In Situ Coating of Li7P3S11 Electrolyte on CuCo2S4/Graphene Nanocomposite as a High-Performance Cathode for All-Solid-State Lithium Batteries

Graphene in Solid-State Batteries: An Overview

Solid-state batteries (SSBs) have emerged as a potential alternative to conventional Li-ion batteries (LIBs) since they are safer and offer higher energy density. Despite the hype, SSBs are yet to surpass their liquid counterparts in terms of electrochemical performance. This is mainly due to challenges at both the materials and cell integration levels. Various strategies have been devised to address the issue of SSBs. In this review, we have explored the role of graphene-based materials (GBM) in enhancing the electrochemical performance of SSBs. We have covered each individual component of an SSB (electrolyte, cathode, anode, and interface) and highlighted the approaches using GBMs to achieve stable and better performance. The recent literature shows that GBMs impart stability to SSBs by improving Li+ ion kinetics in the electrodes, electrolyte and at the interfaces. Furthermore, they improve the mechanical and thermal properties of the polymer and ceramic solid-state electrolytes (SSEs). Overall, the enhancements endowed by GBMs will address the challenges that are stunting the proliferation of SSBs.

Amorphous Titanium Polysulfide Composites with Electronic/Ionic Conduction Networks for All-Solid-State Lithium Batteries

All-solid-state lithium/sulfide batteries are considered as next-generation high-energy-density batteries with unrivaled safety. However, sulfide cathodes generally suffer from insulating properties and huge volume expansion in all-solid-state lithium batteries. Based on amorphous TiS₄ (a-TiS₄), a certain proportion of Super P is introduced to suppress the volume expansion and increase the electronic conductivity. Meanwhile, a Li₇P₃S₁₁ solid electrolyte is in situ coated on the surface of 20% Super P/a-TiS₄, and the close interfacial contact between the active material and the solid electrolyte constructs a favorable ionic conduction path. As a result, a Li/75% Li₂S-24% P₂S₅-1% P₂O₅/Li₁₀GeP₂S₁₂/20% Super P/a-TiS₄@Li₇P₃S₁₁ battery shows a high reversible capacity of 507.4 mAh g^-1 after 100 cycles at 0.1 A g^-1. Even the current density increases to 1.0 A g^-1, and it can also provide a reversible capacity of 349.8 mAh g^-1 after 200 cycles. These results demonstrate a promising 20% Super P/a-TiS₄@Li₇P₃S₁₁ cathode material with electronic/ionic conduction networks for all-solid-state lithium batteries.

2D Materials for All-Solid-State Lithium Batteries

Although one of the most mature battery technologies, lithium-ion batteries still have many aspects that have not reached the desired requirements, such as energy density, current density, safety, environmental compatibility, and price. To solve these problems, all-solid-state lithium batteries (ASSLB) based on lithium metal anodes with high energy density and safety have been proposed and become a research hotpot in recent years. Due to the advanced electrochemical properties of 2D materials (2DM), they have been applied to mitigate some of the current problems of ASSLBs, such as high interface impedance and low electrolyte ionic conductivity. In this work, the background and fabrication method of 2DMs are reviewed initially. The improvement strategies of 2DMs are categorized based on their application in the three main components of ASSLBs: The anode, cathode, and electrolyte. Finally, to elucidate the mechanisms of 2DMs in ASSLBs, the role of in situ characterization, synchrotron X-ray techniques, and other advanced characterization are discussed.

The effect of solvent on reactivity of the Li2S-P2S5 system in liquid-phase synthesis of Li7P3S11 solid electrolyte

Synthesis technology for sulfide-based solid electrolytes based on liquid-phase processing has attracted significant interest in relation to achieving the optimal design for all-solid-state batteries. Herein, guidelines to solvent selection for the liquid-phase synthesis of superionic conductor Li₇P₃S₁₁ are described through systematic examination. 70Li₂S-30P₂S₅ system, a source of Li₇P₃S₁₁, is treated via a wet chemical reaction using eight organic solvents with different physical and chemical properties (i.e., dielectric constant, molecule structure, and boiling point). We reveal that the solvent's polarity, characterized by the dielectric constant, plays an important role in the formation of crystalline Li₇P₃S₁₁ via wet chemical reaction. In addition, acetonitrile (ACN) solvent with a high dielectric constant was found to lead to high-purity crystalline Li₇P₃S₁₁ and intrinsically high ionic conductivity. Further, solvents with a high boiling point and ring structures that cause steric hindrance were found to be unfavorable for the wet chemical synthesis of Li₇P₃S₁₁ solid electrolyte. Overall, we demonstrate that ACN solvent is the most suitable for the liquid-phase synthesis of a crystalline Li₇P₃S₁₁ solid electrolyte with high purity based on its dielectric constant, molecular structure, and boiling point.