as a single component of the positive electrode without affecting or even slightly increasing the overall energy density of the cell. [17][18][19] So, in our ongoing quest to increase the energy density of highly efficient Li-rich 3d-metal chalcogenides, we delve deeper into the design strategies offered by the rich chalcogenide chemistry. In this study, we explore new phases by investigating monosubstitutions of Ti for Mn in Li 2-2y/3 Ti 1-y/3 Mn y Ch 3 (Ch = S, Se), as well as dual-substitutions of Ti for Fe and S for Se, resulting in Li 1.7 Ti 0.85 Fe 0.45 S 3-z Se z phases.…”

Interfacial Degradation Mechanism of Nanostructured LiCoO2 for Li6PS5Cl-Based All-Solid-State Batteries

“…Lithium-ion battery (LIB) technology, typically reliant on organic solvent-based electrolytes, currently confronts challenges in simultaneously achieving high energy density and safety for electric vehicles. To tackle these issues, there is a growing interest in transitioning from conventional LIBs to the next generation of all-solid-state batteries (ASSBs) using solid electrolytes. , Although various solid electrolytes, including oxide, sulfide, and polymer-based ionic conductors, have been explored for ASSBs, thiophosphate-based solid electrolytes, such as Li 6 PS 5 Cl (LPSCl), have attracted intensive attention due to their mechanical flexibility, high ionic conductivity, and manufacturability. − However, the transition to ASSBs also encounters difficulties related to structural and mechanical degradation at the interface between thiophosphate solid electrolytes and layered oxide-based cathode materials. This gradual interfacial degradation during cycling gives rise to an increasing charge-transfer resistance and, eventually, poor capacity retention. − …”

Atmospheric-Pressure Operation of All-Solid-State Batteries Enabled by Halide Solid Electrolyte

“…Current strategies to enable low-pressure cycling include increasing cycling temperature, lowering upper cutoff potential to limit CAM volume changes, optimizing CAM and SE particle sizes to improve percolation, , or using solid-electrolyte-free cathode systems , to minimize interfaces. More recently Gao et al utilized the chloride-based Li 3 InCl 6 SE and NMC to reach pressures of 2 MPa at 30 °C with a limited oxidation cutoff of 4.2 V vs Li + /Li.…”