High Areal Loading Research Articles

H+-Induced 3D Porous Ti3C2Tx Foam Coupled with S Nanoparticles by the Drop Infusion Melting Method as a High Areal Loading Cathode for Li–S with Enhanced Performance

H⁺-Induced 3D Porous Ti₃C₂T_<i>x</i> Foam Coupled with S Nanoparticles by the Drop Infusion Melting Method as a High Areal Loading Cathode for Li–S with Enhanced Performance

3D Tunnel Copper Tetrathiovanadate Nanocube Cathode Achieving Ultrafast Magnesium Storage Reactions through a Charge Delocalization and Displacement Mechanism.

Rechargeable magnesium batteries are attractive candidates for large-scale energy storage applications because of the low cost and high safety, but the scarcity and inferior performance of the cathode materials are hindering the development. In the present study, a kind of copper tetrathiovanadate (Cu3VS4) cathode is designed and developed with a comprehensive consideration of the chemical and electronic structures. The vanadium and sulfur atoms form chemical bonds with high covalent proportion, facilitating electron delocalization via the vanadium-sulfur bonds. This reduces the interaction with the bivalent magnesium cation and induces the coredox of vanadium and sulfur. The crystal structure of Cu3VS4 has interlaced 3D tunnels for solid-state magnesium cation transport. The Cu3VS4 cathode shows a high capacity of 350 mA h g-1 at 100 mA g-1, an outstanding rate performance of 67 mA h g-1 at 10 A g-1, and stable cycling for 1000 cycles at 5 A g-1 without obvious capacity fading. Prominently, a high areal mass load of 3.5 mg cm-2 could be achieved without obvious rate capability decay, which is quite favorable to pair with the high-capacity magnesium metal anode in practical application. The mechanism investigation and theoretical computation demonstrate that Cu3VS4 undergoes first a magnesium intercalation and then a displacement reaction, during which the crystal structure is maintained, assisting the reaction reversibility and cycling stability. All the copper, vanadium, and sulfur elements experience redox and contribute to the high capacity. Moreover, the weakened interaction with magnesium cations, well-kept 3D cation transport tunnels, and high electronic conductivity result in the superior rate performance and high areal active material loading. The present study develops a high-performance cathode for rechargeable magnesium batteries and reveal the design principle based on both of chemical and electronic structures.

Constructing LiF‐Enriched Solid Electrolyte Interface on Graphene Arrays with Abundant Edges on Microscale Si‐C Anodes Toward High‐Energy Lithium‐Ion Batteries

AbstractSilicon (Si) anodes offer excellent lithium storage capacity for lithium‐ion batteries but face practical limitations due to significant volume expansion and low intrinsic electrical conductivity. These issues lead to side reactions that consume the electrolyte and impede ion‐electron transport, resulting in low areal loading (&lt;2 mg cm⁻²) and restricted energy density. To address this, a scalable method is developed using spray drying of commercial graphite flakes (s‐Gr) and nanosilicon particles (n‐Si), followed by chemical vapor deposition to create microscale Si/C anodes (s‐Gr/n‐Si/VGs). Thin vertical graphene nanosheets (VGs) are grown on the surfaces and within the internal pores, forming a robust, micron‐sized Si/C spherical composite material. The VGs construct the conductive network, allowing the electrodes to operate at high areal loadings without pulverization and promoting LiF‐enriched solid electrolyte interphase for improved cycling stability. The s‐Gr/n‐Si/VGs maintain a capacity of 641.9 mAh g⁻¹ after 1000 cycles at 11.0 mg cm⁻², retaining 95.9% capacity. In pouch cells with NCM811 cathodes, the 5.0 Ah‐level cells achieved 80.0% capacity retention after 510 cycles at 1.0 C. This research provides a feasible pathway for manufacturing high‐performance, low‐cost, and scalable Si/C anodes suitable for high‐energy‐density lithium‐ion batteries.

A Flexible Multifunctional Cyanoethyl-Modified Bacterial Cellulose Nanofiber Framework for High-Energy and High-Power Density Aqueous Li-Ion Batteries.

Aqueous rechargeable lithium-ion batteries (ARLIBs) are extensively researched due to their inherent safety, typical affordability, and potential high energy density. However, fabricating ARLIBs with both high energy density and power performance remains challenging. Herein, based on cyanoethyl-modified bacterial cellulose nanofibers (CBCNs), a multifunctional fast ion transport framework is developed to construct the flexible free-standing ARLIBs with high areal loading and excellent rate performance. Benefiting from the unique merits of CBCNs, such as ultra-high aspect ratio, excellent toughness, superior adhesion, good lithiophilicity and ideal stability, the flexible free-standing and highly robust electrodes are fabricated and exhibit a long-term stable cycling of 1200 cycles with a high specific capacity of 117 mAh∙g-1 at 15 C. Remarkably, the corresponding full cell with the free-standing high mass loading (45.5 mg∙cm-2) electrodes under the condition of ultra-low addition of battery binder demonstrates a cycle lifespan of over 1000 cycles with a specific capacity of 120 mAh∙g-1 and a capacity decay as low as 0.03% per cycle, which is far superior to those of almost all previous reports. This work provides a strategy for constructing ARLIBs with high energy density and power performance by introducing a unique fast ion transport nanofiber framework.

Embedded Micro-Interdigitated Flow Fields for Efficient Intercalation-Based Desalination at Seawater Scale

During the past decade, intensifying water crises around the globe have motivated research in electrochemical desalination. Among such technologies, Faradaic deionization (FDI) has shown great promise for seawater desalination with the use of intercalation electrode materials that possess at least ten-fold higher charge storage concentration (~5 M) than seawater salinity (~0.5 M). Despite many efforts focused either on developing electrode materials or modifying flow-cell architectures, the promise of intercalative FDI was not previously realized experimentally. This work demonstrates for the first time salt removal approaching seawater-level salinity by using a flow cell containing symmetric cation intercalation electrodes separated by an anion-exchange membrane [Do et al., Energy Environ. Sci., 16, 3025–3039 (2023)]. We show removal of 96% of salt from ~500 mM NaCl feeds with ~50% water recovery at a thermodynamic energy efficiency (TEE) of 7%. In addition, the flow cell readily produces fresh water (< 0.017 M NaCl) from brackish water with 40% TEE and substantially lowered hypersaline brine concentration from 0.78 M down to 0.23 M at 11.7% TEE. We note that (1) scaling up the charge capacity of intercalation electrodes is crucial to improve salt removal in FDI and (2) rational design of flow-through electrodes is equally important to make FDI more energy-efficient by mitigating pumping energy consumption. Upscaling was achieved by using large-area electrodes with high areal loading of nickel hexacyanoferrate (NiHCF), up to 21 mg cm-2. Pumping energy was drastically reduced by embedding an interdigitated array of 70 µm wide channels into the NiHCF electrodes using laser micromaching to form novel embedded, micro-interdigitated flow fields (eµ-IDFFs). The dimensions of the eµ-IDFFs were tailored for our low-permeability electrodes based on analytical and numerical modeling, resulting in two orders of magnitude improvement in the apparent hydraulic permeability of these electrodes while minimizing active-material loss. Evidence of water transport between diluted and concentrated streams, as well as feed-concentration-dependent charge efficiency were reported, which potentially contributed to energy efficiency and water recovery losses, motivating their investigation to further improve FDI performance. In addition to their application toward desalination, the present eµ-IDFFs show promise for use in electrochemical energy storage and conversion processes that employ nanomaterials

Integrating Polymer Electrolytes-Based Thick Composite Cathodes in All-Polymer Solid-State Lithium Metal Batteries

High energy density solid-state batteries require high areal loading composite cathodes (>4 mAh/cm2). However, increasing the cathode loading or thickness can introduce additional challenges apart from the expected rate capability limitations, which are much less pronounced in low loading or thin composite cathodes. These include greater volume changes during cycling at the cell level, which can introduce stresses at the various interfaces. While there are many successful reports showing long-term stable cycling of high loading composite cathode in all-inorganic solid-state cells, these cells are typically cycled under high pressures (>10 MPa), which may be impractical to commercialize. Such high pressures can alleviate the interfacial contact loss issues generated due to volume changes during cycling. Polymer electrolytes are non-rigid and can potentially accommodate strains to maintain contact at the interfaces during cycling, given sufficient adhesion. In this work, we will show some of the design strategies that were implemented to alleviate the contact loss issue at the polymer electrolyte separator/composite cathode interface in order to achieve stable cycling with thick polymer electrolyte-based composite cathodes in coil-cell configuration. Nickel-rich NMC (LiNixMnyCozO2) cathodes (NMC811 or 622) were used as the active materials. Since polymer electrolytes are known to be unstable with high voltage cathodes such as NMCs, the contribution of oxidative instability to the overall capacity decay will also be discussed by comparing two polymer electrolytes with different oxidative stability (a PEO-based dual-ion polymer electrolyte, and a single-ion polymer electrolyte). This research was sponsored by the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy for the Vehicle Technologies Office’s Advanced Battery Materials Research Program (Simon Thompson, Program Manager). A part of this research was sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory (ORNL), managed by UT-Battelle, LLC for the U.S. Department of Energy under Contract No. DE-AC05-00OR22725. The SEM in this work was performed and supported at the Center for Nanophase Materials Sciences in Oak Ridge National Lab, a DOE Office of Science user facility.

Practical SPAN||Li cells enabled by insitu polymerized electrolyte

Sulfurized polyacrylonitrile (SPAN) is a promising cathode material for long-life lithium-sulfur batteries (LSBs) due to its enhanced electronic conductivity as well as the eliminated shuttle effect. However, the uncontrollable lithium dendrite issue as well as slow kinetics of thick electrodes still hinders its practical application. Herein, an in situ polymerized electrolyte (PGE) based on vinyl carbonate and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is designed and prepared to enhance the plating/stripping stability of the metal lithium while ensuring the cathode/electrolyte interfacial ion transportation. The optimized electrolyte, PGE-D, shows a satisfying ionic conductivity of 0.46 mS/cm at 25 °C; in the meantime, the polymer matrix hinders the diffusion of TFSI− anion and results in a high Li+ transference number (tLi+) of 0.73. Benefiting from the high affinity of the flowable PGE precursor to the thick SPAN cathode as well as enhanced lithium compatibility, the Li||SPAN battery with high areal loading of 14.1 mg/cm2 exhibits a high reversible specific capacity of 556.5 mAh/g and retains 76.3% of its capacity after 90 cycles.

Regulation of Zn2+ Solvation Configuration in Aqueous Batteries via Selenium-Substituted Crown Ether Engineering.

The efficient utilization of the metallic Zn in rechargeable aqueous Zn-ion batteries (RAZBs) struggle to suffer from parasitic Zn dendrite formation, hydrogen evolution reactions as well as severe interfacial degradation at high areal capacity loadings. This study thus proposes to employ the modified crown ether as an aqueous electrolyte additive to regulate the Zn2+ desolvation kinetic and facilitates the horizontally oriented (002) deposition of Zn, extending the lifespan of both the symmetric cell and full cell models. Specifically, zincophilic cyano and hydrophobic selenium atoms are incorporated into the crown ether supramolecule to enhance Zn2+ coordination and desolvation capability. The addition of 4-cyanobenzo-21-crown-7-selenium at a low concentration of 0.5 wt.% effectively mitigates hydrogen evolution and Zn corrosion caused by water, promoting the oriented deposition of Zn2+. The Zn||V2O5 full cell prototype, assembled with the areal capacity loadings of 2 mAh cm-2 and N/P ratio of 2.95, exhibits negligible capacity fading at 2.0A g-1 for 300 cycles, highlighting the commercial feasibility of supramolecular macrocycles additive for practical RAZBs applications.

Significance of homogeneous conductive network in layered oxide-based cathode for high-rate capability of electric vehicle batteries

The trade-off between battery energy density and power performance is the core problem that puzzles the development of electric vehicles (EVs). Although intensive researches are performed to explore active materials with good dynamics, the heterogeneous reactivity has been identified as an important cause for inferior capability and early death, especially for electrodes characterized with high areal loading and high compacted density. Herein, the heterogeneity and its origination of layered oxide-based (LiNixCoyMn1-x-yO2, NCM) electrodes at high C-rate are investigated through operando X-ray diffraction and ex-situ time-of-flight secondary ion mass spectrometry probe. By introducing Li3V2(PO4)3@G composite as a mixed conductor additive, the heterogeneous reactivity intro-particles are successfully mitigated, enabling NCM electrodes with both high rate capability, high energy density and high cyclability. In detail, the capacity retention at 20C is increased by 2.3 times, and the capacity retention at 0.5C after 160 full cycles is increased by 1.6 times, without electrolyte additive or material modification. This study demonstrates the significance of the homogeneous electronic/ionic transportation network to the rate capability and lifetime of an electrode, and discloses the design strategy of multifunctional additives to enhance the power density of a battery by maximizing the utility of the active particles.

Facile one-pot synthesis of Co3Mo3N-loaded inside hierarchical porous bead-on-string as cathode host material for high-performance lithium-sulfur batteries

A critical factor impeding the development of lithium-sulfur batteries is the deleterious shuttle effect. To address the issue, we devise a facile electrospinning approach to integrate catalysts and hierarchically porous structures into bead-on-string carbon host material as the host material. Compared to the traditional preparation of hierarchical porous structures, the upgraded electrospinning eliminates the need for etching templates, providing a larger specific surface area (333.39 m2 g−1) and tremendous potential for large-scale production. The cathode utilizing bead-on-string Co3Mo3N as host material exhibits a remarkable capacity of 1257 mAh g−1 at 0.2 C and maintains a capacity retention rate of 90 % after 100 cycles. Even at 4.0 C, the capacity remains at 648 mAh g−1 with minimal capacity loss. Under harsh conditions (including high sulfur loading, high areal loading, and lean electrolyte), the composite cathode consistently delivers a capacity of 8 mAh cm−2. Simultaneously, systematic electrochemical testing, in-situ assessments, and DFT calculations unveil the dual-metal synergistic effects of Co3Mo3N in suppressing the shuttle effect and catalyzing the conversion of lithium polysulfides. Co3Mo3N provides chemical adsorption to significantly promote the reaction kinetics of polysulfides. This work establishes a neoteric technique and a theoretical strategy for exploring the catalytic efficacy of dual-metal nitrides for Li-S batteries.

General Fabrication of Robust Alloyed Metal Anodes for High-Performance Metal Batteries.

Revitalizing metal anodes for rechargeable batteries confronts challenges such as dendrite formation, limited cyclicity, and suboptimal energy density. Despite various efforts, a practical fabrication method for dendrite-free metal anodes remains unavailable. Herein, focusing on Li as exemplar, a general strategy is reported to enhance reversibility of the metal anodes by forming alloyed metals, which is achieved by induction heating of 3D substrate, lithiophilic metals, and Li within tens of seconds. It is demonstrated that preferred alloying interactions between substrates and lithiophilic metals created a lithiophilic metal-rich region adjacent to the substrate, serving as ultrastable lithiophilic host to guide dendrite-free deposition, particularly during prolonged high-capacity cycling. Simultaneously, an alloying between lithiophilic metals and Li creates a Li-rich region adjacent to electrolyte that reduces nucleation overpotential and constitutes favorable electrolyte-Li interface. The resultant composite Li anodes paired with high areal loading LiNi0.8Co0.1Mn0.1O2 cathodes achieve superior cycling stability and remarkable energy density above 1200 Wh L-1 (excluding packaging). Furthermore, this approach shows broader applicability to other metal anodes plagued by dendrite-related challenges, such as Na and Zn. Overall, this work paves the way for development of commercially viable metal-based batteries that offer a combination of safety, high energy density, and durability.

SPAN secondary particles enabled high energy density Lithium-Sulfur battery

High-areal-capacity electrodes and lean electrolyte are practical approaches for batteries to enhance their energy density, while it’s challenge for the lithium-sulfur batteries using nano-sized sulfurized polyacrylonitrile (SPAN) cathodes due to the sluggish charge transportation. Here, a spray-drying (SD) technique for mass production of micron-sized SPAN secondary particles (PC-SPAN) with composite coating is proposed. The composite involves polydopamine (PDA), polyacrylic acid (PAA) and polyvinyl alcohol (PVA) that physiochemically crosslinking. The rich catecholamine, hydroxyl and carboxyl groups not only construct strong and flexible adhesion among the SPAN primary particles to keep the electrode integrity, but also render built-in ion passage within the secondary particles to allow the electrode working under lean electrolyte condition. Consequently, PC-SPAN electrode with a high areal loading of 8.4 mg cm−2 delivers a higher specific capacity of 547.4 mAh g−1 at 0.3C when that of SPAN is less than 400.0 mAh g−1. In the meantime, prototype Li-SPAN battery with high energy density of 530.2 Wh kg−1 is achieved using PC-SPAN electrode with an areal capacity of 19.1 mAh cm−2 and low electrolyte/SPAN ratio of 0.93 μL mg−1, which demonstrates the feasibility of this strategy toward applicable high energy LSBs.

Construction of Hierarchical Conductive Networks for LiNi0.8Mn0.1Co0.1O2 Cathode toward Stable Cycling at High Areal Mass Loadings.

Realizing high-performance thick electrodes is considered as a practical strategy to promote the energy density of lithium-ion batteries. However, establishing effective transport pathways for both lithium-ions and electrons in a thick electrode is very challenging. This study develops a hierarchical conductive network structure for constructing high-performance NMC811 (LiNi0.8Mn0.1Co0.1O2) cathode toward stable cycling at high areal mass loadings. The hierarchical conductive networks are composed of a Li+/e- mixed conducting interface (lithium polyacrylate/hydroxyl-functionalized multiwalled carbon nanotubes) on NMC811 particles, and a segregated network of single-walled carbon nanotubes in the electrode, without any additional binders or carbon black. Such strategy endows the NMC811 cathode (up to 250µm and 50mg cm-2) with low porosity/tortuosity, ultrahigh Li+/e- conductivities and excellent mechanical property at low carbon nanotube content (1.8 wt%). It significantly improves the electrochemical reaction homogeneity along the electrode depth, meanwhile effectively inhibits the side reactions at the electrode/electrolyte interface and cracks in the NMC particles during cycling. This work emphasizes the crucial role of the electronic/ionic cooperative transportation in the performance deterioration of thick cathodes, and provide guidance for architecture optimization and performance improvement of thick electrodes toward practical applications, not just for the NMC811 cathode.

Hierarchical porous nanofibers comprising N-doped graphitic C and ZIF-8 derived hollow N-doped C nanocages for long-life K-ion battery anodes

Hierarchical porous carbon nanofibers (NFs) are designed via electrospinning, followed by simple carbonization, and applied as the anode for K-ion batteries (KIBs). The carbonization process is optimized to simultaneously satisfy sufficient graphitization of polyacrylonitrile (PAN)-derived soft carbon and complete conversion of zeolitic imidazolate framework-8 (ZIF-8) to hollow N-doped C nanocages. The prepared NFs through an optimized carbonization consists of porous and hollow N-doped C nanocages, which are encapsulated within the conductive graphitic carbon (GC) matrix, that acts as an efficient electron transport pathway. Moreover, the interconnected porous and hollow nanocages ensure a high contact area between the electrode and electrolyte and reduces the K-ion diffusion length. The N-doped GC with high electrical conductivity in the structure demonstrates reinforcing structural integrity as well as providing additional transport pathways for the unique electron transport. Therefore, the hierarchical porous carbon NFs show outstanding energy storage properties, such as stable cycle performance up to 10,000 cycles at the high current density of 1.0 A g-1 with high areal loading mass (1.8–1.9 mg cm−2) of the active material, which clearly suggests the structural advantages of the nanostructure introduced in this study.

Anion-Involved Solvation Structure of Lithium Polysulfides in Lithium-Sulfur Batteries.

Lithium polysulfides (LiPSs) are pivotal intermediates involved in all the cathodic reactions in lithium-sulfur (Li-S) batteries. Elucidating the solvation structure of LiPSs is the first step for rational design of electrolyte and improving Li-S battery performances. Herein, we investigate the solvation structure of LiPSs and find that Li salt anions tend to enter the first solvation sheath of LiPSs and form contact ion pairs in electrolyte. The anion-involved solvation structure of LiPSs significantly influences the intrinsic kinetics of the sulfur redox reactions. In particular, the LiPS solvation structure modified by lithium bis(fluorosulfonyl)imide endows Li-S batteries with reduced polarization and enhanced rate performances under high sulfur areal loading and lean electrolyte volume conditions. This work updates the fundamental understanding of the solvation chemistry of LiPSs and highlights electrolyte engineering for promoting the performances of Li-S batteries.

Anion‐Involved Solvation Structure of Lithium Polysulfides in Lithium–Sulfur Batteries

AbstractLithium polysulfides (LiPSs) are pivotal intermediates involved in all the cathodic reactions in lithium–sulfur (Li−S) batteries. Elucidating the solvation structure of LiPSs is the first step for rational design of electrolyte and improving Li−S battery performances. Herein, we investigate the solvation structure of LiPSs and find that Li salt anions tend to enter the first solvation sheath of LiPSs and form contact ion pairs in electrolyte. The anion‐involved solvation structure of LiPSs significantly influences the intrinsic kinetics of the sulfur redox reactions. In particular, the LiPS solvation structure modified by lithium bis(fluorosulfonyl)imide endows Li−S batteries with reduced polarization and enhanced rate performances under high sulfur areal loading and lean electrolyte volume conditions. This work updates the fundamental understanding of the solvation chemistry of LiPSs and highlights electrolyte engineering for promoting the performances of Li−S batteries.

Cathode Design and Evaluation for the High-Sulfur-Loading, Lean-Electrolyte Lithium–Sulfur Battery

Sulfur is a promising active material for the lithium rechargeable batteries because of its high theoretical capacity, a relatively low cost, and an environmentally friendly nature. Lithium–sulfur battery with a high-energy-density is regarded as a third-generation rechargeable battery with high potential for commercialization. The well charged and discharged lithium–sulfur battery can generate specific energy density of up to 600 W∙h kg−1. However, the charging product, sulfur, and the discharging product, lithium sulfide, both have low conductivity, which lead to low active material utilization and excessive addition of conductive materials, lowering the active material content and performance in the cathode region. The liquid active material, polysulfides, formed in the middle of the cycling reaction will dissolve in the electrolyte, causing leakage to the lithium anode to form a non-reactive lithium sulfide layer, causing severe capacity fading. Furthermore, the repeated transformation of sulfur (solid-state), polysulfides (liquid-state), and lithium sulfur (solid-state) active materials led to the sluggish battery reaction and irreversible electrolyte consumption. All and all, the chemical and physical properties of the sulfur and the combination with lithium resulted in low active material utilization, low cycling ability, low capacity-retention rate, and shortened cycle life.To fully realize the potential of the high-energy-density lithium–sulfur battery, the cathode material, configuration, and fabrication must be carefully considered. Herein, a sulfur cathode fabricated by a hot-pressing method and the evaluation of different porous substrate was also conducted. Porous conductive network is a common cathode material, which provides a large surface area and great polysulfides absorbability. However, as a result of high-sulfur-loading and lean-electrolyte cathode batteries, a low specific capacity and short cycle life are discovered, which is affected by the high electrolyte consumption. Accordingly, a carbon electrospun substrate with a non-nanoporous structure was introduced as the conductive network to achieve the high-energy-density battery design. To fabricate the free-standing sulfur cathode, sulfur powder was loaded between two porous carbon electrospun substrate by a hot-pressing technique. The cathode consists of three layers: carbon current collector, melt-in sulfur layer, and carbon interlayer, forming a sandwich-like cathode.With this design, we can accommodate high areal loading of sulfur (8 mg cm−2) in the cathode area while lessening the conductive additive (sulfur content of 73 wt%). The hot-pressed electrospun cathode, conducted under low electrolyte usage (i.e., the low electrolyte-to-sulfur ratio of 7 µL mg−1) can achieve excellent energy density (11.8 mW∙h cm−2) with a stable areal capacity up to 5.9 mA∙h cm− 2 let alone with an extended cycle life over 200 cycles. Furthermore, this devised cathode can also retain excellent cycling ability with lower ratios of electrolyte to sulfur (6–4 µL mg−1) and great rate dependent performance up to C/2 cycling rate. Figure 1

3D networked MXene thin films for high performance supercapacitors

Maximizing the energy and power density of supercapacitors requires thick electrodes, enabling a high areal loading. Simultaneously, a sophisticated, hierarchical pore structure for the active material is needed, granting high accessibility for electrons and ions. However, porosity and thickness need to be carefully balanced to maximize the active material density while ensuring high performance. Here, we show that by forming hierarchical electrodes from Ti3C2Tx 2D nanosheets in the form of interconnected 3D networked thin films (up to ∼220 nm), we can fabricate high performance thick film electrodes of up to ∼50 µm with a well-defined, hierarchical, porous structure. By balancing porosity and thickness, we demonstrate electrodes that combine a high areal loading of up to ∼7.2 mg cm−2, high material density of ∼1440 mg cm−3, and high electrochemical performance of 240 F g−1 and 140 F cm−3. Thus, we achieve electrodes with a remarkable areal capacitance of ∼1.4 F cm−2, even at high rates of 200 mV s−1, outperforming other state of the art MXene based electrodes of comparable density and thickness. We anticipate that this concept, will pave the way to transfer the exceptional properties of nanomaterial thin film electrodes to the next, macroscopic level, enabling the development of advanced, high-performance electrodes for practically relevant energy storage applications and beyond.

Precipitated Iodine Cathode Enabled by Trifluoromethanesulfonate Oxidation for Cathode/Electrolyte Mutualistic Aqueous Zn-I Batteries.

Aqueous Zn-I batteries hold great potential for high-safety and sustainable energy storage. However, the iodide shuttling effect and the hydrogen evolution reaction that occur in the aqueous electrolyte remain the main obstacles for their further development. Herein, the design of a cathode/electrolyte mutualistic aqueous (CEMA) Zn-I battery based on the inherent oxidation ability of aqueous trifluoromethanesulfonate ((OTf)- ) electrolyte toward triiodide species is presented. This results in the formation of iodine sediment particles assembled by fine iodine nanocrystals (≈10 nm). An iodine host cathode with high areal iodine loading is realized via a spontaneous absorption process that enriched redox-active iodine and iodide species from aqueous electrolyte onto nanoporous carbon based current collector. By tuning iodide redox process and suppressing competitive hydrogen evolution reaction, the assembled CEMA Zn-I batteries demonstrate a remarkable capacity retention of 76.9% over 1000 cycles at 0.5 mA cm-2 . Moreover, they exhibit a notable rate capability, with a capacity retention of 74.6% when the current density is increased from 0.5 to 5.0 mA cm-2 . This study demonstrates the feasibility of using the oxidation effect to repel redox-active species from the electrolyte to the cathode, paving a new avenue for high-performance aqueous Zn-I batteries.

Self‐Assembled Lithiophilic Interface with Abundant Nickel‐Bis(Dithiolene) Sites Enabling Highly Durable and Dendrite‐Free Lithium Metal Batteries

AbstractDespite its ultrahigh theoretical capacity and ultralow redox electrochemical potential, the practical application of lithium metal anodes is still hampered by severe dendrite growth and unstable solid electrolyte interphase (SEI). Herein, a self‐assembled lithiophilic interface (SALI) for regulating Li electroplating behavior is constructed by introducing a meticulously synthesized Ni‐bis(dithiolene)‐based molecule (NiS4‐COOH) into a hybrid fluorinated ester‐ether electrolyte. The NiS4‐COOH molecules with carboxyl functional groups can spontaneously anchor on the Li metal surface to form a SALI, whose abundant Ni‐bis(dithiolene) sites can effectively reduce the initial Li deposition overpotential and guide the subsequent uniform Li electrodeposition. Moreover, due to the interaction between the coordination unsaturated Ni atom and the negatively charged PF6−, the NiS4‐COOH additive can significantly change the ionic coordination environment in the electrolyte, which is greatly conducive to suppressing PF6− decomposition, optimizing SEI composition and accelerating Li‐ion transfer. Consequently, the NiS4‐COOH‐modified electrolyte leads to impressive electrochemical performance of Li||LiFePO4 and Li||LiNi0.8Co0.1Mn0.1O2 batteries, delivering ultrahigh Coulombic efficiencies, considerable capacity retention, and good rate performance even at high areal active material loadings. This study presents the great potential of SALIs derived from multifunctional metal‐organic hybrid electrolyte additives toward high‐specific‐energy Li metal batteries.