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Anion‐reinforced solvation structure favors the formation of inorganic‐rich robust electrode‐electrolyte interface, which endows fast ion transport and high strength modulus to enable improved electrochemical performance. However, such a unique solvation structure inevitably injures the ionic conductivity of electrolytes and limits the fast‐charging performance. Herein, a trade‐off in tuning anion‐reinforced solvation structure and high ionic conductivity is realized by the entropy‐assisted hybrid ester‐ether electrolyte. Anion‐reinforced solvation sheath with more anions occupying the inner Na+ shell is constructed by introducing the weakly coordinated ether tetrahydrofuran into the commonly used ester‐based electrolyte, which merits the accelerated desolvation energy and gradient inorganic‐rich electrode‐electrolyte interface. The improved ionic conductivity is attributed to the weakly diverse solvation structures induced by entropy effect. These enable the enhanced rate performance and cycling stability of Prussian blue||hard carbon full cells with high electrode mass loading. More importantly, the practical application of the designed electrolyte was further demonstrated by industry‐level 18650 cylindrical cells. [ABSTRACT FROM AUTHOR]

Sodium‐ion batteries (SIBs) are considered as a beneficial complement to lithium‐ion batteries for large‐scale energy storage systems because of the abundant sodium resources. However, the relatively large ionic radius of Na+ inevitably results in a huge volume change and sluggish electrochemical reaction kinetics, which put forward higher requirements for electrode materials. Among the reported cathode materials for SIBs, the manganese hexacyanoferrate (MnHCF) with the merits of large channels for fast sodium ion transport, high theoretical capacity and low cost has attracted extensive attention. In this review, the recent achievements of MnHCF for SIBs are focused. The key challenges of MnHCF limiting the practical application include the interstitial water, vacancies, low electronic conductivity, and the Jahn‐Teller effect. Subsequently, the mainstream strategies to boost the sodium storage performance of MnHCF are summarized (such as structure regulation, surface coating, hybridization with carbon materials, and element substitution). Finally, the potential research directions are also proposed to promote the practical application of MnHCF for SIBs. This review is expected to provide a whole insight into exploring MnHCF cathode materials for SIBs. [ABSTRACT FROM AUTHOR]

Sodium‐ion batteries (SIBs) are a promising candidate for large‐scale energy storage due to the low cost and abundant sodium resources. However, the formation of sodium dendrites on the surface of hard carbon (HC) anodes is the most intractable challenge for full cells during charging, leading to severe performance degradation and safety hazards. Here, a robust additive‐induced borate and fluoride‐rich interphase is constructed by introducing sodium difluoro(oxalato)borate (NaDFOB) as additive in the ether‐based electrolyte to relieve the performance deterioration for SIBs. NaDFOB can participate in the passivation process of electrolyte‐electrode interfaces through preferential oxidation and reduction of DFOB− to effectively restrain the growth of sodium dendrites. Moreover, the electrolyte decomposition and dissolution of transition metal ions are effectively inhibited. Benefiting from that, FeMn‐based Prussian blue (FeMnHCF) || HC full cell with a negative/positive capacity ratio (N/P ratio) of 1.09 displays a capacity retention of 82.1%, especially with a low N/P ratio of 0.96 the cell still demonstrates a stable Coulombic efficiency of over 99.9% after 500 cycles via using NaDFOB as additive. As a practical demonstration, the designed 18650 full cells display enhanced cycling stability with NaDFOB additive. The findings provide insights into the additive‐induced inorganic‐rich interfacial layers for dendrite‐free SIBs. [ABSTRACT FROM AUTHOR]

Electrolytes with anion‐dominated solvation are promising candidates to achieve dendrite‐free and high‐voltage potassium metal batteries. However, it's challenging to form anion‐reinforced solvates at low salt concentrations. Herein, we construct an anion‐reinforced solvation structure at a moderate concentration of 1.5 M with weakly coordinated cosolvent ethylene glycol dibutyl ether. The unique solvation structure accelerates the desolvation of K+, strengthens the oxidative stability to 4.94 V and facilitates the formation of inorganic‐rich and stable electrode‐electrolyte interface. These enable stable plating/stripping of K metal anode over 2200 h, high capacity retention of 83.0 % after 150 cycles with a high cut‐off voltage of 4.5 V in K0.67MnO2//K cells, and even 91.5 % after 30 cycles under 4.7 V. This work provides insight into weakly coordinated cosolvent and opens new avenues for designing ether‐based high‐voltage electrolytes. [ABSTRACT FROM AUTHOR]

Sodium‐ion batteries (SIBs) with wide operating temperature are regarded as promising candidates for large‐scale energy storage systems. However, SIBs operating under elevated temperature aggravate the electrolyte decomposition with unstable cathode‐electrolyte interphase (CEI), causing a rapid capacity degradation. Herein, anion receptor tris(pentafluorophenyl)borane (TPFPB) is selected as electrolyte additive to construct robust NaF‐rich CEI. The strong interactions between anion and TPFPB via the electron‐deficient boron atoms weaken ClO4− solvation and promote the coordination capability between solvents and Na+ cations, demonstrating greatly improved oxidative stability. Na3V2(PO4)3 cathode in TPFPB‐containing electrolyte delivers long‐term stability with a capacity retention of 86.9% after 100 cycles at a high cut‐off voltage of 4.2 V (vs. Na+/Na) and a high temperature of 60 °C. Besides, TPFPB also works well with enhanced performance over a temperature range from −30 to 60 °C. This study proposes a prospective method by manipulating the solvation chemistry for constructing high‐temperature rechargeable SIBs. [ABSTRACT FROM AUTHOR]

The initial Coulombic efficiency (ICE) of electrode materials is closely related to the energy density of lithium‐ion batteries (LIBs). However, some promising electrode materials for next generation LIBs suffer from low ICE, which inevitably hinders their practical application. Among the discovered modified strategies for LIBs, electrolyte optimization has attracted extensive attention due to its facile operation process. Herein, the role of ICE in LIBs is first analyzed. Subsequently, the recent progress on effective electrolyte optimization strategies for boosting ICE in LIB is summarized (including the optimization of lithium salt, salt concentration, solvent, and electrolyte additive). Finally, future research directions of electrolyte optimization for boosting ICE are proposed. This review provides valuable guidance for developing advanced electrolyte for LIBs. [ABSTRACT FROM AUTHOR]

High‐voltage lithium‐ion batteries (LIBs) have attracted great attention due to their promising high energy density. However, severe capacity degradation is witnessed, which originated from the incompatible and unstable electrolyte‐electrode interphase at high voltage. Herein, a robust additive‐induced sulfur‐rich interphase is constructed by introducing an additive with ultrahigh S‐content (34.04 %, methylene methyl disulfonate, MMDS) in 4.6 V LiNi0.5Co0.2Mn0.3O2 (NCM523)||graphite pouch cell. The MMDS does not directly participate the inner Li+ sheath, but the strong interactions between MMDS and PF6− anions promote the preferential decomposition of MMDS and broaden the oxidation stability, facilitating the formation of an ultrathin but robust sulfur‐rich interfacial layer. The electrolyte consumption, gas production, phase transformation and dissolution of transition metal ions were effectively inhibited. As expected, the 4.6 V NCM523||graphite pouch cell delivers a high capacity retention of 87.99 % even after 800 cycles. This work shares new insight into the sulfur‐rich additive‐induced electrolyte‐electrode interphase for stable high‐voltage LIBs. [ABSTRACT FROM AUTHOR]

Rechargeable aqueous Zn batteries are potential for large‐scale electrochemical energy storage due to their low cost and high security. However, Zn metal anode suffers from the dendritic growth and interfacial hydrogen evolution reaction (HER), resulting in the deterioration of electrode/battery performance. Here we propose that both dendrites and HER are related to the water participated Zn2+ solvation structure‐Zn(H2O)62+ and thus can be resolved by transforming Zn(H2O)62+ to an anion‐type water‐free solvation structure‐ZnCl42−, which is achieved in traditional ZnSO4 aqueous electrolyte after adding chloride salt with a bulky cation (1‐ethyl‐3‐methylimidazolium chloride). The elimination of cation‐water interaction suppresses HER, while the electrostatic repulsion between Zn tips and the anion solvation structure inhibits dendrite formation. As a result, the electrolyte shows uniform Zn deposition with an average Zn plating/stripping Coulombic efficiency of ≈99.9 %, enabling a capacity retention of 78.8 % after 300 cycles in anode‐free Zn batteries with pre‐zincificated polyaniline as the cathode. This work provides a novel electrolyte design strategy to prevent HER and realize long‐lifespan metal anode. [ABSTRACT FROM AUTHOR]

Diluents have been extensively employed to overcome the disadvantages of high viscosity and sluggish kinetics of high-concentration electrolytes, but generally do not change the pristine solvation structure. Herein, a weakly coordinating diluent, hexafluoroisopropyl methyl ether (HFME), is applied to regulate the coordination of Na + with diglyme and anion and form a diluent-participated solvate. This unique solvation structure promotes the accelerated decomposition of anions and diluents, with the construction of robust inorganic-rich electrode-electrolyte interphases. In addition, the introduction of HFME reduces the desolvation energy of Na + , improves ionic conductivity, strengthens the antioxidant, and enhances the safety of the electrolyte. As a result, the assembled Na||Na symmetric cell achieves a stable cycle of over 1800 h. The cell of Na||P'2-Na 0.67 MnO 2 delivers a high capacity retention of 87.3 % with a high average Coulombic efficiency of 99.7 % after 350 cycles. This work provides valuable insights into solvation chemistry for advanced electrolyte engineering., (© 2024 Wiley-VCH GmbH.)

Zn deposition with a surface-preferred (002) crystal plane has attracted extensive attention due to its inhibited dendrite growth and side reactions. However, the nucleation and growth of the Zn(002) crystal plane are closely related to the interfacial properties. Herein, oriented growth of Zn(002) crystal plane is realized on Ag-modified surface that is directly visualized by in situ atomic force microscopy. A solid solution HCP-Zn (~1.10 at. % solubility of Ag, 30 °C) is formed on the Ag coated Zn foil (Zn@Ag) and possesses the same crystal structure as Zn to reduce its nucleation barrier caused by their lattice mismatch. It merits oriented Zn deposition and corrosion-resistant surface, and presents long cycling stability in symmetric cells and full cells coupled with V 2 O 5 cathode. This work provides insights into interfacial regulation of Zn anodes for high-performance aqueous zinc metal batteries., (© 2024 Wiley-VCH GmbH.)

Na 3 V 2 (PO 4 ) 3 (NVP) cathode materials with the advantages of long cycle life and superior thermal stability have been considered promising cathode candidates for SIBs. However, the unsatisfactory energy density derived from low theoretical capacity and operating voltage (3.35 V vs. Na + /Na, based on the V 3+ /V 4+ redox couple) inevitably limits their practical application. Therefore, the activation of the V 4+ /V 5+ redox couple (∼4.0 V vs. Na + /Na) in NVP-based cathode materials to boost the energy density of SIBs has attracted extensive attention. Herein, we first analyze the challenges of activation of the V 4+ /V 5+ redox couple in NVP-based cathode materials. Subsequently, the recent achievement of NVP-based cathode materials with activated V 4+ /V 5+ redox reactions for SIBs is overviewed. Finally, further research directions of high voltage V 4+ /V 5+ redox reactions in NVP-based cathodes are proposed. This review provides valuable guidance for developing high energy density NVP-based cathode materials for SIBs., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Garnet-type solid-state Li metal batteries (SSLMBs) are viewed as hopeful next-generation batteries due to their high energy density and safety. However, the major obstacle to the development of garnet-type SSLMBs is the lithiophobicity of Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 (LLZTO), resulting in a large interfacial impedance. Herein, a LiI/ZnLi x mixed ion/electron conductive buffer layer is constructed at the interface by an in situ reaction of molten Li metal with ZnI 2 film. This mixed buffer layer ensures close contact between the Li metal and garnet, significantly reducing interfacial impedance. As a result, the Li symmetrical cell with the LiI/ZnLi x buffer layer shows an interface impedance of 10.3 Ω cm 2 , much lower than that of the cell with bare LLZTO (1173.4 Ω cm 2 ). The critical current density (CCD) is up to 2.3 mA cm -2 , and the symmetric cells present a long cycle life of 2000 h at 0.1 mA cm -2 and 800 h at 1.0 mA cm -2 . In addition, the full cells assembled with the LiFePO 4 cathode show a capacity of 143.9 mA h g -1 after 200 cycles at 0.5C with a low-capacity decay of 0.021% per cycle. This work reveals a simple, feasible, and practical interface modification strategy for solid-state Li metal batteries., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

High-voltage lithium-ion batteries (LIBs) have attracted great attention due to their promising high energy density. However, severe capacity degradation is witnessed, which originated from the incompatible and unstable electrolyte-electrode interphase at high voltage. Herein, a robust additive-induced sulfur-rich interphase is constructed by introducing an additive with ultrahigh S-content (34.04 %, methylene methyl disulfonate, MMDS) in 4.6 V LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523)||graphite pouch cell. The MMDS does not directly participate the inner Li + sheath, but the strong interactions between MMDS and PF 6 - anions promote the preferential decomposition of MMDS and broaden the oxidation stability, facilitating the formation of an ultrathin but robust sulfur-rich interfacial layer. The electrolyte consumption, gas production, phase transformation and dissolution of transition metal ions were effectively inhibited. As expected, the 4.6 V NCM523||graphite pouch cell delivers a high capacity retention of 87.99 % even after 800 cycles. This work shares new insight into the sulfur-rich additive-induced electrolyte-electrode interphase for stable high-voltage LIBs., (© 2023 Wiley-VCH GmbH.)

Metallic Na is a promising anode for rechargeable batteries, however, it is plagued by an unstable solid electrolyte interphase (SEI) and Na dendrites. Herein, a robust anion-derived SEI is constructed on Na anode in a high-concentration 1,2-dimethoxyethane (DME) based electrolyte with a cosolvent hydrofluoroether, which effectively restrains Na dendrite growth. The hydrofluoroether can tune the solvation configuration of the electrolyte from three-dimensional network aggregates to solvent-cation-anion clusters, enabling more anions to enter and reinforce the inner solvation sheath and their stepwise decomposition. The gradient inorganic-rich SEI leads to a reduced energy barrier of Na + migration and enhanced interfacial kinetics. These render the Na||Na 3 V 2 (PO 4 ) 3 battery with an excellent rate capability of 79.9 mAh g -1 at 24 C and a high capacity retention of 94.2 % after 6000 cycles at 2 C. This highlights the modulation of the electrode-electrolyte interphase chemistry for advanced batteries., (© 2022 Wiley-VCH GmbH.)

Rechargeable aqueous Zn batteries are potential for large-scale electrochemical energy storage due to their low cost and high security. However, Zn metal anode suffers from the dendritic growth and interfacial hydrogen evolution reaction (HER), resulting in the deterioration of electrode/battery performance. Here we propose that both dendrites and HER are related to the water participated Zn 2+ solvation structure-Zn(H 2 O) 6 2+ and thus can be resolved by transforming Zn(H 2 O) 6 2+ to an anion-type water-free solvation structure-ZnCl 4 2- , which is achieved in traditional ZnSO 4 aqueous electrolyte after adding chloride salt with a bulky cation (1-ethyl-3-methylimidazolium chloride). The elimination of cation-water interaction suppresses HER, while the electrostatic repulsion between Zn tips and the anion solvation structure inhibits dendrite formation. As a result, the electrolyte shows uniform Zn deposition with an average Zn plating/stripping Coulombic efficiency of ≈99.9 %, enabling a capacity retention of 78.8 % after 300 cycles in anode-free Zn batteries with pre-zincificated polyaniline as the cathode. This work provides a novel electrolyte design strategy to prevent HER and realize long-lifespan metal anode., (© 2021 Wiley-VCH GmbH.)