Rechargeable magnesium batteries (RMBs) have been considered as one of the most viable battery chemistries amongst the “post” lithium‐ion battery (LIB) technologies owing to their high volumetric ...capacity and the natural abundance of their key elements. The fundamental properties of Mg‐ion conducting electrolytes are of essence to regulate the overall performance of RMBs. In this Review, the basic electrochemistry of Mg‐ion conducting electrolytes batteries is discussed and compared to that of the Li‐ion conducting electrolytes, and a comprehensive overview of the development of different Mg‐ion conducting electrolytes is provided. In addition, the remaining challenges and possible solutions for future research are intensively discussed. The present work is expected to give an impetus to inspire the discovery of key electrolytes and thereby improve the electrochemical performances of RMBs and other related emerging battery technologies.
The fundamental physical and electrochemical properties of Mg‐ion conducting electrolytes are scrutinized with particular attention paid to the similarity and difference between Mg‐ion and the popular Li‐ion based electrolytes. The Review was written with the intention of accelerating the development of sustainable and high‐performance battery technologies.
For sodium (Na)‐rechargeable batteries to compete, and go beyond the currently prevailing Li‐ion technologies, mastering the chemistry and accompanying phenomena is of supreme importance. Among the ...crucial components of the battery system, the electrolyte, which bridges the highly polarized positive and negative electrode materials, is arguably the most critical and indispensable of all. The electrolyte dictates the interfacial chemistry of the battery and the overall performance, having an influence over the practical capacity, rate capability (power), chemical/thermal stress (safety), and lifetime. In‐depth knowledge of electrolyte properties provides invaluable information to improve the design, assembly, and operation of the battery. Thus, the full‐scale appraisal of both tailored electrolytes and the concomitant interphases generated at the electrodes need to be prioritized. The deployment of large‐format Na‐based rechargeable batteries also necessitates systematic evaluation and detailed appraisal of the safety‐related hazards of Na‐based batteries. Hence, this review presents a comprehensive account of the progress, status, and prospect of various Na+‐ion electrolytes, including solvents, salts and additives, their interphases and potential hazards.
Sodium batteries (SBs) are seen as a sustainable alternative for electrochemical energy storage. However, progresses on electrolytes is required to enable future commercialization. A comprehensive review of the status, and the prospects of various Na‐ion electrolytes, including solvents, salts, additives, electrode/electrolyte interphases, and potential hazards, is presented.
Among the contenders in the new generation energy storage arena, all-solid-state batteries (ASSBs) have emerged as particularly promising, owing to their potential to exhibit high safety, high energy ...density and long cycle life. The relatively low conductivity of most solid electrolytes and the often sluggish charge transfer kinetics at the interface between solid electrolyte and electrode layers are considered to be amongst the major challenges facing ASSBs. This review presents an overview of the state of the art in solid lithium and sodium ion conductors, with an emphasis on inorganic materials. The correlations between the composition, structure and conductivity of these solid electrolytes are illustrated and strategies to boost ion conductivity are proposed. In particular, the high grain boundary resistance of solid oxide electrolytes is identified as a challenge. Critical issues of solid electrolytes beyond ion conductivity are also discussed with respect to their potential problems for practical applications. The chemical and electrochemical stabilities of solid electrolytes are discussed, as are chemo-mechanical effects which have been overlooked to some extent. Furthermore, strategies to improve the practical performance of ASSBs, including optimizing the interface between solid electrolytes and electrode materials to improve stability and lower charge transfer resistance are also suggested.
This critical review presents the state of the art research progress, proposes strategies to improve the conductivity of solid electrolytes, discusses the chemical and electrochemical stabilities, and uncovers future perspectives for solid state batteries.
Lithium metal (Li0) rechargeable batteries (LMBs), such as systems with a Li0 anode and intercalation and/or conversion type cathode, lithium‐sulfur (Li‐S), and lithium‐oxygen (O2)/air (Li‐O2/air) ...batteries, are becoming increasingly important for electrifying the modern transportation system, with the aim of sustainable mobility. Although some rechargeable LMBs (e.g. Li0/LiFePO4 batteries from Bolloré Bluecar, Li‐S batteries from OXIS Energy and Sion Power) are already commercially viable in niche applications, their large‐scale deployment is hampered by a number of formidable challenges, including growth of lithium dendrites, electrolyte instability towards high voltage intercalation‐type cathodes, the poor electronic and ionic conductivities of sulfur (S8) and O2, as well as their corresponding reduction products (e.g. Li2S and Li2O), dissolution, and shuttling of polysulfide (PS) intermediates. This leads to a short lifecycle, low coulombic/energy efficiency, poor safety, and a high self‐discharge rate. The use of electrolyte additives is considered one of the most economical and effective approaches for circumventing these problems. This Review gives an overview of the various functional additives that are being applied and aims to stimulate new avenues for the practical realization of these appealing devices.
Better batteries: The use of electrolyte additives is considered one of the most viable, economical, and effective approaches to circumvent the problems of rechargeable Li metal batteries (LMBs). This Review assesses the current status of research on electrolyte additives for rechargeable LMBs and considers new avenues for the realization of these appealing devices.
Rechargeable Li-based battery technologies utilising silicon, silicon-based, and Si-derivative anodes coupled with high-capacity/high-voltage insertion-type cathodes have reaped significant interest ...from both academic and industrial sectors. This stems from their practically achievable energy density, offering a new avenue towards the mass-market adoption of electric vehicles and renewable energy sources. Nevertheless, such high-energy systems are limited by their complex chemistry and intrinsic drawbacks. From this perspective, we present the progress, current status, prevailing challenges and mitigating strategies of Li-based battery systems comprising silicon-containing anodes and insertion-type cathodes. This is accompanied by an assessment of their potential to meet the targets for evolving volume- and weight-sensitive applications such as electro-mobility.
Ambient‐temperature sodium–sulfur (Na–S) batteries are considered a promising energy storage system due to their high theoretical energy density and low costs. However, great challenges remain in ...achieving a high rechargeable capacity and long cycle life. Herein we report a stable quasi‐solid‐state Na‐S battery enabled by a poly(S‐pentaerythritol tetraacrylate (PETEA))‐based cathode and a (PETEA‐tris2‐(acryloyloxy)ethyl isocyanurate (THEICTA))‐based gel polymer electrolyte. The polymeric sulfur electrode strongly anchors sulfur through chemical binding and inhibits the shuttle effect. Meanwhile, the in situ formed polymer electrolyte with high ionic conductivity and enhanced safety successfully stabilizes the Na anode/electrolyte interface, and simultaneously immobilizes soluble Na polysulfides. The as‐developed quasi‐solid‐state Na‐S cells exhibit a high reversible capacity of 877 mA h g−1 at 0.1 C and an extended cycling stability.
Energy storage: A stable quasi‐solid‐state Na–S battery has been obtained using a poly(S‐pentaerythritol tetraacrylate (PETEA)) cathode and a (PETEA‐tris2‐(acryloyloxy)ethyl isocyanurate (THEICTA)) gel polymer electrolyte. The electrode strongly anchors sulfur by chemical binding, meanwhile the polymer electrolyte with high ionic conductivity and stable Na/electrolyte interface effectively suppresses the shuttle of polysulfides.
High-temperature sodium-sulfur batteries operating at 300-350 °C have been commercially applied for large-scale energy storage and conversion. However, the safety concerns greatly inhibit their ...widespread adoption. Herein, we report a room-temperature sodium-sulfur battery with high electrochemical performances and enhanced safety by employing a "cocktail optimized" electrolyte system, containing propylene carbonate and fluoroethylene carbonate as co-solvents, highly concentrated sodium salt, and indium triiodide as an additive. As verified by first-principle calculation and experimental characterization, the fluoroethylene carbonate solvent and high salt concentration not only dramatically reduce the solubility of sodium polysulfides, but also construct a robust solid-electrolyte interface on the sodium anode upon cycling. Indium triiodide as redox mediator simultaneously increases the kinetic transformation of sodium sulfide on the cathode and forms a passivating indium layer on the anode to prevent it from polysulfide corrosion. The as-developed sodium-sulfur batteries deliver high capacity and long cycling stability.
Solid‐state lithium metal batteries (SSLMBs) are believed to be important pathway to overcome the limitations that state‐of‐the‐art lithium‐ion batteries face in terms of safety and energy density. ...In addition to transporting ionic species in solid‐state configuration, solid polymer electrolytes (SPEs) are structurally designable and processable, and have been deemed as an auspicious kind of solid electrolyte to access highly‐performant SSLMBs. In this essay, we provide a historical overview on the development of SPE‐based SSLMBs, aiming to highlight the main achievements being made at both material and cell levels. It is hoped that the personal reflection and retrospect presented in this essay give an impetus to inspire the discovery of tantalizing battery materials and improve the overall performance of SPE‐based SSLMBs and other emerging battery technologies.
Abstract
The practical applications of lithium metal anodes in high-energy-density lithium metal batteries have been hindered by their formation and growth of lithium dendrites. Herein, we discover ...that certain protein could efficiently prevent and eliminate the growth of wispy lithium dendrites, leading to long cycle life and high Coulombic efficiency of lithium metal anodes. We contend that the protein molecules function as a “self-defense” agent, mitigating the formation of lithium embryos, thus mimicking natural, pathological immunization mechanisms. When added into the electrolyte, protein molecules are automatically adsorbed on the surface of lithium metal anodes, particularly on the tips of lithium buds, through spatial conformation and secondary structure transformation from α-helix to β-sheets. This effectively changes the electric field distribution around the tips of lithium buds and results in homogeneous plating and stripping of lithium metal anodes. Furthermore, we develop a slow sustained-release strategy to overcome the limited dispersibility of protein in the ether-based electrolyte and achieve a remarkably enhanced cycling performance of more than 2000 cycles for lithium metal batteries.
The current Li-based battery technology is limited in terms of energy contents. Therefore, several approaches are considered to improve the energy density of these energy storage devices. Here, we ...report the combination of a heteroatom-based gel polymer electrolyte with a hybrid cathode comprising of a Li-rich oxide active material and graphite conductive agent to produce a high-energy "shuttle-relay" Li metal battery, where additional capacity is generated from the electrolyte's anion shuttling at high voltages. The gel polymer electrolyte, prepared via in situ polymerization in an all-fluorinated electrolyte, shows adequate ionic conductivity (around 2 mS cm
at 25 °C), oxidation stability (up to 5.5 V vs Li/Li
), compatibility with Li metal and safety aspects (i.e., non-flammability). The polymeric electrolyte allows for a reversible insertion of hexafluorophosphate anions into the conductive graphite (i.e., dual-ion mechanism) after the removal of Li ions from Li-rich oxide (i.e., rocking-chair mechanism).
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