Lithium Bis(oxalate)borate Additive for Self-repairing Zincophilic Solid Electrolyte Interphases towards Ultrahigh-rate and Ultra-stable Zinc Anodes

The artificial solid electrolyte interphase (SEI) plays a pivotal role in Zn anode stabilization but its long-term effectiveness at high rates is still challenged. Herein, to achieve superior long-life and high-rate Zn anode, an exquisite electrolyte additive, lithium bis(oxalate)borate (LiBOB), is proposed to in situ derive a highly Zn²⁺-conductive SEI and to dynamically patrol its cycling-initiated defects. Profiting from the as-constructed real-time, automatic SEI repairing mechanism, the Zn anode can be cycled with distinct reversibility over 1800 h at an ultrahigh current density of 50 mA cm⁻², presenting a record-high cumulative capacity up to 45 Ah cm⁻². The superiority of the formulated electrolyte is further demonstrated in the Zn||MnO₂ and Zn||NaV₃O₈ full batteries, even when tested under harsh conditions (limited Zn supply (N/P≈3), 2500 cycles). This work brings inspiration for developing fast-charging Zn batteries toward grid-scale storage of renewable energy sources.     

Synergistic Dual-Additive Electrolyte Enables Practical Lithium-Metal Batteries

A rechargeable Li metal anode coupled with a high-voltage cathode is a promising approach to high-energy-density batteries exceeding 300 Wh kg⁻¹. Reported here is an advanced dual-additive electrolyte containing a unique solvation structure and it comprises a tris(pentafluorophenyl)borane additive and LiNO₃ in a carbonate-based electrolyte. This system generates a robust outer Li₂O solid electrolyte interface and F- and B-containing conformal cathode electrolyte interphase. The resulting stable ion transport kinetics enables excellent cycling of Li/LiNi_0.8Mn_0.1Co_0.1O₂ for 140 cycles with 80 % capacity retention under highly challenging conditions (≈295.1 Wh kg⁻¹ at cell-level). The electrolyte also exhibits high cycling stability for a 4.6 V LiCoO₂ (160 cycles with 89.8 % capacity retention) cathode and 4.95 V LiNi_0.5Mn_1.5O₄ cathode.     

可充锌电池电解(质)液调控策略

高安全、低成本、长寿命的大规模储能新技术的突破事关未来能源结构调整以及智能电网建设。可充锌电池由于其安全性高、环境友好、成本低等优势而成为将来储能系统的重要选择。然而,常规水系电解液的应用通常导致正极活性物质溶解、水溶剂分解、锌负极腐蚀、枝晶等问题。因此,本文对水系电解质（液）体系导致的问题及相应的调控方案进行了讨论与总结。主要从电解质（液）改性角度分析了通过调控组成成分、浓度、添加剂等变量以达到改变自由水含量和锌离子溶剂化结构的目的。另外,对可充电锌电池这一新兴技术实现应用所面临的挑战进行了总结与展望。     

Electrolyte and interphase engineering through solvation structure regulation for stable lithium metal batteries

Lithium metal batteries (LMBs) are considered to be one of the most promising high-energy-density battery systems. However, their practical application in carbonate electrolytes is hampered by lithium dendrite growth, resulting in short cycle life. Herein, an electrolyte regulation strategy is developed to improve the cyclability of LMBs in carbonate electrolytes by introducing LiNO₃ using trimethyl phosphate with a slightly higher donor number compared to NO₃⁻ as a solubilizer. This not only allows the formaion of Li⁺-coordinated NO₃⁻ but also achieves the regulation of electrolyte solvation structures, leading to the formation of robust and ion-conductive solid-electrolyte interphase films with inorganic-rich inner and organic-rich outer layers on the Li metal anodes. As a result, high Coulombic efficiency of 99.1% and stable plating/stripping cycling of Li metal anode in Li||Cu cells were realized. Furthermore, excellent performance was also demonstrated in Li||LiNi_0.83Co_0.11Mn_0.06O₂ (NCM83) full cells and Cu||NCM83 anode-free cells using high mass-loading cathodes. This work provides a simple interphase engineering strategy through regulating the electrolyte solvation structures for high-energy-density LMBs.     

Solvation Modulation Enhances Anion-Derived Solid Electrolyte Interphase for Deep Cycling of Aqueous Zinc Metal Batteries

Stable Zn anodes with a high utilization efficiency pose a challenge due to notorious dendrite growth and severe side reactions. Therefore, electrolyte additives are developed to address these issues. However, the additives are always consumed by the electrochemical reactions over cycling, affecting the cycling stability. Here, hexamethylphosphoric triamide (HMPA) is reported as an electrolyte additive for achieving stable cycling of Zn anodes. HMPA reshapes the solvation structures and promotes anion decomposition, leading to the in situ formation of inorganic-rich solid-electrolyte-interphase. More interestingly, this anion decomposition does not involve HMPA, preserving its long-term impact on the electrolyte. Thus, the symmetric cells with HMPA in the electrolyte survive ≈500 h at 10 mA cm⁻² for 10 mAh cm⁻² or ≈200 h at 40 mA cm⁻² for 10 mAh cm⁻² with a Zn utilization rate of 85.6 %. The full cells of Zn||V₂O₅ exhibit a record-high cumulative capacity even under a lean electrolyte condition (E/C ratio=12 μL mAh⁻¹), a limited Zn supply (N/P ratio=1.8) and a high areal capacity (6.6 mAh cm⁻²).     

Proton-Reservoir Hydrogel Electrolyte for Long-Term Cycling Zn/PANI Batteries in Wide Temperature Range

Advanced aqueous batteries are promising for next generation flexible devices owing to the high safety, yet still requiring better cycling stability and high capacities in wide temperature range. Herein, a polymeric acid hydrogel electrolyte (PAGE) with 3 M Zn(ClO₄)₂ was fabricated for high performance Zn/polyaniline (PANI) batteries. With PAGE, even at −35 °C the Zn/Zn symmetrical battery can keep stable for more than 1 500 h under 2 mA cm⁻², and the Zn/PANI battery can provide ultra-high stable specific capacity of 79.6 mAh g⁻¹ for more than 70 000 cycles at 15 A g⁻¹. This can be mainly ascribed to the −SO₃⁻H⁺ function group in PAGE. It can generate constant protons and guide the (002) plane formation to accelerate the PANI redox reaction kinetics, increase the specific capacity, and suppress the side reaction and dendrites. This proton-supplying strategy by polymeric acid hydrogel may further propel the development of high performance aqueous batteries.     

Synergistic Dual‐Additive Electrolyte Enables Practical Lithium‐Metal Batteries

A rechargeable Li metal anode coupled with a high‐voltage cathode is a promising approach to high‐energy‐density batteries exceeding 300 Wh kg^?1. Reported here is an advanced dual‐additive electrolyte containing a unique solvation structure and it comprises a tris(pentafluorophenyl)borane additive and LiNO₃ in a carbonate‐based electrolyte. This system generates a robust outer Li₂O solid electrolyte interface and F‐ and B‐containing conformal cathode electrolyte interphase. The resulting stable ion transport kinetics enables excellent cycling of Li/LiNi_0.8Mn_0.1Co_0.1O₂ for 140 cycles with 80 % capacity retention under highly challenging conditions (≈295.1 Wh kg^?1 at cell‐level). The electrolyte also exhibits high cycling stability for a 4.6 V LiCoO₂ (160 cycles with 89.8 % capacity retention) cathode and 4.95 V LiNi_0.5Mn_1.5O₄ cathode.     

High-Current Capable and Non-Flammable Protic Organic Electrolyte for Rechargeable Zn Batteries

Rechargeable Zinc batteries (RZBs) are considered a potent competitor for next-generation electrochemical devices, due to their multiple advantages. Nevertheless, traditional aqueous electrolytes may cause serious hazards to long-term battery cycling through fast capacity fading and poor Coulombic efficiency (CE), which happens due to complex reaction kinetics in aqueous systems. Herein, we proposed the novel adoption of the protic amide solvent, N-methyl formamide (NMF) as a Zinc battery electrolyte, which possesses a high dielectric constant and high flash point to promote fast kinetics and battery safety simultaneously. Dendrite-free and granular Zn deposition in Zn-NMF electrolyte assures ultra-long lifespan of 2000 h at 2.0 mA cm⁻²/2.0 mAh cm⁻², high CE of 99.57 %, wide electrochemical window (≈3.43 V vs. Zn²⁺/Zn), and outstanding durability up to 10.0 mAh cm⁻². This work sheds light on the efficient performance of the protic non-aqueous electrolyte, which will open new opportunities to promote safe and energy-dense RZBs.     

A Polarized Gel Electrolyte for Wide-Temperature Flexible Zinc-Air Batteries

The development of flexible zinc-air batteries (FZABs) has attracted broad attention in the field of wearable electronic devices. Gel electrolyte is one of the most important components in FZABs, which is urgent to be optimized to match with Zn anode and adapt to severe climates. In this work, a polarized gel electrolyte of polyacrylamide-sodium citric (PAM-SC) is designed for FZABs, in which the SC molecules contain large amount of polarized −COO⁻ functional groups. The polarized −COO⁻ groups can form an electrical field between gel electrolyte and Zn anode to suppress Zn dendrite growth. Besides, the −COO⁻ groups in PAM-SC can fix H₂O molecules, which prevents water from freezing and evaporating. The polarized PAM-SC hydrogel delivers a high ionic conductivity of 324.68 mS cm⁻¹ and water retention of 96.85 % after being exposed for 96 h. FZABs with the PAM-SC gel electrolyte exhibit long cycling life of 700 cycles at −40 °C, showing the application prospect under extreme conditions.     

Amphoteric Cellulose-Based Double-Network Hydrogel Electrolyte Toward Ultra-Stable Zn Anode

Zinc (Zn) metal anode suffers from uncontrollable Zn dendrites and parasitic side reactions at the interface, which restrict the practical application of aqueous rechargeable zinc batteries (ARZBs). Herein, an amphoteric cellulose-based double-network is introduced as hydrogel electrolyte to overcome these obstacles. On one hand, the amphoteric groups build anion/cation transport channels to regulate electro-deposition behavior on Zn (002) crystal plane enabled by homogenizing Zn²⁺ ions flux. On the other hand, the strong bonding between negatively charged carboxyl groups and Zn²⁺ ions promote the desolvation process of [Zn(H₂O)₆]²⁺ to eliminate side reactions. Based on the above two functions, the hydrogel electrolyte enables an ultra-stable cycling with a cumulative capacity of 7 Ah cm⁻² at 20 mA cm⁻²/20 mAh cm⁻² for Zn||Zn cell. This work provides significant concepts for developing hydrogel electrolytes to realize stable anode for high-performance ARZBs.     

Metallic Nickel Hydroxide Nanosheets Give Superior Electrocatalytic Oxidation of Urea for Fuel Cells

The direct urea fuel cell (DUFC) is an important but challenging renewable energy production technology, it offers great promise for energy‐sustainable developments and mitigating water contamination. However, DUFCs still suffer from the sluggish kinetics of the urea oxidation reaction (UOR) owing to a 6 e^? transfer process, which poses a severe hindrance to their practical use. Herein, taking β‐Ni(OH)₂ nanosheets as the proof‐of‐concept study, we demonstrated a surface‐chemistry strategy to achieve metallic Ni(OH)₂ nanosheets by engineering their electronic structure, representing a first metallic configuration of transition‐metal hydroxides. Surface sulfur incorporation successfully brings synergetic effects of more exposed active sites, good wetting behavior, and effective electron transport, giving rise to greatly enhanced performance for UOR. Metallic nanosheets exhibited a much higher current density, smaller onset potential and stronger durability.     

Enhancing the Electrochemical Performance of a High-Voltage LiNi0.5Mn1.5O4 Cathode in a Carbonate-Based Electrolyte with a Novel and Low-Cost Functional Additive

Butyric anhydride (BA) is used as an effective functional additive to improve the electrochemical performance of a high-voltage LiNi_0.5Mn_1.5O₄ (LNMO) cathode. In the presence of 0.5 wt % BA, the capacity retention of a LNMO/Li cell is significantly improved from 15.3 to 88.4 % after 200 cycles at 1 C. Furthermore, the rate performance of the LNMO/Li cell is also effectively enhanced, and the capacity goes up to 112 mAh g⁻¹ even at 5 C, which is considerably higher than that of a LNMO/Li cell in electrolyte without BA additive (95.4 mAh g⁻¹ at 5 C). Linear sweep voltammetry and cyclic voltammetry results reveal that the BA additive can be preferentially oxidized to construct a stable cathode electrolyte interphase (CEI) film on the LNMO cathode. Subsequently, the BA-derived CEI film can alleviate the decomposition of the electrolyte and the dissolution of Mn and Ni ions from the LNMO cathode as well as maintain the structural stability of LNMO during the cycling process; this leads to outstanding electrochemical performance. Thus, this work provides an effective and low-cost functional electrolyte for high-voltage LNMO-based LIBs.     

How Water Accelerates Bivalent Ion Diffusion at the Electrolyte/Electrode Interface

The effect of H₂O in electrolytes and in electrode lattices on the thermodynamics and kinetics of reversible multivalent‐ion intercalation chemistry based on a model platform of layered VOPO₄ has been investigated. The presence of H₂O at the electrolyte/electrode interface plays a key role in assisting Zn²⁺ diffusion from electrolyte to the surface, while H₂O in the lattice structure alters the working potential. More importantly, a dynamic equilibrium between bulk electrode and electrolyte is eventually reached for H₂O transport during the charge/discharge cycles, with the water activity serving as the key parameter determining the direction of water movement and the cycling stability.     

Boosting Zn Anode Utilization by Trace Iodine Ions in Organic-Water Hybrid Electrolytes through Formation of Anion-rich Adsorbing Layers

Aqueous Zn batteries are attracting extensive attentions, but their application is still hindered by H₂O-induced Zn-corrosion and hydrogen evolution reactions. Addition of organic solvents into aqueous electrolytes to limit the H₂O activity is a promising solution, but at the cost of greatly reduced Zn anode kinetics. Here we propose a simple strategy for this challenge by adding 50 mM iodine ions into an organic-water (1,2-dimethoxyethane (DME)+water) hybrid electrolyte, which enables the electrolyte simultaneously owns the advantages of low H₂O activity and accelerated Zn kinetics. We demonstrate that the DME breaks the H₂O hydrogen-bond network and exclude H₂O from Zn²⁺ solvation shell. And the I⁻ is firmly adsorbed on the Zn anode, reducing the Zn²⁺ de-solvation barrier from 74.33 kJ mol⁻¹ to 32.26 kJ mol⁻¹ and inducing homogeneous nucleation behavior. With such electrolyte, the Zn//Zn symmetric cell exhibits a record high cycling lifetime (14.5 months) and achieves high Zn anode utilization (75.5 %). In particular, the Zn//VS₂@SS full cell with the optimized electrolyte stably cycles for 170 cycles at a low N : P ratio (3.64). Even with the cathode mass-loading of 16.7 mg cm⁻², the full cell maintains the areal capacity of 0.96 mAh cm⁻² after 1600 cycles.     

Bi-affinity Electrolyte Optimizing High-Voltage Lithium-Rich Manganese Oxide Battery via Interface Modulation Strategy

The practical implementation of high-voltage lithium-rich manganese oxide (LRMO) cathode is limited by the unanticipated electrolyte decomposition and dissolution of transition metal ions. The present study proposes a bi-affinity electrolyte formulation, wherein the sulfonyl group of ethyl vinyl sulfone (EVS) imparts a highly adsorptive nature to LRMO, while fluoroethylene carbonate (FEC) exhibits a reductive nature towards Li metal. This interface modulation strategy involves the synergistic use of EVS and FEC as additives to form robust interphase layers on the electrode. As-formed S-endorsed but LiF-assisted configuration cathode electrolyte interphase with a more dominant −SO₂− component may promote the interface transport kinetics and prevent the dissolution of transition metal ions. Furthermore, the incorporation of S component into the solid electrolyte interphase and the reduction of its poorly conducting component can effectively inhibit the growth of lithium dendrites. Therefore, a 4.8 V LRMO/Li cell with optimized electrolyte may demonstrate a remarkable retention capacity of 97 % even after undergoing 300 cycles at 1 C.     

Enhancement of Sodium Ion Battery Performance Enabled by Oxygen Vacancies

The utilization of oxygen vacancies (OVs) in sodium ion batteries (SIBs) is expected to enhance performance, but as yet it has rarely been reported. Taking the MoO_3?x nanosheet anode as an example, for the first time we demonstrate the benefits of OVs on SIB performance. Moreover, the benefits at deep‐discharge conditions can be further promoted by an ultrathin Al₂O₃ coating. A series of measurements show that the OVs increase the electric conductivity and Na‐ion diffusion coefficient, and the promotion from ultrathin coating lies in the effective reduction of cycling‐induced solid‐electrolyte interphase. The coated nanosheets exhibited high reversible capacity and great rate capability with the capacities of 283.9 (50 mA g^?1) and 179.3 mAh g^?1 (1 A g^?1) after 100 cycles. This work may not only arouse future attention on OVs for sodium energy storage, but also open up new possibilities for designing strategies to utilize defects in other energy storage systems.     

Simultaneous Stabilization of Potassium Metal and Superoxide in K–O2 Batteries on the Basis of Electrolyte Reactivity

In superoxide batteries based on O₂/O₂^? redox chemistry, identifying an electrolyte to stabilize both the alkali metal and its superoxide remains challenging owing to their reactivity towards the electrolyte components. Bis(fluorosulfonyl)imide (FSI^?) has been recognized as a “magic anion” for passivating alkali metals. The KFSI–dimethoxyethane electrolyte passivates the potassium metal anode by cleavage of S?F bonds and the formation of a KF‐rich solid–electrolyte interphase (SEI). However, the KFSI salt is chemically unstable owing to nucleophilic attack by superoxide and/or hydroxide species. On the other hand, potassium bis(trifluorosulfonyl)imide (KTFSI) is stable to KO₂, but results in mossy potassium deposits and irreversible plating and stripping. To circumvent this dilemma, we developed an artificial SEI for the metal anode and thus long‐cycle‐life K–O₂ batteries. This study will guide the development of stable electrolytes and artificial SEIs for metal–O₂ batteries.     

A Plastic–Crystal Electrolyte Interphase for All‐Solid‐State Sodium Batteries

The development of all‐solid‐state rechargeable batteries is plagued by a large interfacial resistance between a solid cathode and a solid electrolyte that increases with each charge–discharge cycle. The introduction of a plastic–crystal electrolyte interphase between a solid electrolyte and solid cathode particles reduces the interfacial resistance, increases the cycle life, and allows a high rate performance. Comparison of solid‐state sodium cells with 1) solid electrolyte Na₃Zr₂(Si₂PO₄) particles versus 2) plastic–crystal electrolyte in the cathode composites shows that the former suffers from a huge irreversible capacity loss on cycling whereas the latter exhibits a dramatically improved electrochemical performance with retention of capacity for over 100 cycles and cycling at 5 C rate. The application of a plastic–crystal electrolyte interphase between a solid electrolyte and a solid cathode may be extended to other all‐solid‐state battery cells.     

Constructing a Super-Saturated Electrolyte Front Surface for Stable Rechargeable Aqueous Zinc Batteries

Rechargeable aqueous zinc batteries (RAZB) have been re-evaluated because of the superiority in addressing safety and cost concerns. Nonetheless, the limited lifespan arising from dendritic electrodeposition of metallic Zn hinders their further development. Herein, a metal–organic framework (MOF) was constructed as front surface layer to maintain a super-saturated electrolyte layer on the Zn anode. Raman spectroscopy indicated that the highly coordinated ion complexes migrating through the MOF channels were different from the solvation structure in bulk electrolyte. Benefiting from the unique super-saturated front surface, symmetric Zn cells survived up to 3000 hours at 0.5 mA cm⁻², near 55-times that of bare Zn anodes. Moreover, aqueous MnO₂–Zn batteries delivered a reversible capacity of 180.3 mAh g⁻¹ and maintained a high capacity retention of 88.9 % after 600 cycles with MnO₂ mass loading up to 4.2 mg cm⁻².     

Mitigating Swelling of the Solid Electrolyte Interphase using an Inorganic Anion Switch for Low-temperature Lithium-ion Batteries

In overcoming the Li⁺ desolvation barrier for low-temperature battery operation, a weakly-solvated electrolyte based on carboxylate solvent has shown promises. In case of an organic-anion-enriched primary solvation sheath (PSS), we found that the electrolyte tends to form a highly swollen, unstable solid electrolyte interphase (SEI) that shows a high permeability to the electrolyte components, accounting for quickly declined electrochemical performance of graphite-based anode. Here we proposed a facile strategy to tune the swelling property of SEI by introducing an inorganic anion switch into the PSS, via LiDFP co-solute method. By forming a low-swelling, Li₃PO₄-rich SEI, the electrolyte-consuming parasitic reactions and solvent co-intercalation at graphite-electrolyte interface are suppressed, which contributes to efficient Li⁺ transport, reversible Li⁺ (de)intercalation and stable structural evolution of graphite anode in high-energy Li-ion batteries at a low temperature of −20 °C.