Defect Modulation in Cobalt Manganese Oxide Sheets for Stable and High-Energy Aqueous Aluminum-Ion Batteries

Rechargeable aqueous Al-ion batteries (AIBs) are promising low-cost, safe, and high energy density systems for large-scale energy storage. However, the strong electrostatic interaction between the Al³⁺ and the host material, usually leads to sluggish Al³⁺ diffusion kinetics and severe structure collapse of the cathode material. Consequently, aqueous AIBs currently suffer from low energy density as well as inferior rate capability and cycling stability. Here, defective cobalt manganese oxide nanosheets are reported as cathode material for aqueous AIBs to improve both reaction kinetics and stability, delivering a record high energy density of 685 Wh kg⁻¹ (based on the masses of the cathode and anode) and a reversible capacity of 585 mAh g⁻¹ at 100 mA g⁻¹ with a retention of 78% after 300 cycles. The impressive energy density and cycling stability are due to a synergistic effect between the substituted cobalt atoms and the manganese vacancies, which improve the structural stability and promote both electron conductivity and ion diffusion. When applied in aqueous Zn-ion batteries, a high specific energy of 390 Wh kg⁻¹ at 100 mA g⁻¹ is realized while retaining 84% initial capacity over 1000 cycles. The study offers a new pathway to building next-generation high-energy aqueous rechargeable metal batteries.     

Controlled Nitrogen Doping in Crumpled Graphene for Improved Alkali Metal-Ion Storage under Low-Temperature Conditions

The significant performance decay in conventional graphite anodes under low-temperature conditions is attributed to the slow diffusion of alkali metal ions, requiring new strategies to enhance the charge storage kinetics at low temperatures. Here, nitrogen (N)-doped defective crumpled graphene (NCG) is employed as a promising anode to enable stable low-temperature operation of alkali metal-ion storage by exploiting the surface-controlled charge storage mechanisms. At a low temperature of −40 °C, the NCG anodes maintain high capacities of ≈172 mAh g⁻¹ for lithium (Li)-ion, ≈107 mAh g⁻¹ for sodium (Na)-ion, and ≈118 mAh g⁻¹ for potassium (K)-ion at 0.01 A g⁻¹ with outstanding rate-capability and cycling stability. A combination of density functional theory (DFT) and electrochemical analysis further reveals the role of the N-functional groups and defect sites in improving the utilization of the surface-controlled charge storage mechanisms. In addition, the full cell with the NCG anode and a LiFePO₄ cathode shows a high capacity of ≈73 mAh g⁻¹ at 0.5 °C even at −40 °C. The results highlight the importance of utilizing the surface-controlled charge storage mechanisms with controlled defect structures and functional groups on the carbon surface to improve the charge storage performance of alkali metal-ion under low-temperature conditions.     

Si/SiO2@Graphene Superstructures for High-Performance Lithium-Ion Batteries

The superstructure composed of various functional building units is promising nanostructure for lithium-ion batteries (LIBs) anodes with extreme volume change and structure instability, such as silicon-based materials. Here, a top-down route to fabricate Si/SiO₂@graphene superstructure is demonstrated through reducing silicalite-1 with magnesium reduction and depositing carbon layers. The successful formation of superstructure lies on the strong 3D network formed by the bridged-SiO₂ matrix coated around silicon nanoparticles. Furthermore, the mesoporous Si/SiO₂ with amorphous bridged SiO₂ facilitates the deposition of graphene layers, resulting in excellent structural stability and high ion/electron transport rate. The optimized Si/SiO₂@graphene superstructure anode delivers an outstanding cycling life for ≈1180 mAh g⁻¹ at 2 A g⁻¹ over 500 cycles, excellent rate capability for ≈908 mAh g⁻¹ at 12 A g⁻¹, great areal capacity for ≈7 mAh cm⁻² at 0.5 mA cm⁻², and extraordinary mechanical stability. A full cell test using LiFePO₄ as the cathode manifests a high capacity of 134 mAh g⁻¹ after 290 loops. More notably, a series of technologies disclose that the Si/SiO₂@graphene superstructure electrode can effectively maintain the film between electrode and electrolyte in LIBs. This design of Si/SiO₂@graphene superstructure elucidates a promising potential for commercial application in high-performance LIBs.     

Effective Coupling of Amorphous Selenium Phosphide with High-Conductivity Graphene as Resilient High-Capacity Anode for Sodium-Ion Batteries

It is of great importance to develop high-capacity electrodes for sodium-ion batteries (SIBs) using low-cost and abundant materials, so as to deliver a sustainable technology as alternative to the established lithium-ion batteries (LIBs). Here, a facile ball milling process to fabricate high-capacity SIB anode is devised, with large amount of amorphous SeP being loaded in a well-connected framework of high-conductivity crystalline graphene (HCG). The HCG substrate enables fast transportation of Na ions and electrons, while accommodating huge volumetric changes of the active anode matter of SeP. The strong glass forming ability of NaxSeP helps prevent crystallization of all stable compounds but ultrafine nanocrystals of Na2Se and Na3P. Thus, the optimized anode delivers excellent rate performance with high specific capacities being achieved (855 mAh g⁻¹ at 0.2 A g⁻¹ and 345 mAh g⁻¹ at 5 A g⁻¹). More importantly, remarkable cycling stability is realized to maintain a steady capacity of 732 mAh g⁻¹ over 500 cycles, when the SeP in the SeP@HCG still remains 86% of its theoretical capacity. A high areal capacity of 2.77 mAh is achieved at a very high loading of 4.1 mg cm⁻² anode composite.     

Soft and Self-Adhesive Thermal Interface Materials Based on Vertically Aligned,Covalently Bonded Graphene Nanowalls for Efficient Microelectronic Cooling

Urged by the increasing power and packing densities of integrated circuits and electronic devices, efficient dissipation of excess heat from hot spot to heat sink through thermal interface materials (TIMs) is a growing demand to maintain system reliability and performance. In recent years, graphene-based TIMs received considerable interest due to the ultrahigh intrinsic thermal conductivity of graphene. However, the cooling efficiency of such TIMs is still limited by some technical difficulties, such as production-induced defects of graphene, poor alignment of graphene in the matrix, and strong phonon scattering at graphene/graphene or graphene/matrix interfaces. In this study, a 120  µ m-thick freestanding film composed of vertically aligned, covalently bonded graphene nanowalls (GNWs) is grown by mesoplasma chemical vapor deposition. After filling GNWs with silicone, the fabricated adhesive TIMs exhibit a high through-plane thermal conductivity of 20.4 W m⁻¹ K⁻¹ at a low graphene loading of 5.6 wt%. In the TIM performance test, the cooling efficiency of GNW-based TIMs is ≈ 1.5 times higher than that of state-of-the-art commercial TIMs. The TIMs achieve the desired balance between high through-plane thermal conductivity and small bond line thickness, providing superior cooling performance for suppressing the degradation of luminous properties of high-power light-emitting diode chips.     

Besides the Capacitive and Diffusion Control: Inner-Surface Controlled Bismuth Based Electrode Facilitating Potassium-Ion Energy Storage

One of the major challenges of potassium-ion hybrid capacitors (PIHCs) is to explore favorable anode materials with fast reaction kinetics to match the cathodes. Here, an “inner-surface” controlled electrochemistry mechanism based on bismuth electrode is proposed and in-depth studied, which is different from the capacitive or diffusion controlled electrode. Such inner-surface controlled electrochemistry performance gives a high K ion diffusion ability under not only room temperature (RT) but also low temperature (LT). In this study, a kind of conjunct-like bismuth nanoparticle (CBN) is fabricated to model such an advantage. The CBN anode for PIBs displays ultra-long cycling stability and excellent rate capability, especially with a reversible capacity of 212.9 mAh g⁻¹ at 30 A g⁻¹ after 5000 cycles under RT. At −20 °C, the CBN anode achieves a capacity of 191.9 mAh g⁻¹ at 10 A g⁻¹ after 10 000 cycles. Coupling with activate carbon cathode, the as-assembled PIHCs deliver high energy/power densities (111.8 Wh kg⁻¹/412.8 W kg⁻¹ and 29 Wh kg⁻¹/14 312.6 W kg⁻¹), which outperforms those of previously reported PIHCs and other hybrid capacitors. The study provides a new understanding of the energy storage mechanism for bismuth-based electrodes and accelerates the development of advancing potassium ion storage devices, especially at LT.     

Bilayered VOPO4⋅2H2O Nanosheets with High-Concentration Oxygen Vacancies for High-Performance Aqueous Zinc-Ion Batteries

2D materials with atomically precise thickness and tunable chemical composition hold promise for potential applications in nanoenergy. Herein, a bilayer-structured VOPO₄⋅2H₂O (bilayer-VOP) nanosheet is developed with high-concentration oxygen vacancies ([Vo˙˙]) via a facile liquid-exfoliation strategy. Galvanostatic intermittent titration technique study indicates a 6 orders of magnitude higher zinc-ion coefficient in bilayer-VOP nanosheets (4.6 × 10⁻⁷ cm⁻² s⁻¹) compared to the bulk counterpart. Assistant density functional theory (DFT) simulation indicates a remarkably enhanced electron conductivity with a reduced bandgap of ≈ 0.2 eV (bulk sample: 1.5 eV) along with an ultralow diffusion barrier of ≈ 0.08 eV (bulk sample: 0.13 eV) in bilayer-VOP nanosheets, thus leading to superior diffusion kinetics and electrochemical performance. Mott–Schottky (impedance potential) measurement also demonstrates a great increase in electronic conductivity with ≈ 57-fold increased carrier concentration owing to its high concentration [Vo˙˙]. Benefited by these unique features, the rechargeable zinc-ion battery composed of bilayer-VOP nanosheets cathode exhibits a remarkable capacity of 313.6 mAh g⁻¹ (0.1 A g⁻¹), an energy density of 301.4 Wh kg⁻¹, and a prominent rate capability (168.7 mAh g⁻¹ at 10 A g⁻¹).     

Outstanding Low-Temperature Performance of Structure-Controlled Graphene Anode Based on Surface-Controlled Charge Storage Mechanism

The energy and power performance of lithium (Li)-ion batteries is significantly reduced at low-temperature conditions, which is mainly due to the slow diffusion of Li-ions in graphite anode. Here, it is demonstrated that the effective utilization of the surface-controlled charge storage mechanism through the transition from layered graphite to 3D crumpled graphene (CG) dramatically improves the Li-ion charge storage kinetics and structural stability at low-temperature conditions. The structure-controlled CG anode prepared via a one-step aerosol drying process shows a remarkable rate-capability by delivering ≈206 mAh g^–1 at a high current density of 10 A g^–1 at room temperature. At an extremely low temperature of −40 °C, CG anode still exhibits a high capacity of ≈154 mAh g^–1 at 0.01 A g^–1 with excellent rate-capability and cycling stability. A combination of electrochemical studies and density functional theory (DFT) reveals that the superior performance of CG anode stems from the dominant surface-controlled charge storage mechanism at various defect sites. This study establishes the effective utilization of the surface-controlled charge storage mechanism through structure-controlled graphene as a promising strategy to improve the charge storage kinetics and stability under low-temperature conditions.     

Phase Engineering of Nickel Sulfides to Boost Sodium- and Potassium-Ion Storage Performance

Sulfides are promising anode candidates because of their relatively large theoretical discharge/charge specific capacity and pretty small volume changes, but suffers from sluggish kinetics and structural instability upon cycling. Phase engineering can be designed to overcome the weakness of the electrochemical performance of sulfide anodes. By choosing nickel sulfides (α-NiS, β-NiS, and NiS₂) supported by reduced graphene oxide (rGO) as model systems, it is demonstrated that the nickel sulfides with different crystal structures show different performances in both sodium-ion and potassium-ion batteries. In particular, the α-NiS/rGO display superior stable capacity (≈426 mAh g⁻¹ for 500 cycles at 500 mA g⁻¹) and exceptional rate capability (315 mAh g⁻¹ at 2000 mA g⁻¹). The combined density functional theory calculations and experimental studies reveal that the hexagonal structure is more conducive to ion absorption and conduction, a higher pseudocapacitive contribution, and higher mechanical ability to relieve the stress caused by the volume changes. Correspondingly, the phase engineered nickel sulfide coupled with the conducting rGO network synergistically boosts the electrochemical performance of batteries. This work sheds light on the use of phase engineering as an essential strategy for exploring materials with satisfactory electrochemical performance for sodium-ion and potassium-ion batteries.     

Efficient Charge Storage in Zinc–Iodine Batteries based on Pre-Embedded Iodine-Ions with Reduced Electrochemical Reaction Barrier and Suppression of Polyiodide Self-Shuttle Effect

Aqueous zinc Iodine batteries are considered as a promising energy storage system due to their high energy/power density, and safety. However, polyiodide shuttling leads to severe active mass loss, which results in lower Coulombic efficiency and limits the cyclic life. Herein, a novel structure-limiting strategy to pre-embed iodide ions into Prussian blue (PBI) is proposed. The DFT calculations and electrochemical characterization reveal that the formation of Ferrum Iodine bond reduces the electrochemical reaction energy barrier of subsequent iodide-ions at the pre-embedding sites, improves the I⁻ oxidation reaction kinetic process, and suppresses the polyiodide self-shuttle. The PBI//Zn batteries exhibit a low Tafel slope (155 mV dec⁻¹). Moreover, UV–vis spectroscopy confirms that the proposed strategy suppresses the polyiodide self-shuttle. As a result, the PBI//Zn battery achieves high iodide utilization and Coulomb efficiency (242 mAh g⁻¹ at 0.2 A g⁻¹, CEs ≈ 100%), as well as high multiplicity performance of 197.2 mAh g⁻¹ even at 10 A g⁻¹(82% of initial capacity). The PBI//Zn battery also renders excellent cyclic stability with a capacity retention of 94% at 4 A g⁻¹ after 1500 cycles. The device exhibits a high energy density of 142 W h kg⁻¹ at a power density of 5538 W kg⁻¹.     

A Self-Growth Strategy for Simultaneous Modulation of Interlayer Distance and Lyophilicity of Graphene Layers toward Ultrahigh Potassium Storage Performance

Herein, a simple but effective self-growth strategy to simultaneously modulate the interlayer distance and lyophilicity of graphene layers, which results in ultrahigh potassium-storage performances for carbon materials, is reported. This strategy involves the uniform adsorption of individual metal ions on the oxygen-containing groups on graphene oxide via electrostatic/coordination interactions and in situ self-conversion reaction between the metal ions and the oxygen-containing groups to form lyophilic ultrasmall metal oxide nanoparticles modified/intercalated graphene skeleton (OM-G) with precisely regulated interlayer distance. The synergistic effect of expanded interlayer distance and enhanced lyophilicity is revealed for the first time to significantly reduce the ion diffusion barrier and enhance ion transport kinetics by experimental and theoretical analysis. As a result, such unique OM-G monolith as free-standing anode for potassium-ion battery (PIB) delivered an ultrahigh reversible capability of 496.4 mAh g⁻¹ at 0.1 A g⁻¹, excellent rate capability (306.6 mAh g⁻¹ at 10 A g⁻¹), and remarkable long-term cycling stability (96.3% capacity retention over 2000 cycles at 1 A g⁻¹), which are not only much better than those of previous graphene/carbon materials but also among the best performances for all PIB anodes ever reported. This study provides new fundamental insights for boosting the electrochemical properties of electrode materials.     

Fast-Charging and Ultrahigh-Capacity Zinc Metal Anode for High-Performance Aqueous Zinc-Ion Batteries

Although some strategies have been triggered to address the intrinsic drawbacks of zinc (Zn) anodes in aqueous Zn-ion batteries (ZIBs), the larger issue of Zn anodes unable to cycle at a high current density with large areal capacity is neglected. Herein, the zinc phosphorus solid solution alloy (ZnP) coated on Zn foil (Zn@ZnP) prepared via a high-efficiency electrodeposition method as a novel strategy is proposed. The phosphorus (P) atoms in the coating layer are beneficial to fast ion transfer and reducing the electrochemical activation energy during Zn stripping/plating processes. Besides, a lower energy barrier of Zn²⁺ transferring into the coating can be attained due to the additional P. The results show that the as-prepared Zn@ZnP anode in the symmetric cell can be cycled at a current density of 15 mA cm⁻² with an areal capacity of 48 mAh cm⁻² (depth of discharge, DOD ≈ 82%) and even at an ultrahigh current density of 20 mA cm⁻² and DOD ≈ 51%. Importantly, a discharge capacity of 154.4 mAh g⁻¹ in the Zn/MnO₂ full cell can be attained after 1000 cycles at 1 A g⁻¹. The remarkable effect achieved by the developed strategy confirms its prospect in the large-scale application of ZIBs for high-power devices.     

In Situ Synthesis of Graphene-Coated Silicon Monoxide Anodes from Coal-Derived Humic Acid for High-Performance Lithium-Ion Batteries

Silicon monoxide (SiO) is attaining extensive interest amongst silicon-based materials due to its high capacity and long cycle life; however, its low intrinsic electrical conductivity and poor coulombic efficiency strictly limit its commercial applications. Here low-cost coal-derived humic acid is used as a feedstock to synthesize in situ graphene-coated disproportionated SiO (D-SiO@G) anode with a facile method. HR-TEM and XRD confirm the well-coated graphene layers on a SiO surface. Scanning transmission X-ray microscopy and X-ray absorption near-edge structure spectra analysis indicate that the graphene coating effectively hinders the side-reactions between the electrolyte and SiO particles. As a result, the D-SiO@G anode presents an initial discharge capacity of 1937.6 mAh g⁻¹ at 0.1 A g⁻¹ and an initial coulombic efficiency of 78.2%. High reversible capacity (1023 mAh g⁻¹ at 2.0 A g⁻¹), excellent cycling performance (72.4% capacity retention after 500 cycles at 2.0 A g⁻¹), and rate capability (774 mAh g⁻¹ at 5 A g⁻¹) results are substantial. Full coin cells assembled with LiFePO₄ electrodes and D-SiO@G electrodes display impressive rate performance. These results indicate promising potential for practical use in high-performance lithium-ion batteries.     

Ni (II) Coordination Supramolecular Grids for Aqueous Nickel-Zinc Battery Cathodes

Aqueous rechargeable nickel-zinc batteries (NZBs) have the advantages of economical cost and reliable safety. Despite reports of success in achieving high-utilization and stable Zn anodes, the practical application of NZBs has been plagued by the restrictive capacity density and degradation of the Ni-based cathode. Herein, it is reported that nickel-ligand coordination grids (NCGs) with a high theoretical capacity of 128.12 mAh g⁻¹ offer a fast faradic reaction while maintaining good reversibility due to the abundant open metal sites and flexible network structures. In situ and ex situ characterizations demonstrate that the graphene nanosheet (GN) modification of NCGs supramolecular substantially boosts surface charge and reducing the work function of supramolecular compounds. A Ni//Zn battery using such a graphene organic-inorganic material (G-NCGs) achieve a high gravimetric capacity of 113.8 mAh g⁻¹ at 0.5 A g⁻¹ with 50% of its initial capacitance retained after 2000 cycles and an exceptional rate capacity of 43.3 mAh g⁻¹ even at the current density of 5.0 A g⁻¹.     

Integrating Energy Band Alignment and Oxygen Vacancies Engineering of TiO2 Anatase/Rutile Homojunction for Kinetics-Enhanced Li–S Batteries

The inferior shuttle effect of intermediate lithium polysulfides and the sluggish kinetics of sulfur redox reaction are two serious puzzles for the application of lithium–sulfur batteries. Herein, energy band alignment is combined with oxygen vacancies engineering to obtain TiO₂ anatase/rutile homojunction (A/R-TiO₂) with effective immobilization and high-efficiency catalytic conversion of polysulfides. Theoretical calculations and experiments reveal that the near perfect energy band alignment in A/R-TiO₂ is conducive to fluent charge transfer and high catalytic activity, while the rich oxygen vacancies are engineered to provide abundant active sites for anchoring and accelerating conversion of soluble polysulfides. As a result, a battery with A/R-TiO₂-modified separator delivers a marked sulfur utilization (1210 mAh g⁻¹ at 0.1 C and 689 mAh g⁻¹ at 1 C, 3.75 mg cm⁻²) and a high capacity retention of 63% over 300 cycles at 0.5 C (3.25 mg cm⁻²). More importantly, the A/R-TiO₂-modified separator endows the pouch cell with a high capacity of 128.5 mAh at 0.05 C with a lean electrolyte/sulfur ratio for practical application (S loading: 4 mg cm⁻²).     

A Shape-Variable,Low-Temperature Liquid Metal–Conductive Polymer Aqueous Secondary Battery

A shape-variable aqueous secondary battery operating at low temperature is developed using Ga₆₈In₂₂Sn₁₀ (wt%) as a liquid metal anode and a conductive polymer (polyaniline (PANI)) cathode. In the GaInSn alloy anode, Ga is the active component, while Sn and In increase the acid resistance and decrease the eutectic point to -19 °C. This enables the use of strongly acidic aqueous electrolytes (here, pH 0.9), thereby improving the activity and stability of the PANI cathode. Consequently, the battery exhibits excellent electrochemical performance and mechanical stability. The GaInSn–PANI battery operates via a hybrid mechanism of Ga³⁺ stripping/plating and Cl⁻ insertion/extraction and delivers a high reversible capacity of over 223.9 mAh g⁻¹ and an 80.3% retention rate at 0.2 A g⁻¹ after 500 cycles, as well as outstanding power and energy densities of 4300 mW g⁻¹ and 98.7 mWh g⁻¹, respectively. Because of the liquid anode, the battery without packaging can be deformed with a small force of several millinewtons without any capacity loss. Moreover, at approximately -5 °C, the battery delivers a capacity of 67.8 mAh g⁻¹ at 0.2 A g⁻¹ with 100% elasticity. Thus, the battery is promising as a deformable energy device at low temperatures and in demanding environments.     

On the Practical Applicability of Rambutan-like SiOC Anode with Enhanced Reaction Kinetics for Lithium-Ion Storage

Silicon oxycarbide (SiOC) possesses great potential in lithium-ion batteries owing to its tunable chemical component, high reversible capacity, and small volume expansion. However, its commercial application is restricted due to its poor electrical conductivity. Herein, rambutan-like vertical graphene coated hollow porous SiOC (Hp-SiOC@VG) spherical particles with an average diameter of 302 nm are fabricated via a hydrothermal treatment combined CH₄ pyrolysis strategy for the first time. As-prepared Hp-SiOC@VG exhibits a large reversible capacity of 729 mAh g⁻¹ at 0.1 A g⁻¹, remarkable cycling stability of 98% capacity retention rate after 600 cycles at 1.0 A g⁻¹ and high rate capability of 289 mAh g⁻¹ at 5.0 A g⁻¹ owing to the unique structure of the particles and the electrical conductivity of the vertical graphene. Density functional theory calculations reveal that the higher contents of SiO₃C and SiO₂C₂ structural units in the SiOC are beneficial to enhance the Li⁺ storage capacity. Additionally, the full-cell assembled with Hp-SiOC@VG and LiFePO₄ delivers up to 74% capacity retention rate after 100 cycles at 0.2 A g⁻¹. This work reports a new way for the facile preparation of template-free hollow porous materials and expands the application prospects of SiOC-based anode for lithium-ion batteries.     

Modified Solid Electrolyte Interphases with Alkali Chloride Additives for Aluminum–Sulfur Batteries with Enhanced Cyclability

Aluminum–sulfur batteries employing high-capacity and low-cost electrode materials, as well as non-flammable electrolytes, are promising energy storage devices. However, the fast capacity fading due to the shuttle effect of polysulfides limits their further application. Herein, alkaline chlorides, for example, LiCl, NaCl, and KCl are proposed as electrolyte additives for promoting the cyclability of aluminum–sulfur batteries. Using NaCl as a model additive, it is demonstrated that its addition leads to the formation of a thicker, Na_xAl_yO₂-containing solid electrolyte interphase on the aluminum metal anode (AMA) reducing the deposition of polysulfides. As a result, a specific discharge capacity of 473 mAh g⁻¹ is delivered in an aluminum–sulfur battery with NaCl-containing electrolyte after 50 dis-/charge cycles at 100 mA g⁻¹. In contrast, the additive-free electrolyte only leads to a specific capacity of 313 mAh g⁻¹ after 50 cycles under the same conditions. A similar result is also observed with LiCl and KCl additives. When a KCl-containing electrolyte is employed, the capacity increases to 496 mA h g⁻¹ can be achieved after 100 cycles at 50 mA g⁻¹. The proposed additive strategy and the insight into the solid electrolyte interphase are beneficial for the further development of long-life aluminum–sulfur batteries.     

Covalently Interlinked Graphene Sheets with Sulfur-Chains Enable Superior Lithium–Sulfur Battery Cathodes at Full-Mass Level

Sulfur represents a low‑cost, sustainable, and high theoretical capacity cathode material for lithium–sulfur batteries, which can meet the growing demand in portable power sources, such as in electric vehicles and mobile information technologies. However, the shuttling effect of the formed lithium polysulfides, as well as their low conductivity, compromise the electrochemical performance of lithium–sulfur cells. To tackle this challenge, a so far unexplored cathode, composed of sulfur covalently bonded directly on graphene is developed. This is achieved by leveraging the nucleophilicity of polysulfide chains, which react readily with the electrophilic centers in fluorographene, as experimental and theoretical data unveil. The reaction leads to the formation of carbon–sulfur covalent bonds and a particularly high sulfur content of 80 mass%. Owing to these features, the developed cathode exhibits excellent performance with only 5 mass% of conductive carbon additive, delivering very high full‑cathode‑mass capacities and rate capability, combined with superior cycling stability. In combination with a fluorinated ether as electrolyte additive, the capacity persists at ≈700 mAh g⁻¹ after 100 cycles at 0.1 C, and at ≈644 mAh g⁻¹ after 250 cycles at 0.2 C, keeping ≈470 mAh g⁻¹ even after 500 cycles.     

Large Cumulative Capacity Enabled by Regulating Lithium Plating with Metal–Organic Framework Layers on Porous Carbon Nanotube Scaffolds

The high specific capacity of lithium metal is ideal to meet the current demand in rechargeable batteries but lithium dendrites and irreversible volume expansions are major hurdles. 3D lithium host materials can alleviate these problems by lowering the current density with large surface areas and accommodating lithium metal in their pores. However, lithium dendrites are persistently observed because of sluggish lithium-ion diffusion through tortuous pores, resulting in clogging and thereby dendrite growth. Herein, layered metal–organic frameworks (MOFs) are deposited on carboxylated carbon nanotube (CNT) scaffolds via coordination bonding. The MOF layer on the outside of the CNT scaffold has augmented lithium insertion into the porous scaffolds (24 mAh cm⁻² at 8 mA cm⁻²) and lithium plating/stripping lifetime (over 1700 h with 20 mAh cm⁻² cycle⁻¹). MOF has pores large enough for lithium ions to permeate through, and its electronically insulating property creates capacitive effects, distributing lithium ions over the surface of the MOF layer to avoid dendrite growth and clogging during lithium plating. Outstanding volumetric and gravimetric capacities (≈940 mAh cm⁻³ and ≈980 mAh g⁻¹) along with exceptional cumulative capacity (≈4.9 Ah cm⁻²) are obtained. This promising approach can store lithium without dendrites to deliver high energy densities required for the current rechargeable batteries.