Promising Anode Material Research Articles

A novel sheet perovskite type oxides LaFeO3 anode for nickel-metal hydride batteries

Compared with traditional hydrogen storage alloys, perovskite oxide LaFeO3 materials are considered as one of the most promising anode materials for nickel-metal hydride batteries owing to their low cost, environmental friendliness, and superior temperature resistance. However, the biggest problem faced by perovskite oxide LaFeO3 as an anode material for Nickel/metal hydride (Ni-MH) batteries is the low electrical conductivity and poor specific capacity, which is mainly due to the serious agglomeration phenomenon in its structure. To solve the above problems, lamellar LaFeO3 material with large specific surface area and small particle size has been synthesized by adding N,N-Dimethylformamide (DMF) and polyvinyl pyrrolidone (PVP) inhibitor materials to the precursor. By changing the sintering temperature, the lamellar composite LaFeO3 material can be controlled. Consequently, the maximum discharge capacity of lamellar LaFeO3 is up to 372.1 mA h g–1 at the discharge current density of 60 mA g–1. Meanwhile, after 100 cycles, the specific discharge capacity of the lamellar LaFeO3 can still reach 293.1 mA h g–1, which is much higher than that of 98.5 mA h g–1 for LaFeO3. In addition, the kinetics of LaFeO3 has been investigated and the lamellar LaFeO3 shows excellent dynamic properties. Notably, the exchange current density I0 (300 mA g–1) of the layered LaFeO3 electrode is higher than that of LaFeO3 (150 mA g–1). Overall, this work provides insights into a structure-performance relationship for the further development of high-performance perovskite-type oxide nickel-metal hydride battery anodes.

Pitch-derived P-doped carbon/GeP3 composite via ball milling towards enhanced sodium-ion storage

GeP3 is a promising anode material for sodium ion battery due to better conductivity, relatively high theoretical capacity and improved mechanical endurance compared to phosphorus and other phosphides. However unsatisfied rate capability and cycling stability is still an annoying issue that hinders the application of GeP3. Here, GeP3 was hybridized with P doped carbon (PPC) derived from low-cost coal tar pitch to prepare composite electrode. Through ball-milling process, the GeP3 and PPC was homogenously mixed and form fused, secondary particles as confirmed by electron microscope. The formation of P-C and P-O-C bond between GeP3 and carbon matrix was evidenced by XPS, and prompted by P doping level and O content in PPC. The electrochemical performance of the composite electrodes was evaluated, demonstrated much enhanced properties compared to bare GeP3 and also GeP3/carbon black electrode. High reversible capacity of 781 mAh/g was achieved by GeP3/PPC-950 at 0.05 A/g. At higher current density of 2 A/g, the capacity can maintain at 360 mAh/g, 46% of the value that obtained at 0.05 A/g. The correlation between the structure of carbon and battery performance was discussed. The improvement in battery performance can be attributed to suppressed volume expansion and good conductive network of the GeP3/PPC composite, which affected by P doping level and O content of PPC.

High-Performance Li-Organic Batteries Based on Conjugated and Nonconjugated Schiff-Base Polymer Anode Materials.

In recent years, organic materials have been increasingly studied as anode materials in lithium-ion batteries (LIBs) due to their remarkable advantages, including abundant raw materials, low prices, diverse structures, and high theoretical capacity. In this paper, three types of aromatic Schiff-base polymer materials have been synthesized and examined as anode materials in LIBs. Among them, the polymer [C6H4N = CHC6H4CH=N]n (TTD-PDA) has a continuous conjugated backbone (label as conjugated polymer), while polymers [(CH2)2N=CHC6H4CH=N]n (TTD-EDA) and [C6H4N=CH(CH2)3CH=N]n (GA-PDA) have discontinuous conjugated back-bones (label as nonconjugated polymer). The organic anodes based on TTD-PDA, TTD-EDA, and GA-PDA for LIBs are discovered to represent high reversible specific capacities of 651, 492, and 416 mAh g-1 at a current density of 100 mA g-1 as well as satisfactory rate capabilities with high capacities of 210, 90, and 178 mAh g-1 and 105, 57, and 122 mAh g-1 at current densities of 2 and 10 A g-1, indicating that these Schiff-base polymers are all promising anode materials for LIBs, which broadens the design of organic anode materials with high specific capacity, superior rate performance, and stable cycling stability.

Liquid phase oxidation enables stable soft carbon anodes for potassium-ion batteries

Soft carbon has been recognized as a promising anode material for potassium-ion batteries (PIBs), due to low cost, high conductivity and low voltage platform. However, their practical application is hampered by slow storage kinetics and unsatisfactory cycle life. In this work, pitch-derived needle coke, a typical soft carbon, was incorporated with oxygenated functional groups through liquid phase oxidation by using H2O2 oxidant. When used as anode materials for PIBs, the oxidized needle coke delivers a high reversible capacity of 322.7 mAh g−1, significantly superior to that of the needle coke (237.9 mAh g−1). The enhanced electrochemical performance can be attributed to the abundant oxygenated functional groups and resultant defects on the surface of oxidized needle coke, which not only serve as extra active sites for potassium storage, but also provide sufficient pathways for K+ migration across the adjacent carbon layers. Moreover, the expanded interlayer spacing derived from H2O2 oxidation facilitates rapid K+ intercalation and deintercalation. This work offers an effective modification strategy for the fabrication of high-performance pitch-based soft carbon anodes for PIBs.Graphical

The conductivity of Nb2O5 enhanced by the triple effect of fluorine doping, oxygen vacancy, and carbon modification for improving the lithium storage performance.

In view of the inherent pseudocapacitance, rich redox pairs (Nb5+/Nb4+ and Nb4+/Nb3+), and high lithiation potential (1.0-3.0V vs Li/Li+), Nb2O5 is considered a promising anode material. However, the inherent low electronic conductivity of Nb2O5 limits its lithium storage performance, and the rate performance after carbon modification is still unsatisfactory because the intrinsic conductivity of Nb2O5 has not been substantially improved. In this experiment, taking the improvement of the intrinsic electrical conductivity of Nb2O5 as the guiding ideology, we prepared F-doped Nb2O5@fluorocarbon composites (F-Nb2O5@FC) with a large number of oxygen vacancies by one-step annealing. As the anode electrode of lithium-ion batteries, the reversible specific capacity of F-Nb2O5@FC reaches 150 mA g-1 at 5Ag-1 after 1100 cycles, and the rate performance is particularly outstanding, with a capacity up to 130 mA g-1 at 16Ag-1, which is far superior to other Nb2O5@carbon-based anode electrodes. Compared with other single conductivity sources of Nb2O5@carbon-based composites, the electrical conductivity of F-Nb2O5@FC composites is greatly improved in many aspects, including the introduction of free electrons by F- doping, the generation of oxygen vacancies, and the provision of a three-dimensional conductive network by FC. Through analytical chemistry (work function, UV-Vis diffuse reflectance spectroscopy, and EIS) and theoretical calculations, it is proved that F-Nb2O5@FC has high electrical conductivity and realizes rapid electron transfer.

Effect of ball milling on the structure and electrochemical hydrogen storage properties of a RE-Mg-Ni alloy

RE-Mg-Ni alloy is considered a highly promising anode material for the next generation of MH-Ni batteries. However, the low cycle life, fast performance, and high manufacturing cost of this ideal MH-Ni battery anode material have become obstacles to its optimization. In this work, an as-cast La0.7Sm0.3MgNi3.6Co0.4 superlattice alloy was prepared by vacuum medium frequency induction melting. Then, La0.7Sm0.3MgNi3.6Co0.4 + 10 wt% Ni (0–2 h) composite hydrogen storage alloys with excellent properties were prepared by adding a catalyst (Ni) and conducting ball milling. XRD, SEM, and HRTEM were conducted to analyse the phase compositions, microstructures and macrostructures of the samples. The experimental results showed that with the increase in ball milling time, the microstructural characteristics of the alloy changed, such as the phase abundance, grain refinement, particle size reduction, and amorphous structure increase, directly leading to the change in electrochemical performance. The discharge capacity (Cmax) of the sample decayed from 264.0 mAh/g to 219.1 mAh/g, the cycle stability (Sn) gradually increased with the extension of the grinding time, and the rate discharge performance first increased and then decreased. When the grinding time was 1 h, the best performance was HRD900 = 36.53%. The critical factors affecting the dynamic performance, such as the charge transfer resistance (Rct), limiting current density (IL), and hydrogen diffusion coefficient (D), all exhibited the same trend and reached their respective optimal values at 1 h.

MOF-derived cobalt nanoparticles in silicon suboxide-based anodes for enhanced lithium storage

The ultra-high theoretical capacity of silicon-based (Si) materials makes them promising anode materials for high energy density lithium-ion batteries. Unfortunately, the dramatic volume change (∼300%) and low electrical conductivity of silicon have severely hindered the commercial use of silicon anodes. Silicon suboxide (SiOx) is one of the ideal candidates for high energy density batteries due to its reduced swelling and lower cost as compared to silicon. However, it remains a huge challenge to address the low conductivity, low (initial) coulombic efficiency and apparent volume effects of SiOx. In this paper, SiOx/Co@C composite anode materials loaded with metal Co nanoparticles were uniformly and efficiently prepared by using 3-aminopropyl triethoxysilane (APTES) as silicon source and Co-MOF as Co source via molecular self-assembly strategy. The experimental results and density functional theory (DFT) calculation showed that the catalytic action of embedded Co nanoparticles had activated the silico-oxygen bond of SiOx and the irreversible product Li2O, thereby improving the initial coulombic efficiency (ICE) and enhancing the reversible capacity. At the same time, the metal Co with mechanical rigidity and electrical conductivity alleviated the volume fluctuation during alloying and improved the charge transfer capacity and ion transport rate of the composite. When compared with SiOx@C anodes, SiOx/Co@C-600 composites showed higher initial CE, superior cyclic stability and good rate performance. In particular, the successful matching of the anode with the lithium iron phosphate (LFP) cathode in full cell systems validated the possibility of its practical application. This work provides important insights into the application of Si-based materials in lithium-ion battery electrode materials and the development of high energy density batteries.

Nanohoneycomb rGO foam as a promising anode material for unprecedented ultrahigh Li storage and excellent endurance at ampere current stability

Most rechargeable lithium-ion batteries (LIBs) exploit bulk carbon (e.g., graphite with low interlayer spacing of 0.335 nm) as an anode material despite its low theoretical capacity of 372 mAh/g because it has a high coulombic efficiency, good cycling performance, and low production costs. However, it is difficult to increase the specific capacity of graphite-based anodes without sacrificing these inherent advantages. In the present study, we developed reduced graphene oxide nanohoneycomb foam (H-rGO) as an anode material with higher surface area, porosity, and interlayer spacing for the rapid and efficient lithiation-delithiation of Li-ions. The combination of the hierarchical three-dimensional sponge-like mesoporous structure with highly efficient Li-ion conduction pathways and enlarge active surface area leads to a significantly improved specific capacity (1031 mAh/g at 0.1 A/g) and rapid charging with exceptional stability over 5,000 cycles. The H-rGO anode achieves an outstanding reversible capacity of ∼534 mAh/g over 2,500 cycles at 1.0 A/g, with a capacity retention of 87 and 84 % at high current densities of 10 and 20 A/g, respectively. Our approach is fully compatible with current LIBs technology and offer a simple and efficient strategy to significantly increase Li-storage capacity of under current graphite-based anode technology.

Volume contractible Antimony bromide electrode as negative electrode for long-lasting Li-ion batteries

Antimony is one of the promising anode materials for lithium-ion batteries due to its high volumetric and gravimetric capacity (theoretical specific capacity 660 mAh g-1) and stable voltage window (0.87-0.91V vs Li/Li+). However, a high-volume expansion ( ∼130%) of Sb on lithiation degrades the electrochemical performance and restricts its application. In this work, a novel strategy is explored to use antimony halide (SbBr3) instead of Sb as the starting anode material. In the first step, Li will react with SbBr3 to form LiBr and pure Sb, leading to a 78% contraction in volume, and then this pure Sb further lithiates to form Li3Sb expanding the volume (of the lithiated Sb by 130%). LiBr, which is a byproduct of the first reaction, dissolves into the solvent, leaving a porous Sb. In a nutshell, the two-step lithiation process results in a net volume-contacted porous antimony, ideal as an electrode to counter volumetric stress in subsequent charge-discharge cycles. The electrochemical performance of this electrode is much superior when compared with the pure antimony electrode, taking advantage of initial volume reduction and porous scaffold. It achieves a high specific discharge capacity of 345 mAh g-1 at a rate of 100mAg-1 even after the end of the 100th cycle and losing only 20% of its capacity. This shows that this volume contractible technique can be successfully employed for metals and metallic alloys having drastically higher Li-storing capacities than graphite.

Encapsulating Bi Nanoparticles in Reduced Graphene Oxide with Strong Interfacial Bonding toward Advanced Potassium Storage.

Bismuth (Bi) is regarded as a promising anode material for potassium ion batteries (PIBs) due to its high theoretical capacity, but the huge volume expansion during potassiation and intrinsic low conductivity cause poor cycle stability and rate capability. Herein, a unique Bi nanoparticles/reduced graphene oxide (rGO) composite is fabricated by anchoring the Bi nanoparticles over the rGO substrate through a ball-milling and thermal reduction process. As depicted by the in-depth XPS analysis, strong interfacial Bi-C bonding can be formed between Bi and rGO, which is beneficial for alleviating the huge volume expansion of Bi during potassiation, restraining the aggregation of Bi nanoparticles and promoting the interfacial charge transfer. Theoretical calculation reveals the positive effect of rGO to enhance the potassium adsorption capability and interfacial electron transfer as well as reduce the diffusion energy barrier in the Bi/rGO composite. Thereby, the Bi/rGO composite exhibits excellent potassium storage performances in terms of high capacity (384.8 mAh g-1 at 50mA g-1), excellent cycling stability (197.7 mAh g-1 after 1000 cycles at 500mA g-1 with no capacity decay) and superior rate capability (55.6 mAh g-1 at 2 A g-1), demonstrating its great potential as an anode material for PIBs.

Self-Assembly of Silicon Nanotubes Driven by a Biphasic Transition from the Natural Mineral Montmorillonite in Molten Salt Electrolysis.

Silicon nanotubes (SNTs) have been considered as promising anode materials for lithium-ion batteries (LIBs). However, the reported strategies for preparing SNTs generally have special requirements for either expensive templates or complex catalysts. It is necessary to explore a cost-effective and efficient approach for the preparation of high-performance SNTs. In this work, a biphasic transformation strategy involving "solid-state reduction" and "dissolution-deposition" in molten salts is developed to prepare SNTs using montmorillonite as a precursor. The rod-like intermediate of silicon-aluminum-calcium is initially reduced in solid state, which then triggers the continuous dissolution and deposition of calcium silicate in the inner space of the intermediate to form a hollow structure during the subsequent reduction process. The transition from solid to liquid is crucial for improving the kinetics of deoxygenation and induces the self-assembly of SNTs during electrolysis. When the obtained SNTs is used as anode materials for LIBs, they exhibit a high capacity of 2791mAhg-1 at 0.2Ag-1, excellent rate capability of 1427mAhg-1 at 2Ag-1, and stable cycling performance with a capacity of 2045mAhg-1 after 200 cycles at 0.5Ag-1. This work provides a self-assembling, controllable, and cost-effective approach for fabricating SNTs.

Graphene-like BGe monolayer as anode material for metal-ions batteries: Computational predictions

Magnesium-, calcium- and potassium-ion batteries (MIBs, CIBs and PIBs) have attracted extraordinary attention as alternative batteries of lithium-ion batteries, due to their due to their abundancies, the low cost, safety. Herein, we investigated the suitability of BGe monolayer as anode material for MIBs, CIBs, and PIBs by using first-principles calculations in framework of density functional theory (DFT). The energy adsorption calculations and the charge transfer analysis show that the hollow site is the most favorable site for Mg, Ca, and K atoms adsorption on the BGe monolayer. In addition, the BGe monolayer has remained the same, preserving its metallic behavior after Mg, Ca and K atoms adsorption, which is suitable for batteries applications. The open circuit voltage ranges from 1.03 V to 1.02, 1.86 V to 1.67 V, and 2.85 V to 2.28 V for Mg, Ca, and K, respectively. Especially, the BGe monolayer exhibits a high theoretical specific capacity, up to 1284.63 mAhg−1 for Mg and Ca, and 642.31 mAhg−1 for K, which are higher than other monolayers. In addition, the BGe monolayer can provide a good charging-discharging processes with a low diffusion barrier of 0.80, 0.52, and 0.17 eV for Mg, Ca, and K-ion, respectively. All these properties indicate that the BGe monolayer is promising anode material for Mg/Ca/K ion batteries.

CO2-derived nitrogen doped porous carbon as advanced anodes for lithium-ion capacitors

Porous carbon is considered one of the most promising anode materials for lithium-ion capacitors due to its high ionic and electronic conductivity, high lithium storage capacitance and high chemical stability. However, the green and low-carbon preparation is a great challenge for the current porous carbon, especially for heteroatoms doped porous carbon. Herein, we report a low-carbon and environmentally friendly method to prepare N-doped porous carbon by the novel reaction of greenhouse gas CO2 with 5LiH-LiNH2. N-doped porous carbon delivers a reversible lithium storage capacity of 904 mAh g−1 at 0.1 A g−1, When paired with commercial activated carbon, the as-assembled lithium-ion capacitors provide a high energy density of 112 Wh kg−1 at a power density of 198.6 W kg−1 with a capacitance retention of 72% at 1.0 A g−1 after 6000 cycles. This work provides a green and low-carbon strategy for converting greenhouse gas CO2 into N-doped porous carbon for high-performance lithium-ion capacitors.

Self-Catalyzed Synthesis of Length-Controlled One-Dimensional Nickel Oxide@N-Doped Porous Carbon Nanostructures from Metal Ion Modified Nitrogen Heterocycles for Efficient Lithium Storage.

Transition metal oxides with the merits of high theoretical capacities, natural abundance, low cost, and environmental benignity have been regarded as a promising anodic material for lithium ion batteries (LIBs). However, the severe volume expansion upon cycling and poor conductivity limit their cycling stability and rate capability. To address this issue, NiO embedded and N-doped porous carbon nanorods (NiO@NCNR) and nanotubes (NiO@NCNT) are synthesized by the metal-catalyzed graphitization and nitridization of monocrystalline Ni(II)-triazole coordinated framework and Ni(II)/melamine mixture, respectively, and the following oxidation in air. When applied as an anodic material for LIBs, the NiO@NCNR and NiO@NCNT hybrids exhibit a decent capacity of 895/832 mA h g-1 at 100 mA g-1, high rate capability of 484/467 mA h g-1 at 5.0 A g-1, and good long-term cycling stability of 663/634 mA h g-1 at 600th cycle at 1 A g-1, which are much better than those of NiO@carbon black (CB) control sample (701, 214, and 223 mA h g-1). The remarkable electrochemical properties benefit from the advanced nanoarchitecture of NiO@NCNR and NiO@NCNT, which offers a length-controlled one-dimensional porous carbon nanoarchitecture for effective e-/Li+ transport, affords a flexible carbon skeleton for spatial confinement, and forms abundant nanocavities for stress buffering and structure reinforcement during discharge/charging processes. The rational structural design and synthesis may pave a way for exploring advanced metal oxide based anodic materials for next-generation LIBs.

Investigation of the structural, electronic, and optical properties of arsenic doped blue phosphorene as a promising anode material

Using the first principle method based on density functional theory (DFT), we systematically studied the possibility of arsenic doped single-layer blue phosphorene (AsP) as anode material for Li, Mg, Ca, and Al ion batteries. The calculation of formation energy against temperature shows good thermal and dynamic stability of monolayer AsP, which can provide inherent advantages for electron transmission in materials. Meanwhile, the calculation indicates that AsP can provide excellent mobility for adsorbed atoms. The diffusion barriers of Li, Mg, Ca, and Al on the upper and lower surfaces of AsP are 0.18/0.16 eV, 0.10/0.17 eV, 0.45/0.43 eV, and 0.17/0.18 eV, respectively. These properties indicate that AsP can increase the charging/discharging rate without metal aggregation. The specific capacities of Mg, Ca, and Al can reach over 505.7 mAhg−1, greater than the values of corresponding graphite or some other 2D materials. In addition, AsP has a lower open circuit voltage, and the charge transferred from metal atoms to AsP enhances its conductivity, which is beneficial to the anode material.

Two‐Dimensional Ultrathin C2N Nanosheets for High‐Performance Sodium‐Ion Storage

AbstractIn this study, we have created and investigated ultrathin, large‐size two‐dimensional C2N nanosheets, which serve as promising anode materials for sodium ion batteries. Those ultrathin C2N nanosheets were produced through a chemical vapor deposition process, involving the polymerization of the precursor molecule HAT‐CN on sodium chloride templates. Notably, these nanosheets inherit an abundance of nitrogen sites from the precursor molecules, which are highly advantageous for sodium ion storage. In addition, the ultrathin nature of these nanosheets leads to significantly shorter ion transport pathways, enhancing their capacity for rapid ion storage compared to C2N particles. As a result, the anode constructed using C2N nanosheets demonstrates a notably higher capacity of 335.1 mAh g−1 at 0.5 A g−1, outperforming the 211.5 mAh g−1 of C2N particles. Furthermore, it exhibits outstanding rate performance, achieving 255.4 mAh g−1 at a current density of 2.0 A g−1, along with excellent cycle stability, maintaining a reversible capacity retention of 92.9 % over 1500 cycles at 2.0 A g−1. This research introduces a novel approach to developing high‐capacity anode materials for sodium storage by utilizing carbon nitride materials.

Inert salt-assisted solvent-free synthesis of high-entropy oxide towards high-performance lithium-ion batteries

High-entropy oxide (HEO) is a promising anode material for lithium-ion battery (LIB) due to the synergistic effect of various metal species. Conventional HEO preparations typically involve a solid-state route or liquid-phase mixing followed by high-temperature calcination, leading to either a small surface area or environmental contamination. Herein, a novel, facile solvent-free preparation of HEOs is introduced, applying inert salt, NaCl, as an easily removable, eco-friendly and recyclable template. This approach realizes high-purity porous HEO (NPHEO) with specific surface area (28.1 m2 g−1) for high-performance lithium-ion batteries. With the enhanced electrochemical kinetics, the NPHEO anodes deliver a high reversible specific capacities of 1143.6 at 0.2 A/g. In addition, the NPHEO-based cells exhibit a desirable rate capability of 315.7 mAh/g at 5 A/g. At 1 A/g the cell delivers a good cyclability of 71.8 % capacity retention over 600 cycles, corresponding to an average coulombic efficiency of above 99.94 % per cycle. Ex-situ X-ray diffraction and in-situ electrochemical impedance spectroscopy experiments further probe the structural evolution and electrochemical behavior during lithiation/delithiation, confirming the structural stability and fast electrochemical kinetics of NPHEO. The proposed advanced synthesis approach offers a new platform for the preparation of HEOs with high quality.

Theoretical Investigation of Cyanographene and Cyanographite for Potential Sodium‐Ion Battery

Sodium‐ion batteries (SIBs) draw much attention as alternative charge carrier to lithium because of their abundance and cost‐effectiveness. However, SIBs are limited by their low capacity to achieve comparable loadings in graphite. Herein, cyanographene and cyanographite are proposed as materials exhibiting superior storage capacity, facilitating sodium ionization. First‐principle calculations are performed to evaluate the sodium adsorption and diffusion of cyanographene and cyanographite. In the calculation, it is shown that sodium atoms diffuse with relatively low activation energy over cyanographene and cyanographite. It is found out that cyanographene and cyanographite have greater sodium‐storage capacity than graphite. The high sodium mobility and large sodium‐storage capacity demonstrate that cyanographene and cyanographite are a promising anode material for SIBs.

Superior initial Coulombic efficiency and areal capacity of hard carbon anode enabled by graphite-assisted carbonization for sodium-ion battery

Hard carbons are perceived as promising anode materials in sodium-ion batteries, while their practical implementation is largely impeded by the insufficient initial Coulombic efficiency (ICE). Hard carbons with self-supporting architecture are intriguing to enhance ICE owing to the omission of binder and conductive agent; whereas elaborate architecture and microstructure design are still required to further raise the ICE to the level of commercial graphite in lithium-ion batteries, especially under high areal capacity. Herein, we propose a graphite-assisted pressurization strategy during carbonization to achieve remarkable ICE and high areal capacity in resulting self-supporting cellulose tissue derived hard carbon anode. The intimate contact of graphite plate enables suitable local ordering of pseudo-graphitic nanodomains with low intrinsic defects, responsible for enhanced ICE. While the pressure-reinforced dense yet self-interwoven fibrous networks render high areal capacity. Consequently, the as-prepared self-supporting hard carbon anode displays remarkable ICE to 95% and areal capacity of 2.4 mAh cm−2, far exceeding the reported value of less than 0.8 mAh cm−2. Meanwhile, the rate and durability are not scarified under such superior ICE due to the well-manipulated pseudo-graphitic nanodomains and porous fibrous networks. The practicality is further demonstrated in coin-type and pouch-type full cells delivering high capacity and long-term stability. Our finding offers an impetus for the development of high ICE and areal capacity for sodium-ion battery anode.

Flexible Self-Supporting MOF-Based Bean Pod Cube Hollow Nanofibers for Ultralong Cycling and High Rate Na Storage.

Sodium-ion batteries (SIBs) have garnered significant attention due to their potential as an emerging energy storage solution. Tin sulfide (SnS) has emerged as a promising anode material for SIBs due to its impressive theoretical specific capacity of 1022 mA h g-1 and excellent electrical conductivity. However, its practical application has been hindered by issues such as large volume expansion, which adversely affects cycling stability and rate performance during the charge/discharge processes. In this study, a novel approach to address these issues by synthesizing the bean pod cube hollow metal-organic framework (MOF)-SnSx/NC@N-doped carbon nanofibers through a process involving electrospinning, PDA coating, and calcination. The Sn-MOF serves as a self-sacrificing template, facilitating the simultaneous dissociation of MOF and polymerization of dopamine, leading to the creation of hollow intermediates that retain tin components. Subsequent sulfidation results in the integration of the hollow MOF-SnSx/NC nanoparticles within 3D nitrogen-doped carbon nanofibers, forming the distinctive bean pod cube composite structure. This unique configuration effectively shortens the diffusion path and mitigates volume expansion for sodium ions, ultimately yielding an exceptional high rate performance of 130 mA h g-1 (10 A g-1) and an ultralong cycling performance of 328 mA h g-1 even after 3500 cycles (2 A g-1) as the anode for SIBs.