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Solid-state polyether electrolytes formed by in-situ ring-opening polymerization (ROP) of 1,3-dioxolane (DOL) have attracted great attention due to their high lithium-ion conductivity, and good interface compatibility. However, DOL ring-opening polymerization is difficult to control, resulting in the formation of poly(1,3-dioxolane) (PDOL) with high molecular weight and high crystallinity, which hinder Li + diffusion and deteriorate the interfacial contact. Herein, trimethylsilyl isocyanate (IPTS) was introduced into DOL ring-opening system as a moisture eliminating agent to weaken the Li salt-based initiating system and regulate the polymerization process. Based on this, the resultant PDOL electrolytes with 3 wt.% IPTS exhibit ionic conductivity of 2.8×10 -4  S cm -1 , a high Li + transference number (0.68) and excellent stability with Li anode. The Li|PDOL-3 %IPTS|Li battery exhibits a stable cycling performance for more than 1100 h under 0.5 mA cm -2 and 0.5 mAh cm -2 . Furthermore, the LiFePO 4 |PDOL-3 %IPTS|Li cell shows a capacity retention rate of 89.2 % after 200 cycles (25 °C, 1 °C) and 94.5 % (60 °C, 1 °C) after 500 cycles, which is much higher than that of PDOL (6.6 %) after 70 cycles (25 °C, 1 °C). This work provides guidance for the manipulation of ROP process further to enhance the performance of solid-state lithium metal batteries., (© 2024 Wiley-VCH GmbH.)

Coulombic efficiency of over 99 % is rarely achieved for Li metal anode below -40 °C, hindering the practical application of high-energy-density Li metal batteries under extreme conditions. Herein, limiting factors for Li metal reversibility are investigated utilizing ether-based localized high-concentration electrolytes of different solvent-diluent combinations. We find that along with the desolvation barrier, bulk ion transport properties including ionic conductivity, transference number, and diffusivity are also crucial factors for low-temperature Li deposition behavior. Superior Li metal reversibility was observed within the combination of the solvent with moderately weak solvating power and the diluent with minimal viscosity, highlighting the role of ion transport and the necessity for a trade-off with desolvation. The optimized electrolyte composed of lithium bis(fluorosulfonyl)imide, methyl n-propyl ether, and 1,1,2,2-tetrafluoroethyl methyl ether delivers exceptional Coulombic efficiency of 99.34 % at -40 °C and 98.96 % at -60 °C under a current density of 0.5 mA cm -2 . Furthermore, Li||LiCoO 2 (2.7 mAh cm -2 ) cells demonstrate impressive reversible capacity and cycling stability at these temperatures. This work sheds light on the less-recognized relevance of bulk ion transport to low-temperature performance and provides guidelines for the electrolyte design of Li metal batteries operating in cold environments., (© 2024 Wiley-VCH GmbH.)

Lithium metal batteries paired with high-voltage LiNi 0.5 Mn 1.5 O 4 (LNMO) cathodes are a promising energy storage source for achieving enhanced high energy density. Forming durable and robust solid-electrolyte interphase (SEI) and cathode-electrolyte interface (CEI) and the ability to withstand oxidation at high potentials are essential for long-lasting performance. Herein, advanced electrolytes are designed via trio-functional additives to carbonate-based electrolytes for 5 V Li||LNMO and graphite||LNMO cells achieving 88.3% capacity retention after 500 charge-discharge cycles. Theoretical calculations reveal that adding adiponitrile facilitates the presence of more hierarchical DFOB - and PF 6 - dual anion structure in the solvation sheath, leading to a faster de-solvation of the Li cation. By combining both fluorine and nitrile additives, an efficient synergistic effect is obtained, generating robust thin inorganic SEI and CEI films, respectively. These films enhance microstructural stability; Li dendrite growth on the Li electrode is being suppressed at the anode side and transition-metals dissolution from the cathode is being mitigated, as evidenced by cryo-transmission electron microscopy and synchrotron studies., (© 2024 The Author(s). Advanced Materials published by Wiley‐VCH GmbH.)

Improving the wide-temperature operation of rechargeable batteries is crucial for boosting the adoption of electric vehicles and further advancing their application scope in harsh environments like deep ocean and space probes. Herein, recent advances in electrolyte solvation chemistry are critically summarized, aiming to address the long-standing challenge of notable energy diminution at sub-zero temperatures and rapid capacity degradation at elevated temperatures (>45°C). This review provides an in-depth analysis of the fundamental mechanisms governing the Li-ion transport process, illustrating how these insights have been effectively harnessed to synergize with high-capacity, high-rate electrodes. Another critical part highlights the interplay between solvation chemistry and interfacial reactions, as well as the stability of the resultant interphases, particularly in batteries employing ultrahigh-nickel layered oxides as cathodes and high-capacity Li/Si materials as anodes. The detailed examination reveals how these factors are pivotal in mitigating the rapid capacity fade, thereby ensuring a long cycle life, superior rate capability, and consistent high-/low-temperature performance. In the latter part, a comprehensive summary of in situ/operational analysis is presented. This holistic approach, encompassing innovative electrolyte design, interphase regulation, and advanced characterization, offers a comprehensive roadmap for advancing battery technology in extreme environmental conditions., (© 2024 The Authors. Small Methods published by Wiley‐VCH GmbH.)

Advancing grid-scale energy storage technologies is crucial for realizing a fully renewable energy landscape, with non-aqueous redox flow batteries (NRFBs) presenting a promising solution. One of the current challenges in NRFBs stems from the low energy density of redox active materials, primarily due to their limited solubility in non-aqueous solvents. Herein, this study explores the solubility of vanadium(IV/V) bis-hydroxyiminodiacetate (VBH) crystals in acetonitrile, aiming to use them as anionic catholytes in NRFBs. We focused on enhancing VBH solubility by modifying the structure of the alkylammonium cation. Employing periodic density functional theory and a solvation model, we calculated the dissolution free energy ([[EQUATION]]), which includes sublimation ([[EQUATION]]) and solvation ([[EQUATION]]) energies. Our results indicate that neither elongating straight-chain alkyl groups beyond a tetrabutylammonium baseline nor introducing bulky substituents at the nitrogen center significantly enhances solubility. However, the introduction of carbon spacers combined with terminal bulky substituents markedly improves solubility by favorably altering both [[EQUATION]] and [[EQUATION]]. These findings underline the nuanced impact of cation structure on solubility and suggest a viable approach to optimize VBH-based anionic catholytes. This advancement promises to enhance NRFB efficiency and sustainability, marking a significant step forward in energy storage technology., (© 2024 Wiley‐VCH GmbH.)

In situ polymerized solid-state electrolytes have attracted much attention due to high Li-ion conductivity, conformal interface contact, and low interface resistance, but are plagued by lithium dendrite, interface degradation, and inferior thermal stability, which thereby leads to limited lifespan and severe safety hazards for high-energy lithium metal batteries (LMBs). Herein, an in situ polymerized electrolyte is proposed by copolymerization of 1,3-dioxolane with 1,3,5-tri glycidyl isocyanurate (TGIC) as a cross-linking agent, which realizes a synergy of battery thermal safety and interface compatibility with Li anode. Functional TGIC enhances the electrolyte polymeric level. The unique carbon-formation mechanism facilitates flame retardancy and eliminates the battery fire risk. In the meantime, TGIC-derived inorganic-rich interphase inhibits interface side reactions and promotes uniform Li plating. Intrinsically safe LMBs with nonflammability and outstanding electrochemical performances under extreme temperatures (130 °C) are achieved. This functional polymer design shows a promising prospect for the development of safe LMBs., (© 2024 Wiley‐VCH GmbH.)

High-energy-density lithium-metal batteries (LMBs) coupling lithium-metal anodes and high-voltage cathodes are hindered by unstable electrode/electrolyte interphases (EEIs), which calls for the rational design of efficient additives. Herein, we analyze the effect of electron structure on the coordination ability and energy levels of the additive, from the aspects of intramolecular electron cloud density and electron delocalization, to reveal its mechanism on solvation structure, redox stability, as-formed EEI chemistry, and electrochemical performances. Furthermore, we propose an electron reconfiguration strategy for molecular engineering of additives, by taking sorbide nitrate (SN) additive as an example. The lone pair electron-rich group enables strong interaction with the Li ion to regulate solvation structure, and intramolecular electron delocalization yields further positive synergistic effects. The strong electron-withdrawing nitrate moiety decreases the electron cloud density of the ether-based backbone, improving the overall oxidation stability and cathode compatibility, anchoring it as a reliable cathode/electrolyte interface (CEI) framework for cathode integrity. In turn, the electron-donating bicyclic-ring-ether backbone breaks the inherent resonance structure of nitrate, facilitating its reducibility to form a N-contained and inorganic Li 2 O-rich solid electrolyte interface (SEI) for uniform Li deposition. Optimized physicochemical properties and interfacial biaffinity enable significantly improved electrochemical performance. High rate (10 C), low temperature (-25 °C), and long-term stability (2700 h) are achieved, and a 4.5 Ah level Li||NCM811 multilayer pouch cell under harsh conditions is realized with high energy density (462 W h/kg). The proof of concept of this work highlights that the rational ingenious molecular design based on electron structure regulation represents an energetic strategy to modulate the electrolyte and interphase stability, providing a realistic reference for electrolyte innovations and practical LMBs.

The practical application of aqueous Zn-ion batteries (AZIBs) is hindered by the crazy Zn dendrites growth and the H 2 O-induced side reactions, which rapidly consume the Zn anode and H 2 O molecules, especially under the lean electrolyte and Zn anode. Herein, a natural disaccharide, d-trehalose (DT), is exploited as a novel multifunctional co-solvent to address the above issues. Molecular dynamics simulations and spectral characterizations demonstrate that DT with abundant polar -OH groups can form strong interactions with Zn 2+ ions and H 2 O molecules, and thus massively reconstruct the coordination structure of Zn 2+ ions and the hydrogen bonding network of the electrolyte. Especially, the strong H-bonds between DT and H 2 O molecules can not only effectively suppress the H 2 O activity but also prevent the rearrangement of H 2 O molecules at low temperature. Consequently, the AZIBs using DT30 electrolyte can show high cycling stability even under lean electrolyte (E/C ratio = 2.95 µL mAh -1 ), low N/P ratio (3.4), and low temperature (-12 °C). As a proof-of-concept, a Zn||LiFePO 4 pack with LiFePO 4 loading as high as 506.49 mg can be achieved. Therefore, DT as an eco-friendly multifunctional co-solvent provides a sustainable and effective strategy for the practical application of AZIBs., (© 2024 The Authors. Advanced Science published by Wiley‐VCH GmbH.)

Lithium batteries employing Li or silicon (Si) anodes hold promise for the next-generation energy storage systems. However, their cycling behavior encounters rapid capacity degradation due to the vulnerability of solid electrolyte interphases (SEIs). Though anion-derived SEIs mitigate this degradation, the unavoidable reduction of solvents introduces heterogeneity to SEIs, leading to fractures during cycling. Here, we elucidate how the reductive stability of solvents, dominated by the electrophilicity (EPT) and coordination ability (CDA), delineates the SEI formed on Li or Si anodes. Solvents exhibiting lower EPT and CDA demonstrate enhanced tolerance to reduction, resulting in inorganic-rich SEIs with homogeneity. Guided by these criteria, we synthesized three promising solvents tailored for Li or Si anodes. The decomposition of these solvents is dictated by their EPTs under similar solvation structures, imparting distinct characteristics to SEIs and impacting battery performance. The optimized electrolyte, 1 M lithium bis(fluorosulfonyl)imide (LiFSI) in N-Pyrrolidine-trifluoromethanesulfonamide (TFSPY), achieves 600 cycles of Si anodes with a capacity retention of 81 % (1910 mAh g -1 ). In anode-free Cu||LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523) pouch cells, this electrolyte sustains over 100 cycles with an 82 % capacity retention. These findings illustrate that reducing solvent decomposition benefits SEI formation, offering valuable insights for the designing electrolytes in high-energy lithium batteries., (© 2024 Wiley‐VCH GmbH.)

Continuous lithium (Li)/electrolyte interfacial reactions and uncontrollable Li dendrites severely hamper the application of paradigmatic Li metal batteries (LMBs). Aiming to address the above-mentioned crucial issues, N-rich polymer-inorganic bilayers at the Li/electrolyte interface are designed via nitrate-rich electrolytes, achieving high-energy-density and long-lifespan LMBs. The inner layer of Li 3 N favors rapid and uniform Li + deposition, while the outer layer of N-containing flexible polymers facilitates uniform Li + distribution at the interlayer and accommodates volume changes during cycling. The synergistic effect of N-rich polymer-inorganic bilayers promotes the formation of dense uniform spherical nuclei morphology instead of dendrites, thus significantly improving the plating-stripping reversibility of LMBs. Attributed to the unique interphase, the Li|Li cell can stably run for over 1000 h at 1.0 mA cm -2 with an even deposition morphology, which is monitored and proven by in situ optical microscopy. Moreover, the assembled Li|S cell displays a high capacity of 697.6 mA h g -1 for over 150 cycles and a 99% Coulombic efficiency. This work paves the way for designing high-energy and long-lifespan LMBs.

With increasing energy storage demands across various applications, reliable batteries capable of performing in harsh environments, such as extreme temperatures, are crucial. However, current lithium-ion batteries (LIBs) exhibit limitations in both low and high-temperature performance, restricting their use in critical fields like defense, military, and aerospace. These challenges stem from the narrow operational temperature range and safety concerns of existing electrolyte systems. To enable LIBs to function effectively under extreme temperatures, the optimization and design of novel electrolytes are essential. Given the urgency for LIBs operating in extreme temperatures and the notable progress in this research field, a comprehensive and timely review is imperative. This article presents an overview of challenges associated with extreme temperature applications and strategies used to design electrolytes with enhanced performance. Additionally, the significance of understanding underlying electrolyte behavior mechanisms and the role of different electrolyte components in determining battery performance are emphasized. Last, future research directions and perspectives on electrolyte design for LIBs under extreme temperatures are discussed. Overall, this article offers valuable insights into the development of electrolytes for LIBs capable of reliable operation in extreme conditions., (© 2023 The Authors. Advanced Materials published by Wiley‐VCH GmbH.)

A key challenge in electrocatalysis remains controlling a catalyst's structural, chemical, and electrical properties under reaction conditions. While organic coatings showed promise for enhancing the selectivity and stability of catalysts for CO 2 electroreduction (CO 2 RR), their impact on the chemical state of underlying metal electrodes has remained unclear. In this study, we show that organic thin films on polycrystalline copper (Cu) enable retaining Cu + species at reducing potentials down to -1.0 V vs RHE, as evidenced by operando Raman and quasi in situ X-ray photoelectron spectroscopy. In situ electrochemical atomic force microscopy revealed the integrity of the porous organic film and nearly unaltered Cu electrode morphology. While the pristine thin film enhances the CO 2 -to-ethylene conversion, the addition of organic modifiers into electrolytes gives rise to improved CO 2 RR performance stability. Our findings showcase hybrid metal-organic systems as a versatile approach to control, beyond morphology and local environment, the oxidation states of catalysts and energy conversion materials.

Anion solvation in electrolytes can largely change the electrochemical performance of the electrolytes, yet has been rarely investigated. Herein, three anions of bis(trifluoromethanesulfonyl)imide (TFSI), bis(fluorosulfonyl)imide (FSI), and derived asymmetric (fluorosulfonyl)(trifluoro-methanesulfonyl)imide (FTFSI) are systematically examined in a weakly Li + cation solvating solvent of bis(3-fluoropropyl)ether (BFPE). In-situ liquid secondary ion mass spectrometry demonstrates that FTFSI - and FSI - anions are associated with BFPE solvent, while weak TFSI - /BFPE cluster signals are detected. Molecular modeling further reveals that the anion-solvent interaction is accompanied by the formation of H-bonding-like interactions. Anion solvation enhances the Li + cation transfer number and reduces the organic component in solid electrolyte interphase, which enhances the Li plating/stripping Coulombic efficiency at a low temperature of -30 °C from 42.4% in TFSI-based electrolytes to 98.7% in 1.5 m LiFTFSI and 97.9% in LiFSI-BFPE electrolytes. The anion-solvent interactions, especially asymmetric anion solvation also accelerate the Li + desolvation kinetics. The 1.5 m LiFTFSI-BFPE electrolyte with strong anion-solvent interaction enables LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811)||Li (20 µm) full cell with stable cyclability even under -40 °C, retaining over 92% of initial capacity (115 mAh g -1 , after 100 cycles). The anion-solvent interactions insights allow to rational design the electrolyte for lithium metal batteries and beyond to achieve high performance., (© 2023 Wiley-VCH GmbH.)

Discovery of stable and efficient electrolytes that are compatible with magnesium metal anodes and high-voltage cathodes is crucial to enabling energy storage technologies that can move beyond existing Li-ion systems. Many promising electrolytes for magnesium anodes have been proposed with chloride-based systems at the forefront; however, Cl-containing electrolytes lack the oxidative stability required by high-voltage cathodes. In this work, we report magnesium trifluoromethanesulfonate (triflate) as a viable coanion for Cl-free, mixed-anion magnesium electrolytes. The addition of triflate to electrolytes containing bis(trifluoromethane sulfonyl) imide (TFSI - ) anions yields significantly improved Coulombic efficiency, up to a 100 mV decrease in the plating/stripping overpotential, improved tolerance to trace H 2 O, and improved oxidative stability (0.35 V improvement compared to that of hybrid TFSI-Cl electrolytes). Based on 19 F nuclear magnetic resonance and Raman spectroscopy measurements, we propose that these improvements in performance are driven by the formation of mixed-anion contact ion pairs, where both triflate and TFSI - are coordinated to Mg 2+ in the electrolyte bulk. The formation of this mixed-anion magnesium complex is further predicted by the density functional theory to be thermodynamically driven. Collectively, this work outlines the guiding principles for the improved design of next-generation electrolytes for magnesium batteries.

With its efficient nitrogen fixation kinetics, electrochemical lithium-mediated nitrogen reduction reaction (LMNRR) holds promise for replacing Haber-Bosch process and realizing sustainable and green ammonia production. However, the general interface problem in lithium electrochemistry seriously impedes the further enhancement of LMNRR performance. Inspired by the development history of lithium battery electrolytes, here, we extend the ring-chain solvents coupling law to LMNRR system to rationally optimize the interface during the reaction process, achieving nearly a two-fold Faradaic efficiency up to 54.78±1.60 %. Systematic theoretical simulations and experimental analysis jointly decipher that the anion-rich Li + solvation structure derived from ring tetrahydrofuran coupling with chain ether successfully suppresses the excessive passivation of electrolyte decomposition at the reaction interface, thus promoting the mass transfer of active species and enhancing the nitrogen fixation kinetics. This work offers a progressive insight into the electrolyte design of LMNRR system., (© 2023 Wiley-VCH GmbH.)

Electrolyte design holds the greatest opportunity for the development of batteries that are capable of sub-zero temperature operation. To get the most energy storage out of the battery at low temperatures, improvements in electrolyte chemistry need to be coupled with optimized electrode materials and tailored electrolyte/electrode interphases. Herein, this review critically outlines electrolytes' limiting factors, including reduced ionic conductivity, large de-solvation energy, sluggish charge transfer, and slow Li-ion transportation across the electrolyte/electrode interphases, which affect the low-temperature performance of Li-metal batteries. Detailed theoretical derivations that explain the explicit influence of temperature on battery performance are presented to deepen understanding. Emerging improvement strategies from the aspects of electrolyte design and electrolyte/electrode interphase engineering are summarized and rigorously compared. Perspectives on future research are proposed to guide the ongoing exploration for better low-temperature Li-metal batteries., (© 2023. The Author(s).)

Lithium (Li) metal electrodes show significantly different reversibility in the electrolytes with different salts. However, the understanding on how the salts impact on the Li loss remains unclear. Herein, using the electrolytes with different salts (e.g., lithium hexafluorophosphate (LiPF 6 ), lithium difluoro(oxalato)borate (LiDFOB), and lithium bis(fluorosulfonyl)amide (LiFSI)) as examples, we decouple the irreversible Li loss (SEI Li + and "dead" Li) during cycling. It is found that the accumulation of both SEI Li + and "dead" Li may be responsible to the irreversible Li loss for the Li metal in the electrolyte with LiPF 6 salt. While for the electrolytes with LiDFOB and LiFSI salts, the accumulation of "dead" Li predominates the Li loss. We also demonstrate that lithium nitrate and fluoroethylene carbonate additives could, respectively, function as the "dead" Li and SEI Li + inhibitors. Inspired by the above understandings, we propose a universal procedure for the electrolyte design of Li metal batteries (LMBs): (i) decouple and find the main reason for the irreversible Li loss; (ii) add the corresponding electrolyte additive. With such a Li-loss-targeted strategy, the Li reversibility was significantly enhanced in the electrolytes with 1,2-dimethoxyethane, triethyl phosphate, and tetrahydrofuran solvents. Our strategy may broaden the scope of electrolyte design toward practical LMBs., (© 2023. Shanghai Jiao Tong University.)

As a promising cathode material for high-performance lithium-ion batteries, olivine LiFe 1-x Mn x PO 4 (0 < x < 1, LFMP) combines the high safety of LiFePO 4 and the high energy density of LiMnPO 4 . During the charge-discharge process, poor interface stability of active materials leads to capacity decay, which prevents its commercial application. Here, to stabilize the interface, a new electrolyte additive potassium 2-thienyl tri-fluoroborate (2-TFBP) is developed to boost the performance of LiFe 0.3 Mn 0.7 PO 4 at 4.5 V vs. Li/Li + . Specifically, after 200 cycles, the capacity retention remains at 83.78% in the electrolyte containing 0.2% 2-TFBP while the capacity retention without 2-TFBP addition is only 53.94%. Based on the comprehensive measurements results, the improved cyclic performance is attributed to that 2-TFBP has a higher highest occupied molecular orbit (HOMO) energy and its thiophene group can be electropolymerized above 4.4 V vs. Li/Li + for generating uniform cathode electrolyte interphase (CEI) with poly-thiophene, which can stable materials structure and suppress the decomposition of electrolytes. Meanwhile, 2-TFBP both promotes the deposition/exfoliation of Li + at anode-electrolyte interfaces and regulates Li deposition by K + cations through the electrostatic mechanism. This work presents that 2-TFBP has a great application prospect as a functional additive for high-voltage and high-energy-density lithium metal batteries., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Enabling highly stable alkali metal anodes in gas atmospheres, such as oxygen and carbon dioxide, is critical for the implementation of emerging metal-gas batteries with high energy density and improved safety. Herein, we demonstrate a three-salt electrolyte system to tackle the problems of gas crossover and uncontrolled metallic dendrite growth for all-climate sodium-gas batteries by the formation of an electrochemically/chemically stable solid electrolyte interphase that is rich in fluoride and sulfate compounds. Consequently, the sodium metal anodes present high reversible capacity (10 mAh cm -2 at 1.5 mA cm -2 ) and long cycle life (2000 h) in gas atmospheres across a wide operating temperature range. Using the three-salt electrolyte, all-climate sodium-oxygen and sodium-carbon dioxide batteries are demonstrated with a reversible capacity of 1000 mAh g -1 over 100 cycles at ambient temperature and good adaptability to temperatures from -60 to 60 °C.

Reversible metal electrodeposition (RME) is an emerging and promising method for designing dynamic windows with electrically controllable transmission, excellent color neutrality, and wide dynamic range. Zn is a viable option for metal-based dynamic windows due to its fast switching kinetics and reversibility despite its very negative deposition voltage. In this manuscript, we study the effect of the supporting electrolyte anions for Zn electrodeposition on transparent tin-doped indium oxide. Through systematic additions or removal of components of the electrolytes, we are able to establish a link between the anions and the effectiveness of Zn RME. This insight allows us to design practical two-electrode 25 cm 2 Zn dynamic windows that switch to <1% within 20 s. Lastly, we demonstrate that the accumulation of Zn(OH) 2 species on the working electrode degrades the optical contrast of Zn windows during long-term cycling. However, the elimination of these species through acid immersion allows the windows to cycle at least 500 times. Reversible Zn electrodeposition in the presence of a polyethylene glycol additive further improves the cycle life to greater than 1000 cycles. Taken together, these studies highlight important design principles for the construction of robust dynamic windows based on Zn RME.

Zinc-ion batteries (ZIBs) feature high safety, low cost, environmental-friendliness, and promising electrochemical performance, and are therefore regarded as a potential technology to be applied in large-scale energy storage devices. However, ZIBs still face some critical challenges and bottlenecks. The electrolyte is an essential component of batteries and its properties affect the mass transport, energy storage mechanisms, reaction kinetics, and side reactions of ZIBs. The adjustment of electrolyte formulas usually has direct and obvious impacts on the overall output and performance. In this review, advanced electrolyte strategies are overviewed for optimizing the compatibility between cathode materials and electrolytes, inhibiting anode corrosion and dendrite growth, extending electrochemical stability windows, enabling wearable applications, and enhancing temperature tolerance. The underlying scientific mechanisms, electrolyte design principles, and recent progress are presented to provide a better understanding and inspiration to readers. In addition, a comprehensive perspective about electrolyte design and engineering for ZIBs is included., (© 2022 Wiley-VCH GmbH.)

The thermal stability window of current commercial carbonate-based electrolytes is no longer sufficient to meet the ever-increasing cathode working voltage requirements of high energy density lithium-ion batteries. It is crucial to construct a robust cathode-electrolyte interphase (CEI) for high-voltage cathode electrodes to separate the electrolytes from the active cathode materials and thereby suppress the side reactions. Herein, this review presents a brief historic evolution of the mechanism of CEI formation and compositions, the state-of-art characterizations and modeling associated with CEI, and how to construct robust CEI from a practical electrolyte design perspective. The focus on electrolyte design is categorized into three parts: CEI-forming additives, anti-oxidation solvents, and lithium salts. Moreover, practical considerations for electrolyte design applications are proposed. This review will shed light on the future electrolyte design which enables aggressive high-voltage cathodes., (© 2022. The Author(s).)

Given the limitations inherent in current intercalation-based Li-ion batteries, much research attention has focused on potential successors to Li-ion batteries such as lithium-sulfur (Li-S) batteries and lithium-oxygen (Li-O 2 ) batteries. In order to realize the potential of these batteries, the use of metallic lithium as the anode is essential. However, there are severe safety hazards associated with the growth of Li dendrites, and the formation of "dead Li" during cycles leads to the inevitable loss of active Li, which in the end is undoubtedly detrimental to the actual energy density of Li-metal batteries. For Li-metal batteries under practical conditions, a low negative/positive ratio (N/P ratio), a electrolyte/cathode ratio (E/C ratio) along with a high-voltage cathode is prerequisite. In this Review, we summarize the development of new electrolyte systems for Li-metal batteries under practical conditions, revisit the design criteria of advanced electrolytes for practical Li-metal batteries and provide perspectives on future development of electrolytes for practical Li-metal batteries., (© 2021 Wiley-VCH GmbH.)

Rechargeable aqueous Zn-ion batteries promise high capacity, low cost, high safety, and sustainability for large-scale energy storage. The Zn metal anode, however, suffers from the dendrite growth and side reactions that are mainly due to the absence of an appropriate solid electrolyte interphase (SEI) layer. Herein, the in situ formation of a dense, stable, and highly Zn 2+ -conductive SEI layer (hopeite) in aqueous Zn chemistry is demonstrated, by introducing Zn(H 2 PO 4 ) 2 salt into the electrolyte. The hopeite SEI (≈140 nm thickness) enables uniform and rapid Zn-ion transport kinetics for dendrite-free Zn deposition, and restrains the side reactions via isolating active Zn from the bulk electrolyte. Under practical testing conditions with an ultrathin Zn anode (10 µm), a low negative/positive capacity ratio (≈2.3), and a lean electrolyte (9 µL mAh -1 ), the Zn/V 2 O 5 full cell retains 94.4% of its original capacity after 500 cycles. This work provides a simple yet practical solution to high-performance aqueous battery technology via building in situ SEI layers., (© 2021 Wiley-VCH GmbH.)

Developing next-generation battery chemistries that move beyond traditional Li-ion systems is critical to enabling transformative advances in electrified transportation and grid-level energy storage. In this work, we provide the first evidence for common descriptors for improved reversibility of metal plating/stripping in nonaqueous electrolytes for multivalent ion batteries. Focusing first on the specific role of chloride (Cl - ) in promoting electrochemical reversibility in multivalent systems, rotating disk (RDE) and ring-disk electrode (RRDE) investigations were performed utilizing a variety of divalent cations (Mg 2+ , Zn 2+ , and Cu 2+ ) and the bis-(trifluoromethane sulfonyl) imide (TFSI - ) anion. By introducing varying concentrations of Cl - , a cooperative effect is observed between TFSI - and Cl - that yields the more reversible behavior of mixed electrolytes relative to electrolytes containing only TFSI - . This effect is shown to be general for Mg, Zn, and Cu electrodeposition, and mechanistic understanding of the role of Cl - in improving reversibility of TFSI-based electrolytes is obtained through the combination of R(R)DE experimental results and density functional theory (DFT) evaluation of the redox activity and thermodynamic stability of various TFSI- and Cl-based solution complexes of metal ions. The cooperative anion effect is further generalized to other mixed-anion systems, where systematic variations in anion association strength predicted from DFT (i.e., Cl - > OTf - ≈ TFSI - > BF 4 - > PF 6 - ) yield corresponding trends in redox potentials and improvements of ≥200 mV in the reversibility of metal deposition/dissolution. These results identify anion association strength as a common descriptor for the reversibility of divalent metal anodes and suggest a set of general design principles for developing new electrolytes with improved activity and stability.

The lack of suitable cathodes is one of the key reasons that impede the development of aqueous zinc-ion batteries. Because of the inherently unsuitable structure and inferior physicochemical properties, the low-valent V 2 O 3 as Zn 2+ host could not be effectively discharged. Herein, we demonstrate that V 2 O 3 (theoretical capacity up to 715 mAh g -1 ) can be utilized as a high-performance cathode material by an in situ anodic oxidation strategy. Through simultaneously regulating the concentration of the electrolyte and the morphology of the V 2 O 3 sample, the ultraefficient anodic oxidation process of the V 2 O 3 cathode was achieved within the first charging, and the mechanism was also schematically investigated. As expected, the V 2 O 3 cathode with a hierarchical microcuboid structure achieved a nearly two-electron transfer process, enabling a high discharging capacity of 625 mAh g -1 at 0.1 A g -1 (corresponding to a high energy density of 406 Wh kg -1 ) and cycling stability (100% capacity retention after 10 000 cycles). This work not only sheds light on the phase transition process of low-valent V 2 O 3 but also exploits a method toward design of advanced cathode materials.

Electrolyte is a key component in high-voltage lithium-ion batteries (LIBs). Bis(trifluoromethanesulfonyl)imide-based ionic liquid (IL)/organic carbonate hybrid electrolytes have been a research focus owing to their excellent balance of safety and ionic conductivity. Nevertheless, corrosion of Al current collectors at high potentials usually happens for this kind of electrolyte. In this study, this long-standing problem is solved via the modulation of the IL/carbonate ratio and LiPF 6 concentration in the hybrid electrolyte. The proposed electrolyte suppresses Al dissolution and electrolyte oxidation at 5 V (vs Li + /Li) and thus allows for ideal lithiation/delithiation performance of a high-voltage LiNi 0.5 Mn 1.5 O 4 (LNMO) cathode even at 55 °C. The underlying mechanism is examined in this work. Excellent cycling stability (97% capacity retention) for an LNMO cathode after 300 cycles is achieved. This electrolyte shows good wettability toward a polyethylene separator and low flammability. In addition, satisfactory compatibility with both graphite and Si-based anodes is confirmed. The proposed electrolyte design strategies have great potential for applications in high-voltage LIBs.

Electrolyte instability is one of the most challenging impediments to enabling Lithium-Oxygen (Li-O 2 ) batteries for practical use. The use of physical organic chemistry principles to rationally design new molecular components may enable the discovery of electrolytes with stability profiles that cannot be achieved with existing formulations. Here, we report on the development of sulfamide- and sulfonamide-based small molecules that are liquids at room temperature, capable of dissolving reasonably high concentration of Li salts (e.g., LiTFSI), and are exceptionally stable under the harsh chemical and electrochemical conditions of aprotic Li-O 2 batteries. In particular, N , N -dimethyl-trifluoromethanesulfonamide was found to be highly resistant to chemical degradation by peroxide and superoxide, stable against electrochemical oxidation up to 4.5 V Li , and stable for > 90 cycles in a Li-O 2 cell when cycled at < 4.2 V Li . This study provides guiding principles for the development of next-generation electrolyte components based on sulfamides and sulfonamides.

Bipolar electrochemistry involves spatial separation of charge balanced reduction and oxidation reactions on an electrically floating electrode, a result of intricate coupling of the work piece with the ohmic drop in the electrochemical cell and to the thermodynamics and kinetics of the respective bipolar reactions. When paired with a rastering microjet electrode, in a scanning bipolar cell (SBC), local electrodeposition and patterning of metals beneath the microjet can be realized without direct electrical connections to the workpiece. Here, we expand on prior research detailing electrolyte design guidelines for electrodeposition and patterning with the SBC, focusing on the relationship between kinetics and thermodynamics of the respective bipolar reactions. The kinetic reversibility or irreversibility of the desired deposition reaction influences the range of possible effective bipolar counter reactions. For kinetically irreversible deposition systems (i.e., nickel), a wider thermodynamic window is available for selection of the counter reaction. For kinetically reversible systems (i.e., copper or silver) that can be easily etched, tight thermodynamic windows with a small downhill driving force for spontaneous reduction are required to prevent metal patterns from electrochemical dissolution. Furthermore, additives used for the bipolar counter reaction can influence not only the kinetics of deposition, but also the morphology and microstructure of the deposit. Cyclic voltammetry measurements help elucidate secondary parasitic reduction reactions occurring during bipolar nickel deposition and describe the thermodynamic relationship of both irreversible and reversible bipolar couples. Finally, finite element method simulations explore the influence of bipolar electrode area on current efficiency and connect experimental observations of pattern etching to thermodynamic and kinetic relationships.

Lithium-sulfur (Li-S) batteries are, in theory, considering their basic reactions, very promising from a specific energy density point of view, but have poor power rate capabilities. The dissolution of sulfur from the C/S cathode in the electrolyte is a rate-determining and crucial step for the functionality. To date, time-consuming experimental methods, such as HPLC/UV, have been used to quantify the corresponding solubilities. Here, we use a computational fluid-phase thermodynamics approach, the conductor-like screening model for real solvents (COSMO-RS), to compute the solubilities of sulfur in different binary and ternary electrolytes. By using both explicit and implicit solvation approaches for lithium bistrifluoromethanesulfonimidate (LiTFSI)-containing electrolytes, a deviation of <0.4 log units was achieved with respect to experimental data, within the range of experimental error, thus proving COSMO-RS to be a useful tool for exploring novel Li-S battery electrolytes., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)