Coulombic Efficiency Stability Research Articles

Facile preparation of Hf3N4 thin films directly used as electrodes for lithium-ion storage.

Transition-metal nitride thin-film electrodes are potential electrode materials for all-solid-state thin-film lithium-ion batteries. In this study, orthorhombic Hf3N4 thin-film electrodes applied in lithium-ion batteries were fabricated by the magnetron sputtering deposition of Hf followed by N2 plasma immersion and post-annealing for the first time. This electrode material without additives such as binders and conductive agents exhibited a high specific capacity, high cycling stability, and excellent rate performance. At a current density of 0.1 A g-1, the initial discharge capacity was 583.2 mA h g-1 and the stable Coulombic efficiency was 96.6%. At a high current density of 2 A g-1, the Hf3N4 thin-film electrodes could still provide a stable discharge capacity of about 260 mA h g-1 and Coulombic efficiency close to 100%. By analyzing the cyclic voltammetry curves at different scan rates, it was found that the Li+ storage in Hf3N4 thin-film electrodes was mainly contributed by a pseudo-capacitance mechanism.

Enhancing interfacial stability in lithium orthosilicate/polymer blended novel hybrid solid-state electrolytes for all-solid-state lithium metal batteries

Hybrid solid-state electrolyte (HSSE) is a key component for the advancement of all-solid-state lithium metal batteries. The key challenges with the existing HSSEs are to ensure high ionic conductivity, activate dead inorganic/organic interface, and stimulate interfacial stability with electrodes. In this study, a novel HSSE is fabricated by integration of appropriately engineered end-of-life photovoltaic recycled high purity silicon derived nano size inorganic lithium orthosilicate and poly (vinylidene fluoride-co-hexafluoropropylene) polymer matrix through entrapping ionic liquid electrolytes. The obtained lithium orthosilicate-polymer blended HSSE is self-standing, soft, and flexible which delivers a low activation energy, leading a high ionic conductivity of 4.4x10-4 Scm-1. A critical lithium plating/stripping behaviour shows improved interfacial stability (both inorganic/organic interface and interfaces of HSSE/electrodes) under different current densities (0.05 mA cm-2 to 0.13 mA cm-2) when a drop of ionic liquid electrolyte is added, permitting cycling of an all-solid-state full cell (Li/HSSE/LiFePO4) at room temperature with high capacity (132 mAh g-1), stable cycle life and high Coulombic efficiency (initial ∼98%; subsequent > 99.5%). Shaping the interfaces between inorganic/organic phases in the HSSE as well as the interfaces between electrodes/HSSE appears to be a workable path towards constructing very effective HSSE for the advancement of all-solid-state lithium metal batteries.

Reversing lithium dendrites via trigger-type carbonized ZIF-8 gradient for stable lithium metal anodes

Although metallic lithium is one of the most potential anode candidates for next-generation batteries, its applications are still restricted by several problems, especially the formation of lithium dendrites. However, insufficient emphasis has been placed on dealing with the incipient lithium dendrites. Herein, a three-dimensional insulating glass-fiber skeleton with gradient-distributed trigger-type carbonized ZIF-8 (GF-cZIF8) was developed. In this structure, plentiful conductive cZIF-8 on the collector/skeleton interface guided uniform lithium nucleation, while highly conductive and lithophilic cZIF-8 on the skeleton passivated and reversed lithium dendrites to a stable part of lithium anode when trigged by lithium dendrites. In addition, insulating glass fibers improved the homogeneity of Li ions. As a consequence, the GF-cZIF8/Cu collector exhibited a high and stable coulombic efficiency of 98% after 280 cycles, and the GF-cZIF8-Li anode exhibited a low voltage hysteresis of 17 mV and a long cycling life up to 1100 h.

Manipulation of facet zincophilicity of protective coatings for long lifetime zinc anodes

Aqueous zinc-ion batteries are considered to be a promising technology for large scale energy storage deployment due to their advantages of low cost and high security. However, the zinc anodes suffer long-standing problems of uncontrollable dendrite growth and unstable interfacial chemistry that hinder their industrial applications. In this work, we manage to manipulate the facet zincophilicity of commercial titanium oxide (TiO2) by nitrogen implanting as a protective coating to realize long-term zinc plating/stripping. The nitrogen-implanting significantly increases the habitual facet zincophilicity of TiO2 layer to enable uniform and fast zinc deposition kinetics. Impressively, the as-protected Zn anode could be operated for a long lifespan of 2400 hours accompanying with a high cumulative capacity of 4.1 Ah cm-2 and a stable Coulombic efficiency of 99.53% over 900 cycles. This work will shed new insight on the importance of manipulating the facet zincophicility of protective coatings for dendrite-free metal anodes beyond zinc chemistry.

Constructing a Li–Zn lithiophilic layer by a scalable method of magnetron sputtering for a high-quality Li–B alloy anode

Lithium metal anodes offer high theoretical capacity and low redox potential but face challenges like dendritic growth, fragile solid electrolyte interface (SEI), "dead lithium" formation, and volume expansion. Composite anodes or artificial SEIs can address these issues, but often suffer from poor lithiophilicity and mass burdens. This study presents a Li–Zn–B alloy anode combining a Li–Zn lithiophilic layer with a bulk Li–B alloy. The Li–Zn lithiophilic layer, formed by magnetron sputtering of Zinc oxide (ZnO), improves surface lithiophilicity. Symmetrical cells with this alloy cycled stably for 1300 (1 mA cm−2, 1 mAh cm−2) and 550 h (2 mA cm−2, 2 mAh cm−2) with minimal overpotentials. The LiBZn||NCM811 full cell showed a specific discharge capacity of 130.8 mAh/g and stable Coulombic efficiency of 98.9 % after 300 cycles.

Disruptive Semi-Solid Lithium Sulfur Battery Cell Design with Fully Separated Anolyte and Catholyte

Lithium-Sulfur-Batteries (LSBs) have been discussed as one of the most promising post-lithium-ion-battery technologies in literature for the last decade due to their high theoretical specific energy of 2600 Wh/kg. However, several drawbacks still exist in case of liquid LSB-concepts, especially cycling stability with low electrolyte excess in combination with a reasonable sulfur utilization plus cycle stability still hinders the commercial breakthrough of this battery technology. One main reason for both issues is the dissolution of the active material, sulfur, as polysulfides in the electrolyte, which leads to the so-called polysulfide shuttle that comprises polysulfide diffusion through the cell to the lithium metal anode resulting in decomposition reactions, and therefore, loss of active material. Several electrolyte approaches in order to limit polysulfide dissolution have been developed over the last 5-10 years, however, those electrolyte formulations usually lead to a strong lithium metal corrosion. Electrolytes that enable stable cycling of lithium metal batteries in combination with a nickel manganese cobalt oxide cathode have been successfully developed, however, they are ususally not compatible with the polysulfides of Li-S batteries. Hence, decoupling the anolyte from the catholyte has been much desirable. Recently introduced solid-state lithium sulfur batteries based on sulfidic solid electrolytes might overcome some challenges of conventional liquid LSBs since no formation or diffusion of polysulfide species can take place, and very high sulfur utilization have been already reached. However, solid-state LSBs have not been cycleable so far when a thin layer of solid electrolyte and lithium metal anode (without indium) were employed, especially in pouch cells, due to the formation of lithium dendrites, resulting in short circuits.Herein, a completely new battery design, a “semi-solid”-LSB, is presented. The concept combines the advantages of liquid and solid state LSBs. On the cathode side, an electrode comprising carbon, sulfur and sulfidic solid electrolyte (argyrodite) enables a solid to solid conversion of sulfur resulting in a complete suppression of the polysulfide shuttle.On the anode side, a liquid electrolyte enabling stable cycling of a lithium metal anode is employed. A careful design of the liquid electrolyte is crucial in order to obtain high stability of the liquid electrolyte against the lithium metal anode as well as to avoid side reaction between the solid electrolyte of the cathode and the liquid electrolyte. Different electrolytes are discussed for the new cell design and proof of concept was successfully reached in coin cells leading to 100 cycles with a stable coulombic efficiency of over 99 % which outperforms the majority of previously published Li-S cycling data. In addition, the concept was also transferred into first semi-solid lithium sulfur-pouch cells which is an important step in the direction of practical applications.

Superhydrophobic and Highly Flexible Artificial Solid Electrolyte Interphase Inspired by Lotus Effect Toward Highly Stable Zn Anode

AbstractDue to their cost‐effectiveness, high safety, and environmental friendliness, aqueous zinc‐ion batteries (AZIBs) are among the most promising technologies for next‐generation energy storage systems. Nonetheless, dendrite growth, hydrogen evolution, and corrosion at zinc (Zn) anode severely hinder their practical application. In this study, a combination of molecular self‐assembly engineering, squeegee coating, and air spraying process is employed to create a superhydrophobic and highly flexible artificial solid‐electrolyte‐interface layer on Zn anode (denoted as SFM/Zn). Self‐assembled monolayer of triethoxy‐3‐aminopropylsilane optimizes Zn2+ migration kinetics. The superhydrophobic interface, formed by polydimethylsiloxane (PDMS) and trimethoxy(octadecyl)silane (OTS)‐modified nanosilicon dioxide particles, inhibits water‐related side reactions. Furthermore, the highly flexible PDMS serves as a dynamic adaptive interface for Zn anode, effectively alleviating the “tip effect”. Consequently, the SFM/Zn||SFM/Zn symmetrical cells enable reversible and stable Zn plating/stripping at both ultralow current density (0.2 mA cm−2) and ultrahigh current density (45 mA cm−2). The assembled Zn‐vanadium (SFM/Zn||NH4V4O10) cell deliver stable average Coulombic efficiency (nearly 100%) and ultralong cycling stability (135.5 mAh g−1 after 500 cycles at 5 A g−1 and 173.2 mAh g−1 after 1000 cycles at 2 A g−1). This innovative superhydrophobic three‐layered strategy sheds new light on designing highly durable Zn anode for high‐performance AZIBs.

Flexible high electrochemical active hydrogel for wearable sensors and supercapacitor electrolytes

With the rapid advancement of flexible, portable devices, hydrogel electrolytes have gained considerable attention as potential replacements for conventional liquid electrolytes. A hydrogel electrolyte was synthesised by cross-linking acrylic acid (AA), acrylamide (AM), carboxymethyl cellulose (CMC), and zinc sulphate (ZnSO4). The formation of hydrogen bonds and chelate interactions between the P(AA-co-AM) polymer, CMC, and ZnSO4 created a robust network, enhancing the mechanical properties of the hydrogel electrolytes. Notably, the hydrogel electrolyte containing 0.6 % CMC demonstrated superior mechanical strength (compression strength of 1.22 MPa, tensile stress of 230 kPa, tensile strain of 424 %, adhesion strength of 1.98 MPa on wood). Additionally, the CMC/P(AA-co-AM) hydrogels exhibited commendable electrical performance (38 mS/cm) and a high gauge factor (2.9), enabling the precise detection of physiological activity signals through resistance measurements. The unique network structure of the hydrogel electrolyte also ensured a stable bonding interface between the electrode and the electrolyte. After 2000 charge–discharge cycles, the supercapacitor maintained good capacitance characteristics, with a capacitance retention rate of 71.21 % and a stable Coulombic efficiency of 98.85 %, demonstrating excellent cyclic stability. This study introduces a novel methodology for fabricating multifunctional all-solid-state supercapacitors and suggests that the hydrogel can significantly advance the development of wearable energy storage devices.

High-Concentrated Binary-Salt Ether Electrolytes for High-Voltage Lithium Metal Batteries with Ni-Rich Cathode.

The incompatibility of ether electrolytes with a cathode dramatically limits its application in high-voltage Li metal batteries. Herein, we report a new highly concentrated binary salt ether-based electrolyte (HCBE, 1.25 M LiTFSI + 2.5 M LiFSI in DME) that enables stable cycling of high-voltage lithium metal batteries with the Ni-rich (NCM83, LiNi0.83Co0.12Mn0.05O2) cathode. Experimental characterizations and density functional theory (DFT) calculations reveal the special solvation structure in HCBE. A solvation structure rich in aggregates (AGGs) can effectively broaden the electrochemical window of the ether electrolyte. The anions in HCBE preferentially decompose under high voltage, forming a CEI film rich in inorganic components to protect the electrolyte from degradation. Thus, the high-energy-density Li||NCM83 cell has a capacity retention of ≈95% after 150 cycles. Significantly, the cells in HCBE have a high and stable average Coulombic efficiency of over 99.9%, much larger than that of 1 M LiPF6 + EC + EMC + DMC (99%). The result emphasizes that the anionic-driven formation of a cathode electrolyte interface (CEI) can reduce the number of interface side reactions and effectively protect the cathode. Furthermore, the Coulombic efficiency of Li||Cu using the HCBE is 98.5%, underscoring the advantages of using ether-based electrolytes. This work offers novel insights and approaches for the design of high-performance electrolytes for lithium metal batteries.

Revisiting porous foam Cu host based Li metal anode: The roles of lithiophilicity and hierarchical structure of three-dimensional framework

Lithium (Li) metal anode (LMA) is one of the most promising anodes for high energy density batteries. However, its practical application is impeded by notorious dendrite growth and huge volume expansion. Although the three-dimensional (3D) host can enhance the cycling stability of LMA, further improvements are still necessary to address the key factors limiting Li plating/stripping behavior. Herein, porous copper (Cu) foam (CF) is thermally infiltrated with molten Li-rich Li-zinc (Li-Zn) binary alloy (CFLZ) with variable Li/Zn atomic ratio. In this process, the LiZn intermetallic compound phase self-assembles into a network of mixed electron/ion conductors that are distributed within the metallic Li phase matrix and this network acts as a sublevel skeleton architecture in the pores of CF, providing a more efficient and structured framework for the material. The as-prepared CFLZ composite anodes are systematically investigated to emphasize the roles of the tunable lithiophilicity and hierarchical structure of the frameworks. Meanwhile, a thin layer of Cu-Zn alloy with strong lithiophilicity covers the CF scaffold itself. The CFLZ with high Zn content facilitates uniform Li nucleation and deposition, thereby effectively suppressing Li dendrite growth and volume fluctuation. Consequently, the hierarchical and lithiophilic framework shows low Li nucleation overpotential and highly stable Coulombic efficiency (CE) for 200 cycles in conventional carbonate based electrolyte. The full cell coupled with LiFePO4 (LFP) cathode demonstrates high cycle stability and rate performance. This work provides valuable insights into the design of advanced dendrite-free 3D LMA toward practical application.

Preparation of Expanded Graphite-VO2 Composite Cathode Material and Performance in Aqueous Zinc-Ion Batteries.

Due to safety problems caused by the use of organic electrolytes in lithium-ion batteries and the high production cost brought by the limited lithium resources, water-based zinc-ion batteries have become a new research focus in the field of energy storage due to their low production cost, safety, efficiency, and environmental friendliness. This paper focused on vanadium dioxide and expanded graphite (EG) composite cathode materials. Given the cycling problem caused by the structural fragility of vanadium dioxide in zinc-ion batteries, the feasibility of preparing a new composite material is explored. The EG/VO2 composites were prepared by a simple hydrothermal method, and compared with the aqueous zinc-ion batteries assembled with a single type of VO2 under the same conditions, the electrode materials composited with high-purity sulfur-free expanded graphite showed more excellent capacity, cycling performance, and multiplicity performance, and the EG/VO2 composites possessed a high discharge ratio of 345 mAh g-1 at 0.1 A g-1, and the Coulombic efficiency was close to 100%. The EG/VO2 composite has a high specific discharge capacity of 345 mAh g-1 at 0.1 A g-1 with a Coulombic efficiency close to 100%, a capacity retention of 77% after 100 cycles, and 277.8 mAh g-1 with a capacity retention of 78% at a 20-fold increase in current density. The long cycle test data demonstrated that the composite with expanded graphite effectively improved the cycling performance of vanadium-based materials, and the composite maintained a stable Coulombic efficiency of 100% at a high current density of 2 A/g and still maintained a specific capacity of 108.9 mAh/g after 2000 cycles.

Surface Modification Induces Oriented Zn(002) Deposition for Highly Stable Zinc Anode

Aqueous zinc metal batteries (AZMBs) are considered a promising candidate for grid-scale energy storage systems owing to their high capacity, high safety and low cost. However, Zn anodes suffer from notorious dendrite growth and undesirable surface corrosion, severely hindering the commercialization of AZMBs. Herein, a strategy for engineering a dense ZnO coating layer on Zn anodes using the atomic layer deposition (ALD) technique is developed, aiming to improve its long-term cycling stability with fewer Zn dendrites. The surface-modified Zn anode (ZnO@Zn) exhibits an excellent long-cycling life (680 h) and stable coulombic efficiency when being used in a symmetric cell. Moreover, the ZnO@Zn electrode shows a high stability with almost no capacity decay after 1100 cycles at 2C in a full cell using MnO2 as the cathode. The ZnO coating is conducive to reducing corrosion and the generation of by-products, thus increasing the reversibility of Zn2+/Zn stripping/plating. Particularly, density functional theory (DFT) calculation results reveal that the ZnO coating layer could effectively lower the adsorption energy of the Zn(002) plane in ZnO@Zn, inducing the preferential deposition of Zn2+ towards the (002) crystal plane with fewer Zn dendrites. The surface ZnO coating protocol provides a promising approach to achieve a dendrite-free Zn anode for stable AZMBs.

The art of Lithiation Revisited: Solvent-free room temperature reaction

The lithiation reaction holds immense significance across various branches of chemistry, particularly in the realm of electrochemical energy storage. Here, we report a new method that enables a solvent-free process at room temperature, exhibiting remarkably swift reaction kinetics. Through this process, the chemical integration of Li+ into charged materials based on transition metals is achieved using lithium iodide, LiI. An evident application of this method lies in advancing the direct recycling of cathode materials reclaimed from spent batteries. Notably, the process facilitates the efficient and direct recycling of spent Li(1-x)FePO4 cathode material, sourced from a commercial LIB, without the need for any solvents or heat treatments. The regenerated material exhibits a fully reversible capacity of approximately 168 mAh/g against Li metal, even under high current density conditions, with a consistently stable coulombic efficiency surpassing 99 % over 45 cycles. This regenerative approach holds the potential for seamless extension to other LIB cathode materials, including but not limited to LMFP, LMO, LCO and NMC.

Exploring the potential of Mbenes in energy storage

MBene, a layered metal boride similar to MXene, has garnered significant attention in recent times. Nevertheless, there is still a lack of comprehensive understanding regarding their structure and properties, necessitating further research and investigation. In this study, theoretical calculations were employed first to study the binding energy, band structures and density of states of three MBenes, namely MoB, MgB2, and ZrB2, providing insights into their electronic characteristics. In addition, open circuit voltage (OCV) and adsorption energy were also conducted using the three MBenes as cathode materials for zinc ion batteries, indicating their low ion migration barrier and potential in energy storage application. Subsequently, MoB, MgB2, and ZrB2 were experimentally synthesized using etching or exfoliation method and utilized as cathode materials for zinc ion batteries. Results demonstrates that the specific capacity of MoB is 60 mAh g-1 at 0.1 A g-1. Systematic investigation including kinetics simulation and ex situ XRD suggests the cation insertion mechanism of the MoB electrodes. Building upon these findings, attempts were made to enhance the performance of MoB through the incorporation of 1 T-MoS2 composites, urea molecular intercalation. Notably, the modified composite exhibited a specific capacity exceeding 150 mAh g-1 at 0.1 A g-1, with a stable Coulombic efficiency of 100% after 100 cycles. This study provides novel directions and insights for the research of MBene in the context of aqueous zinc-ion batteries.

Tuning the End Alkyl Chain of the Ether Solvent to Stabilize the Electrode/Electrolyte Interfaces in the NCM-Li Battery.

Lithium metal batteries (LMBs) combined with a high-voltage nickel-rich cathode show great potential in meeting the growing need for high energy density. The lack of advanced electrolytes has been a major obstacle in the commercialization of high-voltage lithium metal batteries (LMBs), as these electrolytes need to effectively support both a stable lithium metal anode (LMA) and a high-voltage cathode (>4 V vs Li+/Li). In this work, by extending the two terminal methyl groups in DIGDME and TEGDME to n-butyl groups, we design a new weakly solvating electrolyte (2 M LIFSI+TEGDBE) that enables the stable cycling of NMC83 (LiNi0.83Co0.12Mn0.05O2) cathodes. The NMC83 cell exhibits a high and stable Coulombic efficiency (CE) of over 99%, as well as capacity retention of approximately 99.8% after 100 cycles at 0.3 C. X-ray photoelectron spectroscopy analysis (XPS) and high-resolution transmission electron microscope (HRTEM) images revealed that the anion species decomposed first, resulting in the formation of a cathode-electrolyte interface (CEI) film predominantly consisting of decomposition products from the anions on the positive electrode surface. This work links the functional group of solvents with the solvation structure and electrochemical performance of ether-based electrolytes, providing a distinctive sight to design advanced electrolytes for high-energy-density LMBs.

Introduction of a nitrate anion with solubility mediator in a carbonate-based electrolyte for a stable potassium metal anode

In this study, sodium nitrate (NaNO3) dissolves in a carbonate electrolyte for K-metal batteries (KMBs) using a dimethylacetamide (DMA) solvent with a higher Gutmann donor number than that of NO3−. The K-metal anode in 0.02 M NaNO3 electrolyte exhibits enhanced stability due to the modified solid-electrolyte interphase (SEI) layer resulting from the preferential reduction of NaNO3. Reduced NaNO3 forms ionically conductive and mechanically robust compounds in the SEI layer. This compound plays a critical role in altering the morphology of electrodeposited K-metal from dendritic to spherical, reducing the barrier energy of nucleation potential for K-ions. These unique features make K-metal highly resistant to dendrite formation and aggressive electrolyte chemistry. Therefore, the K-metal anode in the proposed electrolyte containing 0.02 M NaNO3 additive ensures excellent cycle life with stable Coulombic efficiency in both symmetrical K/K half cells and full-cells coupled with a Prussian green FeFe(CN)6 cathode.

Achieving Long Cycle Life of Zn-Ion Batteries through Three-Dimensional Copper Foam.

Metallic zinc anodes in aqueous zinc-ion batteries (ZIBs) suffer from dendritic growth, low Coulombic efficiency, and high polarization during cycling. To mitigate these challenges, current collectors based on three-dimensional (3D) commercial copper foam (CCuF) are generally preferred. However, their utilization is constrained by their thickness, low electroactive surface area, and increased manufacturing expenses. In this study, the synthesis of cost-effective current collectors with exceptionally large surface areas designed for ZIBs that can be cycled hundreds of times is reported. A zinc-coated CuF anode (Zn/CuF) was prepared with a 3D porous CuF current collector produced by the dynamic hydrogen bubble template (DHBT) method. Electrochemically generated copper foam could be obtained within seconds while offering a thickness as low as 30-40 μm (CuF5 achieved a thickness of ∼38 μm in 5 s) via the DHBT method. The excellent electrical conductivity and open pore structure of the 3D porous copper scaffold ensured the uniform deposition/stripping of Zn during cycling. During the 500 h Zn deposition/stripping process, the as-synthesized CuF5 current collector offered fast electrochemical kinetics and low polarization as well as a relatively high average Coulombic efficiency of 99% (at a current density of 5 mA cm-2 and a capacity of 1 mAh cm-2). Furthermore, the symmetric cell exhibited low voltage polarization and a stable voltage profile for 1000 h at a current density of 0.1 mA cm-2. In addition, full cells containing the Zn/CuF anode coupled with an as-synthesized α-MnO2 nanoneedle cathode in aqueous electrolyte were also prepared. Capacities of 266 mAh g-1 at 0.1 A g-1 and 94 mAh g-1 at 2 A g-1 were achieved after 200 charge/discharge cycles with a stable Coulombic efficiency value close to 99.9%.

Controlling intermolecular interaction and interphase chemistry enabled highly stable aqueous ammonium-ion batteries

Aqueous ammonium-ion batteries (AIBs) show great potential in the large scale energy storage systems due to the advantages of low cost, high safety and environmental friendliness. However, they face the challenges of low output voltage and unsatisfactory electrochemical performance because of the narrow voltage window and unstable interfacial structure in conventional aqueous electrolytes. Herein, we design an aqueous AIB based on hydrogen-bond anchored electrolyte, Mn-based Prussian blue analogues (MnHCF) cathode and NaTi2(PO4)3@carbon (NTP@C) anode. In this electrolyte, the intermolecular hydrogen-bond interaction is constructed between water and sulfolane molecules, leading to the decreased water activity and wide voltage window. Furthermore, the coordination environment of NH4+ ions between sulfolane and CF3SO3- anions produces a unique solvation structure with low hydrated degree, which favors the formation of protective interfacial layer between electrode and electrolyte. Accordingly, the dissolution of MnHCF is largely inhibited and the side reactions between electrode and electrolyte are suppressed. As a result, the MnHCF electrode displays stable cycling performance and high Coulombic efficiency compared with the cases in conventional aqueous electrolytes. Moreover, the constructed full cells demonstrate high output voltage and superior stability. This work provides a synergistic route to design high-performance aqueous AIBs.

Sodium Difluoro(oxalato)borate Additive‐Induced Robust SEI and CEI Layers Enable Dendrite‐Free and Long‐Cycling Sodium‐Ion Batteries

AbstractSodium‐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.

Li3N/SiO2 modified 3D collectors to extend the cycle life of lithium anode

Despite the many benefits of lithium-metal anodes in next-generation lithium-metal batteries, they are limited by their infinite volume expansion and lithium dendrite growth. In this study, we propose a novel method for producing stable lithium-metal anodes by first coating a Cu current collector with a thin insulating silica layer, then laser etching to create holes where lithium deposition can take place. Additionally, an artificial solid electrolyte interphase layer of Li3N, which is generated in situ on the deposited lithium metal surface can reduced electrolyte consumption and promote uniform lithium deposition, and the confined space within the holes prevent dendrite formation. The above design realizes the use of limited lithium and improves the utilization of lithium metal while increasing the safety of the cells. The 3D Cu supported Li anode exhibited stable average coulombic efficiency of 99.8 % for 300 cycles at a current density of 1 Ma cm−2. Specifically, full cells made of such a 3D Cu anode coupled with a LiFePO4 cathode exhibited a capacity of 125 mA h g−1 after 250 cycles (low N/P capacity ratio of 2.38), providing a dendrite-free lithium metal anode.