Excellent Cycling Stability Research Articles

ZnxMnO2/PPy Nanowires Composite as Cathode Material for Aqueous Zinc‐Ion Hybrid Supercapacitors

ABSTRACTOver the past decade, the extensive consumption of finite energy resources has caused severe environmental pollution. Meanwhile, the promotion of renewable energy sources is limited by their intermittent and regional nature. Thus, developing effective energy storage and conversion technologies and devices holds considerable importance. Zinc‐ion hybrid supercapacitors (ZISCs) merge the beneficial aspects of both supercapacitors and batteries, rendering them an exceptionally promising energy storage method. As an important cathode material for ZISCs, the tunnel structure MnO2 has poor conductivity and structural stability. Herein, the ZnxMnO2/PPy (ZMOP) electrode materials are prepared by hydrothermal method. Doping with Zn2+ is used to enhance its structural stability, while adding polypyrrole to improve its conductivity. Therefore, the fabricated ZMOP cathode presents superb specific capacity (0.1 A g−1, 156.4 mAh g−1) and remarkable cycle performance (82.6%, 5000 cycles, 0.2 A g−1). Furthermore, the assembled aqueous ZISCs with ZMOP cathode and PPy‐derived porous carbon nanotube anode obtain a superb capacity of 109 F g−1 at 0.1 A g−1. Meanwhile, at a power density of 867 W kg−1, the corresponding energy density can achieve 20 Wh kg−1. And over 5000 cycles at 0.2 A g−1, the cycle performance of ZISCs maintains at 86.4%, which exhibits excellent cycle stability. This suggests that ZMOP nanowires are potential cathode materials for superior‐performance aqueous ZISCs.

Diketopyrrolopyrrole‐Activated Dynamic Condensation Approach to Narrow‐Band Gap Vinylene‐Linked Covalent Organic Frameworks

Vinyl units intrinsically featuring less steric, nonpolarity, and unsaturated character, are well‐known π‐bridge used in the synthesis of high‐performance semiconducting materials. Two‐dimensional (2D) vinylene‐linked covalent organic frameworks (COFs) represent a promising class of π‐conjugated structures, however, the range of available monomers for the reversible formation of carbon‐carbon double bonds remains limited. In this study, a new class of 2D vinylene‐linked COFs were synthesized using dimethyldiketopyrrolopyrrole (DM‐DPP) as the key monomer. The strong electron deficiency of diketopyrrolopyrrole (DPP) makes its methyl substituents readily activated upon the cocatalysis of L‐proline and 4‐dimethylaminopyridine in aqueous solution to conduct dynamic condensation with tritopic aromatic aldehydes. The resulting COFs crystallized in an eclipsed AA stacking arrangement and featured abundant, regular nanochannels. Their robust vinyl DPP‐linking mode enhanced donor‐π‐acceptor conjugation and promoted π‐stacked alignment along the vertical direction. Consequently, the synthesized COFs exhibited band gaps as narrow as 1.02 eV and demonstrated excellent light‐harvesting capability across the visible to near‐infrared I (NIR‐I) regions. Furthermore, the COFs could be converted into free‐standing thin pellets through simple pressure casting, and show excellent photothermal response and cycling stability under different light sources.

Diketopyrrolopyrrole‐Activated Dynamic Condensation Approach to Narrow‐Band Gap Vinylene‐Linked Covalent Organic Frameworks

Vinyl units intrinsically featuring less steric, nonpolarity, and unsaturated character, are well‐known π‐bridge used in the synthesis of high‐performance semiconducting materials. Two‐dimensional (2D) vinylene‐linked covalent organic frameworks (COFs) represent a promising class of π‐conjugated structures, however, the range of available monomers for the reversible formation of carbon‐carbon double bonds remains limited. In this study, a new class of 2D vinylene‐linked COFs were synthesized using dimethyldiketopyrrolopyrrole (DM‐DPP) as the key monomer. The strong electron deficiency of diketopyrrolopyrrole (DPP) makes its methyl substituents readily activated upon the cocatalysis of L‐proline and 4‐dimethylaminopyridine in aqueous solution to conduct dynamic condensation with tritopic aromatic aldehydes. The resulting COFs crystallized in an eclipsed AA stacking arrangement and featured abundant, regular nanochannels. Their robust vinyl DPP‐linking mode enhanced donor‐π‐acceptor conjugation and promoted π‐stacked alignment along the vertical direction. Consequently, the synthesized COFs exhibited band gaps as narrow as 1.02 eV and demonstrated excellent light‐harvesting capability across the visible to near‐infrared I (NIR‐I) regions. Furthermore, the COFs could be converted into free‐standing thin pellets through simple pressure casting, and show excellent photothermal response and cycling stability under different light sources.

Direct Epitaxial Growth of Polycrystalline MOF Membranes on Cu Foils for Uniform Li Deposition in Long‐life Anode‐free Li Metal Batteries

AbstractAnode‐free Li‐metal battery (AFLMB) is being developed as the next generation of advanced energy storage devices. However, the low plating and stripping reversibility of Li on Cu foil prevents its widespread application. A promising avenue for further improvement is to enhance the lithophilicity of Cu foils and optimise their surfaces through a metal–organic framework (MOF) functional layer. However, excessive binder usage in the current approaches obscures the active plane of the MOF, severely limiting its performance. In response to this challenge, MOF polycrystalline membrane technology has been integrated into the field of AFLMB in this work. The dense and seamless HKUST‐1 polycrystalline membrane was deposited on Cu foil (HKUST‐1 M@Cu) via an epitaxial growth strategy. In contrast to traditional MOF functional layers, this binder‐free polycrystalline membrane fully exposes lithophilic sites, effectively reducing the nucleation overpotential and optimising the deposition quality of Li. Consequently, the Li plating layer becomes denser, eliminating the effects of dendrites. When coupled with LiFePO4 cathodes, the battery based on the HKUST‐1 membrane exhibits excellent rate performance and cycling stability, achieving a high reversible capacity of approximately 160 mAh g−1 and maintaining a capacity retention of 80.9 % after 1100 cycles.

Ultra‐Tough Dynamic Supramolecular Ion‐Conducting Elastomer Induced Uniform Li+ Transport and Stabilizes Interphase Ensures Dendrite‐Free Lithium Metal Anodes

AbstractArtificial polymer solid electrolyte interphases (SEIs) with microphase‐separated structures provide promising solutions to the inhomogeneity and cracking issues of natural SEIs in lithium metal batteries (LMBs). However, achieving homogeneous ionic conductivity, excellent mechanical properties, and superior interfacial stability remains challenging due to interference from hard‐phase domains in ion transport and solid‐solid interface issues with lithium metal. Herein, we present a dynamic supramolecular ion‐conducting poly (urethane‐urea) interphase (DSIPI) that achieves these three properties through modulating the hard‐phase domains and constructing a composite SEI in situ. The soft‐phase polytetrahydrofuran backbone, featuring loose Li+−O coordinating interactions, ensures uniform Li+ transport. Concurrently, sextuple hydrogen bonds in the hard phase dissipate strain energy through sequential bond cleavage, thereby imparting exceptional mechanical properties. Moreover, enriched bis (trifluoromethanesulfonyl) imide anion (TFSI−) in DSIPI promotes the in situ formation of a stable polymer‐inorganic composite SEI during cycling. Consequently, the DSIPI‐protected lithium anode (DSIPI@Li) enables symmetric cells with exceptional cyclability exceeding 4,000 hours at an ultra‐high current density of 20 mA cm−2, thereby demonstrating excellent cycling stability. Furthermore, DSIPI@Li facilitates stable operation of the pouch cells under the constraints of a high‐loading LiNi0.8Co0.1Mn0.1O2 cathode and low negative/positive capacity (N/P) ratio. This work presents a powerful strategy for designing artificial SEIs and high‐performance LMBs.

Design of high-performance binary carbonate/hydroxide Ni-based supercapacitors for photo-storage systems

Silicon solar cells were used to convert solar energy into electrical energy, and a supercapacitor was designed to store this energy. To maximize the surface area of the electrodes, a three-dimensional Ni foam substrate was employed, onto which Ni-based compounds were deposited to enhance the electrochemical performance of the electrodes. Specifically, to address the conductivity reduction problem that arises when using only Ni ions, we introduced transition metal ions such as Mn, Co, Cu, Fe, and Zn to create binary compounds as electrode material. These binary metal compounds provided high electronic conductivity, structural stability, and reversible capacity, thereby optimizing the performance of the supercapacitor. As a result, the optimized NiCo(CO3)(OH)2 electrode demonstrated high capacity and excellent cycle stability, exhibiting an energy density of 35.5 Wh kg−1 and a power density of 2555.6 W kg−1 as an asymmetric supercapacitor device. Furthermore, when this device was combined directly with silicon solar cells, it achieved a storage efficiency of 63 % and an overall efficiency of 5.17 % under an illumination intensity of 10 mW cm−2. These findings suggest the potential for commercializing high-performance self-charging energy storage devices and contribute significantly to the advancement of energy storage technology.

Ultra-Tough Dynamic Supramolecular Ion-Conducting Elastomer Induced Uniform Li+ Transport and Stabilizes Interphase Ensures Dendrite-Free Lithium Metal Anodes.

Artificial polymer solid electrolyte interphases (SEIs) with microphase-separated structures provide promising solutions to the inhomogeneity and cracking issues of natural SEIs in lithium metal batteries (LMBs). However, achieving homogeneous ionic conductivity, excellent mechanical properties, and superior interfacial stability remains challenging due to interference from hard-phase domains in ion transport and solid-solid interface issues with lithium metal. Herein, we present a dynamic supramolecular ion-conducting poly (urethane-urea) interphase (DSIPI) that achieves these three properties through modulating the hard-phase domains and constructing a composite SEI in situ. The soft-phase polytetrahydrofuran backbone, featuring loose Li+-O coordinating interactions, ensures uniform Li+ transport. Concurrently, sextuple hydrogen bonds in the hard phase dissipate strain energy through sequential bond cleavage, thereby imparting exceptional mechanical properties. Moreover, enriched bis (trifluoromethanesulfonyl) imide anion (TFSI-) in DSIPI promotes the in situ formation of a stable polymer-inorganic composite SEI during cycling. Consequently, the DSIPI-protected lithium anode (DSIPI@Li) enables symmetric cells with exceptional cyclability exceeding 4,000 hours at an ultra-high current density of 20 mA cm-2, thereby demonstrating excellent cycling stability. Furthermore, DSIPI@Li facilitates stable operation of the pouch cells under the constraints of a high-loading LiNi0.8Co0.1Mn0.1O2 cathode and low negative/positive capacity (N/P) ratio. This work presents a powerful strategy for designing artificial SEIs and high-performance LMBs.

Strong Replaces Weak: ​Hydrogen Bond‐Anchored Electrolyte Enabling Ultra‐Stable and Wide‐Temperature Aqueous Zinc‐Ion Capacitors

Despite aqueous electrolytes offer a great opportunity for large‐scale energy storage owing to their safety and cost‐effectiveness, their practical application suffers from the parasitic side reactions and poor temperature adaptability stemming from weak hydrogen‐bond (HB) network in free water. Here, we propose the guiding thought “strong replaces weak” to design hydrogen bond‐anchored electrolyte by introducing sulfolane (SL) for disrupting the regular weak HB network and contributing to superior temperature tolerance. Judiciously combined experimental characterization and theoretical calculation confirm that SL can remodel the primary solvation shell of metal ions, customize stable electrode interface chemistry and restrain the side reactions. Consequently, symmetric supercapacitor constructed by activated carbon (AC) electrodes is able to fully work within a voltage range of 2.4 V and reach high capacitance retention of 89.8% after 60000 cycles. Additionally, Zn anodes exhibit ultra‐stable Zn plating/stripping behaviors and a wide temperature range (‐20 ~ 60 °C), and zinc‐ion capacitor (Zn//AC) also delivers an excellent cycling stability with capacity retention of 99.7% after 55000 cycles, implying that the designed electrolyte has practical application potential in extreme environments. This work proposes a novel critical solvation strategy that paves the route for the construction of ultra‐stable and wide‐temperature aqueous energy storage devices.

Strong Replaces Weak: ​Hydrogen Bond‐Anchored Electrolyte Enabling Ultra‐Stable and Wide‐Temperature Aqueous Zinc‐Ion Capacitors

Despite aqueous electrolytes offer a great opportunity for large‐scale energy storage owing to their safety and cost‐effectiveness, their practical application suffers from the parasitic side reactions and poor temperature adaptability stemming from weak hydrogen‐bond (HB) network in free water. Here, we propose the guiding thought “strong replaces weak” to design hydrogen bond‐anchored electrolyte by introducing sulfolane (SL) for disrupting the regular weak HB network and contributing to superior temperature tolerance. Judiciously combined experimental characterization and theoretical calculation confirm that SL can remodel the primary solvation shell of metal ions, customize stable electrode interface chemistry and restrain the side reactions. Consequently, symmetric supercapacitor constructed by activated carbon (AC) electrodes is able to fully work within a voltage range of 2.4 V and reach high capacitance retention of 89.8% after 60000 cycles. Additionally, Zn anodes exhibit ultra‐stable Zn plating/stripping behaviors and a wide temperature range (‐20 ~ 60 °C), and zinc‐ion capacitor (Zn//AC) also delivers an excellent cycling stability with capacity retention of 99.7% after 55000 cycles, implying that the designed electrolyte has practical application potential in extreme environments. This work proposes a novel critical solvation strategy that paves the route for the construction of ultra‐stable and wide‐temperature aqueous energy storage devices.

Modulating Local Oxygen Coordination to Achieve Highly Reversible Anionic Redox and Negligible Voltage Decay in O2‐Type Layered Cathodes for Li‐Ion Batteries

AbstractO2‐type layered oxides have emerged as promising cathode materials for high‐energy lithium‐ion batteries, offering a solution to mitigate voltage decay through reversible transition metal (TM) migration between TM and Li layers during cycling. However, achieving a fully reversible oxygen redox remains a significant challenge. Here, this is addressed by introducing Li─O─Li configurations in the layered structure of Li0.85□0.15[Li0.08□0.04Ni0.22Mn0.66]O2 (O2‐LLNMO), where □ represents vacancies. This adjustment alters the redox‐active oxygen environment and increases the energy gap between the O 2p nonbonding and TM─O antibonding bands. As a result, the contribution of lattice oxygen to capacity is significantly enhanced, improving the reversibility of oxygen redox processes. The O2‐LLNMO cathode demonstrates minimal voltage decay (0.13 mV per cycle) and excellent cycling stability, retaining 95.8% of its capacity after 100 cycles. A novel strategy is presented to design high‐performance layered oxides with stable anionic redox activity, advancing the development of next‐generation lithium‐ion batteries.

Ultrafast Tailoring Amorphous Zn0.25V2O5 with Precision‐Engineered Artificial Atomic‐Layer 1T′‐MoS2 Cathode Electrolyte Interphase for Advanced Aqueous Zinc‐Ion Batteries

AbstractVanadium (V)‐based oxides as cathode materials for aqueous zinc‐ion batteries (AZIBs) still encounter challenges such as sluggish Zn2+ diffusion kinetics and V‐dissolution, thus leading to severe capacity fading and limited life span. Here, we designed an ultrafast and facile colloidal chemical synthesis strategy based on crystalline Zn0.25V2O5 (c‐ZVO) to successfully prepare a‐ZVO@MoS2 core@shell heterostructures, where atomic‐layer MoS2 uniformly coats on the surface of amorphous a‐ZVO. The tailored amorphous structure of a‐ZVO provides more isotropic pathways and active sites for Zn2+, thus significantly enhancing the Zn2+ diffusion kinetics during charge–discharge processes. Meanwhile, as an efficient artificial cathode electrolyte interphase, the precision‐engineered atomic‐layer MoS2 with semi‐metallic 1T′ phase not only contributes to improved electron transport but also effectively inhibits the V‐dissolution of a‐ZVO. Therefore, the prepared a‐ZVO@MoS2 and conceptually validated a‐V2O5@MoS2 derived from commercial c‐V2O5 exhibit excellent cycling stability at an ultralow current density (0.05 A g−1) while maintaining good rate capability and capacity retention. This research achievement provides a new effective strategy for various amorphous cathode designs for AZIBs with superior performance.

One-Step Synthesis of NiCo-LDH@Ni(OH)2 Heterostructure Foams on Biomass-Derived Porous Carbon for High-Performance Supercapacitors.

Layered double hydroxides (LDHs) have attracted much attention as pseudocapacitor supercapacitor electrodes because of their high theoretical specific capacity. However, LDHs have drawbacks such as poor electrical conductivity, and their specific capacities are lower than the theoretical values. In this work, NNCLDH@OPC electrodes are constructed via in situ synthesis of heterostructure foams (NNCLDH) consisting of NiCo-LDH and Ni(OH)2 on pomelo peel-derived porous carbon (OPC) through a one-step solvothermal method using ZIF-67 as a template. Owing to the synergistic effect of the 3D nanofoam structure and the multicomponent heterostructure as well as the conductive porous carbon support, the NNCLDH/OPC exhibited ultrahigh electrochemical performance as well as excellent cycling stability: a specific capacity of 3290 F g-1 at 1 A g-1 and a capacitance retention of 77.8% after 4000 cycles at a current density of 10 A g-1. In addition, the assembled NNCLDH@OPC//OPC asymmetric supercapacitor (ASC) has a maximum energy density of 51Wh kg-1 with a power density of 812W kg-1 and a maximum power density of 16kW kg-1 at a current density of 20 A g-1. These results demonstrate the significant application potential of NNCLDH/OPC composites in supercapacitor electrodes.

A High-Performance Polyimide Composite Membrane with Flexible Polyphosphazene Derivatives for Vanadium Redox Flow Battery.

A sulfonated polyimide, S-F-abSPI, with alkyl sulfonic acid side chains, and a polyphosphonitrile derivative, poly[4-methoxyphenoxy (4-fluorophenoxy) phosphazene] (PFMPP), were designed and synthesized. Composite modification of the S-F-abSPI membrane was carried out using PFMPP, resulting in the preparation of composite membranes with different composite ratios, which were then subjected to performance testing and characterization. Experimental results revealed a significant enhancement in the proton conductivity of the S-F-abSPI membrane, reaching 0.116 S cm-1, slightly higher than that of the N212 membrane. The S-F-abSPI/1% PFMPP composite membrane exhibited the optimal comprehensive performance, with a surface resistance as low as 0.54 Ω cm2, comparable to that of the N212 membrane. At a high current density of 200 mA cm-2 during charge-discharge, the composite membrane achieved a voltage efficiency (VE) of 83.12% and an energy efficiency (EE) of 81.95%. Cycling tests over 200 cycles demonstrated the composite membrane's excellent long-term cycling stability. The alkyl sulfonic acid side chains enhanced the proton conductivity of the membrane, while electrostatic potential distribution calculations indicated strong interactions between PFMPP and the base membrane, enhancing the membrane's mechanical strength, reducing vanadium ion permeability, and improving chemical stability and vanadium ion selectivity. This composite membrane holds promise for high-performance VRFB applications.

Molten salt assisted synthesis of Si/C nanocomposite derived from palygorskite and sodium alginate for electrochemical lithium storage.

Silicon/carbon (Si/C) nanocomposites are considered as one of the most promising anode materials for lithium-ion batteries due to their high capacity and suitable lithiation potential. However, the complex and time-consuming preparation processes of silicon-based nanocomposites and the unexpected silicon carbide generated during high treatment make it difficult to achieve high-performance Si/C nanocomposites for practical applications. Herein, a silicon/carbon nanocomposite is successfully prepared through a facile and eco-friendly molten salt assisted precarbonization-reduction method using palygorskite (PAL) and sodium alginate as raw materials. Based on physical characterizations, it is demonstrated that the sodium alginate plays a key role in the successful preparation of Si/C nanocomposite, which not only boosts uniform embedding of PAL nanoparticles in the carbon matrix but also releases molten sodium salt to suppress the formation of unexpected SiC. When used as an alternative anode material for lithium-ion battery applications, the as-obtained Si/C composite delivers a high reversible specific capacity of 1362.7 mA h g-1 with an initial Coulombic efficiency of 70.3% at a current density of 200 mA g-1 and excellent long-term cycling stability. The findings here provide a facile and eco-friendly molten salt assisted precarbonization-reduction method for high-performance silicon/carbon anode materials.

Tailoring-Orientated Deposition of Li2S for Extreme Fast-Charging Lithium-Sulfur Batteries.

Precipitation/dissolution of insulating Li2S has long been recognized as the rate-determining step in lithium-sulfur (Li-S) batteries, which dramatically undermines sulfur utilization at elevated charging rates. Herein, we present an orientated Li2S deposition strategy to achieve extreme fast charging (XFC, ≤15 min) through synergistic control of porosity, electronic conductivity, and anchoring sites of electrode substrate. Via magnesiothermic reduction of a zeolitic imidazolate framework, a nitrogen-doped and hierarchical porous carbon with highly graphitic phase was developed. This design effectively reduces interfacial resistance and ensures efficient sequestration of polysulfides during deposition, leading to (110)-preferred growth of Li2S nanocrystalline between (002)-dominated graphitic layers. Our approach directs an alternative Li2S deposition pathway to the commonly reported lateral growth and 3D thickening growth mode, ameliorating the electrode passivation. Therefore, a Li-S cell capable of charging/discharging at 5C (12 min) while maintaining excellent cycling stability (82% capacity retention) for 1000 cycles is demonstrated. Even under high S loading (8.3 mg cm-2) and low electrolyte/sulfur ratio (3.8 mL mg-1), the sulfur cathode still delivers a high areal capacity of >7 mAh cm-2 for 80 cycles.

Effect of calcination temperature on the presence pattern of calcium ions in slag-based geopolymer microspheres and visible light photocatalytic degradation of tetracycline hydrochloride

Tetracycline hydrochloride (TC) is currently treated mostly with photocatalysts that the preparation process is complicated and costly, limiting its large-scale application. In this study, slag-based geopolymer microspheres (SGMs) photocatalysts were prepared from low-cost slag as raw material using geopolymer technology, and excellent visible-light degradation properties for TC could be obtained by simple calcination. When the water addition was 4 g, the stirring speed was 1000 rpm and the calcination temperature was 800 °C for 3 h, the initial pH was 4.72 and the photocatalyst dosage was 0.4 g/L, SGMs showed excellent photocatalytic performance for TC with 94.76 % degradation in visible-light. Compared with the traditional powder materials, SGMs can achieve rapid separation with excellent settling performance (it can be completely settled within 1 min). With degradation rate remaining over 90 % after five cycles, it showed excellent cyclic stability. The degradation mechanism of SGMs on TC was as follows: firstly, TC adsorption takes place on the SGMs surface during the dark reaction stage; secondly, with Ca2+ in the SGMs enter the solution, it complexed with the TC, making it positively charged and accelerating the generation of free radicals, adsorption and degradation occurred simultaneously, with the order of active free radical action on TC degradation being ·O2- >·OH > h+. The SGMs prepared in this project has the benefits of being inexpensive, easy to operate, environmental protection, excellent visible-light photocatalyst performance, and potential industrial application prospects.

Synergistic Regulation of Anode and Cathode Interphases via an Alum Electrolyte Additive for High‐Performance Aqueous Zinc‐Vanadium Batteries

AbstractA zinc (Zn) metal anode paired with a vanadium oxide (VOx) cathode is a promising system for aqueous Zn–ion batteries (AZIBs); however, side reactions proliferating on the Zn anode surface and the infinite dissolution of the VOx cathode destabilise the battery system. Here, we introduce a multi‐functional additive into the ZnSO4 (ZS) electrolyte, KAl(SO4)2 (KASO), to synchronise the in situ construction of the protective layer on the surface of the Zn anode and the VOx cathode. Theoretical calculations and synchrotron radiation have verified that the high‐valence Al3+ plays dual roles of competing with Zn2+ for solvation and forming a Zn−Al alloy layer with a homogeneous electric field on the anode surface to mitigate the side reactions and dendrite generation. The Al‐containing cathode–electrolyte interface (CEI) considerably alleviates the irreversible dissolution of the VOx cathode and the accumulation of byproducts. Consequently, the Zn||Zn cell with KASO exhibits an ultra‐long cycle of 6000 h at 2 mA cm−2. Importantly, the VOx cathodes (VO2, V2O5 and NH4V4O10) in the ZS−KASO electrolyte showed excellent cycling stability, including Zn powder||VO2 cells and Zn||VO2 pouch cells. Even better, the full cell exhibits excellent cycling stability at low negative/positive (N/P) ratio of 2.83 and high mass loading (~16 mg cm−2). This study offers a straightforward and practical reference for concurrently addressing challenges at the anode and cathode of AZIBs.

N, F Co-Doped Carbon Material Self-Supporting Cathode for High-Performance Lithium-Oxygen Batteries.

The Li-O2 battery has emerged as a promising energy storage system due to its exceptionally high theoretical energy density of 3500 Wh kg-1. However, the sluggish kinetics associated with the formation and decomposition of discharge product Li2O2 poses several challenges in Li-O2 batteries, including excessive over-potential, limited rate performance, and reduced actual specific energy. Consequently, the development of cost-effective cathode catalysts with enhanced catalytic activity and long-term stability represents a viable approach to address these challenges. In this study, commercial melamine foam is utilized as a precursor material which was subjected to pyrolysis at elevated temperatures with PVDF to synthesize N, F co-doped self-supporting carbon cathode (NF-NSC). Remarkably, thanks to the synergistic effects of N, F heteroatomic in conjunction with the inherent three-dimensional reticular porous structure, NF-NSC exhibited enhanced electrochemical performance when utilized in Li-O2 batteries. Specifically, the NF-NSC cathode demonstrated an impressive discharge specific capacity of up to 35204 mAh g-1 alongside a low over-potential (0.86 V) and excellent cycling stability (146 cycles).

Engineering Dual-Defective 0D/2D VN-CNQDs/VBi-Bi4O5Br2 S-Scheme Heterostructure for Boosting CO2 Photoreduction in Air.

The direct photocatalytic reduction of CO2 in air is the future trend of photocatalyst application. Herein, the 0D carbon nitride quantum dots with nitrogen vacancies (VN-CNQDs) and 2D bismuth-deficient Bi4O5Br2 (VBi-Bi4O5Br2) are integrated by hydrothermal method. The S-scheme heterostructure of VN-CNQDs/VBi-Bi4O5Br2 composite promotes the separation rate of photogenerated carriers and enhances the redox capacity. The dual defects provide a large number of adsorption and catalytic sites that enhance the ability to capture and reduce CO2. The synergistic effect of S-scheme heterostructure and defect engineering enables the efficiency of CO2 photoreduction to CO with VN-CNQDs/VBi-Bi4O5Br2 to reach 16.89µmolg-1h-1 in air and 55.69µmolg-1h-1 in VCO2: VAir = 3:1 condition, which is 17 and 21 times higher than that of Bi4O5Br2, respectively. The dual-defective VN-CNQDs/VBi-Bi4O5Br2 exhibits more lower energy barrier for forming *CO2, *COOH, and *CO and is easier to release CO gas. And it exhibits excellent cycling stability for photocatalytic CO2 reduction to CO. The photocatalytic reduction mechanism of CO2 to CO in the VN-CNQDs/VBi-Bi4O5Br2 S-scheme heterostructure is further analyzed. This work provides new perspectives for the design of the photocatalysts with defect engineering for efficient photoconversion at low CO2 concentrations.

Redox Mediator as Highly Efficient Charge Storage Electrode Additive for All‐Solid‐State Lithium Metal Batteries

AbstractAll‐solid‐state lithium metal batteries (ASSLBs) have the potential to provide a significant increase in energy density and safety. However, most ASSLBs are still suffering from low cathode loading, poor rate capability, and low attainable energy/power densities, which seriously limit their practical application. Besides developing solid electrolytes with high conductivity, constructing a highly loaded cathode with rapid reaction kinetics is also essential for achieving high‐performance ASSLBs. Herein, the methylamine hydroiodide (CH6NI) is investigated as a functional electrode additive to enable rapid Li+ transport and charge transfer in LiFePO4 (LFP) cathode, whereby the CH6NI serves as a charge storage carrier that facilitates the reaction kinetics during the delithiation and lithiation process of LFP. As a result, the ASSLB assembled with LFP@CH6NI cathode shows excellent cycling stability over 700 cycles at 2 C with a high capacity retention of 87.6%, while the cell with bare LFP cathode shows no capacity at high current rates (≥0.5 C). Moreover, the ASSLB pared with a high active loading cathode (5.6 mg cm−2) still exhibits a high specific capacity of 144.9 mAh g−1 at 0.5 C. This work provides a facile strategy that opens new possibilities for designing high‐loading electrodes for high‐performance ASSLBs.