Recent Advances and Perspectives in Lithium-Sulfur Pouch Cells

Electrochemical Performance of Deposited LiPON Film/Lithium Electrode in Lithium-Sulfur Batteries

This paper presents a composed lithium phosphate (LiPON) solid electrolyte interface (SEI) film which was coated on a lithium electrode via an electrodeposit method in a lithium-sulfur battery, and the structure of the product was characterized through infrared spectrum (IR) analysis, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), environment scanning electron microscope (ESEM), etc. Meanwhile, the electrochemical impedance spectrum and the interface stability of the lithium electrode with the LiPON film was analyzed, while the coulomb efficiency and the cycle life of the lithium electrode with the LiPON film in the lithium-sulfur battery were also studied. It was found that this kind of film can effectively inhibit the charge from transferring at the interface between the electrode and the solution, which can produce a more stable interface impedance on the electrode, thereby improving the interface contact with the electrolyte, and effectively improve the discharge performance, cycle life, and the coulomb efficiency of the lithium-sulfur battery. This is of great significance for the further development of solid electrolyte facial mask technology for lithium-sulfur batteries.

Synthesis of Solketal Catalyzed by Acid-Modified Pyrolytic Carbon Black from Waste Tires

Solketal, a widely used glycerol-derived solvent, can be efficiently synthesized through heterogeneous catalysis, thus avoiding the significant product losses typically encountered with aqueous work-up in homogeneous catalysis. This study explores the catalytic synthesis of solketal using solid acid catalysts derived from recovered carbon blacks (rCBs), which are obtained through the pyrolysis of end-of-life tires. This was further converted into solid acid catalysts through the introduction of acidic functional groups using concentrated H2SO4 or 4-benzenediazonium sulfonate (BDS) as sulfonating agents. Additionally, post-pyrolytic rCB treated with glucose and subsequently sulfonated with sulfuric acid was also prepared. Comprehensive characterization of the initial and modified rCBs was performed using techniques such as elemental analysis, powder X-ray diffraction, thermogravimetric analysis, a back titration method, and both scanning and transmission electron microscopy, along with X-ray photoelectron spectroscopy. The catalytic performance of these samples was evaluated through the batch mode glycerol acetalization to produce solketal. The modified rCBs exhibited substantial catalytic activity, achieving high glycerol conversions (approximately 90%) and high solketal selectivity (around 95%) within 30 min at 40 °C. This notable activity was attributed to the presence of -SO3H groups on the surface of the functionalized rCBs. Reusability tests indicated that only rCBs modified with glucose demonstrated acceptable catalytic stability in subsequent acetalization cycles. The findings underscore the potential of utilizing end-of-life tires to produce effective acid catalysts for glycerol valorization processes.

Optimization of the Form Factors of Advanced Li-S Pouch Cells

Lithium-sulfur (Li-S) batteries hold immense promise as next-generation energy storage due to their high theoretical energy density (2600 Wh kg⁻¹), low cost, and non-toxic nature. However, practical implementation faces challenges, primarily from Li polysulfide (LiPS) shuttling within the cathode and Li dendrite growth at the anode. Optimized electrodes/electrolytes design effectively confines LiPS to the cathode, boosting cycling performance in coin cells to up to hundreds of cycles. Scaling up to larger pouch cells presents new obstacles, requiring further research for long-term stability. A 1.45 Ah pouch cell, with optimized sulfur loading and electrolyte/sulfur ratio is developed, which delivers an energy density of 151 Wh kg-1 with 70% capacity retention up to 100 cycles. Targeting higher energy density (180 Wh kg-1), the developed 1Ah pouch cell exhibits 68% capacity retention after 50 cycles. Morphological analysis reveals that pouch cell failure is primarily from Li metal powdering and resulting polarization, rather than LiPS shuttling. This occurs for continuous Li ion stripping/plating during cycling, leading to dendrite growth and formation of non-reactive Li powder, especially under high currents. These issues increase ion diffusion resistance and reduce coulombic efficiency over time. Therefore, the study highlights the importance of a protected Li metal anode for achieving high-energy-dense batteries.

Progress and Perspectives on the Development of Pouch-Type Lithium Metal Batteries

Lithium (Li) metal batteries (LMBs) are the "holy grail" in the energy storage field due to their high energy density (theoretically >500 Wh kg-1 ). Recently, tremendous efforts have been made to promote the research & development (R&D) of pouch-type LMBs toward practical application. This article aims to provide a comprehensive and in-depth review of recent progress on pouch-type LMBs from full cell aspect, and to offer insights to guide its future development. It will review pouch-type LMBs using both liquid and solid-state electrolytes, and cover topics related to both Li and cathode (including LiNix Coy Mn1-x-y O2 , S and O2 ) as both electrodes impact the battery performance. The key performance criteria of pouch-type LMBs and their relationship in between are introduced first, then the major challenges facing the development of pouch-type LMBs are discussed in detail, especially those severely aggravated in pouch cells compared with coin cells. Subsequently, the recent progress on mechanistic understandings of the degradation of pouch-type LMBs is summarized, followed with the practical strategies that have been utilized to address these issues and to improve the key performance criteria of pouch-type LMBs. In the end, it provides perspectives on advancing the R&Ds of pouch-type LMBs towards their application in practice.

Adsorption of lithium ions from aqueous solution by magnetic aluminum-based adsorbents

Magnetic aluminum-based adsorbents (MLDHs) were prepared with a coprecipitation method and used to separate lithium ions from the aqueous solutions. In static adsorption experiment, the adsorption capacity of MLDHs for lithium ions reached 8.22 mg/g. In a mixed solution of various metal ions, the adsorbents exhibited higher selectivity for lithium ions. Kinetic studies indicated that the adsorption process conformed to a pseudo-second-order model. The experimental data were fitted with nonlinear regression using commonly used adsorption isotherms. It was found that the adsorption isotherm process could be described by the Langmuir model. In addition, the thermodynamic parameters revealed that the adsorption of lithium was a spontaneous endothermic process.

Hierarchical Porous and Three-Dimensional MXene/SiO2 Hybrid Aerogel through a Sol-Gel Approach for Lithium–Sulfur Batteries

A unique porous material, namely, MXene/SiO₂ hybrid aerogel, with a high surface area, was prepared via sol-gel and freeze-drying methods. The hierarchical porous hybrid aerogel possesses a three-dimensional integrated network structure of SiO₂ cross-link with two-dimensional MXene; it is used not only as a scaffold to prepare sulfur-based cathode material, but also as an efficient functional separator to block the polysulfides shuttle. MXene/SiO₂ hybrid aerogel as sulfur carrier exhibits good electrochemical performance, such as high discharge capacities (1007 mAh g^–1 at 0.1 C) and stable cycling performance (823 mA h g^–1 over 200 cycles at 0.5 C). Furthermore, the battery assembled with hybrid aerogel-modified separator remains at 623 mA h g^–1 over 200 cycles at 0.5 C based on the conductive porous framework and abundant functional groups in hybrid aerogel. This work might provide further impetus to explore other applications of MXene-based composite aerogel.

Dynamic Liquid Metal Catalysts for Boosted Lithium Polysulfides Redox Reaction

Designing efficient electrocatalysts with high electroconductivity, strong chemisorption, and superior catalytical efficiency to realize rapid kinetics of the lithium polysulfides (LiPSs) conversion process is crucial for practical lithium-sulfur (Li-S) battery applications. Unfortunately, most current electrocatalysts cannot maintain long-term stability due to the possible failure of catalytic sites. Herein, a novel dynamic electrocatalytic strategy with the liquid metal (i.e., gallium-tin, EGaSn) to facilitate LiPSs redox reaction is reported. The combined theoretical simulations and microstructure experiment analysis reveal that Sn atoms dynamically distributed in the liquid Ga matrix act as the main active catalytic center. Meanwhile, Ga provides a uniquely dynamic environment to maintain the long-term integrity of the catalytic system. With the participation of EGaSn, a tailor-made 2 Ah Li-S pouch cell with a specific energy density of 307.7 Wh kg^-1 is realized. This work opens up new opportunities for liquid-phase binary alloys as electrocatalysts for high-specific-energy Li-S batteries.