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This review explores the challenges and advancements in the development of high‐energy lithium‐ion batteries (LIBs), particularly focusing on the electrochemical and structural stability of Ni‐rich cathode materials. Despite their potential to increase the energy density of LIBs, these cathode materials encounter issues such as irreversible phase transitions and structural degradation during cycling, which ultimately affect their electrochemical performance. Elemental doping/substitution has emerged as promising strategies to address these challenges. However, the precise mechanisms underlying their performance enhancement remain unclear. The objective is to elucidate the complex reaction mechanisms triggered by doping and substitution in Ni‐rich cathode materials by employing in situ operando analyses to uncover their effects on electrochemical behavior and structural integrity during cycling. This comprehensive investigation aims to clarify the roles of elemental dopants or substituents in the crystal structures of Ni‐rich cathode materials, thereby offering valuable insights for the structural engineering of cathode materials in high‐energy LIBs. By elucidating these intricate mechanisms, this review provides a practical roadmap for future research and significantly contributes to LIB technology by guiding material design and optimization strategies in the development of advanced LIBs. [ABSTRACT FROM AUTHOR]

Thick and dense graphite anodes used in lithium‐ion batteries (LIBs) suffer from sluggish reaction kinetics at the electrode level, causing Li metal plating on their surfaces and significant capacity decay at high charging currents. Thus, it is crucial to tailor electrodes based on a comprehensive understanding of the complex reaction kinetics to realize fast‐charging LIBs. A multi‐interface strategy is proposed for electrode tailoring using Al2O3 nanoparticles to enhance fast‐charging capability while suppressing Li metal plating. Molecular dynamics simulations suggest that the incorporated Al2O3 nanoparticles perturb the charge and molecule distributions in the boundary layer, forming an "interfacial highway" for facile Li+ transport at the Al2O3/electrolyte interface. This pushes Li+ deeper into the electrode and homogenizes the Li+ flux across the electrode's top surface. A full cell assembled with the Al2O3‐decorated graphite electrode (areal capacity of 4.4 mAh cm−2) exhibits excellent cyclability with a capacity retention of 83.4% over 500 cycles even at a 2C rate without any noticeable signal for undesirable Li plating. The role of interfacial highways predicted by theoretical computations is further validated using a pouch‐type full cell (500 mAh). These findings provide insights into the interfacial and microstructural design of high‐capacity graphite electrodes for fast‐charging, long‐cycling LIBs. [ABSTRACT FROM AUTHOR]

The application of Li metal anodes in rechargeable batteries is impeded by safety issues arising from the severe volume changes and formation of dendritic Li deposits. Three‐dimensional hollow carbon is receiving increasing attention as a host material capable of accommodating Li metal inside its cavity; however, uncontrollable and nonuniform deposition of Li remains a challenge. In this study, we synthesize metal–organic framework‐derived carbon microcapsules with heteroatom clusters (Zn and Ag) on the capsule walls and it is demonstrated that Ag‐assisted nucleation of Li metal alters the outward‐to‐inward growth in the microcapsule host. Zn‐incorporated microcapsules are prepared via chemical etching of zeolitic imidazole framework‐8 polyhedra and are subsequently decorated with Ag by a galvanic displacement reaction between Ag+ and metallic Zn. Galvanically introduced Ag significantly reduces the energy barrier and increases the reaction rate for Li nucleation in the microcapsule host upon Li plating. Through combined electrochemical, microstructural, and computational studies, we verify the beneficial role of Ag‐assisted Li nucleation in facilitating inward growth inside the cavity of the microcapsule host and, in turn, enhancing electrochemical performance. This study provides new insights into the design of reversible host materials for practical Li metal batteries. [ABSTRACT FROM AUTHOR]

Voids are widely disseminated in a powder when mixed, and hence the typical dry‐electrode preparation method yields a sparse dry‐electrode because the external pressure applied to the surface of the mixed powder is not evenly distributed. Consequently, particle cracking and void remnants appear in the electrode after calendaring. This study introduces a practically applicable bi‐functionalized electrode additive to simultaneously reinforce the chemo‐mechanical properties of millimeter‐thick dry electrodes. The agyrodite Li6PS5Cl solid electrolyte and lithium difluorophosphate (LiPO2F2) additive have different sizes, as demonstrated by their densification from their elaborate bimodal structure, which is densely packed. Because the additive is filled into the interparticle voids in the electrode sheet during electrode fabrication, a decrease in electrode cracking after calendaring is possible because of the uniform distribution of external pressure. Hence, a thin, highly ionic/electronic‐conductive electrode can be constructed by the addition of LiPO2F2 additive. Furthermore, during the formation, the active material surface‐contacted LiPO2F2 promptly produces a surface layer comprising LiF and LixPFy. Thus, the addition of LiPO2F2 further reduces the degradation of Li6PS5Cl solid electrolytes. As a result, the LiPO2F2 additive simultaneously improves the electrochemical and physicochemical properties of millimeter‐thick dry‐electrodes for high‐energy all‐solid‐state battery systems. [ABSTRACT FROM AUTHOR]

Utilizing hyper‐lithiated materials can offer a variety of options for designing high‐energy lithium‐ion batteries. As sacrificial cathodes, they compensate for the initial loss of Li+ at the anode. During the first delithiation process, a Fe‐substituted Li6CoO4 (Li5.7Co0.7Fe0.3O4) supplies a large amount of Li+. Especially, the peroxide species formation and oxygen evolution are suppressed even though the charge compensation of oxygen is facilitated in Li5.7Co0.7Fe0.3O4. From a structural viewpoint, the anti‐fluorite structure changes to defective disordered phases during the Li+ extraction, and the proportion of the electrochemical‐inactive phase is more dominant in the case of Li5.7Co0.7Fe0.3O4 at the end of the charge. Consequently, the delithiated LixCo0.7Fe0.3O4 is deactivated in subsequent cycles, reducing unexpected electrochemical reactions after the Li+ provision as sacrificial cathodes. These findings provide a comprehensive understanding of the reaction mechanism of hyper‐lithiated materials and represent a significant step forward in developing high‐performance sacrificial cathodes. [ABSTRACT FROM AUTHOR]

Lithium metal batteries (LMBs) are in the spotlight as a next‐generation battery due to their high theoretical capacity. However, LMBs still suffer from inferior cycle stability owing to dendritic lithium (Li) growth during Li plating and stripping, leading to battery explosion. To solve this problem, solid electrolytes have emerged as a promising candidate by suppressing the dendritic Li growth. Despite numerous efforts, however, many challenges, such as low ionic conductivity, air stability, space charge layer, and contact loss issues, have been encountered. This review aims to provide the current challenges and new insights of solid electrolytes and then explore optimal solutions for next‐generation solid electrolytes. [ABSTRACT FROM AUTHOR]

The utilization of lithium (Li) metal as an anode has attracted significant attention for high‐energy Li batteries. Unfortunately, uncontrollable Li dendrite cannot be avoided during Li plating and stripping. Much intensive research has been conducted to suppress the dendritic growth by confinement of metallic Li in host architectures. Recently, zeolitic imidazolate frameworks (ZIFs) with a porous features have been used to explore a new approach to storing the Li metal with the advantages of their structural and chemical stability, large surface areas, and large pore cavities. Herein, we investigate the storage capability of metallic Li in a porous carbon framework derived from ZIFs as a function of carbonization temperature. Diversities in pore volumes and channels, the degree of crystallinity, the amount of residual zinc (Zn) metal, and the electrical conductivity can all be controlled by temperature. We demonstrate that well‐connected pore channels and adequate electrical conductivity secure the Li‐ion pathways and that well‐distributed Zn clusters in porous carbon trigger the outward growth of metallic Li from inside the frameworks, resulting in a relatively low overpotential and long‐lasting cyclability. Our findings can provide practical insight into advanced electrode design for next‐generation Li metal batteries. [ABSTRACT FROM AUTHOR]

Utilization of lithium (Li) metal anode is highly desirable for achieving high energy density batteries. Even so, the unavoidable features of Li dendritic growth and inactive Li are still the main factors that hinder its practical application. During plating and stripping, the solid electrolyte interphase (SEI) layer can provide passivation, playing an important role in preventing direct contact between the electrolyte and the electrode in Li metal batteries. Because of complexities of the electrolyte chemical and electrochemical reactions, the various formation mechanisms for the SEI are still not well understood. What we do know is that a strategic artificial SEI achieved through additives electrolyte can suppress the Li dendrites. Otherwise, the dendrites keep generating an abundance of irreversible Li, resulting in severe capacity loss, internal short‐circuiting, and cell failure. In this minireview, we focus on the phenomenon of dendritic Li‐growth and provide a brief overview of SEI formation. We finally provide some clear insights and perspectives toward practical application of Li metal batteries. [ABSTRACT FROM AUTHOR]

Lithium (Li) metal is regarded as the most attractive anode material for high‐energy Li batteries, but it faces unavoidable challenges—uncontrollable dendritic growth of Li and severe volume changes during Li plating and stripping. Herein, a porous carbon framework (PCF) derived from a metal–organic framework (MOF) is proposed as a dual‐phase Li storage material that enables efficient and reversible Li storage via lithiation and metallization processes. Li is electrochemically stored in the PCF upon charging to 0 V versus Li/Li+ (lithiation), making the PCF surface more lithiophilic, and then the formation of metallic Li phase can be induced spontaneously in the internal nanopores during further charging below 0 V versus Li/Li+ (metallization). Based on thermodynamic calculations and experimental studies, it is shown that atomically dispersed zinc plays an important role in facilitating Li plating and that the reversibility of Li storage is significantly improved by controlled nanostructural engineering of 3D porous nanoarchitectures to promote the uniform formation of Li. Moreover, the MOF‐derived PCF does not suffer from macroscopic volume changes during cycling. This work demonstrates that the nanostructural engineering of porous carbon structures combined with lithiophilic element coordination would be an effective approach for realizing high‐capacity, reversible Li‐metal anodes. [ABSTRACT FROM AUTHOR]

There are increasing demands for large‐scale energy storage technologies for efficient utilization of clean and sustainable energy sources. Solid‐state lithium batteries (SSLBs) based on non‐ or less‐flammable solid electrolytes (SEs) are attracting great attention, owing to their enhanced safety in comparison to conventional Li‐ion batteries. Moreover, SSLBs can provide great benefits in terms of battery performance (power and energy densities) and cost when constructed using a bipolar design. In this review, we introduce the general aspects of the bipolar battery architecture and provide a brief overview of the essential components and technologies for bipolar SSLBs: Li+‐conducting SEs, composite electrodes, and bipolar plates. Furthermore, we review the recent progress in the design and construction of bipolar SSLBs with emphasis on the fabrication techniques of SEs and SSLBs and the engineering approaches to improve their electrochemical properties. [ABSTRACT FROM AUTHOR]

A potential solid electrolyte for realizing all‐solid‐state battery (ASB) technology has been discovered in the form of Li10GeP2S12 (LGPS), a lithium superionic conductor with a high ionic conductivity (≈12 mS cm−1). Unfortunately, the achievable Li+ conductivity of LGPS is limited in a sheet‐type composite electrode owing to the porosity of this electrode structure. For the practical implementation of LGPS, it is crucial to control the pore structures of the composite electrode, as well as the interfaces between the active materials and solid‐ electrolyte particles. Herein, the addition of an ionic liquid, N‐methyl‐N‐butylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([Py14][TFSI]), is proposed as a pore filler for constructing a highly reliable electrode structure using LGPS. [Py14][TFSI] is coated onto the surface of LGPS powder through a wet process and a sheet‐type composite electrode is prepared using a conventional casting procedure. The [Py14][TFSI]‐embedded composite electrode exhibits significantly improved reversible capacity and power characteristics. It is suggested that pore‐filling with [Py14][TFSI] is effective for increasing contact areas and building robust interfaces between the active materials and solid‐electrolyte particles, leading to the generation of additional Li+ pathways in the composite electrode of ASBs. [ABSTRACT FROM AUTHOR]

Abstract: The use of solid electrolytes provides a technical solution to address the safety issues of lithium‐ion batteries and enables a bipolar design of high‐voltage and high‐energy battery modules. The bipolar design avoids unnecessary components and parts for packaging and electrical connection; therefore, it facilitates an increase in the volumetric energy density of the battery, while enabling easy build‐up of total output voltage. Herein, the design and construction of a multilayered, bipolar‐type, all‐solid‐state battery (ASSB) from a biphasic solid electrolyte (BSE) based on inorganic Li0.29La0.57TiO3 perovskite and poly(ethylene oxide) (PEO) are reported. A flexible and freestanding BSE membrane exhibits high Li+ conductivity of about 1.2×10−4 S cm−1, and shows enhanced electrochemical/thermal stability, in comparison to a PEO‐only solid electrolyte. A single‐layered ASSB assembled with a BSE shows promising electrochemical performance, as evidenced by a high reversible capacity of about 123 mA h g−1 and excellent cycling stability over 100 cycles. Furthermore, a proof‐of‐concept bipolar ASSB comprising three unit cells connected in series is constructed by using the BSE membrane and Al/Cu‐cladded bipolar plates. The bipolar ASSB shows high thermal stability and operates reversibly without any internal short circuit or current leakage during charge–discharge cycles; this demonstrates that BSEs provide a promising approach to the design and fabrication of bipolar ASSBs with improved safety and high energy density. [ABSTRACT FROM AUTHOR]

Abstract: Triplite‐type LiFeSO4F has attracted considerable attention as a promising cathode for next‐generation lithium‐ion batteries because of its high redox potential based on earth‐abundant Fe2+/3+. However, successful extraction/reinsertion of all the lithium ions in triplite host is challenging even at a low current rate, resulting in a low specific capacity. These experimental findings contrast with previous theoretical works that predicted that the triplite structure would be a fast ionic conductor with low activation barriers for lithium‐ion hopping. Origin of this discrepancy is elusive to date. Herein, combined first‐principles calculations and high‐angle annular dark‐field scanning transmission electron microscopy analyses reveal that typical triplite structure is composed of nanodomains consisting of corner‐shared FeO4F2 octahedra, whereas their domain boundaries are regions of mixed corner/edge‐shared FeO4F2 octahedra. More importantly, these locally disordered domain boundaries significantly reduce the overall lithium diffusivity of the materials. Inspired by these findings, this study redesigns triplite structure with sufficiently small sizes to avoid local bottlenecks arising from the domain boundaries, successfully achieving nearly full lithium extraction/reinsertion with high power and energy density. This work represents the first direct observation of the presence of domain boundaries within a crystalline structure playing a critical role in governing the lithium diffusivity in a battery electrode. [ABSTRACT FROM AUTHOR]

All-solid-state lithium batteries offer notable advantages over conventional Li-ion batteries with liquid electrolytes in terms of energy density, stability, and safety. To realize this technology, it is critical to develop highly reliable solid-state inorganic electrolytes with high ionic conductivities and adequate processability. Li1+ xAl xTi2− x(PO4)3 (LATP) with a NASICON (Na superionic conductor)-like structure is regarded as a potential solid electrolyte, owing to its high 'bulk' conductivity (ca. 10−3 S cm−1) and excellent stability against air and moisture. However, the solid LATP electrolyte still suffers from a low 'total' conductivity, mainly owing to the blocking effect of grain boundaries to Li+ conduction. In this study, an LATP-Bi2O3 composite solid electrolyte shows very high total conductivity (9.4×10−4 S cm−1) at room temperature. Bi2O3 acts as a microstructural modifier to effectively reduce the fabrication temperature of the electrolyte and to enhance its ionic conductivity. Bi2O3 promotes the densification of the LATP electrolyte, thereby improving its structural integrity, and at the same time, it facilitates Li+ conduction, leading to reduced grain-boundary resistance. The feasibility of the LATP-Bi2O3 composite electrolyte in all-solid-state Li batteries is also examined in this study. [ABSTRACT FROM AUTHOR]

Although the exceptional theoretical specific capacity (1672 mAh g−1) of elemental sulfur makes lithium-sulfur (Li-S) batteries attractive for upcoming rechargeable battery applications (e.g., electrical vehicles, drones, unmanned aerial vehicles, etc.), insufficient cycle lives of Li-S cells leave a substantial gap before their wide penetration into commercial markets. Among the key features that affect the cyclability, the shuttling process involving polysulfides (PS) dissolution is most fatal. In an effort to suppress this chronic PS shuttling, herein, a separator coated with poled BaTiO3 or BTO particles is introduced. Permanent dipoles that are formed in the BTO particles upon the application of an electric field can effectively reject PS from passing through the separator via electrostatic repulsion, resulting in significantly improved cyclability, even when a simple mixture of elemental sulfur and conductive carbon is used as a sulfur cathode. The coating of BTO particles also considerably suppresses thermal shrinkage of the poly(ethylene) separator at high temperatures and thus enhances the safety of the cell adopting the given separator. The incorporation of poled particles can be universally applied to a wide range of rechargeable batteries (i.e., metal-air batteries) that suffer from cross-contamination of charged species between both electrodes. [ABSTRACT FROM AUTHOR]

In lithium-ion batteries (LIBs) comprising spinel cathode materials, the dissolution of transition metals (TMs) in the cathodes causes severe cyclic degradation. We investigate the origin and mechanism of surface TM dissolution in high-voltage spinel oxide (LiNi0.5.Mn1.5O4) nanoparticles to find a practical method for its mitigation. Atomic structures of the LiNi0.5.Mn1.5O4 surfaces are developed, and the electronic structures are investigated by first-principles calculations. The results indicate that titanium is a promising dopant for forming a more stable surface structure by reinforcing metal-oxygen bonds in LiNi0.5.Mn1.5O4. Experimentally synthesized LiNi0.5.Mn1.5O4 with titanium surface doping exhibits improved electrochemical performance by suppressing undesirable TM dissolution during cycles. The theoretical prediction and experimental validation presented here suggest a viable method to suppress TM dissolution in LiNi0.5.Mn1.5O4. [ABSTRACT FROM AUTHOR]

Non-stoichiometric SiO x based materials have gained much attention as high capacity lithium storage materials. However, their anode performance of these materials should be further improved for their commercial success. A conductive polymer, poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS), is employed as a flexible electrical interconnector to improve the electrochemical performance of Si/SiO x nanosphere anode materials for lithium ion batteries (LIBs). The resulting Si/SiO x-PEDOT:PSS core-shell structured material with the small amount (1 wt %) of PEDOT:PSS shows the improved initial reversible capacity of 968.2 mA h g−1 with excellent long-term cycle performance over 200 cycles. These promising properties can be attributed to the use of the electroconductive and flexible PEDOT:PSS shell layer, which protects the electrical conduction pathways in the electrode from the large volume changes of silicon during cycling. [ABSTRACT FROM AUTHOR]

Nonstoichiometric SiO x -based nanocomposites have gained considerable attention as promising anode materials for lithium-ion batteries because of their high capacity and relatively good cycle performance. However, their commercial use is still limited by some technical problems such as poor thermal reliability, dimensional stability, and safety. Herein we show that surface modification with TiO2 can effectively improve the thermal reliability of SiO x nanocomposites without sacrificing their capacity and cycle performance. We suggest that the TiO2 coating layer could significantly improve the thermal reliability of the SiO x nanocomposites. Even though the TiO2 phase introduced is less active, TiO2-coated nonstoichiometric SiO x nanocomposites showed electrochemical performance comparable with that of bare nonstoichiometric SiO x nanocomposite. We believe that the surface modification approach proposed herein will open up a new route toward high capacity Si-based anode materials for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

A newly prepared type of carbon felt with oxygen-rich phosphate groups is proposed as a promising electrode with good stability for all-vanadium redox flow batteries (VRFBs). Through direct surface modification with ammonium hexafluorophosphate (NH4PF6), phosphorus can be successfully incorporated onto the surface of the carbon felt by forming phosphate functional groups with −OH chemical moieties that exhibit good hydrophilicity. The electrochemical reactivity of the carbon felt toward the redox reactions of VO2+/VO2+ (in the catholyte) and V3+/V2+ (in the anolyte) can be effectively improved owing to the superior catalytic effects of the oxygen-rich phosphate groups. Furthermore, undesirable hydrogen evolution can be suppressed by minimizing the overpotential for the V3+/V2+ redox reaction in the anolyte of the VRFB. Cell-cycling tests with the catalyzed electrodes show improved energy efficiencies of 88.2 and 87.2 % in the 1st and 20th cycles compared with 83.0 and 81.1 %, respectively, for the pristine electrodes at a constant current density of 32 mA cm−2. These improvements are mainly attributed to the faster charge transfer allowed by the integration of the oxygen-rich phosphate groups on the carbon-felt electrode. [ABSTRACT FROM AUTHOR]

A combined experimental and computational study of an oxygen-deficient Li2MnO3− δ ( δ≈0.071) cathode for understanding the role and effects of oxygen vacancies on phase transformation and electrochemical activity in Li-ion batteries is presented. The oxygen-deficient Li2MnO3− δ exhibits improved electrochemical reactivity toward Li+ ions without significant loss of structural stability. The oxidation of O during Li+ ion extraction can be suppressed by the enhanced redox reaction of Mn in this material. Furthermore, the inevitable phase transformation of Li2MnO3 can be impeded by the increased kinetic barriers to Mn migration in Li2MnO3− δ (Δ Ebarrier=1.0-2.5 eV), which disfavors the formation of stable intermediate coordination geometries due to the oxygen vacancies. These findings reveal the underlying mechanism on the role of the oxygen vacancies in changing phase transformation and electrochemical activity in inactive Li2MnO3, and provide a scientific insight to the electrochemical reactivity and sustainability of Li-rich oxide cathode materials in Li-ion batteries. [ABSTRACT FROM AUTHOR]

Critical degradation mechanism of many cathode materials for Li-ion batteries is closely related to phase transformations at the surface/interface. Li2MnO3 in x Li2MnO3⋅(1− x) LiMO2 (M=Ni, Co, Mn) provides high capacity, but the Li2MnO3 phase is known to degrade during cycling through phase transformation and O2 evolution. To resolve such degradation problems, it is critical to develop a fundamental understanding of the underlying mechanism. Using first-principles calculations, we identified the surface delithiation potential (<4.5 V vs. Li/Li+) of Li2MnO3, which is significantly lower than the bulk redox potential. A lower Mn oxidation state at the surface would reduce the delithiation potential compared with the fully oxidized Mn4+ in the bulk. As a result, the delithiation would be initiated from the surface, which induces a phase transformation of Li2MnO3 into a spinel-like structure from the surface. These theoretical findings have been confirmed by experimental analyses. Based on these detailed mechanistic understanding, it would be possible to develop rational approaches to modify and coat the surface to suppress degradation mechanisms. [ABSTRACT FROM AUTHOR]

This study presents a simple and effective method of reducing amorphous silica (a-SiO2) with Ti metal through high-energy mechanical milling for improving its reactivity when used as an anode material in lithium-ion batteries. Through thermodynamic calculations, it is determined that Ti metal can easily take oxygen atoms from a-SiO2 by forming a thermodynamically stable SiO2− x/TiO x composite, meaning that electrochemically inactive a-SiO2 is partially reduced by the addition of Ti metal powder during milling. This mechanically reduced SiO2− x/TiO x composite anode exhibits a greatly improved electrochemical reactivity, with a reversible capacity of more than 700 mAh g−1 and excellent cycle performance over 100 cycles. Furthermore, an enhancement in the mechanical and thermal stability of the composite during cycling can be mainly attributed to the in situ formation of the SiO2− x/TiO x phase. These findings provide new insight into the rational design of robust, high-capacity, Si-based anode materials, as well as their reaction mechanism. [ABSTRACT FROM AUTHOR]

The demand for new energy storage systems to be employed in large-scale electrical energy storage systems (EESs) has grown recently, particularly for green energy storage and grid-supporting applications. Rechargeable Mg batteries are promising candidates for such applications because of their good safety characteristics and raw materials' abundance. Recent progress in the field is noticeable, but further efforts are required to support the successful implementation of rechargeable Mg batteries. We address progress in the development of rechargeable Mg batteries and problems to be resolved in future research, briefly summarize the most recent advances in the development of rechargeable Mg batteries, from a materials perspective, and cover progress on each of the major components of Mg batteries: the electrolyte, the cathode material, and the anode material. We provide a practical guideline for further development of self-sustainable rechargeable Mg batteries as a future power source. [ABSTRACT FROM AUTHOR]

Submicrosized chevrel Mo6S8 powder is synthesized using mechanical milling of the starting materials and the powder yield is increased by using modified synthesis method. The effect of particle size is investigated using various electrochemical techniques. The submicrosized chevrel shows enhanced discharge capacity compared with that of microsized chevrel, and voltage profile indicates that the low capacity arising from Mg trapping at the Mg-1 site is improved for submicrosized chevrel. Mg trapping is also verified by ex situ X-ray diffraction measurement and the results are in good agreement with the electrochemical profile. Open-circuit voltage measurements and AC-impedance spectroscopy are used to identify the kinetics of Mg2+ insertion. The improved electrochemical properties obtained with the submicrosized chevrel are attributed to the smaller particles that provide shorter diffusion lengths for Mg2+ ions. [ABSTRACT FROM AUTHOR]

Ferrocene and cobaltocene and their derivatives are studied as new redox materials for redox flow cells. Their high reaction rates and moderate solubility are attractive properties for their use as active materials. The cyclability experiments are carried out in a static cell; the results showed that these materials exhibit stable capacity retention and predictable discharge potentials, which agree with the potential values from the cyclic voltammograms. The diffusion coefficients of these materials are 2 to 7 times higher than those of other non-aqueous materials such as vanadium acetylacetonate, iron tris(2,2′-bipyridine) complexes, and an organic benzene derivative. [ABSTRACT FROM AUTHOR]

Hard carbon-coated natural graphite materials have been prepared and evaluated as a negative electrode for high-energy and high-power lithium-ion capacitors. The graphite surface was coated with hard carbon by using polyacrylonitrile as a precursor, which was confirmed by X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. The hard carbon coating on natural graphite particles significantly affects the electrochemical characteristics of lithium-ion capacitors. The full-cell using the hard carbon-coated graphite electrode showed much higher energy and power densities than those with pristine natural graphite and hard carbon electrodes, respectively. Furthermore, the hard carbon-coated graphite electrode exhibited an enhanced cycle performance with a capacity retention of 74.6% after 10,000 cycles, higher than those of pristine natural graphite (33.3%) and the mixture of hard carbon and natural graphite (51.4%). The results clearly indicate that the hard carbon-coated graphite electrode is suitable as a negative electrode material for high-energy and high-power lithium-ion capacitors. [ABSTRACT FROM AUTHOR]

Lithium-ion hybrid capacitors have attracted great interest due to their high specific energy relative to conventional electrical double-layer capacitors. Nevertheless, the safety issue still remains a drawback for lithium-ion capacitors in practical operational environments because of the use of metallic lithium. Herein, single-phase Li5FeO4 with an antifluorite structure that acts as an alternative lithium source (instead of metallic lithium) is employed and its potential use for lithium-ion capacitors is verified. Abundant Li+ amounts can be extracted from Li5FeO4 incorporated in the positive electrode and efficiently doped into the negative electrode during the first electrochemical charging. After the first Li+ extraction, Li+ does not return to the Li5FeO4 host structure and is steadily involved in the electrochemical reactions of the negative electrode during subsequent cycling. Various electrochemical and structural analyses support its superior characteristics for use as a promising lithium source. This versatile approach can yield a sufficient Li+-doping efficiency of >90 % and improved safety as a result of the removal of metallic lithium from the cell. [ABSTRACT FROM AUTHOR]

One-dimensional nanomaterials have short Li+ diffusion paths and promising structural stability, which results in a long cycle life during Li+ insertion and extraction processes in lithium rechargeable batteries. In this study, we fabricated one-dimensional spinel Li4Ti5O12 (LTO) nanofibers using an electrospinning technique and studied the Zr4+ doping effect on the lattice, electronic structure, and resultant electrochemical properties of Li-ion batteries (LIBs). Accommodating a small fraction of Zr4+ ions in the Ti4+ sites of the LTO structure gave rise to enhanced LIB performance, which was due to structural distortion through an increase in the average lattice constant and thereby enlarged Li+ diffusion paths rather than changes to the electronic structure. Insulating ZrO2 nanoparticles present between the LTO grains due to the low Zr4+ solubility had a negative effect on the Li+ extraction capacity, however. These results could provide key design elements for LTO anodes based on atomic level insights that can pave the way to an optimal protocol to achieve particular functionalities. [ABSTRACT FROM AUTHOR]

Keywords: Lithium metal anode; Lithium dendrite growth; Solid-electrolyte interphase (SEI); Electrolyte additives; Anode-free EN Lithium metal anode Lithium dendrite growth Solid-electrolyte interphase (SEI) Electrolyte additives Anode-free 4008 4008 1 12/15/21 20211213 NES 211213 B Lithium metal anode b is highly desirable for high-energy density batteries. Cover Feature: Strategic Approaches to the Dendritic Growth and Interfacial Reaction of Lithium Metal Anode (Chem. Lithium metal anode, Lithium dendrite growth, Solid-electrolyte interphase (SEI), Electrolyte additives, Anode-free. [Extracted from the article]

A piezoelectric nanogenerator based on a ZnO‐NiO core–shell structure with improved output performance by reducing screen effect can be used as a power source for flexible devices by converting mechanical energy into electrical energy. More details can be found in article number 2000462 by Ju‐Hyuck Lee, Sang‐Woo Kim, Jung Ho Kim, and co‐workers. [ABSTRACT FROM AUTHOR]

Given that the performance of a lithium–oxygen battery (LOB) is determined by the electrochemical reactions occurring on the cathode, the development of advanced cathode nanoarchitectures is of great importance for the realization of high‐energy‐density, reversible LOBs. Herein, a robust cathode design is proposed for LOBs based on a dual‐phasic carbon nanoarchitecture. The cathode is composed of an interwoven network of porous metal–organic framework (MOF) derived carbon (MOF‐C) and conductive carbon nanotubes (CNTs). The dual‐phasic nanoarchitecture incorporates the advantages of both components: MOF‐C provides a large surface area for the oxygen reactions and a large pore volume for Li2O2 storage, and CNTs provide facile pathways for electron and O2 transport as well as additional void spaces for Li2O2 accommodation. It is demonstrated that the synergistic nanoarchitecturing of the dual‐phasic MOF‐C/CNT material results in promising electrochemical performance of LOBs, as evidenced by a high discharge capacity of ≈10 050 mAh g−1 and a stable cycling performance over 75 cycles. [ABSTRACT FROM AUTHOR]

Highlights from the article: Cover Feature: Rational Design of a Composite Electrode to Realize a High-Performance All-Solid-State Battery (ChemSusChem 12/2019) Keywords: electrode fabrication; ionic liquid; Li ion; solid-state batteries; solid electrolyte Li ion, ionic liquid, solid electrolyte, electrode fabrication, solid-state batteries.

Review: [82 refs. [ABSTRACT FROM AUTHOR]

A correction to the article "Ferrocene and Cobaltocene Derivatives for Non-Aqueous Redox Flow Batteries" by B. Hwang et al., which appeared in a 2015 issue, is presented.

CuMo3S4 powders are prepared by the molten salt method from mixtures of CuS, Mo, MoS2, and different amounts of KCl (alumina crucible, 850 °C, 60 h). [ABSTRACT FROM AUTHOR]