Nonpolar Cosolvent Driving LUMO Energy Evolution of Methyl Acetate Electrolyte to Afford Lithium-Ion Batteries Operating at −60 °C

The operation of lithium-ion batteries (LIBs) at low temperatures (<−20 °C) is hindered by the low conductivity and high viscosity of conventional carbonate electrolytes. Methyl acetate (MA) has proven to be a competitive low-temperature electrolyte solvent with low viscosity and low freezing point, but its interfacial stability is poor and remains elusive until now. Here, it is revealed thaat the reductive stability of MA-based electrolytes is fundamentally governed by the anion-prevailed solvation structure. Based on this framework, fluorobenzene is employed in the electrolyte to promote the entry of anions into the solvation shell via dipole-dipole interactions and the generation of free MA, thus enhancing the lowest unoccupied molecular orbital energy of MA. The designed electrolyte enables LiCoO₂ (LCO)/graphite cells to exhibit excellent cycling performance at −20 °C (90% retention after 1000 cycles at 1 C) and to remain 91% of their room-temperature capacity at a super-low temperature of −60 °C at 0.05 C. Thanks to the plentiful free MA, this electrolyte has a high conductivity (2.61 mS cm⁻¹) at −60 °C and allows LCO/graphite cell to charge at −60 °C. This study offers the possibility of practical applications for those solvents with poor reductive stability and provides new approaches to designing advanced electrolytes for low-temperature applications.     

Interfacial and Interphasial Chemistry of Electrolyte Components to Invoke High-Performance Antimony Anodes and Non-Flammable Lithium-Ion Batteries

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.     

Engineering Solid Electrolyte Interphase for Pseudocapacitive Anatase TiO2 Anodes in Sodium‐Ion Batteries

Anatase TiO₂ is considered as one of the promising anodes for sodium‐ion batteries because of its large sodium storage capacities with potentially low cost. However, the precise reaction mechanisms and the interplay between surface properties and electrochemical performance are still not elucidated. Using multimethod analyses, it is herein demonstrated that the TiO₂ electrode undergoes amorphization during the first sodiation and the amorphous phase exhibits pseudocapacitive sodium storage behaviors in subsequent cycles. It is also shown that the pseudocapacitive sodium storage performance is sensitive to the nature of solid electrolyte interphase (SEI) layers. For the first time, it is found that ether‐based electrolytes enable the formation of thin (≈2.5 nm) and robust SEI layers, in contrast to the thick (≈10 nm) and growing SEI from conventional carbonate‐based electrolytes. First principle calculations suggest that the higher lowest unoccupied molecular orbital energies of ether solvents/ion complexes are responsible for the difference. TiO₂ electrodes in ether‐based electrolyte present an impressive capacity of 192 mAh g^?1 at 0.1 A g^?1 after 500 cycles, much higher than that in carbonate‐based electrolyte. This work offers the clarified picture of electrochemical sodiation mechanisms of anatase TiO₂ and guides on strategies about interfacial control for high performance anodes.     

Design of Fire-Resistant Liquid Electrolyte Formulation for Safe and Long-Cycled Lithium-Ion Batteries

Turning an unsafe material into a safe one without performance loss for Li-ion battery applications provides opportunities to create a new class of materials. Herein, this strategy is utilized to design a fire-resistant liquid electrolyte formulation consisting of propylene carbonate and 2,2,2-trifluoroethyl group-containing linear ester solvents paired with 1 m LiPF₆ salt and fluoroethylene carbonate additive for a Li–ion battery with improved safety and performance. Traditional carbonate-based electrolytes offer good performance in mild operating conditions, but are however a flammable fuel causing fire and safety hazards. It is shown that the entire replacement of linear carbonate with fluorinated linear ester yields a fire-resistant and outperforming electrolyte under the harsh condition of 4.5 V high-voltage, 45 °C and 2C rate, enabling a higher energy, longer cycle life of 500 cycles, faster charged practical graphite‖NCM622 full-cell than traditional electrolyte-based cell. The strong correlation between cathode–electrolyte and anode–electrolyte interfacial stabilization and highly reversible cycling performance is clearly demonstrated. The fire-resistant electrolyte-incorporated industrial 730 mAh graphite‖NCM811 Li-ion pouch battery achieves 82% retention after 400 cycles under 4.3 V charge voltage, 45 °C and 1C, and markedly improved safety on overcharge abuse tests. The design strategy for electrolyte formulation provides a promising path to safe and long-cycled high-energy Li-ion batteries.     

Surface Defects Reinforced Polymer-Ceramic Interfacial Anchoring for High-Rate Flexible Solid-State Batteries

High Li⁺ conductivity, good interfacial compatibility and high mechanical strength are desirable for practical utilization of all-solid-state electrolytes. In this study, by introducing Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) with surface defects into poly(ethylene oxide) (PEO), a composite solid electrolyte (OV-LLZTO/PEO) is prepared. The surface defects serve as anchoring points for oxygen atoms of PEO chains, forming a firmly bonded polymer-ceramic interface. This bonding effect effectively prevents the agglomeration of LLZTO particles and crystallization of PEO domains, forming a homogeneous electrolyte membrane exhibiting high mechanical strength, reduced interfacial resistance with electrodes as well as improved Li⁺ conductivity. Owing to these favorable properties, OV-LLZTO/PEO can be operated under a high current density (0.7 mA cm⁻²) in a Li–Li symmetric cell without short circuit. Above all, solid-state full-cells employing OV-LLZTO/PEO deliver state-of-the-art rate capability (8 C), power density and capacity retention. As a final proof of concept study, flexible pouch cells are assembled and tested, exhibiting high cycle stability under 5 C and excellent safety feature under abusive working conditions. Through manipulating the interfacial interactions between polymer and inorganic electrolytes, this study points out a new direction to optimizing the performance of all-solid-state batteries.     

Tuning Electrolyte Solvation Structure and CEI Film to Enable Long Lasting FSI−-Based Dual-Ion Battery

Dual-ion battery (DIB) is a promising energy storage system because it can provide high power. However, the stability and rate performance of the battery depend strongly on the type of salt and solvents in the electrolyte. Herein, the use of lithium bis(fluorosulfonyl)imide (LiFSI) is studied, which has better high-temperature stability, as salt in the DIB and develop a 3 m  LiFSI fluoroethylene carbonate/methyl 2,2,2-trifluoroethyl carbonate (FEC/FEMC) = 3:7 electrolyte, which stabilizes graphite–lithium DIB with 94.1% capacity retention after 2000 cycles at 5C. The DIB also exhibits excellent rate performance with 100.4 mAh g⁻¹ capacity at 30C, with a utilization of 96.3% compared to capacity at 2C. The outstanding electrochemical performance is attributed to the thin cathode electrolyte interface (CEI) layer and fast FSI⁻ transport kinetics, confirmed by X-ray photoelectron spectroscopy and activation energy calculation. Superior cycle and rate performances are also obtained from a graphite–graphite full cell. Though, increasing salt concentration to 5 and 6 m leads to sluggish FSI⁻ de-intercalation reaction and lower capacity, which is attributed to solvent co-intercalation. The research suggests that the electrolyte plays an important role in ion transport, surface film formation, and stability of DIB.     

Unravelling the Solvation Structure and Interfacial Mechanism of Fluorinated Localized High Concentration Electrolytes in K-ion Batteries

Electrolyte is critical for the electrochemical properties of potassium-ion batteries. The high-concentration electrolyte has achieved significant effects in inhibiting the growth of dendrites and improving the cycle life of potassium ion batteries. However, the application remains challenging owing to the issues of high viscosity, low conductivity and poor electrode wettability. Herein, a fluorinated localized high concentration electrolyte (LHCE) based on potassium bis(fluorosulfonyl) imide/dimethoxyethane is designed for use in K-ion batteries. The electrolyte structure, interfacial mechanism and diffusion kinetics are analyzed systematically through physical/electrochemical characterization and molecular dynamics simulations. The LHCE is proven to have excellent oxidation stability, low flammability, and excellent electrode wettability. Furthermore, the LHCE is investigated in a half-cell assembled by using polyimide-derived nitrogen doped carbon material as an anode, which exhibits a reversible capacity of 169 mAh g⁻¹ and high-capacity retention upon 200 cycles at a current rate of 100 mA g⁻¹. Fundamental mechanism on enhanced cycling stability of the carbon anodes using optimized LHCE is also investigated. This work demonstrates an example of developing new electrolytes for high performance potassium ion batteries, and also provides theoretical guidance and significant reference for electrode interphase design and engineering.     

A Stable Polymer-based Solid-State Lithium Metal Battery and its Interfacial Characteristics Revealed by Cryogenic Transmission Electron Microscopy

Solid-state lithium metal batteries (SSLMBs) are a promising candidate for next-generation energy storage systems due to their intrinsic safety and high energy density. However, they still suffer from poor interfacial stability, which can incur high interfacial resistance and insufficient cycle lifespan. Herein, a novel poly(vinylidene fluoride‑hexafuoropropylene)-based polymer electrolyte (PPE) with LiBF₄ and propylene carbonate plasticizer is developed, which has a high room-temperature ionic conductivity up to 1.15 × 10⁻³ S cm⁻¹ and excellent interfacial stability. Benefitting from the stable interphase, the PPE-based symmetric cell can operate for over 1000 h. By virtue of cryogenic transmission electron microscopy (Cryo-TEM) characterization, the high interfacial compatibility between Li metal anode and PPE is revealed. The solid electrolyte interphase is made up of an amorphous outer layer that can keep intimate contact with PPE and an inner Li₂O-dominated layer that can protect Li from continuous side reactions during battery cycling. A LiF-rich transition layer is also discovered in the region of PPE close to Li metal anode. The feasibility of investigating interphases in polymer-based solid-state batteries via Cryo-TEM techniques is demonstrated, which can be widely employed in future to rationalize the correlation between solid-state electrolytes and battery performance from ultrafine interfacial structures.     

An Inorganic-Dominate Molecular Diluent Enables Safe Localized High Concentration Electrolyte for High-Voltage Lithium-Metal Batteries

The development of high-voltage Lithium-metal batteries (LMBs) is hindered by suitable electrolytes that are simultaneously compatible with both high-voltage cathodes and Li anodes. Herein, a novel localized high-concentration electrolyte with ethoxy(pentafluoro)cyclotriphosphazene (PFPN) as a nonflammable diluent is developed. The inorganic-dominate diluent improves the safety of the organic electrolyte, and helps to construct robust passivation interphases on both electrodes. Specifically, PFPN accelerates the complete reduction of anions, leading to a stable anion-derived interphase layer on Li anode. Meanwhile, PFPN and anions co-participate in the formation of cathode-electrolyte interphase, suppressing side reactions and the structural damage of high-voltage Ni-rich cathodes. As a result, PFPN-based electrolyte prolongs the cycling life of LMBs based on high-voltage LiNi_0.6Co_0.2Mn_0.2 (NCM622) and LiNi_0.8Co_0.1Mn_0.1 (NCM811) cathodes. Specially, 25-µm-thick Li paired with NCM622 with a N/P ratio of 1.3 (4.4 V) exhibits excellent capacity retention of above 90% after 200 cycles. This study highlights the important role of diluent in tailoring electrode/electrolyte interphases and provides a new strategy for designing high-safety electrolytes toward high-voltage LMBs.     

Dynamic Networks of Cellulose Nanofibrils Enable Highly Conductive and Strong Polymer Gel Electrolytes for Lithium-Ion Batteries

Tunable dynamic networks of cellulose nanofibrils (CNFs) are utilized to prepare high-performance polymer gel electrolytes. By swelling an anisotropically dewatered, but never dried, CNF gel in acidic salt solutions, a highly sparse network is constructed with a fraction of CNFs as low as 0.9%, taking advantage of the very high aspect ratio and the ultra-thin thickness of the CNFs (micrometers long and 2–4 nm thick). These CNF networks expose high interfacial areas and can accommodate massive amounts of the ionic conductive liquid polyethylene glycol-based electrolyte into strong homogeneous gel electrolytes. In addition to the reinforced mechanical properties, the presence of the CNFs simultaneously enhances the ionic conductivity due to their excellent strong water-binding capacity according to computational simulations. This strategy renders the electrolyte a room-temperature ionic conductivity of 0.61 ± 0.12 mS cm⁻¹ which is one of the highest among polymer gel electrolytes. The electrolyte shows superior performances as a separator for lithium iron phosphate half-cells in high specific capacity (161 mAh g⁻¹ at 0.1C), excellent rate capability (5C), and cycling stability (94% capacity retention after 300 cycles at 1C) at 60 °C, as well as stable room temperature cycling performance and considerably improved safety compared with commercial liquid electrolyte systems.     

Self-Healing and Recyclable Polymer Electrolyte Enabled with Boronic Ester Transesterification for Stabilizing Ion Deposition

Damage to solid polymer electrolytes can lead to mechanical degradation, short circuits, or functional failures. Therefore, introducing a self-healing function to solid polymer electrolytes is an ideal strategy to improve the safety and reliability of electrolyte systems. Herein, dynamic boronic ester-based self-healing polymer electrolytes (DB-SHPEs) with excellent mechanical properties and interfacial stability are developed via a thermally initiated ring-opening reaction between thiol and epoxy groups. The DB-SHPEs containing boronic ester bonds can not only alter the topologies via boronic ester transesterification and exhibit good self-healing capability but also enable homogeneous deposition of Li ions on the Li metal through the Lewis acid–base interactions between boron atoms and salt anions. Furthermore, the boronic ester bonds can endow the DB-SHPE with reprocessability and recyclability taking advantage of associative transesterification reaction. More significantly, the Li/DB-SHPE/Li symmetric cells exhibit a stable voltage plateau after cycling for 1200 h and the LiFePO₄/DB-SHPE/Li batteries present excellent cycling performance, suggesting that high-performance self-healing polymer electrolytes with multiple functions are promising materials for the next-generation lithium metal batteries.     

Fluoride-Rich Solid-Electrolyte-Interface Enabling Stable Sodium Metal Batteries in High-Safe Electrolytes

Sodium metal batteries (SMBs) are promising for large scale energy storage due to the remarkable capacity of sodium metal anode (SMA) and the natural abundance of Na-containing resources. However, multiple challenges exist with regards to the usage of SMBs, including dendritic Na growth, poor cyclability of SMA, and severe safety hazards stemming from the employment of the highly flammable liquid electrolytes. Herein, by introducing two functional fluorinated solvents, 1,1,2,2-tetra-fluoroethyl 2,2,3,3-tetrafluoropropyl ether (HFE) and fluoroethylene carbonate (FEC) into trimethyl phosphate (TMP)-based electrolyte, a SMA-compatible flame-retardant electrolyte is enabled, in which Na/Na symmetrical cells can cycle for 800 h at 1.0 mA cm⁻² or 3.0 mAh cm⁻². Specifically, the non-solvating HFE plays a critical role in increasing the local electrolyte concentration and reducing the unfavorable decomposition of TMP molecules. By introducing FEC as the co-solvent simultaneously, its preferential defluorination induces a fluoride-rich solid-electrolyte interphase that prevents Na metal surface against the continuous parasitic reactions. More importantly, the designed electrolyte is endowed with an intrinsic non-flammability, which manifests a prerequisite for the real-life application of SMBs.     

Trifluoropropylene Carbonate‐Driven Interface Regulation Enabling Greatly Enhanced Lithium Storage Durability of Silicon‐Based Anodes

The extremely high specific capacity of Si anodes is a double‐edged sword, bringing both high energy density and poor lifespan to Li‐ion batteries (LIBs). Despite recent advances in constructing nanostructured/composite‐Si anodes with an alleviated volume change and improved cycle life, daunting challenges still remain for Si anodes to suppress the irreversible capacity loss associated with the repeated rupture/reconstruction of the solid electrolyte interphase (SEI) layer. Herein, an electrolyte‐based optimization strategy is devised to in situ construct a thin, continuous, and mechanically stable SEI film on Si surface by using a trifluoropropylene carbonate (TFPC) cosolvent, targeting highly stable Si‐based anodes for LIBs. TFPC is featured with its low unoccupied molecular orbital energy, high reduction potential and outstanding film‐forming capability, outperforming those of the state‐of‐the‐art fluoroethylene carbonate additive. More importantly, TFPC plays a key role in regulating the structure and component of SEI layer. As such, 10 wt% TFPC addition promotes the formation of an optimal SEI film with appropriate amounts of polyolefins and LiF, endowing the SEI layer with enhanced rigidity and toughness as well as high ionic conductivity. Both the Si nanoparticle‐based and Si/C composite electrodes deliver a greatly enhanced cycling stability, rate capability, and overall structural integrity in such optimized electrolyte.     

Intercalated Electrolyte with High Transference Number for Dendrite‐Free Solid‐State Lithium Batteries

Solid‐state lithium (Li) batteries using solid electrolytes and Li anodes are highly desirable because of their high energy densities and intrinsic safety. However, low ambient‐temperature conductivity and poor interface compatibility of solid electrolytes as well as Li dendrite formation cause large polarization and poor cycling stability. Herein, a high transference number intercalated composite solid electrolyte (CSE) is prepared by the combination of a solution‐casting and hot‐pressing method using layered lithium montmorillonite, poly(ethylene carbonate), lithium bis(fluorosulfonyl)imide, high‐voltage fluoroethylene carbonate additive, and poly(tetrafluoroethylene) binder. The electrolyte presents high ionic conductivity (3.5 × 10^?4 S cm^?1), a wide electrochemical window (4.6 V vs Li⁺/Li), and high ionic transference number (0.83) at 25 °C. In addition, a 3D Li anode is also fabricated via a facile thermal infusion strategy. The synergistic effect of high transference number intercalated electrolyte and 3D Li anode is more favorable to suppress Li dendrites in a working battery. The solid‐state batteries based on LiFePO₄ (Al₂O₃ @ LiNi_0.5Co_0.2Mn_0.3O₂), CSE, and 3D Li deliver admirable cycling stability with discharge capacity 145.9 mAh g^?1 (150.7 mAh g^?1) and capacity retention 91.9% after 200 cycles at 0.5 C (92.0% after 100 cycles at 0.2 C) at 25 °C. This work affords a splendid strategy for high‐performance solid‐state battery.     

Dynamic Supramolecular Polymer Electrolyte to Boost Ion Transport Kinetics and Interfacial Stability for Solid-State Batteries

The key hurdle to the practical application of polymeric electrolytes in high-energy-density solid lithium-metal batteries is the sluggish Li⁺ mobility and inferior electrode/electrolyte interfacial stability. Herein, a dynamic supramolecular polymer electrolyte (SH-SPE) with loosely coordinating structure is synthesized based on poly(hexafluoroisopropyl methacrylate-co-N-methylmethacrylamide) (PHFNMA) and single-ion lithiated polyvinyl formal. The weak anti-cooperative H-bonds between the two polymers endow SH-SPE with a self-healing ability and improved toughness. Meanwhile, the good flexibility and widened energy gap of PHFNMA enable SH-SPE with efficient ion transport and superior interfacial stability in high-voltage battery systems. As a result, the as-prepared SH-SPE exhibits an ionic conductivity of 2.30 × 10⁻⁴ S cm⁻¹, lithium-ion transference number of 0.74, electrochemical stability window beyond 4.8 V, and tensile strength up to 11.9 MPa as well as excellent adaptability with volume change of the electrodes. In addition, no major electrolyte decomposition inside batteries made from SH-SPE and LiNi_0.8Mn_0.1Co_0.1O₂ cathode can be observed in the in situ differential electrochemical mass spectrometry test. This study provides a new methodology for the macromolecular design of polymer electrolytes to address the interfacial issues in high-voltage solid batteries.     

Coupling Anion-Capturer with Polymer Chains in Fireproof Gel Polymer Electrolyte Enables Dendrite-Free Sodium Metal Batteries

Sodium metal batteries (SMBs) using gel polymer electrolytes (GPEs) with high theoretical capacity and low production cost are regarded as a promising candidate for high energy-density batteries. However, the inherent flammability of GPEs and uncontrolled Na dendrite caused by inferior mechanical properties and interfacial stability hinder their practical applications. Herein, an anion-trapping fireproof composite gel electrolyte (AT-FCGE) is designed through a chemical grafting–coupling strategy, where functionalized boron nitride nanosheets (M-BNNs) used as both nanosized crosslinker and anion capturer are coupled with poly(ethylene glycol)diacrylate in poly(vinylidene fluoride-co-hexafluoropropylene) matrix, to expedite Na⁺ transport and suppress dendrite growth. Experimental and calculation studies suggest that the anion-trapping effect of M-BNNs with abundant Lewis-acid sites can promote the dissociation of salts, thus remarkably improving the ionic conductivity and Na⁺ transference number. Meanwhile, the formation of highly crosslinked semi-interpenetrating network can effectively in situ encapsulate non-flammable phosphate without sacrificing the mechanical properties. Consequently, the resulting AT-FCGE shows significantly enhanced Na⁺ conductivity, mechanical properties, and excellent interfacial stability. The AT-FCGE enables a long-cycle stability dendrite-free Na/Na symmetric cell, and prominent electrochemical performance is demonstrated in solid-state SMBs. The approach provides a broader promise for the great potential of fire-retardant gel electrolytes in high-performance SMBs and the beyond.     

Elastic Interfacial Layer Enabled the High-Temperature Performance of Lithium-Ion Batteries via Utilization of Synthetic Fluorosulfate Additive

The key to producing high-energy Li-ion cells is ensuring the interfacial stability of Si-containing anodes and Ni-rich cathodes. Herein, 4-(allyloxy)phenyl fluorosulfate (APFS), a multi-functional electrolyte additive that forms a mechanical strain-adaptive solid electrolyte interphase (SEI) comprising LiF and polymeric species, and a thermally stable cathode–electrolyte interface containing S O and S F species. The radical copolymerization of vinylene carbonate (VC) with APFS via electrochemical initiation creates a spatially deformable polymeric SEI on the SiG-C (30 wt.% graphite + 70 wt.% SiC composite) anode, with large volume changes during cycling. Moreover, the APFS-promoted interfacial layers reduce Ni dissolution and deposition. Furthermore, APFS deactivates the Lewis acid PF₅, thereby inhibiting hydrolyses that produce unwanted HF. These results indicate that the combined use of VC with APFS allows capacity retentions of 72.5% with a high capacity of 143.5 mAh g⁻¹ in SiG-C/LiNi_0.8Co_0.1Mn_0.1O₂ full cells after 300 cycles at 45 °C.     

Engineering Solid Electrolyte Interface at Nano-Scale for High-Performance Hard Carbon in Sodium-Ion Batteries

Engineering the structure and chemistry of solid electrolyte interface (SEI) on electrode materials is crucial for rechargeable batteries. Using hard carbon (HC) as a platform material, a correlation between Na⁺ storage performance, and the properties of SEI is comprehensively explored. It is found that a “good” SEI layer on HC may not be directly associated with certain kinds of SEI components, such as NaF and Na₂O. Whereas, arranging nano SEI components with refined structures constructs the foundation of “good” SEI that enables fast Na⁺ storage and interface stability of HC in Na-ion batteries. A layer-by-layer SEI on HC with inorganic-rich inner layer and tolerant organic-rich outer flexible layer can facilitate excellent rate and cycling life. Besides, SEI layer as the gate for Na⁺ from electrolyte to HC electrode can modulate interfacial crystallographic structures of HC with pillar-solvent that function as “pseudo-SEI” for fast and stable Na⁺ storage in optimal 1 m NaPF₆-TEGDME electrolytes. Such a layer-by-layer SEI combined with a “pseudo-SEI” layer for HC enables an outstanding rate of 192 mAh g⁻¹ at 2 C and stable cycling over 1100 cycles at 0.5 C. This study provides valuable guidance to improve the electrochemical performance of electrode materials through regulation of SEI in optimal electrolytes.     

Zincophobic Electrolyte Achieves Highly Reversible Zinc-Ion Batteries

Zinc metal batteries show tremendous applications in wide-scale storages still impeded by aqueous electrolytes corrosion and interfacial water splitting reaction. Herein, a zincophobic electrolyte containing succinonitrile (SN) additive is proposed, the SN electrolyte shows a lower affinity for zinc but a stronger affinity for solid-state interphase (SEI). In the SN electrolyte, zinc hydroxide sulfate (ZHS) is more inclined to accumulate horizontally, forming a dense SEI protective layer on the surface of the Zn anode, effectively slowing down the corrosion of Zn and dendrite growth. The zincophobic SN electrolyte enables excellent performance: zinc plating/stripping Coulombic efficiency of 99.71% for an average of 400 cycles; stable cycles in a symmetric cell for 4000 h (0.9% zinc utilization) and 325 h (86.1% zinc utilization). The soft pack battery using limited zinc delivers maximum energy density of 57.0 Wh kg⁻¹ (based on mass loading of cathode materials and anode materials). Such a simple additive strategy provides a theoretical reference for zinc chemistry in a mild electrolyte environment in practical applications.