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A half‐cell that is composed of electrode and metal (e.g., lithium) is the most classical model for examining electrode performance in battery community, by which the voltage versus capacity profile is the important indicator. However, it is found that these results are not all reliable, as a misconception of electrode performance can be caused once the electrolyte is chemically unstable. As a paradigm, it is demonstrated that the diethyl carbonate (DEC) solvent can chemically react with lithium metal to form insoluble and soluble by‐products, which can accumulate on the lithium anode to influence the lithium potential and/or migrate to the counter electrode to proceed with the uncompleted electrochemical reactions. The resultant voltage‐capacity profile cannot reflect the actual electrode performance, such as the lithium storing capability within the graphite. The reason for this phenomenon is elucidated based on solvation chemistry, particularly the mechanism of mitigating it by introducing ethylene carbonatesolvent to form new hydrogen bonds. The viewpoint is further verified by employing the full cell and also extended in sodium and potassium batteries. This study shows the necessity of discerning the reliability of electrode performance and also sheds light on the importance of designing a compatible electrolyte to examine electrode performance. [ABSTRACT FROM AUTHOR]

Electrolytes play a pivotal role to determine the electrode performances in lithium‐ion batteries (LIBs). However, understanding the function of electrolyte components at the molecular scale remains elusive (e.g., salts, solvents, and additives), particularly how they arrange themselves and affect properties of the bulk, liquid‐solid interfaces, and electrolyte decomposition, rendering a bottleneck for improving the electrolytes. Herein, the function of electrolyte components is thoroughly studied, from Li+ solvation structure in the bulk electrolyte, Li+ (de‐)solvation behaviors at the electrolyte‐solid interfaces, until the formation of solid electrolyte interphase (i.e., SEI) layer on the electrodes. Furthermore, a detailed model by taking into account the effects of solvent, additive, lithium salt, and concentration on the electrochemical properties of the Li+‐solvent‐anion complex to elucidate the electrode performances are depicted. As the ultimate benefit of this study, a completely new non‐flammable ether‐based electrolyte and stabilizing the promising antimony (Sb) anodes can be designed. Remarkably, a high‐performance Sb anode that is superior to previous reports is obtained. This study provides a graphical model to unravel interfacial and interphasial behaviors of electrolyte components in LIBs, which is also significant for developing other metal‐ion batteries. [ABSTRACT FROM AUTHOR]

Engineering the solid electrolyte interphase (SEI) that forms on the electrode is crucial for achieving high performance in metal‐ion batteries. However, the mechanism of SEI formation resulting from electrolyte decomposition is not fully understood at the molecular scale. Herein, a new strategy of switching electrolyte to tune SEI properties is presented, by which a unique and thinner SEI can be pre‐formed on the graphite electrode first in an ether‐based electrolyte, and then the as‐designed graphite electrode can demonstrate extremely high‐rate capabilities in a carbonate‐based electrolyte, enabling the design of fast‐charging and wide‐temperature lithium‐ion batteries (e.g., graphite | LiNi0.6Co0.2Mn0.2O2 (NCM622)). A molecular interfacial model involving the conformations and electrochemical stabilities of the Li+‐solvent‐anion complex is presented to elucidate the differences in SEI formation between ether‐based and carbonate‐based electrolytes, then interpreting the reason for the obtained higher rate performances. This innovative concept combines the advantages of different electrolytes into one battery system. It is believed that the switching strategy and understanding of the SEI formation mechanism opens a new avenue to design SEI, which is universal for pursuing more versatile battery systems with greater stability. [ABSTRACT FROM AUTHOR]

Potassium ion batteries (KIBs) are attracting great attention as an alternative to lithium‐ion batteries due to lower cost and better global sustainability of potassium. However, designing electrolytes compatible with the graphite anode and addressing the safety issue of highly active potassium remains challenging. Herein, a new concept of using additives to engineer non‐flammable electrolytes for safer KIBs is introduced. It is discovered that the additives, such as the ethylene sulfate (i.e., DTD), can make the electrolyte of 1.0 m potassium bis(fluorosulfonyl) imide in trimethyl phosphate compatible with graphite anode for the first time, without the need of concentrated electrolyte strategies. A new coordination mechanism of additives in the electrolyte is presented. It is shown that the additive can change the K+ solvation structure and then determine the interfacial behaviors of K+‐solvent on electrode interface, which are critical to affect the graphite performance (i.e., K+‐solvent co‐insertion, or K+ (de‐)intercalation). Then, an extremely high potassium storage capability is obtained in graphite electrode for potassium (ion) batteries, particularly the presented high‐performance graphite|K0.69CrO2 full battery fully demonstrates the practical application of this newly designed electrolyte. This additive‐based strategy can offer more opportunities to tune the electrolyte properties and then serve for the more mobile ion battery system. [ABSTRACT FROM AUTHOR]

Development of flexible and freestanding electrode is attracting great attention in lithium-sulfur (Li-S) batteries, but the severe capacity fading caused by the lithium polysulfides (PSs) shuttle effect remains challenging. Herein, a completely new polymeric binder of polyethersulfone is introduced. Not only it enables massive production of flexible/current-free electrode by a novel concept of "phase-inversion" approach but also the resultant polymeric networks can effectively trap the soluble polysulfides within the electrode, owing to the higher hydrophilicity and stronger affinity properties than the routine polyvinylidene fluoride. Coupling with polysulfide-based electrolyte, the Li-S cell shows a higher capacity of 1141 mAh g-1, a lower polarization of 192 mV, and a more stable capacity retention with 100% Coulombic efficiency over 100 cycles at 0.25C. The advantages of favored binder and electrolyte are further demonstrated in lithium-ion sulfur full battery with lithiated graphite anode, which demonstrates much improved performance than those previously reported. This work not only introduces a novel strategy for flexible freestanding electrodes but also enlightens the importance of coupling electrodes and electrolytes to higher performances for Li-S battery [ABSTRACT FROM AUTHOR]

Binder plays a pivotal role in the development of lithium‐ion batteries as it must be used to adhere electrode materials on current collectors tightly to guarantee stability. Then, many binder molecules have been designed to enhance the adhesion capability, and conductivity, and/or form a robust solid electrolyte interphase layer for better performance. However, the binder effect on the lithium‐ion (i.e., Li+) de‐solvation on the electrode surface has never been reported before. Herein, it is reported that the binder can influence the Li+ (de‐)solvation process significantly, where its functional group can serve as a probe to detect the dynamic Li+ (de‐)solvation process. It is discovered that different binder functional groups (e.g., *─COO− versus *─F) can affect the Li+‐solvent arrangement on the electrode surface, leading to different degrees of side‐reactions, rate capabilities, and/or the tolerance against Li+‐solvent co‐insertion for the graphite anode, such as in the propylene carbonate‐based electrolyte. A molecular interfacial model related to the electrolyte component's behaviors and binder functional group is proposed to interpret the varied electrode performance. This discovery opens a new avenue for studying the interactions between the binder and electrolyte solvation structure, in turn helping to understand electrode performances underlying the micro‐structures. [ABSTRACT FROM AUTHOR]

Protontransport through an electrolyte layer between platinumelectrodes under a range of applied voltages is explored using reactivemolecular dynamics simulation. The proton transport process is decomposedinto vehicular and Grotthuss hopping components, and the two mechanismsand their correlation are investigated as a function of applied voltage.At higher applied voltages, the effect of the hopping mechanism ismuch larger as compared with the vehicular mechanism. As the voltageis increased, the net correlation between the two mechanisms goesfrom negative to positive, and both the hopping frequency as wellas the number of consecutive forward hops increases. This behaviorresults in a larger total diffusion constant at higher values of thevoltage. The behavior of the hydrated excess proton is therefore substantiallydifferent under an applied external voltage than in the normal bulkwater environment. [ABSTRACT FROM AUTHOR]

Electrolyte is critical for transporting lithium‐ion (Li+) in lithium‐ion batteries (LIBs). However, there is no universally applicable principle for designing an optimal electrolyte. In most cases, the design process relies on empirical experiences and is often treated as highly confidential proprietary information. Herein, a solvation structure‐related model for the quantitative design of electrolytes is introduced, focusing on the principles of coordination chemistry. As a paradigmatic example, a high‐voltage electrolyte (i.e., 4.5 V vs anode) aimed at achieving a high energy density and fast charging LIB, which is specifically composed of an emerging, well‐constructed hybrid hard carbon‐silicon/carbon‐based anode, and lithium cobalt oxide cathode, is developed. Not only the functions of each electrolyte component at the molecular scale within the Li+ solvation structure are analyzed but also an interfacial model is introduced to elucidate their relationship with the battery performance. This study represents a pioneering effort in developing a methodology to guide electrolyte design, in which the mutual effects of the Li+ de‐solvation process and solid electrolyte interface (SEI) on the electrode surface are explored concurrently to understand the root cause of superior performance. This innovative approach establishes a new paradigm in electrolyte design, providing valuable insights at the molecular level. [ABSTRACT FROM AUTHOR]

High‐voltage lithium metal batteries are the most promising energy storage technology due to their excellent energy density (>400 Wh kg−1). However, the oxidation decomposition of conventional carbonate‐based electrolytes at the high‐potential cathode, the detrimental reaction between the lithium anode and electrolyte, particularly the uncontrolled lithium dendrite growth, always lead to a severe capacity decay and/or flammable safety issues, hindering their practical applications. Herein, a solvation structure engineering strategy based on tuning intermolecular interactions is proposed as a strategy to design a novel nonflammable fluorinated electrolyte. Using this approach, this work shows superior cycling stability in a wide temperature range (−40 °C to 60 °C) for a 4.4 V‐class LiNi0.8Co0.1Mn0.1O2 (NCM811)‐based Li‐metal battery. By coupling the high‐loading of NCM811 cathode (3.0 mAh cm−2) and a controlled amount of lithium anode (twofold excess of Li deposition on Cu, Cu@Li) (N/P = 2), the Cu@Li || NCM811 full cell can cycle more than 162 cycles with high‐capacity retention of 80%. This work finds that the change of the coordination environment of Li+ with solvent and PF6− by tuning intermolecular interaction is an effective method to stabilize the electrolyte and electrode performance. These discoveries can provide a pathway for electrolyte design in metal ion batteries. [ABSTRACT FROM AUTHOR]

Electrolyte design has become ever more important to enhance the performance of lithium‐ion batteries (LIBs). However, the flammability issue and high reactivity of the conventional electrolytes remain a major problem, especially when the LIBs are operated at high voltage and extreme temperatures. Herein, we design a novel non‐flammable fluorinated ester electrolyte that enables high cycling stability in wide‐temperature variations (e.g. −50 °C–60 °C) and superior power capability (fast charge rates up to 5.0 C) for the graphite||LiNi0.8Co0.1Mn0.1O2 (NCM811) battery at high voltage (i.e. >4.3 V vs. Li/Li+). Moreover, this work sheds new light on the dynamic evolution and interaction among the Li+, solvent, and anion at the molecular level. By elucidating the fundamental relationship between the Li+ solvation structure and electrochemical performance, we can facilitate the development of high‐safety and high‐energy‐density batteries operating in harsh conditions. [ABSTRACT FROM AUTHOR]

Electrolyte design has become ever more important to enhance the performance of lithium‐ion batteries (LIBs). However, the flammability issue and high reactivity of the conventional electrolytes remain a major problem, especially when the LIBs are operated at high voltage and extreme temperatures. Herein, we design a novel non‐flammable fluorinated ester electrolyte that enables high cycling stability in wide‐temperature variations (e.g. −50 °C–60 °C) and superior power capability (fast charge rates up to 5.0 C) for the graphite||LiNi0.8Co0.1Mn0.1O2 (NCM811) battery at high voltage (i.e. >4.3 V vs. Li/Li+). Moreover, this work sheds new light on the dynamic evolution and interaction among the Li+, solvent, and anion at the molecular level. By elucidating the fundamental relationship between the Li+ solvation structure and electrochemical performance, we can facilitate the development of high‐safety and high‐energy‐density batteries operating in harsh conditions. [ABSTRACT FROM AUTHOR]

Herein, a new solvation strategy enabled by Mg(NO3)2 is introduced, which can be dissolved directly as Mg2+ and NO3− ions in the electrolyte to change the Li+ ion solvation structure and greatly increase interfacial stability in Li‐metal batteries (LMBs). This is the first report of introducing Mg(NO3)2 additives in an ester‐based electrolyte composed of ternary salts and binary ester solvents to stabilize LMBs. In particular, it is found that NO3− efficiently forms a stable solid electrolyte interphase through an electrochemical reduction reaction, along with the other multiple anion components in the electrolyte. The interaction between Li+ and NO3− and coordination between Mg2+ and the solvent molecules greatly decreases the number of solvent molecules surrounding the Li+, which leads to facile Li+ desolvation during plating. In addition, Mg2+ ions are reduced to Mg via a spontaneous chemical reaction on the Li metal surface and subsequently form a lithiophilic Li–Mg alloy, suppressing lithium dendritic growth. The unique solvation chemistry of Mg(NO3)2 enables long cycling stability and high efficiency of the Li‐metal anode and ensures an unprecedented lifespan for a practical pouch‐type LMB with high‐voltage Ni‐rich NCMA73 cathode even under constrained conditions. [ABSTRACT FROM AUTHOR]

Flexible Li‐air batteries (LABs) have been considered as promising power sources for wearable electronics owing to its higher energy density. However, when operated in ambient air, problems arise, such as Li anode passivation, poor cycle life as well as leakage of liquid electrolyte. Herein, we present a LAB with a tetraethylene glycol dimethyl ether (TEGDME, G4) gel electrolyte, in which the gel is formed in situ through a cross‐linking reaction between the liquid G4 and the lithium ethylenediamine (LiEDA) grown on the surface of Li anode. We demonstrate that the gel can efficiently alleviate the corrosion of the Li anode, and thus the LAB shows a cycle performance over 1175 hours (humidity: 10 % to 40 %), which is much superior to previous reports. Furthermore, the in situ formed gel enhances the electrode/electrolyte interfacial contact, which thus enables the cable‐type LAB to exhibit a great flexibility. Air gel: The liquid electrolyte G4 is converted into a gel through an in situ cross‐linking reaction for use in flexible Li–air batteries. The good electrode/electrolyte interfacial contact and improved Li anode stability contribute to the enhanced cycle and bending performance of the battery in ambient air. [ABSTRACT FROM AUTHOR]

Flexible Li‐air batteries (LABs) have been considered as promising power sources for wearable electronics owing to its higher energy density. However, when operated in ambient air, problems arise, such as Li anode passivation, poor cycle life as well as leakage of liquid electrolyte. Herein, we present a LAB with a tetraethylene glycol dimethyl ether (TEGDME, G4) gel electrolyte, in which the gel is formed in situ through a cross‐linking reaction between the liquid G4 and the lithium ethylenediamine (LiEDA) grown on the surface of Li anode. We demonstrate that the gel can efficiently alleviate the corrosion of the Li anode, and thus the LAB shows a cycle performance over 1175 hours (humidity: 10 % to 40 %), which is much superior to previous reports. Furthermore, the in situ formed gel enhances the electrode/electrolyte interfacial contact, which thus enables the cable‐type LAB to exhibit a great flexibility. [ABSTRACT FROM AUTHOR]