Cycling Stability Research Articles

CO2 selectivity and adsorption performance of K2CO3-modified zeolite: a temperature-dependent study.

High-performing zeolite materials for carbon dioxide capture are promising for applications such as flue gas CO2 capture. Potassium carbonate-loaded zeolites can offer a plethora of benefits. In this work, for the first time, zeolite-Y impregnated with K2CO3 was studied as a gas adsorbent (CO2, CH4, and N2) and characterized using TGA (thermogravimetric analyzer), XRD, BET, FTIR, FETEM (Field-Emission Transmission Electron Microscope), and XPS. The effect of carbonate loading, temperature, and pressure was particularly targeted and assessed. Accordingly, for a variation in K2CO3 loading from 5 to 15 wt.%, the CO2 adsorption capacity reduced from 3.61 to 1.73mmolg-1 in the synthesized adsorbents. Among all the cases, KYZC10 exhibited very good cyclic adsorption-desorption performance and thermal stability. Further equilibrium modeling studies indicate that the stable and optimally K2CO3-loaded adsorbent (KYZC10) demonstrates effective adsorption isotherm behavior, making it suitable for different temperature variation processes in commercial carbon dioxide capture applications. The KYZC10 adsorbent's stable performance at varying temperatures contributes to its enhanced economic feasibility. This study also used the ideal adsorbed solution theory (IAST) to predict CO2 selectivity over other gases (CH4 and N2).

A Classical Marxian Two‐Sector Endogenous Cycle Model

ABSTRACTThis paper presents a Classical Marxian Two‐Sector Endogenous Cycle (CMTSEC) model, merging Dutt's two‐sector Classical convergence model with labor dynamics drawn from the Goodwin model and an endogenous labor supply inspired by Harris's interpretation of capitalist dynamics. Empirical support reinforces these assumptions. Utilizing the Hopf bifurcation theorem and numerical simulations, we demonstrate the emergence of persistent and stable limit cycles involving the wage share, employment rate, and sectoral capital distribution, all without relying on specific capital intensity discrepancies between sectors. This result challenges existing two‐sector models, particularly Sato's extension of the Goodwin model, in which endogenous cycles either do not exist or vanish over time, even when endogenous labor supply is incorporated. Notably, sectoral profit rates exhibit cyclical fluctuations in the CMTSEC model, suggesting a reevaluation of long‐run equilibrium. The findings highlight the role of investment sensitivity to sectoral profit rate disparities in determining cycle stability.

Hubbard Gap Closure-Induced Dual-Redox Li-Storage Mechanism as the Origin of Anomalously High Capacity and Fast Ion Diffusivity in MOFs-Like Polyoxometalates.

MOFs-like polyoxometalate (POMs) electrodeshave already emerged as promising candidates for lithium-ion batteries (LIBs), yet the origins of the underlying redox mechanism in such materials remain a matter of uncertainty. Of critical challenges are the anomalously high storage capacities beyond their theoretical values and the fast ion diffusivity that cannot be satisfactorily comprehended in the theory of crystal lattice. Herein, for the first time we decode t2g electron occupation-regulated dual-redox Li-storage mechanism as the true origin of extra capacity in POMs electrodes. Enhanced V-t2g orbital occupation by Li coordination significantly triggers the Hubbard gap closure and reversible Li deposition/dissolution at surface region. Conjugated V-O-Li configuration at interlayers endow Li+ ion pathways along pore walls as the dominant contribution to the low migration barrier and fast diffusivity. As a result, remarkable cycle stability (~100 % capacity retention after 2000 cycles at 1 A g-1), extremely high specific capacity (1200 mAh g-1 at 100 mA g-1) and excellent rate performance (404 mAh g-1 at 8 A g-1) were achieved, providing new understandings on the underlying mechanism of POMs electrodes and pivotal guidance for dual-storage materials.

Zr-MOF composites with zipped and unzipped carbon nanotubes for high-performance electrochemical supercapacitors.

Metal-organic frameworks (MOFs) have gained considerable interest as crystalline porous materials with notable characteristics, such as high surface area and excellent electrochemical performance, particularly in supercapacitor applications. The combination of MOFs with various nanocarbon materials further enhances their performance. This study investigated the combination of zirconium-based MOFs (Zr-MOFs) with graphene oxide nanoribbons (GONRs), zipped carbon nanotubes, and functionalized carbon nanotubes (FCNTs) to fabricate composites with elevated electrical conductivity, adjustable surface area, chemical robustness, mechanical strength, and customizable attributes for specific applications. Zr-MOFs exhibit remarkable capacitance, making them promising electrode materials for supercapacitors. GONRs and FCNTs have recently emerged as focal materials owing to their unique properties, which make them promising materials for electrochemical energy storage devices. A thorough investigation of the supercapacitive behavior of GONRs, FCNTs, Zr-MOFs, Zr-MOFs/FCNTs, and Zr-MOFs/GONRs in 1 M H2SO4 using different evaluation systems (three- and two-electrode systems) revealed a significant enhancement in the capacitance of Zr-MOFs after the introduction of GONRs and FCNTs. Employing Zr-MOF/GONR and Zr-MOF/FCNT composites as positive electrodes and GONRs as negative electrodes in two-electrode measurements demonstrated remarkable cycling stability by retaining their specific capacitances (Cs) even after 10 000 consecutive charge/discharge cycles at a high current density of 10 A g-1. Moreover, they feature a broad potential window of 1.7 V in the three-electrode system. This extends to 2 V in the two-electrode system, achieving high Cs. This highlights the remarkable electrochemical performance of the Zr-MOF/GONR and Zr-MOF/FCNT composites, offering a compelling approach for energy storage applications.

Optimizing Si─O Conjugation to Enhance Interfacial Kinetics for Low-Temperature Rechargeable Lithium-Ion Batteries.

With the growing demand for high-voltage and wide-temperature range applications of lithium-ion batteries (LIBs), the requirements for electrolytes have become increasingly stringent. While fluorination engineering has enhanced the performance of traditional solvent systems, it has also raised concerns regarding cost, environmental hazards, and low reduction stability. Through strategic molecular bond design, a novel class of low-temperature (LT) solvents-siloxanes-is identified, meeting the demands of LT and high-voltage applications in LIBs. The d-p conjugation of the Si─O bond enhances voltage resistance and weakens the Li+-solvent interactions. By modulating the number of Si─O conjugated bonds, the type of anion clusters in the solvation structure can be controlled, ultimately leading to the formation of a LiF and Si─O-rich interfacial layer and facilitating rapid Li+ conduction. Consequently, the graphite||NCM811 pouch cell (2.3 Ah, 4.45 V) with a siloxane-based electrolyte retains 75.1% of room temperature capacity (RTC) at -50°C. The rapid interface kinetics allow a superior reversible charging capacity retention of 67.6% at -40°C, with good cycle stability at -20°C. This study provides new insights into solvent design to fortify LIB performance in harsh conditions.

Mn-Rich Induced Alteration on Band Gap and Cycling Stability Properties of LiMnxFe1-xPO4 Cathode Materials.

Olivine-type LiMnxFe1-xPO4 (LMFP) has inherited the excellent heat-stable structure of LiFePO4 (LFP) and the high-voltage property of LiMnPO4 (LMP), which shows great promise as a high-safety, high-energy-density cathode material. In order to combine the high energy density and excellent electrochemical performance, it is essential to consider the Mn/Fe ratio. This paper presents a theoretical investigation of the lattice structure parameters, embedded lithium voltage, local electron density, migration barrier, and lithium ion delithiation and lithiation mechanism of different LiMnxFe1-xPO4 (0.5 ≤ x ≤ 0.8) compounds. In situ-coated LiMnxFe1-xPO4 (0.5 ≤ x ≤ 0.8) composite cathode materials with a size of 100-200 nm were prepared by a hydrothermal method to verify the theoretical study. LiMn0.6Fe0.4PO4/C exhibited a specific capacity of 140.2 and 97.58 mA h·g-1 at 1 and 5C, respectively, and a remarkable capacity retention rate of 88.5% after 200 cycles at 1C. When LiMn0.6Fe0.4PO4/C was assembled into a flexible pouch battery and subjected to long cycle tests at different rates and squeeze and extrusion tests, it demonstrated a capacity retention rate of 99.35% for 100 cycles at 0.2C and 93.2% for 200 cycles at 0.5C. Moreover, the structural evolution of LiMn0.6Fe0.4PO4/C were analyzed in situ XRD, indicating a high stability and the resulted as obtine electrochemical performance, paving the way for optimization of high-energy-density LMFP cathode materials.

Macroscopically uniform interface layer with Li+ conductive channels for high-performance Li metal batteries

The numerous grainboundaries solid electrolyte interface, whether naturally occurring or artificially designed, leads to non-uniform Li metal deposition and consequently results in poor full-battery performance. Herein, a lithium-ion selective transport layer is reported to achieve a highly efficient and dendrite-free lithium metal anode. The layer-by-layer assembled protonated carbon nitride nanosheets present uniform macroscopical structure without grainboundaries. The carbon nitride with ordered pores in basal plane provides high-speed lithium-ion transport channels with low tortuosity. Consequently, the assembled 324 Wh kg−1 pouch cell exhibits 300 stable cycles with a capacity retention of 90.0% and an average Coulombic efficiency up to 99.7%. The ultra-dense Li metal anode makes current collector-free anode possible, achieving high energy density and long cycle life of a 7 Ah cell (506 Wh kg−1, 160 cycles). Thus, it is proved that a macroscopically uniform interface layer with lithium-ion conductive channels could achieve Li metal battery with promising application potential.

Unlocking the Full Redox Capability of Organic Charge‐Transfer Complex in High‐Loading Electrodes for Organic Rechargeable Batteries

AbstractOrganic charge‐transfer complex (OCTC) comprising redox‐active donor and acceptor molecules is a promising electrode material group, potentially resolving issues of low power and inferior cycle stability of organic electrodes in rechargeable batteries. Strong intermolecular interactions in OCTC such as π–π interaction and hydrogen bonding enable high electronic conductivity and suppress solubility to solvents. However, full redox activities of OCTC have not been achieved yet despite the inherent redox capabilities of respective donor and acceptor molecules. Here, it is revealed that the limited redox activities of OCTC stem from electrolyte‐incorporated complex formation, which weakens the characteristic intermolecular interactions, thereby hindering the redox reaction, particularly in Li‐based electrolytes. It is further shown that tailoring electrolyte types, specifically using Zn‐aqueous electrolytes, can substantially mitigate the complex formation and unlock the four‐electron redox activity of OCTC (phenazine (PNZ)‐7,7,8,8‐tetracyanoquinodimethane (TCNQ), that is, PNZ–TCNQ), with superior cycle stability retaining 88% of maximum capacity over 100 cycles. Surprisingly, the full redox reaction achieves an unprecedentedly high electrode‐level energy density, delivering ≈10 mAh cm−2 of areal capacity (580 µm‐thick electrodes) in Zn‐aqueous batteries. The findings elucidate the complex interplay between organic electrodes and electrolytes in the charge storage mechanism, highlighting the importance of electrolyte design in developing organic electrode materials.

Molecular Chain Rearrangement of Natural Cellulose‐Based Artificial Interphase for Ultra‐Stable Zn Metal Anodes

AbstractThe unstable electrolyte‐anode interface, plagued by parasitic side reactions and uncontrollable dendrite growth, severely hampers the practical implementation of aqueous zinc‐ion batteries. To address these challenges, we developed a regenerated cellulose‐based artificial interphase with synergistically optimized structure and surface chemistry on the Zn anode (RC@Zn), using a facile molecular chain rearrangement strategy. This RC interphase features a drastically increased amorphous region and more exposed active hydroxyl groups, facilitating rapid Zn2+ diffusion and homogeneous Zn2+ interface distribution, thereby enabling dendrite‐free Zn deposition. Additionally, the compact texture and abundant negatively charged surface of the RC interphase effectively shield water molecules and harmful anions, completely preventing H2 evolution and Zn corrosion. The superior mechanical strength and adhesion of the RC interphase also accommodate the substantial volume changes of Zn anodes even under deep cycling conditions. Consequently, the RC@Zn electrode demonstrates an outstanding cycling lifespan of over 8000 hours at a high current density of 10 mA cm−2. Significantly, the electrode maintains stable cycling even at a 90 % depth of discharge and ensures stable operation of full cells with a low negative/positive capacity ratio of 1.6. This study provides new solution to construct highly stable and deep cycling Zn metal anodes through interface engineering.

Understanding and Passivation of Surface Corrosion of Cu for Stable Low‐N/P‐Ratio Lithium‐Sulfur Battery

AbstractThe realization of a low negative/positive capacity (N/P) ratio is essential for attaining high energy density in lithium‐sulfur batteries (LSBs). However, it has been challenging to maintain the stability of the Li metal anode at low N/P ratios. Herein, it is revealed that the corrosion of the Cu current collector by dissolved intermediates of polysulfides ‐a largely overlooked perspective‐ significantly contributes to the instability of Li metal anode at low N/P ratios. The reduced Li/Li+ redox rates on the corroded Cu surface result in uneven and porous Li deposits that severely deteriorate cycling stability. To address this issue, an anti‐corrosion alloy coating is developed to passivate the Cu surface against polysulfides. LSBs with passivated current collectors at a low N/P ratio (1.5) and lean electrolyte (5 µL mgs −1) show a ten fold extension in cycle and calendar life. This study not only provides the initial evidence of the impact of Cu corrosion on the failure mechanism of low N/P ratio LSBs but also proposes a practical yet effective strategy to stabilize high‐energy‐density LSBs.

FeCo Bimetallic ZIF Derivatives Decorated with CoFe-LDH to Promote Bifunctional Oxygen Electrocatalysis Activation.

Reasonably screening the targeted oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) constituents and constructing high-efficiency and stabilized ORR/OER bifunctional electrocatalysts are pivotal for the advancement of rechargeable zinc-air batteries (ZABs). Here, CoFe layered double hydroxide (CoFe-LDH) nanosheets are deposited on nitrogen-doped graphite-carbon polyhedra with FeCo alloy nanoparticles (FeCo/LDH-NGCP). Due to the synergic effect between FeCo-NGCP, CoFe-LDH and FeCo/LDH-NGCP, the electrocatalyst with the abundant and accessible active sites can provide good charge/mass transfer, and thus shows wonderful ORR and OER bifunctional electrocatalytic performance. In ORR tests, FeCo/LDH-NGCP catalyst displays larger half-wave potential (E1/2, 0.89 V vs. 0.85 V), higher limiting current density (JL, 5.91 mA/cm2 vs. 5.14 mA/cm2) and better stability than commercial Pt/C. As for OER, FeCo/LDH-NGCP possesses a smaller overpotential (η) of 299.6 mV at a current density of 10 mA/cm2 and more durable stability than commercial RuO2 (330.6 mV). Furthermore, in ZAB tests, the cycling stability of ZAB-FeCo/LDH-NGCP (over 470 h) outperforms the ZAB-Pt/C+RuO2 (92 h) with commercial electrocatalyst (Pt/C+RuO2). Therefore, the FeCo/LDH-NGCP catalyst offers a new perspective to construct ZABs bifunctional catalysts and their commercial application in ZABs.

Ligand Effect-Induced Electronic Structure Manipulation of Media-Entropy Alloy for Remarkable Stability over 50,000 Cycles in Oxygen Reduction.

Modulating the "trade-off" between activity and durability of Pd-based alloys while eliminating the dissolution of the nonprecious metal element issue is highly significant for the advancement of commercializing anion-exchange membrane fuel cells (AEMFCs). Herein, by harmonizing composition and ligand effects and targeting the stability concerns of Pd-based alloys, we propose PdRhNi ternary medium-entropy-alloy (MEA) networks (PdRhNi ANs) as exceptionally efficient oxygen reduction reaction (ORR) electrocatalysts via ligand effect. The results of theoretical calculations provide compelling evidence that the ligand effect of Ni in PdRhNi ANs, which can endow an inductive effect to reshape the electronic configuration to induce a reduced energy barrier in the rate-determining steps, optimizes the adsorption energy of O-related intermediates and lowers the d-band center of metal species, collectively boosting the anti-CO capacity and the ORR efficiency. Consequently, the as-made PdRhNi ANs not only demonstrate significantly enhanced electrocatalytic properties with a half-wave potential of 0.85 V and excellent resistance to CO toxicity, in contrast to those of commercial Pt/C and binary counterparts, but also exhibit a negligible half-wave potential decline after 50,000 cycle stability examination. More excitingly, the homemade AEMFC with a PdRhNi AN air cathode delivers a higher power density of 109 mW cm-2, surpassing that of the PdRh AN-based battery, highlighting promising prospects for implementing MEA materials with ligand engineering in AEMFC environments.

Engineering Heterointerface to Synergistically Regulate Kinetics and Stress of Copper-Cobalt Selenide toward Reversible Magnesium/Lithium Hybrid Batteries.

Metal chalcogenide-based cathodes are crucial for the development of rechargeable magnesium batteries, yet the strong electrostatic interactions of Mg2+ result in slow ion transport and high polarization. The Mg2+/Li+ hybrid battery holds promise for enhancing the energy storage capability. Herein, we establish a system that utilizes (Co,Cu)Se2/CoSex heterostructure grown on carbon cloth as the cathode and APC-LiCl as a dual-salt electrolyte to achieve high reversible capacity, enhanced cyclic stability, and impressive rate performance. First-principles calculations and kinetic analyses are employed to uncover that constructing the heterointerface stimulates the formation of an intrinsic electric field and high-density electron flows, thereby accelerating charge transfer and ion diffusion processes. Finite element simulations further demonstrate that the heterostructure effectively alleviates stresses associated with magnesiation/lithiation to enhance the structural integrity of the material. Moreover, the multistep reaction unveils a stepwise structural transformation pathway. This study initiates a new chapter in designing heterointerface strategies for advanced energy storage devices.

In-situ reduced Cu3N nanocrystals enable high-efficiency ammonia synthesis and zinc-nitrate batteries.

Nitrate reduction reaction (NO3RR) involves an 8-electron transfer process and competes with the hydrogen evolution reaction process, resulting in lower yields and Faraday efficiency (FE) in the process of NH3 synthesis. Especially, Cu-based catalysts (Cu0 and Cu+) have been investigated in the field of NO3RR due to the energy levels of d-orbital and the least unoccupied molecular orbital (LUMO) π* of nitrate's orbital. Based on the above, we synthesized a Cu-based compound containing Cu3N (Cu+) through a simple one-step pyrolysis method, applied it to electrocatalytic NO3RR, and tested the performance of the Zn-NO3- battery. Through various characterization analyses, Cu-based catalysts (Cu+) are the key active sites in reduction reactions, making Cu3N a potential catalyst for ammonia synthesis. The research results indicate the application of Cu3N catalyst in NO3RR shows the best NH3 yield of 173.7 μmol h-1 cm-2, with FENH3 reaching 91.0% at -0.3 V vs. RHE, which is much higher than that of Cu catalyst without N. In addition, the Zn-NO3- battery based on Cu3N electrode also exhibits an NH3 yield of 39.8 μmol h-1 cm-2, 63.0% FENH3, and a power density of 2.7 mW cm-2, as well as stable cycling charge-discharge stability for 5 hours.

Supramolecular Crystals based Fast Single Ion Conductor for Long‐Cycling Solid Zinc Batteries

AbstractThe solid polymer electrolytes (SPEs) used in Zn‐ion batteries (ZIBs) have low ionic conductivity due to the sluggish dynamics of polymer segments. Thus, only short‐range movement of cations is supported, leading to low ionic conductivity and Zn2+ transference (tZn2+). Zn‐based supramolecular crystals (ZMCs) have considerable potential for supporting long‐distance Zn2+ transport; however, their efficiency in ZIBs has not been explored. The present study developed a ZMC consisting of succinonitrile (SN) and zinc bis (trifluoromethylsulfonyl) imide (Zn(TFSI)2), with a structural formula identified as Zn(TFSI)2SN3. The ZMC has ordered three‐dimensional tunnels in the crystalline lattices for ion conduction, providing high ionic conductivities (6.02×10−4 S cm−1 at 25 °C and 3.26×10−5 S cm−1 at −35 °C) and a high tZn2+ (0.97). We demonstrated that a Zn‖Zn symmetrical battery with ZMCs has long‐term cycling stability (1200 h) and a dendrite‐free Zn plating/stripping process, even at a high plating areal density of 3 mAh cm−2. The as‐fabricated solid‐state Zn battery exhibited excellent performance, including high discharge capacity (1.52 mAh cm−2), long‐term cycling stability (83.6 % capacity retention after 70000 cycles (7 months)), wide temperature adaptability (−35 to 50 °C) and fast charging ability. The ZMC differs from SPEs in its structure for transporting Zn2+ ions, significantly improving solid‐state ZIBs while maintaining safety, durability, and sustainability.

Localized Water Restriction in Ternary Eutectic Electrolytes for Ultra‐Low Temperature Hydrogen Batteries

AbstractProton batteries are promising candidates for next‐generation large‐scale energy storage in extreme conditions due to the small ionic radius and efficient transport of protons. Hydrogen gas, with its low working potentials, fast kinetics, and stability, further enhances the performance of proton batteries but necessitates the development of novel electrolytes with low freezing points and reduced corrosion. This work introduces a localized water restriction strategy by incorporating a tertiary component with a high donor number, which forms strong bonds with water molecules. This approach restricts free water molecules and reduces the average hydrogen bond ratio and strength. As‐prepared ternary eutectic electrolytes lowered the freezing point to −103 °C, significantly lower than the traditional binary electrolyte (9.5 m H3PO4, −93 °C). This electrolyte is highly compatible with the Cu0.79Co0.21[Fe(CN)6]0.64 ⋅ 4H2O (CoCuHCF) cathode, reducing material dissolution and current collector corrosion. The H2||CoCuHCF battery using this electrolyte demonstrated a high‐power density of 23664.3 W kg−1, excellent performance at −80 °C, and stable cyclability over 1000 cycles (>30 days) at −50 °C. These findings provide a framework for proton electrolytes, highlighting the potential of hydrogen batteries in challenging environments.

Embedment of Molybdenum Disulfide in Electrospun Fibers as an Integrated Cathode for Lithium-Ion Batteries

As an important component of LIBs, the electrode material plays a crucial role in determining the lithium (Li) storage performance in LIBs. In this study, MoS2 nano-flowers were synthesized using a one-pot hydrothermal method. The resulting MoS2 nano-flower, along with PAN, were used as raw materials for electrospinning. After annealing treatment, MoS2/(carbon nanofibers) CNFs nano-composites coated with carbon fibers were formed. The CNFs coating exhibited electrical conductivity and enhanced structural stability of the MoS2 due to the stabilizing effect of the carbon fibers. Additionally, electrochemical tests, including CV and GCD, indicated that the optimal capacity and cycling stability were achieved when the MoS2 content was 10%. The results indicated that the charge/discharge capacity of MoS2/CNFs-10% at a current density of 100 mA/g was ~650 mAh/g. After the cycling current returned to 100 mA/g, the current recovery was ~600 mAh/g, thereby indicating outstanding cycling stability. Accordingly, our fabrication technique and new insight could both widen design strategy of multicomponent composite electrode materials and promote the practical applications of the latest emerging transition metal sulfides in next-generation high-performance lithium-ion batteries.

Optimal Control of Nonlinear, Nonautonomous, Energy Harvesting Systems Applied to Point Absorber Wave Energy Converters

Pursuing sustainable energy solutions has prompted researchers to focus on optimizing energy extraction from renewable sources. Control laws that optimize energy extraction require accurate modeling, often resulting in time-varying, nonlinear differential equations. An energy-maximizing optimal control law is derived for time-varying, nonlinear, second-order, energy harvesting systems. We demonstrate that sustaining periodic motion under this control law when subjected to periodic disturbances necessitates identifying appropriate initial conditions, inducing the system to follow a limit cycle. The general optimal solution is applied to two point absorber wave energy converter models: a linear model where the analytical derivation of initial conditions suffices and a nonlinear model demanding a numerical approach. A stable limit cycle is obtained for the latter when the initial conditions lie within an ellipse centered at the origin of the phase plane. This work advances energy-maximizing optimal control solutions for nonautonomous nonlinear systems with application to point absorbers. The results also shed light on the significance of initial conditions in achieving physically realizable periodic motion for periodic energy harvesting systems.

Plasma Carbonization of Sustainable Lignin Fiber‐Derived Papers for Supercapacitor Electrodes

AbstractThe majority of carbon materials on the market are produced from polyacrylonitrile precursor fibers using high‐temperature oven processes. Despite approaches for green carbon fiber precursors, current stabilization and carbonization processes require large amounts of energy and render carbon materials costly and environmentally not sustainable. Here, a plasma carbonization treatment is employed for papers made from lignin/polyvinylpyrrolidone precursor fibers. The process provides carbonization within a timeframe of a few seconds, while the degrees of porosity, conductivity, and hydrophobicity can be tuned. It is shown that the properties of these carbonized papers are suitable for application as supercapacitor electrodes with capacitances in the range of 40 mF g−1 with very good cycling stability dropping by less than 20% over 4000 cycles.

Development of Biomass‐Derived Hard Carbon for Sodium‐Ion Batteries: Optimizing Microstructure and Electrochemical Performance

The development of sodium‐ion batteries (SIBs) as a sustainable alternative to lithium‐ion batteries (LIBs) has garnered considerable attention, mainly due to the abundant supply and economic viability of sodium sources. In this study, we present the synthesis and characterization of hard carbon (HC) derived from biomass coconut shells, with the objective of optimizing its performance as an anode material for SIBs. A series of hard carbon samples (denoted as YHC‐T) were prepared via carbonization at 1000°C, 1100°C, 1200°C, 1300°C and 1400°C. The YHC‐1200 sample, exhibiting an expanded interlayer spacing of approximately 0.384 nm, demonstrated superior sodium storage properties, achieving a high reversible specific capacity of 350 mA h g <sup>‐1</sup> and an initial Coulombic efficiency (ICE) of 92.9% at a current density of 0.1 A g <sup>‐1</sup>. Moreover, YHC‐1200 exhibited excellent cycling stability, retaining a capacity of 198 mA h g <sup>‐1</sup> after 1000 cycles at 1 A g <sup>‐1</sup>.