Cathode For Sodium-ion Batteries Research Articles

Spray-Drying Synthesis of Na4Fe3(PO4)2P2O7@CNT Cathode for Ultra-Stable and High-Rate Sodium-Ion Batteries

Iron-based phosphate is a promising cathode for sodium-ion batteries due to its low cost and abundant resources; however, the practical application is hindered by poor electronic conductivity, sluggish Na+ diffusion, and a lack of low-cost and scalable synthesis methods. To address such issues, herein, we present a low-cost and scalable spray-drying strategy to synthesize Na4Fe3(PO4)2P2O7@CNT (NFPP@CNT) hollow microspheres. The NFPP@CNT composite has the following advantages: highly conductive CNT can significantly improve the electronic conductivity of the cathode, and the flexible CNT-based microsphere architecture facilitates Na+ diffusion and guarantees excellent mechanical properties to mitigate structural degradation during cycling. These merits make the NFPP@CNT cathode display outstanding electrochemical performances: the NFPP@CNT-1% electrode demonstrates a high reversible capacity of 103.9 mAh g−1 at 0.1 C and maintains a very high capacity retention of 99.9% after 1000 cycles even at a high rate of 5 C.

A Cross-Linked Polymer Coating Strategy to Enhance the Performance of NaNi0.33Fe0.33Mn0.33O2 Cathode for Sodium-Ion Batteries.

O3-type layered oxide materials are regarded as optimal cathode candidates for sodium-ion batteries (SIBs) on account of their exceptional energy density. Nevertheless, the rapid decline in capacity resulting from the instability of the interface structure represents a significant challenge to the practical implementation of these materials. In this study, we propose an innovative method to modify the O3-type NaNi0.33Fe0.33Mn0.33O2 (NFM) cathode material by applying a cross-linked polymer (CLP) coating. X-ray photoelectron spectroscopy (XPS) analysis demonstrates that the CLP coating effectively inhibits the decomposition of the cathode electrolyte interface (CEI) membrane in the course of cycling, leading to a substantial improvement in the stability of the electrode material's interface. Moreover, the oxygen-containing groups within the coating can compete with propylene carbonate (PC) solvent molecules in the electrolyte for Na+ coordination, reducing the coordination between Na+ and PC molecules. This process facilitates more efficient diffusion of Na+, thereby enhancing the rate performance. Consequently, CLP-coated NFM (NFM@CLP) materials exhibit enhanced electrochemical performance. After 300 cycles at 25 °C, NFM@CLP retains 72.36% of its capacity, compared to 62.59% for pristine NFM. Even at elevated temperatures (65 °C), the capacity retention of NFM@CLP remains high at 63.84% after 200 cycles, whereas pristine NFM drops to 3.65%. In full-cell tests (vs hard carbon), the NFM@CLP also exhibits better capacity retention (85.07% after 150 cycles). This study offers an effective and simple approach to enhancing the capacity retention and rate performance of O3-type layered materials in SIBs, providing unique insights into advanced energy storage materials.

Intrinsic Distortion Against Jahn-Teller Distortion: A New Paradigm for High-Stability Na-Ion Layered Mn-Rich Oxide Cathodes.

Layered manganese-rich oxides (LMROs) are widely recognized as the leading cathode candidates for grid-scale sodium-ion batteries (SIBs) owing to their high specific capacities and cost benefits, but the notorious Jahn-Teller (J-T) distortion of Mn3+ always induces severe structural degradation and consequent rapid cathode failure, impeding the practical implementation of such materials. Herein, we unveil the"intrinsic distortion against J-T distortion"mechanism to effectively stabilize the layered frameworks of LMRO cathodes. The intrinsic distortion simply constructed by introducing bulk oxygen vacancies is systematically confirmed by advanced synchrotron X-ray techniques, atomic-scale imaging characterizations, and theoretical computations, which can counteract the J-T distortion during cycling due to their opposite deformation orientations. This greatly decreases and uniformizes the lattice strain within the ab plane and along the c axis of the material, thereby alleviating the P2-P'2 phase transition as well as suppressing the edge dislocation and intragranular crack formation upon repeated cycles. As a result, the tailored P2-Na0.72Mg0.1Mn0.9O2 cathode featuring intrinsic distortion delivers a considerably enhanced cycling durability (91.9% capacity retention after 500 cycles) without sacrificing the Mn3+/Mn4+ redox capacity (186.5 mAh g-1 at 0.3 C). This intrinsic distortion engineering paves a brand-new and prospective avenue toward achieving high-performance LMRO cathodes for SIBs.

Intrinsic Distortion Against Jahn‐Teller Distortion: A New Paradigm for High‐Stability Na‐Ion Layered Mn‐Rich Oxide Cathodes

Layered manganese‐rich oxides (LMROs) are widely recognized as the leading cathode candidates for grid‐scale sodium‐ion batteries (SIBs) owing to their high specific capacities and cost benefits, but the notorious Jahn‐Teller (J‐T) distortion of Mn3+ always induces severe structural degradation and consequent rapid cathode failure, impeding the practical implementation of such materials. Herein, we unveil the "intrinsic distortion against J‐T distortion" mechanism to effectively stabilize the layered frameworks of LMRO cathodes. The intrinsic distortion simply constructed by introducing bulk oxygen vacancies is systematically confirmed by advanced synchrotron X‐ray techniques, atomic‐scale imaging characterizations, and theoretical computations, which can counteract the J‐T distortion during cycling due to their opposite deformation orientations. This greatly decreases and uniformizes the lattice strain within the ab plane and along the c axis of the material, thereby alleviating the P2‐P'2 phase transition as well as suppressing the edge dislocation and intragranular crack formation upon repeated cycles. As a result, the tailored P2‐Na0.72Mg0.1Mn0.9O2 cathode featuring intrinsic distortion delivers a considerably enhanced cycling durability (91.9% capacity retention after 500 cycles) without sacrificing the Mn3+/Mn4+ redox capacity (186.5 mAh g‐1 at 0.3 C). This intrinsic distortion engineering paves a brand‐new and prospective avenue toward achieving high‐performance LMRO cathodes for SIBs.

Regulation of Coordination Chemistry To Accelerate Na+ Transfer Kinetics of Polyanionic Cathodes for Ultrastable Sodium-Ion Batteries.

Alluaudite-type iron-based sulfate structure (Na2+2xFe2-x(SO4)3) has attracted wide attention due to its high working voltage and low cost. However, their practical application is hindered by challenges such as limited reversible capacity and sluggish transfer kinetics. Herein, we proposed an anion substitution strategy to optimize iron-based sulfate cathode materials. The electrochemical characterization and theoretical calculations confirmed a reduction in the migration barrier of Na+ ions in various pathways. Besides, fluorine weakened the electron density of the crystal plane, thereby impeding the continuous side reaction of the electrolyte. As expected, the NFSF cathode can exhibit a capacity of 121.5 mAh g-1 at 12 mA g-1 and keep a high retention of 78.8% after 1000 cycles at 600 mA g-1. In addition, the NFSF-based cathode and hard carbon (HC)-based anode were assembled into a laboratory-scale pouch cell to demonstrate the electrochemical performance and practical applications.

Reaction kinetics and capacity decay mechanism of NaNi1/3Fe1/3Mn1/3O2@activated carbon cathode of sodium ion batteries

Layered metal oxides are among the primary cathode materials used in sodium-ion batteries (SIBs), but they face limitations mainly in terms of slow reaction kinetics and structural instability with increasing cycles. Activated carbon (AC) is vital in cathode materials for SIBs. In this study, the charge transfer kinetics and reaction mechanisms of NaNi1/3Fe1/3Mn1/3O2(NFM)/AC composites were investigated. Results showed that the physical doping of AC improved the electrode wettability, provided more conducting channels for ions and reduced the ionic impedance. The addition of AC accelerated the O3–P3 transition of NFM, as observed through ex-situ X-ray diffraction and dQ/dV curves, thus reducing active material consumption during extended cycling processes. COMSOL simulations of the discharge process revealed that AC in NFM created a more homogeneous reactive material, increasing the capacity of NFM/AC composites by nearly three times at 1000 mA g−1 compared to material without AC. In addition, after 100 cycles, the cycle stability increased from 76 % to 81 %. The findings of this study provide a new way to improve the performance of cathode materials for SIBs.

Tailoring local electronic structure to achieve reversible anion redox chemistry of layered oxide cathodes for high-performance sodium-ion batteries

Tailoring local electronic structure to achieve reversible anion redox chemistry of layered oxide cathodes for high-performance sodium-ion batteries

Enhancing Cyclability of Fe2O3-V2O5-P2O5 Ceramic Cathode for High-Performance Sodium-ion Batteries through Heat Treatment

Due to the ability to form more open structures, glass and glass-ceramic materials can accommodate larger Na+ ions and enable rapid solid-state diffusion of Na+ at room temperature (RT). Regardless of the larger ionic radius of Na, iron-based mixed-vanadium-phosphate ceramics show promising potential as cathode materials in sodium-ion batteries (SIBs). However, their practical applicability is significantly hindered by slow Na+ diffusion and low intrinsic electrical conductivity. In the present study, a ceramic sample with the composition of 5Na2O−45Fe2O3−10V2O5−40P2O5, denoted as (5NFVP), was synthesized before (BHT) and after heat treatment (HT) at 500, 600, and 700 °C for 2h to be used as a cathode material in SIBs. The outstanding electrochemical performance of the 5NFVP ceramic is attributed to improved electronic and ionic conductivity and enhanced structural stability during Na+ insertion/de-insertion. This is supported by various analyses, including X-ray diffraction (XRD), X-ray absorption near edge structure (XANES), 57Fe Mössbauer spectroscopy, and electrochemical impedance spectroscopy (EIS). All prepared samples show two doublets, with the first doublet associated with Fe3+(Td), confirming the XRD results that indicate the main crystalline phase of FePO4. The second doublet observed in the 5NFVP-HT500 and 600°C is related to Fe3+(Oh), while 5NFVP-BHT exhibits a large δ value of 1.19 mm s−1, indicating the presence of Fe2+(Oh) due to NaFePO4 crystalline phase. The Fe-K absorption edge analysis reveals that 5NFVP-HT600°C ceramics predominantly consist of Fe3+, whereas 5NFVP-BHT has the most abundant Fe2+ compared with HT samples. The largest DC conductivity is achieved by the 5NFVP-HT600°C ceramic, reaching 5.08×10−9S cm−1 at RT. The initial capacity of 5NFVP-HT ceramics is approximately doubled compared to 5NFVP-BHT. The 5NFVP-HT600°C ceramic as a cathode demonstrates excellent long-cycling stability, retaining 60 % of its capacity over 100 cycles under a current rate of 50 mA g−1. These findings underscore the significant potential of 5NFVP-HT600°C for advanced energy storage systems, given its affordability and robust cyclability.

Mg-B-O Coated P2-Type Hexagonal Na0.5Mn0.95Ni0.05O2 as a High-Performance Cathode for Sodium-Ion Batteries.

P2-type Na0.5Mn0.95Ni0.05O2 as the cathode for sodium-ion batteries, has a relatively high theoretical specific capacity, but its unstable crystal structure and undesirable phase transitions lead to rapid capacity decay. In this work, Mg-B-O coated Na0.5Mn0.95Ni0.05O2 microspheres have been synthesized via a liquid-phase method based on solvothermal synthesized Na0.5Mn0.95Ni0.05O2. The Mg-B-O coating layer significantly improves the electrochemical performance, including specific capacity, rate capability, and cycle stability. Within the voltage window of 2.0-4.0 V, Mg-B-O coated Na0.5Mn0.95Ni0.05O2 could exhibit an initial capacity of 93.2 mAh g-1 at a current density of 500 mA g-1, and maintains a capacity of 74.6 mAh g-1 after 500 cycles, with a capacity retention rate of 80.0%. The Mg-B-O coating effectively inhibits the formation of Na2CO3 on the surface, enhancing air stability, reducing the Jahn-Teller effect induced by Mn3+, as well as ensuring fast Na+ diffusion kinetics. This work provides a new strategy for designing P2-type layered sodium-ion batteries with both high specific capacity and cycling stability.

Activating Reversible V4+/V5+ Redox Couple in NASICON-Type Phosphate Cathodes by High Entropy Substitution for Sodium-Ion Batteries.

Vanadium-based Na superionic conductor (NASICON) type materials (NaxVM(PO4)3, M = transition metals) have attracted extensive attention when used as sodium-ion batteries (SIBs) cathodes due to their stable structures and large Na+ diffusion channels. However, the materials have poor electrical conductivity and mediocre energy density, which hinder their practical applications. Activating the V4+/V5+ redox couple (V4+/V5+≈4.1 V vs Na+/Na) is an effective way to elevate the energy density of SIBs, whereas the irreversible phase transition of V4+/V5+ and severe structural distortion will inevitably result in fast capacity fading and unsatisfactory rate capability. Herein, a high entropy regulation strategy is proposed to optimize the detailed crystal structure and improve the reversibility of crystalline phase transformation and electrical conductivity of the material. With the activated reversible V4+/V5+ redox couple, stable structure, and fast electrochemical kinetics, the high entropy material Na3.2V1.5Fe0.1Al0.1Cr0.1Mn0.1Cu0.1(PO4)3 (NVMP-HE) exhibits an outstanding electrochemical performance with highly reversible specific capacity of 120.1 mAh g-1 at 0.1 C and excellent cycling stability (92.4% retention after 1000 cycles at 20 C). Besides, the in situ X-ray diffraction (XRD) measurement reveals that a smooth three-phase transition reaction is involved in this high-entropy cathode and the existence of mesophase facilitates a fast phase transition.

Elucidating Thermal Decomposition Kinetic Mechanism of Charged Layered Oxide Cathode for Sodium-Ion Batteries.

The safety of the P2-type layered transition metal oxides (P2-NaxTMO2), a promising cathode material for sodium-ion batteries (SIBs), is a prerequisite for grid-scale energy storage systems. However, previous thermal runaway studies mainly focused on morphological changes resulting from gas production detection and thermogravimetric analysis, while the structural transition and chemical reactions underlying these processes are still unclear. Herein, a comprehensive methodology to unveil an interplay mechanism among phase structures, interfacial microcrack, and thermal stability of the charged P2-Na0.8Ni0.33Mn0.67O2 (NNMO) and the P2-Na0.8Ni0.21Li0.12Mn0.67O2 (NNMO-Li) at elevated temperatures is established. Combining a series of crystallographic and thermodynamic characterization techniques, the specific chemical reactions occurring in the NNMO materials during thermal runaway are clarified firstand solidly proved that Li doping effectively hinders the dissolution of transition metal ions, reduces oxygen release, and enhances thermal stability at elevated temperatures. Importantly, based on Arrhenius and nonisothermal kinetic equations, the kinetic triplet model is successfully constructed to in-depth elucidate the thermal decomposition reaction mechanism of P2-NaxTMO2, demonstrating that such thermodynamic assessment provides a new perspective for building high-safety SIBs.

Review of Layered Transition Metal Oxide Materials for Cathodes in Sodium-Ion Batteries

The growing interest in sodium-ion batteries (SIBs) is driven by scarcity and the rising costs of lithium, coupled with the urgent need for scalable and sustainable energy storage solutions. Among various cathode materials, layered transition metal oxides have emerged as promising candidates due to their structural similarity to lithium-ion battery (LIB) counterparts and their potential to deliver high energy density at reduced costs. However, significant challenges remain, including limited capacity at high charge/discharge rates and structural instability during extended cycling. Addressing these issues is critical for advancing SIB technology toward industrial applications, particularly for large-scale energy storage systems. This review provides a comprehensive analysis of layered sodium transition metal oxides, focusing on their structural properties, electrochemical performance, and degradation mechanisms. Special attention is given to the intrinsic and extrinsic factors contributing to their instability, such as structural phase transitions, and cationic/anionic redox behavior. Additionally, recent advancements in material design strategies, including doping, surface modifications, and composite formation, are discussed to highlight the progress toward enhancing the stability and performance of these materials. This work aims to bridge the knowledge gaps and inspire further innovations in the development of high-performance cathodes for sodium-ion batteries.

Ultrafast Preparation of High-Entropy NASICON Cathode Enables Stabilized Multielectron Redox and Wide-Temperature (-50-60°C) Workability in Sodium-Ion Batteries.

Avoiding severe structural distortion, irreversible phase transition, and realizing the stabilized multielectron redox are vital for promoting the development of high-performance NASICON-type cathode materials for sodium-ion batteries (SIBs). Herein, a high-entropy Na3.45V0.4Fe0.4Ti0.4Mn0.45Cr0.35(PO4)3 (HE-Na3.45TMP) cathode material is prepared by ultrafast high-temperature shock, which inhibits the possibility of phase separation and achieves reversible and stable multielectron transfer of 2.4/2.8 e- at voltage range of 2.0-4.45/1.5-4.45 V versus Na+/Na (the capacity of 137.2/162.0 mAh g-1). The galvanostatic charge/discharge and in-situ X-ray diffraction tests indicate the sequential redox reactions and approximate solid solution phase transition behavior of HE-Na3.45TMP. Density functional theory calculations analyze the migration pathways and energy barriers, further confirming the superior reaction kinetics of HE-Na3.45TMP. Accordingly, the HE-Na3.45TMP exhibits outstanding wide temperature applicability and can operate stably in the temperature range of -50-60°C, accompanied by a capacity retention of 92.8% after 400 cycles at -40°C and a capacity of 73.7 mAh g-1 even at -50°C. The assembled hard carbon//HE-Na3.45TMP full-cell offers an energy density of ≈301 Wh kg-1 based on total cathode and anode active mass, verifying the application feasibility of HE-Na3.45TMP. This work provides an innovative and ultrafast pathway to rationally fabricate high-performance cathodes for SIBs.

Doping Engineering of Sodium Vanadium Fluorophosphates Cathodes for Sodium-Ion Batteries

Abstract Sodium-ion batteries offer a promising alternative to lithium-ion batteries due to the abundance and low cost of sodium resources. Na3V2(PO4)2F3−y O y (NVPFO y ) stands out as a cathode material with high average operating potential (~ 3.9 V vs Na+/Na), fast Na⁺ transport, and strong structural stability (minimal volumetric strain of ~ 2%). This review addresses the structural characteristics and charge storage mechanisms of NVPFO y , focusing on charge compensation and Na⁺/vacancy ordering. It also discusses recent advances in lattice regulation and doping strategies to enhance electrochemical properties. Finally, we highlight challenges and future directions for practical applications, emphasizing the correlation between crystal structure and performance.

Local Structure Regulation for Oxygen Redox and Structure Stability of P2-Type Cathodes.

The local structure plays a crucial role in oxygen redox reactions, which boosts the capacity of layered oxide cathodes for sodium-ion batteries. While studies on local structural ordering have primarily focused on the intra-layer ordering, there has been limited research on the inter-layer stacking for the layered cathode materials for sodium-ion batteries. In this work, the impact of the intra-layer and inter-layer local structural regulation on anionic kinetics and the structure stability are explored through experimental analysis and theoretical calculations. Cu2+ substitution is introduced to adjust the transition metal inter-layer structure of P2-Na0.67Mg0.28Mn0.72O2, obtaining a zig-zag stacked honeycomb superlattice structure in P2- Na0.67Cu0.14Mg0.14Mn0.72O2. The local structure regulation mitigates the cation migration, improves the structure reversibility even at a deeply desodiation state of Na0.05, and the reductive coupling between cationic and anionic redox processes facilitates electron transfer from oxygen to copper ions and governs the properties of electrochemical kinetics and hysteresis. A full cell with hard carbon anode shows commendable energy density at high power density. This study paves an optional path for enhancing the structure stability and dynamics of oxygen redox chemistry in P2-type cathode materials for sodium-ion battery systems.

Photo-Rechargeable Sodium-Ion Batteries with a Two-Dimensional MoSe2 Crystal Cathode.

Combining energy harvesting with energy storage systems in a single device could offer great advantages for continuous power supply in both indoor and outdoor electric applications. In this work, we demonstrate a photochargeable sodium-ion battery (PSIB) based on a photoactive cathode of two-dimensional crystals of MoSe2. This photocathode enables spontaneous photodriven charging of a sodium-ion battery cathode under illumination and an increase in the reversible capacity to 29% at 600 mA g-1 compared to that under dark conditions during galvanostatic cycling. Exposure of MoSe2 to light drives the Na+ extraction, prompted by photogenerated holes, and accelerates the charge transfer kinetics with improved ion diffusion, which leads to an increased capacity. Moreover, the PSIB can be charged to 1.68 V under light illumination without applying an external current. Our work paves the way for the development of light-driven rechargeable batteries, which can benefit off-grid technologies such as the Internet of Things.

Synergistically Boosted Na+ Migration and Deep Desodiation Stability of NASICON Cathode via High Entropy Regulation.

Mn-containing sodium superionic conductor (NASICON) compounds have shown considerable potential as cathode for sodium-ion batteries (SIBs) owing to higher working voltage (V5+/V4+: 3.9V), lower cost, and lower toxicity compared to full vanadium-based NASICON Na3V2(PO4)3. Taking Na3.3V1.7Mn0.3(PO4)3 (NVMP) as an example, its practical application is still restricted by poor electronic conductivity, sluggish intrinsic Na+ diffusion, and poor high-voltage stability. In this work, a high entropy strategy is proposed to develop Na3.3V1.613Mn0.3(Cr, Fe, Co, Ni, Zr)0.1(PO4)3 (HE-NVMP) cathode for not only enabling more and rapid Na+ migration but also significantly improving deep desodiation stability. Based on theoretical calculations and experimental findings, such high entropy modification can efficiently alter the coordination environments of both V/Mn and Na sites for reducing Na+ diffusion energy barrier, increasing the occupancy of Na+ at Na(2)sites, and consolidating the structure stability. Thus, the obtained HE-NVMP delivers superior high-rate capability (91.7 mAh g-1) up to 50 C and excellent cycling performance (capacity retention: 81.2%) after 10000 cycles at 20 C at the cutoff voltage of 4.1V. More importantly, such cathode also exhibits superior sodium storage properties at a higher cutoff voltage (4.5V) with electrochemical polarization with 75% reduction at 1 C and higher capacity retention of 80.3% after 2000 cycles at 20 C compared to pristine counterpart, indicating a great potential for practical rechargeable batteries with excellent overcharge resistance capability.

Colloidal Synthesis of Na2Fe2(SO4)3 Nanocrystals as the Cathode Toward High-Rate Capability and High-Energy Density Sodium-ion Batteries.

Alluaudite-type Na2+2xFe2-x(SO4)3 (NFS) with high theoretical energy density is regarded as the promising cathode of sodium-ion batteries (SIBs), while practical rate and cyclic performances are still hindered by intrinsic poor conductivity. Here, a facile method is developed, collaborating high-boiling organic solvents assisted colloidal synthesis (HOS-CS) with sintering for tailoring Na2Fe2(SO4)3 nanocrystals decorated by conductive carbon network toward high-rate-capability cathode of SIBs. Impressively, the as-prepared Na2Fe2(SO4)3@MC provides 60.6 and 46.9 mAh g-1 of reversible capacities even at ultrahigh rates of 20 and 30 C, respectively, ranking the superior state among the current NFS-based cathode. More importantly, Na2Fe2(SO4)3@MC achieves 73% of capacity retention at 20 C after 500 cycles, highlighting its potential for application as a fast chargeable cathode. As a bonus, the full-cell configuration constructed with Na2Fe2(SO4)3@MC cathode and commercial hard carbon (HC) anode delivers 45.6 mAh g-1 at 10 C and 68.3 mAh g-1 of initial capacity with ≈79.4% of retention after 100 cycles at 2 C. Also, Na2Fe2(SO4)3@MC||HC full cell supplies as high as 140Wh kg-1 of practical energy density. This work offers a novel approach to prepare NFS cathode for SIBs with both high energy density and fast-charging ability.

High-Voltage Fe-Based Tunnel-Type Na0.66[Mn0.33Fe0.33Ti0.3Sn0.04]O2 Cathode for Aqueous Rechargeable Sodium-Ion Battery.

Tunnel-type-structure Na0.44MnO2 has been extensively researched for cathode material in aqueous rechargeable sodium-ion battery owing to its high specific capacity (120 mA h g-1), large channels facilitating Na extraction/insertion, chemical and electrochemical stability in aqueous electrolytes, and low cost. However, the low average working potential (0.1 V versus standard hydrogen electrode, SHE) and no more than half of its available theoretical capacity within full batteries limit the practical application. Herein, we develop an Fe-based tunnel-type Na0.66[Mn0.33Fe0.33Ti0.3Sn0.04]O2 cathode, delivering a high reversible specific capacity (95 mA h g-1) under a high working voltage (0.75 V versus SHE). A full battery, assembled with a NaTi2(PO4)3@C anode, exhibits a high energy density of 80 W h kg-1 (total mass of cathode and anode active materials) and a long cycle life with 84% capacity retention after 1000 cycles at 1 C.

High-Performance Sodium-Ion Battery Cathode in Three-Dimensional Covalent Organic Frameworks with Interconnected Microchannels and Dense Redox-Active Sites

High-Performance Sodium-Ion Battery Cathode in Three-Dimensional Covalent Organic Frameworks with Interconnected Microchannels and Dense Redox-Active Sites