High Electrolyte Concentrations Research Articles

A Hybrid-Salt Strategy for Modulating the Li+ Solvation Sheathes and Constructing Robust SEI in Non-Flammable Electrolyte Lithium Metal Batteries.

The electrode interface determines the performance of an electrochemical energy storage system. Using traditional electrolyte organic additives and high-concentration electrolyte emerging recently are two generally strategies for improving the electrode interface. Here, a hybrid-salt electrolyte strategy is proposed for constructing the stable electrode interface. Through the solubilization effect of phosphate ester on LiNO3, a hybrid-salts-based non-flammable phosphate ester electrolyte system (HSPE) with LiPF6 and LiNO3 as Li salts has been developed. By the strong interaction between NO3 - and Li+, the Li+ solvation sheath and solvent behaviors have been modulated, thus the undesirable effects of phosphate ester are eliminated and a robust SEI is formed. Experimental results and theoretical calculations illustrate that NO3 - as a kind of strongly coordinating anion can reduce the number of TEP molecules and lower the reduction reactivity of TEP. The reconfigured Li+ solvation structure allows the formation of an inorganic-rich SEI on the electrode surface. As a result, in the designed HSPE, the average coulombic efficiency of lithium plating/stripping is increased to 99.12 %. This work explored a new approach to construct the electrode interface and addressing the poor interface performance issue of phosphate esters.

Electrolyte regulation achieving MoS2/C nanofiber for stable potassium-ion storage

Due to the pronounced expansion exhibited by sulfides in K-ion batteries (KIBs), achieving both high capacity and extended cycle life remains a formidable challenge. In our study, we utilized electrospinning to craft a self-standing MoS2/C electrode, and the incorporation of one-dimensional carbon was identified as a key factor significantly boosting its electronic conductivity. Addressing stability concerns, we meticulously regulated the salt concentration in ether solvents, revealing that the self-standing MoS2/C electrode exhibited outstanding electrochemical performance at a high-concentration electrolyte. After optimization, the MoS2/C electrode in 5 M ether electrolyte presents a capacity of 315 mA h g−1 after 50 cycles at 50 mA g−1. Impressively, even at 1 A g−1, the MoS2/C electrode still sustained a capacity of 200 mA h g−1 after 5000 cycles, exhibiting excellent electrochemical stability. According to our findings, decomposition occurs when the electrode material comes into contact with the electrolyte, resulting in the formation of a solid electrolyte interface (SEI) layer. In high-concentration electrolytes, a competitive mechanism between anions and ether solvent molecules takes place, with a tendency for preferential decomposition of highly concentrated anions. This behavior triggers the formation of a high-quality KF-rich SEI layer on the electrode interface, further suppressing the decomposition of subsequent electrolytes, which significantly improves the KIB’s electrochemical performance. We believe that this discovery will provide new insights for the development of high-performance KIBs.

Natural low corrosive phytic acid electrolytes enable green, ultrafast, stable and high-voltage aqueous proton battery

Proton is a promising charge carrier for aqueous rechargeable batteries due to its small ionic radius, fast diffusion kinetics and great abundance in nature. However, commonly-used proton battery electrolytes are strong acids, such as sulfuric acid, phosphoric acid, etc., which always leads to the notorious rapid corrosion of electrode and metal components, and thus the poor cyclability, the limited materials option and high maintenance cost. Here, we reported a new-type high-concentration phytic acid (PA) electrolytes, which exhibits marvellous superiorities including environmental friendliness, low corrosiveness, high ionic conductivity (133.3 mS cm−1) and wide working potential window (∼2.9 V) in contrast to conventional acid electrolytes. The experimental and calculation results indicated that the scarcity of free water in high-concentration PA electrolytes and the desolvation effect of the preferentially absorbed PA interfacial layer on the electrode surface work in synergy to inhibit the water activity and thus prevent electrode dissolution and side reactions. Benefiting from this, the assembled K0.2VO0.6[Fe(CN)6]0.8•6H2O (VHCF)//MoO3 button-type proton battery shows an average discharge voltage of 0.7 V with a pair of well-defined redox peak at about 1.4 V, great rate performance, excellent cycling stability (87.9% capacity retention after 1000 cycles at 5 A g−1) and superb coulombic efficiency at various current densities (1 A g−1–50 A g−1). Attributed to good anti-freezing properties of the electrolytes, the proton battery can also run normally at -60 °C and exhibit competent performance (a capacity retention of 45 mAh g−1 at 0.1 A g−1 after 540 cycles). Such green low corrosive electrolyte will be fully compatible with conventional battery fabrication process, and open brand new avenue for the development of aqueous proton battery.

Additive-Driven Nanoscale Architecture of Solid Electrolyte Interphase Revealed by Cryogenic Transmission Electron Microscopy.

In Li metal batteries (LMBs), which boast the highest theoretical capacity, the chemical structure of the solid electrolyte interphase (SEI) serves as the key component that governs the growth of reactive Li. Various types of additives have been developed for electrolyte optimization, representing one of the most effective strategies to enhance the SEI properties for stable Li plating. However, as advanced electrolyte systems become more chemically complicated, the use of additives is empirically optimized. Indeed, their role in SEI formation and the resulting cycle life of LMBs are not well-understood. In this study, we employed cryogenic transmission electron microscopy combined with Raman spectroscopy, theoretical studies including molecular dynamics (MD) simulations and density functional theory (DFT) calculations, and electrochemical measurements to explore the nanoscale architecture of SEI modified by the most representative additives, lithium nitrate (LiNO3) and vinylene carbonate (VC), applied in a localized high-concentration electrolyte. We found that LiNO3 and VC play distinct roles in forming the SEI, governing the solvation structure, and influencing the kinetics of electrochemical reduction. Their collaboration leads to the desired SEI, ensuring prolonged cycle performance for LMBs. Moreover, we propose mechanisms for different Li growth and cycling behaviors that are determined by the physicochemical properties of SEI, such as uniformity, elasticity, and ionic conductivity. Our findings provide critical insights into the appropriate use of additives, particularly regarding their chemical compatibility.

Empowering the Potassium-Sulfur Battery with Commendable Reaction Kinetics and Capacity Output by Localized High-Concentration Electrolytes.

Potassium-sulfur (K-S) batteries are one of the promising high-energy-density candidates beyond current lithium-ion batteries. Nevertheless, in practice, the utilization of K-S batteries is largely hindered due to the dissolution and shuttle effect of the cathode redox intermediates and the scarcity of an effective anode protection layer in conventional electrolytes. Herein, electrolyte engineering is applied to formulate an ether-based localized high-concentration electrolyte (LHCE) for the first time in a K-S cell with the mitigated parasitic effect of polysulfide dissolution and shuttle and the tuned anode-electrolyte interface property. A nonsolvating and polysulfide-stable fluoroether is sieved as a cosolvent in such an LHCE, which possesses the ultralow polysulfides solubility due to less roaming solvents and thus alleviates the polysulfides shuttle effect. The anion-derived solid electrolyte interphase enriched in inorganic components is constructed due to the strengthened cation-anion interplay in the primary solvation sheath and highlighted with accelerated interfacial kinetics in a K-S cell. It is validated that the proposed LHCE unlocks the theoretical capacity of the K-S cell based on the conversion between S and K2S3. It is further revealed that the lifespan is limited to the anode corrosion with severe cosolvent degradation caused by limited solvating solvent compatibility with metallic K, and the inevitable byproduct accumulation at the S cathode. The K-S cell based on the designed LHCE could achieve a prolonged lifespan with a reversible capacity of 448 mA h/gs after 80 cycles with an elaborate cathode design. This work shines a light on the electrolyte design perspective for full utilization and an in-depth mechanistic understanding of high-energy-density K-S batteries.

Suppression of Potasside Reaction in Localized High Concentration Electrolytes Utilizing Fluorine-Substituted Benzene as Bifunctional Additive for Potassium-Metal Batteries

Localized high-concentration electrolytes (LHCEs) have unique solvation structures that do not affect the original salt–solvent coordination from highly concentrated electrolytes. LHCEs enable a wide electrochemical voltage window and mitigate the extensive dendritic growth of metallic anodes. However, in K metal batteries, LHCE undergoes undesirable side reactions because of potasside (K–), triggering aggressive chemistry with a diluent, represented as hydrofluoroethers (HFEs), eventually resulting in poor cycle life. In this study, 1, 3, 5-trifluorobenzene (TFB) was introduced as a functional additive to prevent the parasitic K– reaction. The three symmetrically substituted fluorines prevented TFB from disrupting the as-formed solvation structure of LHCE located in the outer sphere. This characteristic increases the reaction energy barrier between K– and HFE, suppressing the deterioration of the metal anode by adding only 3 wt.% of TFB in LHCE. Moreover, TFB preferentially decomposes at each electrode because of its molecular energy level and increases the reversibility of the cell, reducing unnecessary consumption of electrolytes with a stable interface. This study discusses a novel method to prevent the K– reaction at the electrolyte level and the utilization of LHCE in K batteries to pursue higher energy densities, sustaining the advantage of using a metal anode.

Electrolyte design to regulate the electrode–electrolyte interface on the electrochemical performance for K0.5MnO2||graphite-based potassium-ion batteries

The system of layered-metal-oxide||carbon-anode cells with carbonate electrolytes is highly promising for constructing potassium-ion batteries (PIBs). However, this system faces serious issues of poor compatibility between the electrolyte and electrode, particularly with conventional ethylene carbonate (EC)-based electrolytes. Herein, owing to the regulated coordination environment of cation–anion-solvent and the formed KF-rich interface, a superior rate performance of graphite anode was achieved. The designed 4 M KFSI EC/DEC electrolyte demonstrates superior performance in graphite||K cells, exhibiting a high reversible capacity of approximately 200 mAh g−1 at a high current density of 700 mA g−1, surpassing many reported high-concentration and weak solvation PIB electrolytes. Meanwhile, it exhibits low polarization and maintains stable contact stability with active K metal. Furthermore, it demonstrates great compatibility with Mn-based layered metal oxide cathodes. Remarkably, we reveal a unique formation mechanism of the solvent-anion co-derived solid electrolyte interface (SEI) through a two-stage XPS deep analysis, which has the KF-deficient inorganic inner and KF-rich outer. This SEI can protect the graphite structure and enable great rate performance of graphite anode. This work holds significant reference value for the design of commercial electrolytes.

Extending Calendar Life of Si-Based Lithium-Ion Batteries by a Localized High Concentration Electrolyte

Extending Calendar Life of Si-Based Lithium-Ion Batteries by a Localized High Concentration Electrolyte

Anion‐Derived Solid Electrolyte Interphase Enabled by Diluent Modulated Dimethyl Carbonate‐Based Localized High Concentration Electrolytes for Lithium Metal Batteries

Carbonate‐based electrolytes generally suffer from low Coulombic efficiency and poor cycling stability in lithium metal batteries. In this work, localized high concentration electrolytes (LHCEs) based on dimethyl carbonate (DMC) with varying diluent additions are designed. LHCEs demonstrate higher Li+ transference numbers and a greater proportion of contact ion pairs (CIPs) and ion pair aggregates (AGGs) in the solvation structures, facilitating the formation of anion‐derived solid electrolyte interphase (SEI). Furthermore, LHCEs enhance the Coulombic efficiency of Li||Cu cells and improve the anodic stability against lithium. One of these LHCEs, prepared with appropriate diluent addition, exhibits excellent capacity retention in Li||NCM622 cells at 0.5 C after 150 cycles, thus presenting promising possibilities for the development of high energy density lithium metal batteries.

Tailoring Solvation Solvent in Localized High-Concentration Electrolytes for Lithium||Sulfurized Polyacrylonitrile.

Sulfurized polyacrylonitrile (SPAN) is a promising cathode material for lithium-sulfur (Li-S) batteries due to its significantly reduced polysulfide (PS) dissolution compared to that of elemental S cathodes. Although conventional carbonate-based electrolytes are stable with SPAN electrodes, they are unstable with Li metal anodes. Recently, localized high-concentration electrolytes (LHCEs) have been developed to improve the stability of Li anodes. Here, we report a new strategy to further improve the performance of Li||SPAN batteries by replacing the conventional solvating solvent 1,2-dimethoxyethane (DME) in LHCEs with a new solvating solvent, 1,2-diethoxyethane (DEE). The new optimal DEE-LHCE exhibits less reactivity against Li2S2, alleviates PS dissolution, forms a better cathode-electrolyte interphase layer on the SPAN cathode, and enhances SPAN structural reversibility even at elevated temperatures (45 °C). Compared to DME-LHCE, DEE-LHCE with the same salt and diluent leads to better performance in Li||SPAN batteries (with 82.9% capacity retention after 300 cycles at 45 °C), preservation of the SPAN cathode structure, and suppression of volume change of the Li metal anode. A similar strategy on tailoring the solvating solvents in LHCEs can also be used in other rechargeable batteries to improve their electrochemical performances.

Strongly solvating triglyme-based electrolyte realizes stable lithium metal batteries at high-voltage and high-temperature

The electrolyte in lithium-metal batteries (LMBs) plays a pivotal role in stabilizing the surface of the lithium metal anode (LMA) and high-voltage cathode. However, currently widely studied ether-based electrolytes, although it has good compatibility with LMA due to their lower reactivity, are facing significant challenges related to poor oxidation resistance and cathode/electrolyte interface (CEI) instability when combined with the high-voltage cathode, particularly at elevated temperatures. Therefore, there is an urgent need to design advanced electrolytes capable of maintaining high stability under high-voltage and high-temperature conditions. Here, we have developed an ultra-stable localized high-concentration electrolyte (LHCE) by introducing triethylene glycol dimethyl ether (TG), which exhibits strong solvation ability. Computational and experimental results demonstrate that the designed TG-based dilute high-concentration electrolyte (TG-DHCE) possesses a stable solvation structure, high oxidation resistance, and thermal stability, making it ideal for LMBs. Furthermore, the unique solvation structure of TG-DHCE promotes the preferential decomposition of anions while facilitating the formation of stable, inorganic-rich electrode/electrolyte interfaces on the anode and cathode. Consequently, equipped with TG-DHCE, Li||Li cells (more than 1600 h) and Li||NCM523 cells (80.6%, 250 cycles) show superior stability and also demonstrate remarkable performance even at elevated temperatures (60 °C). Additionally, under the harsh conditions of ultrahigh loading NCM523 cathode (19.7 mg/cm2) and limited Li reservoir (twice excess Li was deposited on Cu, Li@Cu) (N/P = 2), Li@Cu||NCM523 cells still maintain stable operation. This work pioneers a new path by choosing strongly solvating solvents, effectively enhancing the cycle life of LMBs under high-voltage and high-temperature conditions.

An Ultralow-concentration and Moisture-resistant Electrolyte of Lithium Difluoro(oxalato)borate in Carbonate Solvents for Stable Cycling in Practical Lithium-ion Batteries.

The electrolyte concentration not only impacts the battery performance but also affects the battery cost and manufacturing. Currently, most studies focus on high-concentration (>3 M) or localized high-concentration electrolytes (~1 M); however, the expensive lithium salt imposes a major concern. Most recently, ultralow concentration electrolytes (<0.3 M) have emerged as intriguing alternatives for battery applications, which feature low cost, low viscosity, and extreme-temperature operation. However, at such an early development stage, many works are urgently needed to further understand the electrolyte properties. Herein, we introduce an ultralow concentration electrolyte of 2 wt % (0.16 M) lithium difluoro(oxalato)borate (LiDFOB) in standard carbonate solvents. This electrolyte exhibits a record-low salt/solvent mass ratio reported to date, thus pointing to a superior low cost. Furthermore, this electrolyte is highly compatible with commercial Li-ion materials, forming stable and inorganic-rich interphases on the lithium cobalt oxide (LiCoO2) cathode and graphite anode. Consequently, the LiCoO2-graphite full cell demonstrates excellent cycling performance. Besides, this electrolyte is moisture-resistant and effectively suppresses the generation of hydrogen fluoride, which will markedly facilitate the battery assembly and recycling process under ambient conditions.

The Solvation Structure of Localized High Concentration Electrolytes

AbstractThe development of liquid electrolytes receives significant attention within the field of battery research. New concepts are emerging, and one of these groundbreaking ideas is localized high concentration electrolytes (LHCEs). The fundamental characteristic of this type of electrolyte is related to its solvation structure. However, despite the progress made, the solvation process and its relationship towards physicochemical and electrochemical properties are not yet fully understood. A comprehensive understanding of LHCEs and their solvation structure requires further dedicated research and analysis. This concept review offers a thorough examination of the design principles governing LHCEs, elucidates methodologies for investigating solvation structures, connects these insights to interphase chemistry, and explores potential applications in future battery technology.

A sustainable glycolipid hydrotrope‐solubilizer for cleansers and detergents

AbstractAlkyl polyglycosides (APGs), based on renewable glucose and fatty alcohols, are recognized for their performance and biodegradability. Hydrotropic/solubilizing effect properties have already been identified on short‐chain variants such as hexyl and ethylhexyl, but these ingredients were not fully bio‐based. This study investigated the hydrotropic/solubilizing properties of eco‐designed 100% bio‐based heptyl glucoside, under various conditions, compared to industrial and personal care benchmarks and other short chain APGs. Foaming power was firstly evaluated at different temperatures with two static methods. Hydrotropic performance was assessed with a commonly used surfactant in the presence of high electrolyte, acid and alkali concentrations. Further trials were done using ethoxylated rapeseed oil as an oil lubricant model in electrolyte‐charged aqueous solution. The solubilizing effect of hydrophobic additives such as fragrances, essential oils and vitamin E was quantified. Finally, effects on formulation preservation were screened with two natural personal care preservatives. Heptyl glucoside was found to be an effective and versatile hydrotrope for industrial applications, with additional intrinsic lubrication properties. It was also revealed as an efficient solubilizer for personal care products with the additional benefit of reducing the preservative dosage required in natural formulations. Its unusual non‐foaming nature, while not disrupting the foaming capacity of surfactants, makes it suitable for all types of cleansers. The calculated carbon footprint has a low value, making heptyl glucoside a valuable ingredient combining both performance and low environmental impact.

Elucidation of Mass Transport Phenomena in Highly Concentrated Electrolytes during Current Cycling Using In-Situ Interferometry and Finite Difference Method

Understanding electrolyte mass transfer during charge–discharge reactions is essential for developing next-generation storage batteries with high energy densities. In this study, we investigated Li+ transport in a highly concentrated electrolyte (HCE) consisting of an equimolar mixture of lithium bis(fluorosulfonyl)amide (LiFSA) and tetraglyme (G4) under current reversal and re-reversal. Concentration profiles of the electrolyte at a distance of 0–600 μm from the Li electrodes were obtained using in situ laser interferometry. The Li+ transference numbers and LiFSA diffusion coefficients were calculated from these profiles. Raman spectroscopy suggested that the coordination structure surrounding Li+ ions in the electrolytes mainly contributed to the transference number. A one-dimensional unsteady diffusion equation and the finite difference method were employed to simulate the concentration profiles. The maximum error percentage between the measured and simulated values was only 3%, confirming the accuracy and validity of the interferometric measurements. Our findings on Li-ion transfer in HCEs could promote the rational design of high-energy-density Li-ion batteries with higher cation transference numbers of electrolytes and charge–discharge rates.

Characterization of the aluminium-air battery utilizing a polypropylene separator with corrosion inhibition ability

Battery energy storage systems are widely used in modern electronic devices and electric vehicles. Metal-air batteries are among the electrochemical energy storage systems that provide high energy density and eco-friendly solutions. Aluminium-air batteries hold a significant advantage with their high theoretical specific energy and have the potential to replace lithium-ion batteries in the future. In this study, the electrical performance and corrosion inhibition characteristics of a polypropylene-based single and dual electrolyte system for aluminium-air batteries were investigated experimentally. The study revealed that a polypropylene separator can reduce the corrosion of the aqueous aluminium-air battery system by up to 40 %, improving the anodic utilization efficiency to 93 %. Electrochemical impedance spectroscopy analysis was used to characterize the single and dual electrolyte aluminium-air battery and propose equivalent circuit models. Compared to 1 M KOH electrolyte in a single electrolyte system, the solution resistance of a dual electrolyte aluminium-air battery was reduced by about 40 % using a combination of 1 M of KOH electrolyte and 1 M of H2SO4. This reduction is attributed to the enhancement of the oxygen reduction reaction at the air cathode. A high KOH electrolyte concentration will increase the corrosion of the aluminium anode but can improve the battery’s voltage. At 3 M KOH electrolyte, the plateau voltage is recorded at about 0.6 V while the discharge time reached 44 min when using aluminium alloy 6061 as the anode. The battery model developed in this work provides a fundamental basis for predicting the performance of aluminium-air battery packs.

Relating Chemo-Mechanical Hysteresis and Formation Protocols for Anode-Free Lithium Metal Batteries

Cell formation is an energy and time-intensive empirically-guided process crucial to manufacturing secondary lithium-ion batteries. As the rechargeable battery industry moves towards manufacturing lithium metal batteries—where a metallic lithium negative electrode is used instead of a porous graphite composite—the cell formation process may need reconsidering. The effects of formation rate and cycling protocol on lithium metal battery performance are poorly understood. In this work, we used operando acoustic transmission to measure physical changes during the formation cycles and the effect of formation cycling protocols on the long-term cycling of anode-free lithium metal pouch cells—where all the lithium inventory comes from the positive electrode and is deposited as metallic lithium on copper foil during initial charge. We show that a faster C/3 formation protocol results in comparable cycling performance and cell stiffness change to a slower C/10 formation step. Variations in acoustic metrics across different electrolytes tested are attributed to differences in gas formation, cell swelling, and lithium deposition morphology. NMC811 cathodes paired with a high-concentration ether electrolyte are shown to be particularly prone to gas formation, which is mitigated by using a localized high-concentration ether electrolyte and single-crystal NMC532. The results highlight differences in formation behavior between anode-free lithium metal cells and lithium-ion cells. These are important to consider when bringing new manufacturing plants online for lithium metal batteries.

Pore-structure control of porous carbon electrode materials and energy-storage performance in water-in-salt electrolytes

The pore structure of carbon-based materials and the voltage window of the electrolyte are two key factors affecting the energy density of carbon-based supercapacitors (SCs). In this paper, activated carbon materials of different pore sizes is successfully synthesized by chemical activation method by adjusting the mass ratio of ZnCl2 to sucrose, and successfully applied to construct SCs based on different electrolyte systems. As the specific surface area of the prepared porous carbon materials shows a tendency to increase and then decrease, reaching a maximum in the presence of micropores. Further summarizing the constitutive relationship between pore structure-electrochemical performance in the high-concentration electrolyte system, it is found that the normalized specific capacity is larger at smaller pore sizes, and with the increase of mesoporous proportion, the normalized specific capacity decreases and tends to be stable. In addition, the different strengths of solvation of anions and cations in the electrolyte, with the cations contributing more to the contrast, and the presence of mesopores providing ion transport channels to improve the efficiency of ion transport in porous materials, which provide directions for designing a suitable pore structure for highly concentrated salt electrolytes, as well as another way of optimizing the properties of carbon-based materials for SCs.

Deciphering fundamental mechanism of different-type diluents on manipulating interfacial chemistry toward lithium metal anode

The growth of dendrites on lithium metal anode is troublesome because it induces irreversible capacity loss and safety hazards. Formulating localized high-concentration electrolytes (LHCEs) is an alternative solution to satisfy these challenges. However, the role of diluents in tailoring interfacial chemistry remains to be explicated. Herein, we decipher the direct relationship between different-type diluents and Li-coordinated solvation at the molecular scale. Compare to hydrofluoroethers (HFE), the “active” difluoro ethylene carbonate (DFEC) delivers a pronounced interaction with Li+ and 1, 2-dimethoxyethane (DME) molecule, resulting in a compressed but more accumulated aggregates (AGGs) solvation shell, assisting in the expected chemical nature of SEI with defluorination of DFEC. Consequently, DFEC-based LHCEs (D-LHCEs) realize a record-long lifespan over 3000 h with dendrite-free at 1 mA cm−2 and outstanding dendrite tolerance even under 3 mA cm−2 in symmetric cells. The assembled full cells with D-LHCEs outperform a superior capacity retention of ∼86.83 % with average CE of ∼99.42 % after 500 cycles at 0.5C and the remarkable cycling performance even under harsh conditions (including pouch cells or with controlled N/P of 1.8) in 4.45 V-level Li||LiCoO2 cells. This work highlights the decisive role of diluents in pursuing high-efficiency electrolytes for high-energy Li metal batteries.

Compatibility and effect of capacity ratios between Na3V2(PO4)3 and hard carbon in highly concentrated sodium bis (fluorosulfonyl) imide electrolyte

From the standpoint of preserving the Earth's resources and ensuring the long-term viability of humanity, it is imperative to transition away from lithium-ion batteries. High-performance and safe sodium-ion batteries have recently emerged as promising advanced batteries for application in stationary energy storage, attributed to their low cost and abundance of sodium ion. We demonstrate the compatibility and effect of the negative-positive capacity ratio in full-cell Na3V2(PO4)3 and hard carbon in high-concentration electrolytes. Thanks to the excellent oxidation stability of the electrolyte, during 100 cycles, the full cell with a negative-positive capacity ratio of 1.1 demonstrated a consistent capacity of around 100 mAh g-1 with a capacity retention of 90.7%, whereas the full cell with a ratio of 1.0 showed a steady discharge capacity of roughly 90 mAh g-1 with a capacity retention of approaching 100% at a current density of C/5.