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Emerging Era of Electrolyte Solvation Structure and Interfacial Model in Batteries

Sulfide electrolyte (SE)-based all-solid-state lithium batteries (ASSLBs) have gained worldwide attention because of their instrinsic safety and higher energy density over conventional lithium-ion batteries (LIBs). However, poor air stability of SEs, detrimental interfacial reactions, insufficient solid–solid ionic contact, and the large gap between fundamental study and practical engineering have impeded the commercialization of SE-based ASSLBs. This review aims to combine fundamental and engineering perspectives to rationally design practical SE-based ASSLBs with high energy density, covering SEs, interface, and practical all-solid-state pouch cells. First, the latest progress of typical pseudo-binary, pseudo-ternary, and pseudo-quaternary SEs is summarized, and effective strategies to improve ionic conductivity and chemical and electrochemical stability are highlighted. Moreover, challenges and strategies at the cathode and anode interfaces are reviewed separately. Furthermore, advanced in situ characterization techniques are examined to better understand the interface of ASSLBs. Encouraging demonstrations of SE-based all-solid-state lithium-ion and all-solid-state lithium–sulfur batteries are exemplified. Most importantly, energy-density-oriented all-solid-state pouch cells are designed using practical engineering parameters. The proposed design can serve as a quantitative framework to predict the practical energy density of SE-based all-solid-state pouch cells in future. Finally, future directions and our perspectives in SE-based ASSLBs are presented.

All-solid-state lithium batteries enabled by sulfide electrolytes: from fundamental research to practical engineering design

High-entropy nanoparticles have become a rapidly growing area of research in recent years. Because of their multielemental compositions and unique high-entropy mixing states (i.e., solid-solution) that can lead to tunable activity and enhanced stability, these nanoparticles have received notable attention for catalyst design and exploration. However, this strong potential is also accompanied by grand challenges originating from their vast compositional space and complex atomic structure, which hinder comprehensive exploration and fundamental understanding. Through a multidisciplinary view of synthesis, characterization, catalytic applications, high-throughput screening, and data-driven materials discovery, this review is dedicated to discussing the important progress of high-entropy nanoparticles and unveiling the critical needs for their future development for catalysis, energy, and sustainability applications. Description BACKGROUND High-entropy nanoparticles contain more than four elements uniformly mixed into a solid-solution structure, offering opportunities for materials discovery, property optimization, and advanced applications. For example, the compositional flexibility of high-entropy nanoparticles enables fine-tuning of the catalytic activity and selectivity, and high-entropy mixing offers structural stability under harsh operating conditions. In addition, the multielemental synergy in high-entropy nanoparticles provides a diverse range of adsorption sites, which is ideal for multistep tandem reactions or reactions that require multifunctional catalysts. However, the wide range of possible compositions and complex atomic arrangements also create grand challenges in synthesizing, characterizing, understanding, and applying high-entropy nanoparticles. For example, controllable synthesis is challenging given the different physicochemical properties within the multielemental compositions combined with the small size and large surface area. Moreover, random multielemental mixing can make it difficult to precisely characterize the individual nanoparticles and their statistical variations. Without rational understanding and guidance, efficient compositional design and performance optimization within the huge multielemental space is nearly impossible. ADVANCES The comprehensive study of high-entropy nanoparticles has become feasible because of the rapid development of synthetic approaches, high-resolution characterization, high-throughput experimentation, and data-driven discovery. A diverse range of compositions and material libraries have been developed, many by using nonequilibrium “shock”–based methods designed to induce single-phase mixing even for traditionally immiscible elemental combinations. The nanomaterial types have also rapidly evolved from crystalline metallic alloys to metallic glasses, oxides, sulfides, phosphates, and others. Advanced characterization tools have been used to uncover the structural complexities of high-entropy nanoparticles. For example, atomic electron tomography has been used for single-atom-level resolution of the three-dimensional positions of the elements and their chemical environments. Finally, high-entropy nanoparticles have already shown promise in a wide range of catalysis and energy technologies because of their atomic structure and tunable electronic states. The development of high-throughput computational and experimental methods can accelerate the material exploration rate and enable machine-learning tools that are ideal for performance prediction and guided optimization. Materials discovery platforms, such as high-throughput exploration and data mining, may disruptively supplant conventional trial-and-error approaches for developing next-generation catalysts based on high-entropy nanoparticles. OUTLOOK High-entropy nanoparticles provide an enticing material platform for different applications. Being at an initial stage, enormous opportunities and grand challenges exist for these intrinsically complex materials. For the next stage of research and applications, we need (i) the controlled synthesis of high-entropy nanoparticles with targeted surface compositions and atomic arrangements; (ii) fundamental studies of surfaces, ordering, defects, and the dynamic evolution of high-entropy nanoparticles under catalytic conditions through precise structural characterization; (iii) identification and understanding of the active sites and performance origin (especially the enhanced stability) of high-entropy nanoparticles; and (iv) high-throughput computational and experimental techniques for rapid screening and data mining toward accelerated exploration of high-entropy nanoparticles in a multielemental space. We expect that discoveries about the synthesis-structure-property relationships of high-entropy nanoparticles and their guided discovery will greatly benefit a range of applications for catalysis, energy, and sustainability. High-entropy nanoparticles and data-driven discovery. Emerging high-entropy nanoparticles feature multielemental mixing within a large compositional space and can be used for diverse applications, particularly for catalysis. High-throughput and machine-learning tools, coupled with advanced characterization techniques, can substantially accelerate the optimization of these high-entropy nanoparticles, forming a closed-loop paradigm toward data-driven discovery. CREDITS: TOP RIGHT: YANG ET AL., NATURE 592, 60–64 (2021); CENTER: JIAQI DAI; BOTTOM RIGHT: XIE ET AL., NAT. COMMUN.10, 4011 (2019) Diversifying nanoparticles Multielement nanoparticles are attractive for a variety of applications in catalysis, energy, and other fields. A more diverse range and larger number of elements can be mixed together because of high-entropy mixing states accessed by a number of recently developed techniques. Yao et al. review these techniques along with characterization methods, high-throughput screening, and data-driven discovery for targeted applications. The wide range of different elements that can be mixed together presents a large number of opportunities and challenges. —BG A review highlights improvements in synthesizing and stabilizing multielement nanoparticles.

High-entropy nanoparticles: Synthesis-structure-property relationships and data-driven discovery

High-entropy materials (HEMs) have great potential for energy storage and conversion due to their diverse compositions, and unexpected physical and chemical features. However, high-entropy atomic layers with fully exposed active sites are difficult to synthesize since their phases are easily segregated. Here, it is demonstrated that high-entropy atomic layers of transition-metal carbide (HE-MXene) can be produced via the selective etching of novel high-entropy MAX (also termed Mn+1 AXn (n = 1, 2, 3), where M represents an early transition-metal element, A is an element mainly from groups 13-16, and X stands for C and/or N) phase (HE-MAX) (Ti1/5 V1/5 Zr1/5 Nb1/5 Ta1/5 )2 AlC, in which the five transition-metal species are homogeneously dispersed into one MX slab due to their solid-solution feature, giving rise to a stable transition-metal carbide in the atomic layers owing to the high molar configurational entropy and correspondingly low Gibbs free energy. Additionally, the resultant high-entropy MXene with distinct lattice distortions leads to high mechanical strain into the atomic layers. Moreover, the mechanical strain can efficiently guide the nucleation and uniform growth of dendrite-free lithium on HE-MXene, achieving a long cycling stability of up to 1200 h and good deep stripping-plating levels of up to 20 mAh cm-2 .

High-Entropy Atomic Layers of Transition-Metal Carbides (MXenes)

Designing and fabricating bifunctional electrocatalysts for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is crucial to high-performance rechargeable metal–air batter...

Top–Down Synthesis of Noble Metal Particles on High-Entropy Oxide Supports for Electrocatalysis

The solid-electrolyte interphase (SEI) is known to dictate the performance of a Li metal anode, where its inorganic compositions are primarily responsible for Li+ conduction, electron insulation, a...

Tailoring Electrolyte Solvation Chemistry toward an Inorganic-Rich Solid-Electrolyte Interphase at a Li Metal Anode

High entropy materials, a horizon-broadening class of materials with complex stoichiometry, have gained significant interest recently. The ideal regulation and the attractive synergy effect make hi...

Opportunities for High-Entropy Materials in Rechargeable Batteries

Fluoride-Rich Solid-Electrolyte-Interface Enabling Stable Sodium Metal Batteries in High-Safe Electrolytes

Summary Li-metal anode with ultrahigh capacity (3,860 mAh/g) and lowest redox potential (−3.04 V versus standard hydrogen electrode) holds the key in advancing the next-generation high-energy-density batteries. The intrinsic defects of hyper-reactivity, dendritic growth, large volume change, and poor wettability on substrate, however, impede its practical applications. Recently, Li-metal-based composite (LMC), made by compositing metallic Li with various functional materials, has been proposed as an alternative to Li-metal anode, exhibiting unique physicochemical properties and excellent performances. To this end, we summarize recent advances in the synthesis, structure, properties, and electrochemical performance of LMC in terms of different functional materials. A special focus has been placed on the wetting behavior of Li metal with different carbons and the fascinating compositing reactions for LMC. We conclude with a discussion on the prospects and essential research directions for exploiting LMC from the fundamental research and practical application point of view. It is expected that this review will encourage Li-metal batteries to step forward to real applications.

Lithium Metal-Based Composite: An Emerging Material for Next-Generation Batteries

Solid-state lithium metal batteries (SSLMBs), using lithium metal as the anode and garnet-structured Li6.5La3Zr1.5Ta0.5O12 (LLZTO) as the electrolyte, are attractive and promising due to their high energy density and safety. However, the interface contact between the lithium metal and LLZTO is a major obstacle to the performance of SSLMBs. Here, we successfully improve the interface wettability by introducing one-dimensional (1D) TiO2 nanofibers into the lithium metal to obtain a Li-lithiated TiO2 composite anode (Li-TiO2). When 10 wt % TiO2 nanofibers are added, the formed composite anode offers a seamless interface contact with LLZTO and enables an interfacial resistance of 27 Ω cm2, which is much smaller than 374 Ω cm2 of pristine lithium metal. Due to the enhanced interface wettability, the symmetric Li-TiO2|LLZTO|Li-TiO2 cell upgrades the critical current density to 2.2 mA cm-2 and endures stable cycling over 550 h. Furthermore, by coupling the Li-TiO2 composite anode with the LiFePO4 cathode, the full cell shows stable cycling performance. This work proves the role of TiO2 nanofibers in enhancing the interface contact between the garnet electrolyte and the lithium metal anode and improving the performance of SSLMBs and provides an effective approach with 1D additives for solving the interface issues.

Yiming Dai

Papers

Tailoring Electrolyte Solvation Chemistry toward an Inorganic-Rich Solid-Electrolyte Interphase at a Li Metal Anode

Opportunities for High-Entropy Materials in Rechargeable Batteries

Fluoride-Rich Solid-Electrolyte-Interface Enabling Stable Sodium Metal Batteries in High-Safe Electrolytes

Lithium Metal-Based Composite: An Emerging Material for Next-Generation Batteries

TiO2 Nanofiber-Modified Lithium Metal Composite Anode for Solid-State Lithium Batteries.