Next-generation Rechargeable Batteries Research Articles

Multiscale Polymeric Materials for Advanced Lithium Battery Applications.

Riding on the rapid growth in electric vehicles and the stationary energy storage market, high-energy-density lithium-ion batteries and next-generation rechargeable batteries (i.e., advanced batteries) have been long-accepted as essential building blocks for future technology reaching the specific energy density of 400Wh kg-1 at the cell-level. Such progress, mainly driven by the emerging electrode materials or electrolytes, necessitates the development of polymeric materials with advanced functionalities in the battery to address new challenges. Therefore, it is urgently required to understand the basic chemistry and essential research directions in polymeric materials and establish a library for the polymeric materials that enables the development of advanced batteries. Herein, based on indispensable polymeric materials in advanced high-energy-density lithium-ion, lithium-sulfur, lithium-metal, and dual-ion battery chemistry, the key research directions of polymeric materials for achieving high-energy-density and safety are summarized and design strategies for further improving performance are examined. Furthermore, the challenges of polymeric materials for advanced battery technologies are discussed.

Enhancing the Catalytic Activity of Layered Double Hydroxide Supported on Graphene for Lithium–Sulfur Redox Reactions

The lithium–sulfur battery is one of the next-generation rechargeable battery candidates due to its high theoretical energy density and low cost. However, the sluggish conversion kinetics of soluble lithium polysulfides into insoluble Li2S2/Li2S leads to low sulfur utilization, retarded rate responses, and rapid capacity decay. Here, we enhance the sulfur reduction kinetics by designing and synthesizing a lamellar-structured NiFeLDH and reduced graphene oxide (rGO) composite. The assembly of a two-dimensional NiFeLDH with rGO, which has high conductivity and electrocatalytic activity, significantly enhances the electrochemical steps of sulfur reduction. The S@NiFeLDH/rGO cathode delivers an initial discharge capacity of 1014 mAh g−1 at 0.2 C and a capacity of 930 mAh g−1 after 100 cycles at 0.2 C. Even at a high current density of 1 C, the S@NiFeLDH/rGO could maintain a high capacity of 554 mAh g−1 after 400 cycles.

An overlooked parameter in Li-S batteries: The impact of electrolyte-to-sulfur ratio on capacity fading

The Lithium-Sulfur (Li-S) system has gained a lot of interest as a promising next-generation rechargeable battery due to the high theoretical energy density, high theoretical capacity and abundance of sulfur. Many parameters of Li-S batteries such as sulfur loading, electrolyte-to-sulfur (E/S) ratio, type of the conductive network, electrode design, etc. have a profound impact on the capacity, energy density and cycling performance. But the effect of E/S ratio on the electrochemical performance of Li-S batteries is often neglected, although it is one of the most important parameters. A high electrolyte amount in the cells could decrease the energy density and increase the cost, therefore it could limit the practical use of Li-S batteries. In this work, we first presented a statistical study on the sulfur loading and electrolyte quantity in Li-S cells by reviewing 240 selected papers from the state-of-the-art Li-S research. This analysis revealed that the electrolyte quantity was not reported as often as the sulfur loading in the literature, and the reported E/S values differ by a fair amount from each other. Second, in order to explore the effect of different E/S ratios on the performance of Li-S cells, batteries with 5:1, 10:1, 20:1 and 30:1 E/S ratios were prepared. Galvanostatic cycling with potential limitation (GCPL), electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT) were used to analyze the effect of E/S ratio on the capacity fade, impedance, internal resistance and ion diffusivity in Li-S batteries. The effects of different electrolyte penetration conditions on the electrochemical performance of cells with the same E/S ratios were also studied by preparing cells with different resting times. It was shown that E/S ratio has a strong influence on the electrochemical performance of Li-S batteries, and an optimal E/S ratio should be achieved, which is low enough to minimize the free migration of active materials between the electrodes, and at the same time high enough in order to have a sufficient electrolyte wetting of the active material. It is suggested that capacity decay in batteries with low E/S ratios could be originating from electrolyte depletion, whereas the capacity decay in batteries with high E/S ratios could be due to the dissolved lithium polysulfide species in the liquid electrolyte and their diffusion to the lithium anode surface.

(Invited) Discovery of New Capacity Fade Mechanism in Lixsn Batteries with Derivativeoperando (dOp) NMR Spectroscopy

Tin, silicon and other intermetallic forming electrodes have large volumetric lithium capacities—nearly 10 times that of graphite. Such a high capacity combined with their low cost make intermetallics promising materials for the next generation of rechargeable batteries. Unfortunately, severe capacity fade remains the greatest obstacle in their commercial use. For example, in 2005 Sony introduced their NEXELION battery technology using nanostructured SnCo electrodes but eventually had to pull these batteries from the market due to substantial capacity loss with cycling. While a major reason for capacity fade in these electrodes is thought to be cracking from large volume changes during transitions between intermetallic phases, little evidence for cracking in nanostructured electrodes has been found; and the mechanism for capacity fade in nanostructured intermetallic electrodes has remained a mystery.Using derivative operando (dOp) 7Li NMR we have discovered a mechanism for capacity fade in LixSn nanoparticle electrodes that may solve this mystery. In short, the capacity fade in nanoparticle electrodes is the result of nanoparticles losing contact with the carbon/PVDF binder. Yet, it occurs in a peculiar way which causes the cell to reach full capacity at the end of every cycle on lithiation. In other words, capacity fade only occurs during delithiation. We present clear NMR evidence showing that particle disconnection occurs during the delithiation (volume contraction of the electrode particles) process. During lithiation (volume expansion of the electrode particles) our NMR data further reveals that connected particles are surprisingly pushed back into contact with the disconnected particles which then rejoin the circuit and allow the cell to reach full capacity on lithiation. Our dOp 7Li NMR spectra also reveal the structural transformation pathways between Li-Sn intermetallics during lithiation and delithiation of Sn nanoparticles. The disconnecting particles are associated with LixSn phases undergoing large decreases in diameters on delithiation, i.e., Sn, Li2Sn5, LiSn, and Li7Sn3. The Li–Sn phases observed are somewhat consistent with the structural evolution expected from the equilibrium binary phase diagram, but there are some notable exceptions with the observation of a metastable phase Li2Sn3, and two vacancy rich metastable phases, Li7−ζSn3, and Li13−δSn5 during delithiation.Although this new capacity fade mechanism is simple, we know no in-situ microscopy method capable of detecting and following such a disconnection-connection mechanism. Our approach clearly show the power of operando NMR spectroscopy for revealing such fundamental processes. These results point the way for future efforts in both industrial and academic research labs to reduce capacity fade in a wider range of nano-structured intermetallic electrodes, involving Si, Ge and Sb. Figure 1

Structural Analysis of LiCoPO4 Electrode/Nasicon-Type Li1.3Al0.3Ti1.7(PO4)3 Solid Electrolyte Interface

All-solid-state lithium-ion batteries (ASSLIBs) with oxide-based solid electrolytes are a promising candidate for next generation of rechargeable batteries, due to their reliability and high-energy density. The formation of well-defined electrode/solid electrolyte interfaces with an excellent ionic conductivity by co-sintering is one of the key challenges to develop oxide-based ASSLIBs.1 Electrode materials and solid electrolytes often react with each other to form a resistive substance at their interface during co-sintering.2-4 Thus, optimization of the co-sintering conditions is important to control the interfacial structure which governs the ionic conductivity. However, the effect of the interfacial structure on the ionic conductivity remains unclear.In this study, we co-sintered the composites of LiCoPO4 (LCP) electrode material and Li1.3Al0.3Ti1.7(PO4)3 (LATP) oxide-based solid electrolyte and investigated the interfacial structure by using X-ray diffraction (XRD), X-ray absorption fine structure (XAFS) and scanning transmission electron microscopy combined with electron energy loss spectroscopy and an energy-dispersive X-ray spectroscopy (STEM-EELS/EDX).Figure 1(a) shows the XRD patterns of the LCP/LATP composites before and after sintering at 800°C. The diffraction patterns are almost identical to each other and all the diffraction peaks are attributed to the LCP and LATP with an exception of AlPO4 impurity. However, the Co K-edge XANES is slightly changed after sintering as shown in Figure 1(b). These results suggest that a small amount of LCP and LATP react with each other. Figure 1(c) shows a typical STEM image of the LCP/LATP composites after sintering at 800°C. According to EDX analysis, light and dark gray domains correspond to LCP and LATP, respectively. Apart from LCP and LATP, there are two types of LCP/LATP interfaces: interface A and B. Line profile STEM-EELS/EDX analysis revealed that LCP and LATP directly bound to each other at the interface A. On the other hand, a thermally reacted thin layer, possibly cobalt oxide (CoO) and/or cobalt phosphide (Co2P), is formed at interface B. The effect of such thermally reacted interlayer on the ionic conductivity will be discussed in detail.

(Digital Presentation) A Design of Nickel/Sulfur Energy-Storage Materials for Electrochemical Lithium-Sulfur Cells

Introduction As one of the next-generation rechargeable battery technologies beyond the lithium-ion chemistry, the lithium-sulfur chemistry enables the low-cost sulfur cathode to generate a high theoretical capacity of 1,675 mAh g-1 (10 times higher capacity than those of lithium-ion battery cathode). It further exhibits a high theoretical energy density of 2,600 Wh kg-1 in lithium-sulfur batteries (2–3 times higher energy density than lithium-ion batteries). However, as reported in recent publications, the development is far from adequate with respect to the high-loading sulfur cathode with high active-material content in building advanced lithium-sulfur batteries with a high energy density. The material challenges result from the use of an insulating sulfur as the active material, which would generate lithium polysulfides that can easily diffuse out from the cathode. The high cathode resistance and fast loss of the active material lead to the poor electrochemical utilization and efficiency of lithium-sulfur battery cathodes. These negative impacts subsequent derive the additional electrochemical challenges. A high amount of conductive and porous substrates is added in the cathode to replace the active material, which results in the limited amount of sulfur in the cathode and further blocks the improvement of designing high-energy-density sulfur cathodes.To address the above-mentioned issues, the research progresses of high-performance sulfur cathodes aim to design functional host for sulfur cathodes with the use of carbon for high conductivity, polymers for high ionic transfer, porous materials for physical polysulfide retention, polar materials for chemical polysulfide adsorption, catalysts for high reaction kinetics, etc. However, metallic materials that naturally have high conductivity, strong polysulfide adsorption capability, and catalytic conversion ability, are rarely reported. This is because metals have the highest density as compared to the aforementioned host materials, which commonly causes an insufficient amount of active material in the cathode and therefore inhibits the design of metal-sulfur nanocomposite in sulfur cathodes.To explore the metal/sulfur nanocomposite as a new research trend in sulfur cathodes, we propose a design for a nickel/sulfur nanocomposite as a novel energy-storage material by the electroless nickel plating method, and discuss its applications in lithium–sulfur battery cathodes. The nickel/sulfur energy-storage material possesses metallic nickel on the surface of the insulating sulfur particles as a result of the reduction of nickel ions during autocatalytic plating. By controlling the synthesis and fabrications conditions, the nickel/sulfur energy-storage material attains adjustable high sulfur contents of 60–95 wt% and adjustable high sulfur loadings of 2–10 mg cm−2 in the resulting cathode. The high-loading cathode with the nickel/sulfur energy-storage material demonstrates high electrochemical utilization and stability, which attains a high areal capacity of 8.2 mA∙h cm−2, an energy density of 17.3 mW∙h cm−2, and a stable cyclability for 100 cycles. Results and Discussion Here, in our presentation, we discuss our novel method for the fabrication of nickel/sulfur energy-storage material as an advanced composite cathode material for exploring battery electrochemistry and battery engineering. We adopt a modified electroless-plating method to synthesize nickel/sulfur energy-storage materials characterized by adjustable high sulfur contents and promising cathode performance. The plated nickel coating provides the nickel/sulfur energy-storage materials with metallic conductivity and polysulfide adsorption ability, which addresses the two major issues of sulfur cathodes.[1,2] Therefore, the nickel/sulfur energy-storage material attains high sulfur contents in the cathode and exhibits a high charge-storage capacity of 1,362 mA∙h g−1 and an excellent cyclability for 100 cycles. Moreover, the nickel/sulfur energy-storage material enables high-loading sulfur cathodes with a sulfur loading of 10 mg cm−2, a high areal capacity of 8.2 mA∙h cm−2, and an energy density of 17.3 mW∙h cm−2. Conclusion In summary, the summary of our nickel/sulfur energy-storage materials presented in this presentation would demonstrate a light-weight metallic nickel coating technique for fast charge transfer and strong polysulfide retention in the sulfur nanocomposites composite sulfur cathode. Moreover, our systematic analysis of the nickel/sulfur energy-storage materials exhibits their achievements in attaining both high electrochemical designs of high sulfur content and loading as well as possessing high energy density and electrochemical stability. References C.-S. Cheng, S.-H. Chung, Chem. Eng. J. 2022, 429, 132257.C.-S. Cheng, S.-H. Chung, Batter. Supercaps 2022, 5, e202100323.

Nickel Cobalt Oxide Decorated Cerium Oxide Nanorods for Polysulfide Trapping and Catalytic Conversion in Advanced Lithium Sulfur Batteries

Lithium sulfur batteries (LSBs) are promising candidates for next-generation rechargeable batteries due to the active material sulfur being earth abundant, low cost and environmentally friendly element. But the most important feature of LSBs is that the theoretical capacity of sulfur is ~1645 mAh g-1 which is ~5 times higher than the conventional lithium-ion batteries. However, even with these valuable assets, LSB has not yet been commercialized due to the inherent problems of fast capacity loss resulting in low cycle lifetime. This capacity loss originates from the migration of dissolved sulfur discharge products in the electrolyte known as the notorious polysulfide shuttling effect.To deal with this issue, several research efforts have been made to trap the high order lithium polysulfides by a) physically encapsulation using high surface area carbonaceous materials and b) chemically binding the lithium polysulfides in its cathode host. Several materials are very popular to efficiently bind the lithium polysulfides such as transition metal oxides, nitrides, sulfides and have helped making significant advances to long cycle life lithium sulfur batteries. However, to make the transition to design next generation LSBs, there is a need for materials that can facilitate fast polysulfide conversion by catalytic reaction that will reduce the diffusion and agglomeration of polysulfides in the liquid organic electrolyte, resulting in high capacity and long cycle lifetime.With this strategy in mind, we have designed NiCoOx decorated on CeO2 nanorods support as cathode host material for LSBs to provide dual adsorption-catalysis synergy. The CeO2 nanorods with enriched surface defects can effectively bind the lithium polysulfides whereas the NiCoOx nanoclusters can provide highly efficient electrocatalytic sites to improve the conversion kinetics of elemental sulfur to high order lithium polysulfides to finally the lower order polysulfides. As a result, the derived LSBs exhibited excellent electrochemical performance with high capacity of 1236 mAh g-1 at 0.2C with a sulfur loading of 1.33 mg cm-2. Even with high sulfur loading 2.66 mg cm-2 the LSBs exhibits 755 mAh g-1 at 0.2C with a capacity decay of only 0.08% per cycle after 170 cycles. The battery also operates at the sulfur loading of 4 mg cm-2 and 5.33 mg cm-2 for more than 100 which is convincing considering commercialization of LSB. Key words: lithium sulfur batteries, lithium polysulfides, shuttle effect, cerium oxide, catalysis.

Isoindigo-Derived Organic Small-Molecules As Long-Lifespan and High-Rate Cathode Materials for Rechargeable Batteries

Redox-active organic molecules (ROMs) are promising electrode materials for next-generation rechargeable batteries owing to their beneficial advantages of environmental friendliness, natural abundance, low cost, and possible high theoretical capacity. However, they suffer from a serious dissolution problem in organic electrolytes and low electrical conductivity, limiting their practical application. In particular, despite many advantages such as easy synthesis, potential low cost, and convenient processing, small-molecule electrode materials have typically showed far inferior stability and rate performance than polymeric materials.Herein, two isoindigo-based small molecules, isoindigo (Me-IIG) and thienoisoindigo (Me-TIIG), were synthesized and evaluated as a cathode material in lithium-organic batteries. In a Li coin cell, Me-IIG and Me-TIIG electrode exhibited specific capacity of 156 and 168 mAh g-1 at 1C, corresponding to 84% and 95% of capacity utilization, respectively. The Me-TIIG with better planar molecular geometry than the Me-IIG showed much lower solubility in organic electrolytes with the aid of strong intra- and intermolecular interactions. As a result, the Me-TIIG electrode presented remarkably improved cycling stability, retaining 96% of the initial capacity after 500 cycles at 5C rate. Moreover, Me-TIIG exhibited lower reorganization energy than Me-IIG, which can facilitate a kinetically faster electrochemical pathway, leading to superior rate capability. It should be noted that the Me-TIIG electrode showed excellent rate performance achieving 70% capacity retention at a high rate of 20C.

Next-generation Rechargeable Batteries Utilizing Ionic Liquids and Various Charge Carriers

Next-generation Rechargeable Batteries Utilizing Ionic Liquids and Various Charge Carriers

Synthesis of hollow S/FeS2@carbon nanotubes microspheres and their long-term cycling performances as cathode material for lithium-sulfur batteries

• The dissolution of lithium polysulfides is effectively alleviated. • CNTs improve the conductivity of S/FeS 2 @CNTs composites. • Low capacity decay rate of 0.024% per cycle for over 500 cycles is obtained. The lithium-sulfur batteries as a promising next-generation rechargeable battery are practically limited by their poor long-term cycling performance originating from the dissolution of lithium polysulfides. Combining physical and chemical interactions to trap lithium polysulfides is an effective way to improve the long-term cycling performance. Herein we have synthesized the hollow S/FeS 2 @Carbon nanotubes (S/FeS 2 @CNTs) microspheres by loading sulfur into FeS 2 @CNTs microspheres with carbon nanotubes entangling hollow FeS 2 microspheres. The hollow S/FeS 2 @CNTs microspheres working as cathode for lithium-sulfur batteries have delivered initial discharge capacity of 1245 mA h g −1 at 0.2 C. Particularly, the long-term cycling performance has been achieved that the capacity beyond 440.2 mA h g -1 can maintain for 500 cycles at 1 C, with a low capacity decay rate of 0.024 % per cycle. The significantly improved cycling performance of S/FeS 2 @CNTs can be attributed to the synergistic effects that the dissolution of lithium polysulfides diminishes by combining the physical interaction of CNTs with chemical absorption of FeS 2 , as well as the volume expansion of the cathode can be alleviated by the internal void space.

Bimetallic oxide nanoparticles contained hollow spheres with sodium as a core: a promising energy storage advanced structure

The bimetallic oxide nanoparticles as outer shell with sodium entrapped as a core part of a hollow porous core–shell (HoPoCs) can be a promising battery electrode composition. Till now, scientists are struggling to synthesize ternary metal oxide hollow spheres due to the reactions between diverse cations and anions of different metal precursors. Also, the extremely reactive character of sodium prevents it from remaining alone without compound formation is unveiled. Here for the first time, we entrapped sodium and synthesized bimetallic nanoparticles contained outer shell hollowsphere (Na@ZnO@MoO2) successfully by sorption (absorption + adsorption) of two metal precursors (sodium molybdate dihydrate and zinc chloride) in two steps without adding any reaction inhibiting agent. As a result, significantly Na is entrapped as a core and ZnO and MoO2 nanoparticles forming the outer shell of the sphere. ‘Na’ entrapment is confirmed by X-ray photoelectron spectroscopy and high-angle annular dark-field scanning transmission electron microscopy elemental mapping. We employed our sodium entrapped HoPoCs bimetallic oxide nanoparticles sphere (Na@ZnO@MoO2) as a battery anode getting advantages from their structural specialty shows excellent battery properties promising for application in energy storage technologies. The initial specific capacity of these HoPoCs-Na@ZnO@MoO2 sphere is 940 mAh/g (1C), with exceptional stability (790 mAh/g) after 1000 cycles at a current density of 2C) and excellent rate capability. This approach will motivate the synthesis of other superior reactive element entrapped core–shell metal oxides for next-generation rechargeable batteries and other advanced suitable applications like microreactor, protector of explosive materials, and so on.

Nitrogen-doped porous carbon nanofiber decorated with FeNi alloy for dendrite-free high-performance lithium metal anode

Lithium metal has garnered increasing attention, and is considered to be the most promising anode material for the next-generation rechargeable batteries with higher energy density such as lithium-sulfur, lithium-air and solid-state batteries. However, several serious challenges limit the commercial application of lithium metal batteries, including uncontrolled lithium dendrite growth, inherent volume expansion, and low Coulombic efficiency. Here, a nitrogen-doped porous nanofiber scaffold decorated with FeNi alloy nanoparticles with high lithophilicity is proposed by the electrospinning technique. The porous structure and the doping of FeNi alloy can expose more lithium nucleation active sites, and effectively reduce the nucleation overpotential of lithium metal to guide the uniform deposition of lithium. The porous structure formed by the sublimation of polymethyl methacrylate can effectively relieve the volume expansion and structural stress during the cycling process. As a result, excellent cycle stability and outstanding rate performance are observed in the tests of symmetric cells, highlighting the feasibility of the designed bimetallic doped carbon fiber scaffold for developing high-performance lithium metal anodes. The present work provides new strategies to solve the formation of lithium dendrites and brings new inspiration for the design and construction of high-efficiency lithium anodes and other secondary batteries anodes.

Single-material aluminum foil as anodes enabling high-performance lithium-ion batteries: The roles of prelithiation and working mechanism

As alloying-type anode materials, metallic aluminum owns an ultra-high specific capacity (993 mAh gAl-1 to LiAl) for Li storage, which is low-cost and a promising candidate for next-generation rechargeable batteries with high energy densities. However, metallic Al anodes suffer from irreversible lithiation of naturally occurring alumina layer during cycles, resulting in rapid capacity decay of Al anode-based batteries. Herein, Li supplement nucleated on Al foil via a controllably electrochemical pre-lithiation technology is employed for achieving high-performance elemental foil anodes. In full batteries, the pre-lithiated areas continuously supply Li outward during dealloying process to compensate for irreversible lithium loss during alloying process that preferentially alloys the unreacted Al2O3 surface layer along the rolling direction of Al foil until the entire surface is covered by LixAlOy. This lithiation behavior can avoid the severe stress concentration during alloying to prevent the perforation and pulverization of foil, making commercial Al foil succeed as single-material anodes. The produced commercial Al foil anode-based Li-ion batteries employing various commercial cathodes demonstrate promising electrochemical performances. For example, the Al||LiNi0.8Co0.1Mn0.1O2 battery offers a high specific capacity of 180 mAh g−1, an excellent capacity retention of ∼90% after 400 cycles, and relatively stable solid electrolyte interface without any dendrite.

Challenges and advances of organic electrode materials for sustainable secondary batteries.

Organic electrode materials (OEMs) emerge as one of the most promising candidates for the next-generation rechargeable batteries, mainly owing to their advantages of bountiful resources, high theoretical capacity, structural designability, and sustainability. However, OEMs usually suffer from poor electronic conductivity and unsatisfied stability in common organic electrolytes, ultimately leading to their deteriorating output capacity and inferior rate capability. Making clear of the issues from microscale to macroscale level is of great importance for the exploration of novel OEMs. Herein, the challenges and advanced strategies to boost the electrochemical performance of redox-active OEMs for sustainable secondary batteries are systematically summarized. Particularly, the characterization technologies and computational methods to elucidate the complex redox reaction mechanisms and confirm the organic radical intermediates of OEMs have been introduced. Moreover, the structural design of OEMs-based full cells and the outlook for OEMs are further presented. This review will shed light on the in-depth understanding and development of OEMs for sustainable secondary batteries.

Anion Redox in an Amorphous Titanium Polysulfide.

Amorphous transition-metal polysulfides are promising positive electrode materials for next-generation rechargeable lithium-ion batteries because of their high theoretical capacities. In this study, sulfur anion redox during lithiation of amorphous TiS4 (a-TiS4) was investigated by using experimental and theoretical methods. It was found that a-TiS4 has a variety of sulfur valence states such as S2-, S-, and Sδ-. The S2- species became the main component in the Li4TiS4 composition, indicating that sulfur is a redox-active element up to this composition. The simulated a-TiS4 structure changed gradually by lithium accommodation to form a-Li4TiS4: S-S bonds in the disulfide units and polysulfide chains were broken. Bader charge analysis suggested that the average S valency decreased drastically. Moreover, deep lithiation of a-TiS4 provided a conversion reaction to metallic Ti and Li2S, with a high practical capacity of ∼1000 mAh g-1 when a lower cutoff voltage was applied.

Solid-state electrolytes for beyond lithium-ion batteries: A review

Safe energy storage technique is prerequisite for sustainable energy development in the future. Designing Solid-State Electrolytes exhibiting high ionic conductivity, good electrochemical performances, high mechanical/thermal stability, compatible electrolyte/electrode interface is the main concern for developing the next-generation rechargeable batteries. This review presents the state of the art of Solid-State Electrolytes for beyond lithium-ion batteries, mainly, for Sodium-ion batteries, Potassium-ion batteries, Calcium-ion batteries, Magnesium-ion batteries, Zinc-ion batteries, and Aluminum-ion batteries. The main aspects of SSEs, including the synthesis processes, the physico-chemical properties, and the electrochemical performance, are emphasized.

Long-term stable Li metal anode enabled by strengthened and protected lithiophilic LiZn alloys

Li metal are regarded as one of the most promising anodes for next-generation rechargeable batteries. The continuous growth of Li dendrites, however, remains a big challenge for the practical application of Li metal anodes. Herein, an artificial solid-electrolyte interphase layer composed of lithiophilic LiZn alloys under the protection and strengthening of polymer-like [LiNBH]n chains with high Li ion conductivity is built to develop long-term dendrite-free Li metal anodes. The lithiophilic LiZn alloys, acting as homogeneous nucleation sites, effectively reduce the nucleation barrier for Li plating and hence promote uniform Li plating and stripping process. Simultaneously, the homogeneous layer of polymer-like [LiNBH]n chains with high Li ion conductivity that are uniformly built inside of LiZn alloys and on the surface of LiZn alloys facilitates Li diffusion down into LiZn alloys and simultaneously alleviate the volume change of LiZn alloys during long-term Li plating and stripping process. Impressively, the thus-fabricated anode delivers an ultralong lifespan of 1200 h at 5 mA cm−2 with a fixed capacity of 5 mA h cm−2. By pairing with commercial LiFePO4 cathode, the thus-assembled full cell exhibits a specific capacity of 133 mA h g−1, corresponding to a capacity retention of 88%, at 1 C after 400 cycles.

Li Metal Storage in Porous Carbon Frameworks: Effect of Li–Substrate Interaction

Lithium-metal electrodes are of particular interest for next-generation rechargeable batteries because of their high specific capacity and low redox potential. Therefore, Li-metal-based batteries may afford higher energy densities than commercially available Li-ion batteries with graphite anodes. However, various bottlenecks have hampered the commercial development of these batteries, including uncontrolled Li dendrite formation and huge volume changes during cycling. Consequently, Li-metal batteries suffer from low Coulombic efficiency and poor cycling stability. In recent years, there has been extensive research on the design and construction of three-dimensional (3D) porous electrodes that can host metallic Li. However, the low pore utilization and uneven Li plating remain crucial issues. This can be understood in terms of electronic and ionic transport through the framework electrode. The carbon frameworks exhibit high electronic conductance; however, large resistance to Li+ migration in the electrolytes of internal and interparticle pores inhibits the penetration of Li+ deep into the electrode. In this work, we demonstrate that a strong interaction between Li and a lithiophilic nanolayer on a substrate plays a critical role in enhancing pore utilization in carbon framework electrodes. As a model architecture, we examine a Li storage process in a framework electrode consisting of porous carbon derived from metal-organic frameworks (MOFs) and a galvanically displaced Ag layer on a Cu substrate (Cu@Ag). The electrochemical experiments combined with operando XRD measurements and microstructural characterizations suggest that a lithiophilic Ag on the Cu substrate preferentially reacts with Li+ to form Li x Ag during the initial stage of Li plating. This Li x Ag phase acts as a seed that can regulate the subsequent Li plating, promoting confined Li storage in the carbon framework electrode while suppressing top plating. Because of these advantages, the MOF-C framework electrode on Cu@Ag exhibits better cycling stability (>250 cycles) than the MOF-C framework electrode on Cu (140cycles). However, when the thickness of the MOF-C framework is increased to 90 μm, the diffraction peak for Ag remains dominant throughout Li plating-stripping, and the formation of Li x Ag alloys is not clearly detectable in the diffraction patterns, suggesting that only a limited amount of Ag is involved in the alloying reaction with Li+. Based on the computational studies, the efficacy of lithiophilic layers toward improving pore utilization is discussed in terms of the kinetic competition between Li+ transport through porous channels and the interfacial reaction of Li+ with the substrate. This study conveys an important message that the Li-substrate interaction plays a vital role in promoting the confined Li storage; hence, it should be considered a key design factor for porous carbon frameworks with high capacity and long cycle lifetime.References Yun, H. R. Shin, E.-S. Won, H. C. Kang, J.-W. Lee, Confined Li metal storage in porous carbon frameworks promoted by strong Li-substrate interaction, Chem. Eng. J. 430 (2022) 132897.Jin, Y. Ye, Y. Niu, Y. Xu, H. Jin, J. Wang, Z. Sun, A. Cao, X. Wu, Y. Luo, H. Ji, L. J. Wan, Solid-solution-based metal alloy phase for highly reversible lithium metal anode, J. Am. Chem. Soc. 142 (2020) 8818–8826.Kim, J. Lee, J. Yun, S.H. Choi, S.A. Han, J. Moon, J.H. Kim, J.-W. Lee, M.-S. Park, Functionality of dual-phase lithium storage in a porous carbon host for lithium-metal anode, Adv. Funct. Mater. 30 (2020) 1910538.

Vanadium Tetrasulfide for Next-Generation Rechargeable Batteries: Advances and Challenges.

Alkali metal-ion batteries (SIBs and PIBs) and multivalent metal-ion batteries (ZIBs, MIBs, and AIBs), among the next-generation rechargeable batteries, are deemed appealing alternatives to lithium-ion batteries (LIBs) because of their cost competitiveness. Improving the electrochemical properties of electrode materials can greatly accelerate the pace of development in battery systems to cover the increasing demands of realistic applications. Vanadium tetrasulfide (VS4 ) is known as a prospective electrode material due to its unique one-dimensional atomic chain structure with a large chain spacing, weak interactions between adjacent chains, and high sulfur content. This review summarizes the synthetic strategies and recent advances of VS4 as cathodes/anodes for rechargeable batteries. Meanwhile, we describe the structural characteristics and electrochemical properties of VS4 . And we describe in detail its specific applications in batteries such as SIBs, PIBs, ZIBs, MIBs, and AIBs as well as modification strategies. Finally, the opportunities and challenges of VS4 in the domain of energy research are described.

Boosting the energy density of organic cathode materials by designing planarized conjugated p-type polymer with multi-redox-active centers

P-type organic materials with high redox potential are promising electrode materials for next-generation rechargeable batteries with high-energy–density. Unfortunately, most of the reported p-type materials still deliver limited specific capacity because of their single-redox-active center, low electronic conductivity and sluggish diffusion kinetics of the large anions, resulting in the low material utilization. Herein, we design and successfully synthesize two p-type dihydrophenazine-based organic polymer cathodes (DPZPC and DPZPA), both with multi-redox-active centers, for sodium-organic batteries. Substantial characterizations indicate that the DPZPC with planarized conjugated repeat units exhibits better electronic conductivity, higher surface area, and more ordered microporous structure along with enhanced ionic transportation. As a result, the batteries assembled with DPZPC delivery superior performance with a high specific capacity of 184 mAh g−1 at a current density of 100 mA g−1, a long cycling stability (a capacity retention of 92 % after 100 cycles), and a high rate capability (117 mAh g−1 at 500 mA g−1) in sodium-organic batteries. This work provides a new molecular structure design strategy for organic electrode materials toward high performance rechargeable metal–organic batteries.