N-doped Carbon Matrix Research Articles

Fast ionic conductor MnSe supported Micron-Si embedded in three-dimensional N-doped carbon matrix for lithium-ion batteries

Silicon is regarded as the most potential anode for the next generation lithium-ion batteries (LIBs) since its superhigh specific capacity and abundant reserves. Nonetheless, the grievous volume variation and inferior connate conductivity imped its further step on the commercial application. Herein, three-dimensional (3D) porous N-doped carbon microspheres, in which silicon is embedded and supported by MnSe, are fabricated via a simple spray drying method, named as MnSe/Si@NC. Such synergy conduces to the weaker polarization phenomenon and lower reactive barrier. Multi kind of electrochemical tests announce that the 3D network supported by MnSe and synthetical chemical bridge bonds, can remarkably ameliorate electron conductivity and structural stability. Benefit from the reasonably designed materials, the MnSe/Si@NC-10 anode expresses an outstanding cycling stability of 1030.8 mAh·g−1 at 2 A g−1 over 1000 cycles and extremely low-capacity loss rate for each cycle with about 0.27 ‰. In a word, this work can provide reference for the designing and preparation of high-performance anode materials utilized in LIBs.

Insights into interfacial catalysis for aqueous reduction of 4-Nitrophenol catalyzed by Ni metal nanoparticles encapsulated within biomass-derived N-doped carbon matrix

As we strive towards a sustainable future in the field of catalysis, it is imperative to draw inspiration from Mother Nature. In this study, we present a straightforward and environmentally friendly approach for the in situ synthesis of nickel metal nanoparticles encapsulated within nitrogen-doped carbon (NNC), derived from daikon biomass. Among the various examined NNC catalysts, NNC-2 characterized by its substantial surface area and high doping content, emerges as the most promising candidate for catalyzing the reduction of 4-nitrophenol. Ab initio molecular dynamics simulations unveil that NNC-2 facilitates a robust Ni-NC interfacial interaction, which stabilizes Ni nanoparticles and supports the exceptional durability and recyclability. Theoretical calculations further elucidate the structure–activity relationship of the catalyst and the mechanistic aspects of the surface reduction of 4-nitrophenol. This insight enhances our understanding of the catalytic processes over carbon-based catalysts, providing a foundation for optimizing catalytic performance and guiding future developments in the field.

Fabricating composites of multicomponent active substances embedded in carbon matrix for enhancing structural stability and redox kinetics of cathode in aqueous zinc-ion batteries

Rechargeable aqueous zinc-ion batteries (ZIBs) are recognized as a potential candidate for large-scale energy storage due to its high-security and low-expense aspects. However, the poor structural stability and sluggish redox kinetics of cathode material lead to the serious capacity fading and bad rate performances, which hinders its practical applications. Herein, a novel one-step pyrolysis strategy is conducted for fabricating the composites of multicomponent active substances (including WO3, Bi and Bi2O3) embedded in amorphous N-doped carbon matrix (BWO@C) using polydopamine-coated Bi2WO6 micro-flowers as the precursors. The amorphous nitrogen-doped carbon endows BWO@C composite to possess more active-sites and higher electrical conductivity for rapid electrons/ions transport, and meanwhile the active substances could be effectively utilized even undergoing thousands of charge/discharge cycles. Therefore, the resulting BWO@C as cathode for aqueous ZIBs exhibits satisfying rate performances as well as outstanding cycling stability. This work provides a simple and efficient pathway for designing the cathode materials with high conductivity and high structural stability to achieve remarkable performances and long life-span of aqueous ZIBs.

Three-dimensional faveolate porous N-doped carbon skeleton embodied with nano Bi toward stable less-Na sodium metal batteries

Sodium metal batteries (SMBs) have been widely investigated recently due to the low price of Na metal, satisfactory energy density and similar chemical properties to lithium. However, SMBs also face challenges like low Na utilization, dendrite growth, dead sodium accumulation, unstable solid electrolyte interphase and massive bubble generation. To improve their safety and cycling stability, herein, we fabricate a porous hybrid framework, i.e., fine Bi nanoparticles anchored in porous N-doped carbon matrix (Bi@PNC), as a modified layer upon Cu collector toward stable SMBs. Upon electrochemical activation, the nanoscale Bi-derived Na–Bi alloy with high sodiophilicity reduces the nucleation overpotential of Na, inhibits the formation of Na dendrites, and decreases the loss of Na during cycling. Thanks to these striking merits, the half cells assembled with Na undergo 1600 cycles (3200 h) at 1 mA cm−2, 1 mAh cm−2 with the average Coulombic efficiency of 99.95%. The optimized Bi@PNC based symmetric cells still maintain the overpotential of ∼9.2 mV under 1 mA cm−2 and depth of discharge of 16.7% after cycling for 2420 h. Furthermore, the assembled less-Na full SMBs exhibit superb electrochemical properties. Our strategy here provides meaningful avenue to construct stable less-Na metallic anodes for advanced SMBs.

Co-ZIF-derived dual Co and Co3S4 nanoparticles encapsulated in N-doped carbon matrix for efficient photocatalytic CO2 reduction

In this study, a novel N-doped carbon-coated dual Co and Co3S4 nanoparticles composite (Co-Co3S4@NC) has been developed by pyrolysis of an ideal flower-like Co-ZIF precursor followed via subsequent hydrothermal sulfidation. Under visible-light irradiation, the Co-Co3S4@NC exhibits outstanding performances for CO2 reduction with H2O vapor into CO (23.14 μmol g−1 h−1) and CH4 (0.62 μmol g−1 h−1) in a continuous flow system, significantly outperforming the single Co@NC photocatalyst. The experimental results demonstrate that the energy band structure in Co-Co3S4@NC can provide a more favorable reduction potential for the effective reduction of CO2. Moreover, the presence of Co3S4 is beneficial for the rapid separation and transfer of charges, thereby enhancing the utilization of photogenerated charge carriers. Thanks to its unique composition, Co-Co3S4@NC possesses abundant active sites for chemisorption and activation of CO2, which facilitates CO2 photoreduction. The reaction mechanism is revealed in detail by analyzing the key intermediate species obtained through in situ DRIFTS. The current work offers a facile route for the construction of MOF-derived composites for promising photocatalytic reactions.

Design of heterostructured hydrangea-like FeS2/MoS2 encapsulated in nitrogen-doped carbon as high-performance anode for potassium-ion capacitors

The means of structural hybridization such as heterojunction construction and carbon-coating engineering for facilitating charge transfer and electron transport are considered viable strategies to address the challenges associated with the low rate capability and poor cycling stability of sulfide-based anodes in potassium-ion batteries (PIBs). Motivated by these concepts, we have successfully prepared a hydrangea-like bimetallic sulfide heterostructure encapsulated in nitrogen-doped carbon (FMS@NC) using a simple solvothermal method, followed by poly-dopamine wrapping and a one-step sulfidation/carbonization process. When served as an anode for PIBs, this FMS@NC demonstrates a high specific capacity (585 mAh g−1 at 0.05 A/g) and long cycling stability. Synergetic effects of mitigated volume expansions and enhanced conductivity that are responsbile for such high performance have been verified to originate from the heterostructured sulfides and the N-doped carbon matrix. Meanwhile, comprehensive characterization reveals existence of an intercalation-conversion hybrid K-ion storage mechanism in this material. Impressively, a K-ion capacitor with the FMS@NC anode and a commercial activated carbon cathode exhibits a superior energy density of up to 192 Wh kg−1, a high power density, and outstanding cycling stability. This study provides constructive guidance for designing high-performance and durable potassium-ion storage anodes for next-generation energy storage devices.

Synthesis of cobalt phosphide hybrid for simultaneous electrochemical detection of ascorbic acid, dopamine, and uric acid.

Ascorbic acid (AA), dopamine (DA), and uric acid (UA) are important biomarkers for the clinical screening of diseases. However, the simultaneous determination of these three analytes is still challenging. Herein, we report a facile metal-organic framework (MOF)-derived method to synthesize a cobalt phosphide (Co2P) hybrid for the simultaneous electrochemical detection of AA, DA and UA. The introduction of highly dispersed Co2P nanoparticles onto a P, N-doped porous carbon matrix is responsible for providing abundant active sites and facilitating electron transfer, thereby contributing to the improved electrocatalytic performance of the hybrid. Well-resolved oxidation peaks and an enhanced current response for the simultaneous oxidation of AA, DA, and UA were achieved using a Co2P hybrid-modified screen-printed electrode (Co2P hybrid-SPE) with the differential pulse voltammetry (DPV) method. The detection limits for AA, DA, and UA in simultaneous detection were calculated as 17.80 μM, 0.018 μM, and 0.068 μM (S/N = 3), respectively. Furthermore, the feasibility of using Co2P hybrid-SPE for the simultaneous detection of AA, DA, and UA in real serum samples was also confirmed.

Confining micron silicon suboxide (μ-SiOx) into an N-doped carbon matrix modified by Sn nanoparticles as a stabilized anode material for fast charging lithium-ion batteries

Utilizing Sn-modified N-doped carbon networks to encapsulate SiOx to maintain its stability and facilitate lithium-ion and electron migration during charge/discharge.

Highly dispersed ultrafine Ru nanoparticles on a honeycomb-like N-doped carbon matrix with modified rectifying contact for enhanced electrochemical hydrogen evolution.

The manipulation of rectifying contact between metal and semiconductor represents a powerful strategy to modify the electronic configuration of active sites for improved electrocatalytic performance. Herein, we present an NaCl template-assisted approach to rationally construct a Schottky electrocatalyst consisting of a honeycomb-like N-doped carbon matrix decorated with uniformly ultrasmall Ru nanoparticles with an average diameter of 2.5 nm (hereafter abbreviated as Ru NPs@HNC). It is found that the Fermi level difference between Ru and HNC can cause self-driven migration of electrons from Ru NPs to the HNC substrate, which leads to the generation of a built-in electric field and directional flow of electrons, thereby enhancing the intrinsic activity. In addition, the immobilization of ultrafine Ru NPs on the honeycomb-like carbon skeleton can effectively inhibit the undesired migration, agglomeration and detachment of the active sites, thus ensuring remarkable structural stability. As a result, the Ru NPs@HNC with optimal rectifying contact delivers superior electrochemical activity with a small overpotential of 28 mV at 10 mA cm-2 and outstanding long-term stability in an alkaline solution. The design philosophy of grain-size modulation and Schottky contact may widen up insight into the preparation of high-performance electrocatalysts in sustainable energy conversion systems.

Activating iodine redox by enabling single-atom coordination to dormant nitrogen sites to realize durable zinc–iodine batteries

The introduction of a single Ni atom into an inactive N-doped carbon matrix, through its role as an electrocatalyst, awakens the dormant N sites, significantly suppressing the polyiodide shuttle effect and enhancing iodine redox kinetics.

In situ preparation of cobalt@N-doped porous carbon bifunctional electrocatalyst for efficient overall water splitting

Developing highly efficient noble-metal-free bifunctional nanocatalysts for electrocatalytic water splitting is attractive but challenging. Notably, the rational structure engineering could effectively promote electronic transfer and improve the active area. Herein, a free-standing N-doped porous carbon nanosheet arrays encapsulated with metallic Co nanoparticles electrocatalyst (Co@NC-A) for overall water splitting was designed via pyrolysis process followed with acid treatment. The N-doped carbon matrix not only enhances electron mobility and protects the metallic Co nanoparticles from electrolyte corrosion, but also improves the electrochemically active area and facilitates mass transfer. Consequently, the Co@NC-A exhibits superior electrocatalytic performance toward OER (η10 = 270 mV) and HER (η10 = 162 mV) in 1 M KOH. Moreover, the Co@NC-A as a bifunctional catalyst in overall water splitting could approach 10 mA cm−2 at a cell voltage of 1.66 V and operate stably for 50 h. Combined with the density functional theory (DFT) calculations, the improvement of the HER and OER activities is also attributed to the modified electronic structure with N-doped carbon and the optimized free energy toward the adsorption/desorption of intermediates. This work provides a novel and facile non-precious metal catalyst for water splitting and should be instructive for designing more carbon-based nanocatalysts.

High-Capacity, High-Rate Nanosized Bismuth-Antimony Embedded in N-Doped Carbon Matrix Via Facile Pyrolysis As Anodes for Advanced Li Storage

Antimony (Sb) is an attractive anode material for lithium-ion batteries (LIBs) because of its high theoretical capacity (660 mAh g–1). Nevertheless, it suffers from huge volume expansion and severe particle pulverization during lithiation/delithiation processes, which leads to poor cycling performance. Herein, to address this matter, a composite of bismuth-antimony alloy nanoparticles embedded in N doped-carbon coating (BiSb@NC) is fabricated via a simple pyrolysis method. The design of bimetallic Bi-Sb solid solutions is possible at any molar ratio. The coupled pair, metallic Bi itself, does not only provide high volumetric capacity (3765 mAh cm–3) and low working potential (0.8 V hereafter vs. Li+/Li) but could also synergistically buffer the volume fluctuation due to the different working potentials between the two alloys. Nanosized BiSb alloys can enhance the reaction kinetics through shortened Li+-ion diffusion pathways. Additionally, the N-doped carbon coating also effectively cushions the volume changes of BiSb and maintains effective conductive networks during extended alloying/dealloying reactions with Li+ ions. As a result, the BiSb@NC anode achieves a high reversible capacity of 550 mA h g–1 after 100 cycles at 100 mA g–1 and superior high-rate performance of 350 and 220 mA h g–1 at 2 and 5 A g–1, accordingly despite its high BiSb loading (82 wt%).

Nanostructured viologen-phosphate bridged titanium dioxide frameworks: Tuning thermal growth for improving supercapacitance

Titanium dioxide (TiO2) has much potential for usage in supercapacitors because of its unique structural characteristics, outstanding chemical stability, low cost and availability, and lack of environmental impact. However, TiO2 presents a low specific capacitance due to its limited electrical conductivity. Incorporating a conductive matrix (e.g. carbon) is a logical way to exploit TiO2's electrochemical potential, but the efficiency of electron transport from the carbon matrix to TiO2 nanoparticles has been challenged by the weak interfacial stability between the two phases. To further address this issue, we leveraged on the highest stability of phosphate conjugated titanium dioxide (P-O-Ti) and have crafted an ionically-tunable viologen phosphate from which open porous viologen-bridged titanium (oxide) phosphate frameworks could be obtained. Thermal annealing was performed between 180 and 900 °C to investigate the effect of the conductive carbon matrix on supercapacitor performance. During carbonization, viologen serves as a nitrogen-containing carbon precursor while phosphates behave as a stabilizer by end-capping the surface of crystalline anatase titanium dioxide, limiting its thermally-induced sintering to <7 nm at 700 °C and delaying its transition to rutile phase until 900 °C. Based on three-electrode measurement, the material pyrolyzed at 700 °C displayed the best electrochemical performance among samples, with an areal specific capacitance of 283 mF/cm2 at 0.25 mA/mg (3.43 mA/cm2) in the potential range of −1 to +1 V vs. Ag/AgCl. Due to homogeneous dispersion of phosphate stabilized TiO2 nanoparticles within an N-doped conductive carbon matrix, VioP@TiO2–700 displays excellent rate capability. When the discharge current density increased by 16 times, the specific capacitance decrease was only of 14.3 %. The charge storage mechanism of TiO2-based electrodes showed that the surface-controlled process was dominant at the negative potential, while the diffusion-controlled process was dominant at the positive potential. Moreover, the symmetric cell exhibited a high energy density of 21.46 μWh/cm2 at a power density of 272.02 μW/cm2 and good capacitance retention of 95.3 % over 4000 cycles. The outlined supercapacitor performance suggested that the resulting nitrogen-containing carbon/phosphate-stabilized TiO2 nanocomposite is promising for energy storage applications.

2D heterostructural Mn2O3 quantum dots embedded N-doped carbon nanosheets with strongly stable interface enabling high-performance sodium-ion hybrid capacitors

The ingenious architectural structural engineering is extensively identified as a cogent means for facilitating the electrochemical properties of conversion-type anode materials for sodium-ion storage. Herein, a delicate, scalable and controllable solvent-free strategy is proposed to synthesize ultrafine Mn2O3 quantum dots embedded into N-doped carbon to generate two-dimensional (2D) composites (MNC) with robust interfacial heterostructural interactions for high sodium ion storage and fast reaction kinetics, which averts the use of solvents and environmental pollution, greatly reduces time and production costs. The introduction of metallic Mn species simultaneously achieves the construction of ultrafine Mn2O3 quantum dots and strong interfacial heterostructural COMn bonds between metal species and 2D N-doped carbon matrix. The synergistic effect of the formation of oxide quantum dots, the combination of 2D N-doped carbon and the construction of robust interfacial interactions provides the stable electrode structure, fast reaction kinetics and high electrochemical storage capability of anode materials. Hence, MNC composites in SIBs convey remarkable reversible rate capability. Its superior capacity reaches 215 mAh g−1 for 50 cycles at 0.2 A g−1 and 155 mAh g−1 for 1000 cycles at a high current density of 5 A g−1, which shows good long-term stability. The assembled sodium-ion hybrid capacitors (SIHCs) device delivers outstanding energy density of 138 Wh kg−1 at a power density of 126 W kg−1 and 98% capacity retention after 2000 cycles at 2 A g−1, and tremendous capability for practical applications (69 LEDs can be easily lighted). This work not merely offers guidance for the rational interfacial engineering design of high-capacity Mn-based electrode materials in a feasible and scalable solvent-free tactics for Na+ storage, but also broadens the routes for projecting a better electrode material for other battery systems.

Single-atom sites in metal–N4 configuration for efficient abatement of refractory organic pollutants via Fenton-like reaction

Single-atom metal catalyzed peroxymonosulfate (PMS) activation shows great potential in water treatment; and the activity of various metal centers have been explored. The properties of the support contribute significantly to the catalytic performance of the metal centers. The knowledge on the intrinsic distinctions of the elements in single-atom catalyzed PMS activation is, however, relatively in lack. In this work, via a facile one-step method, three representative elements of Fe, Co, and Cu were configured in a metal − N4 structure and anchored on N-doped carbon matrix with similar composition and structure. The atomic dispersity of the metal centers was experimentally substantiated by electronic microscopic technique in atomic scale and X-ray absorption spectroscopy. All these single-atom metal centers exhibit high activity in PMS activation for selective degradation of the organic pollutants, while the durability of the single-atom metal centers is vastly distinct as examined in continuous flow-mode. The water treatment capacity is in an order of Co − N4 ≈ Fe − N4 ≫ Cu − N4 for the elimination of 0.1 mM 4-chlorophenol from water. Based on the analysis of the qunching effect by various probe molecules and electron spin resonance spectra at various reaction conditions, the high-valent Co(IV)O species is proposed to be the predominant active species for pollutant degradation in Co − N4 catalyzed PMS activation. The findings in this work sheds light on the desgin of efficent and durable single-atom catalyst for water treatment.

Hofmann-type MOFs derived intermetallic L10-PtFe/NC electrocatalysts for boosting oxygen reduction reaction

Intermetallic electrocatalysts have demonstrated significant potential in facilitating the cathodic oxygen reduction reaction (ORR) in fuel cells with enhanced activity and durability. However, it is still an enormous challenge to the facile synthesis of Pt-based intermetallic catalysts with uniform size and high ordering degree. Here, we innovatively fabricate the core-shell structured L10-PtFe intermetallics with Pt skins supported on N-doped porous carbon matrix through one-step pyrolysis of PtFe Hofmann-type metal-organic frameworks (denoted as L10-PtFe/NC). Under the constraints of the porous structure and cyano-ligand bonding, most Fe atoms are alloyed with Pt to form uniform-ordered PtFe intermetallics, while some Fe atoms are atomically dispersed in the carbon framework to form FeNx moieties. Notably, a series of intermetallic PtFe catalysts with different ordering degrees are successfully constructed by adjusting the pyrolysis temperature, which verified that the increase of ordering degree is beneficial to promote the electrocatalytic performance. In particular, the ordered L10-PtFe/NC-800 exhibits superb ORR activity with both mass and specific activities, which are 2.7-folds higher than those of commercial Pt/C. Moreover, after an accelerated durability test, L10-PtFe/NC-800 retains over 90 % mass activity. This work provides a promising approach for the development of efficient Pt-based intermetallic electrocatalysts for fuel cells.

Highly accessible dual-metal atomic pairs for enhancing oxygen redox reaction in zinc−air batteries

The bifunctional oxygen electrocatalyst acts as a key component for zinc−air batteries; however, the design of economically-feasible bifunctional electrocatalysts showing outstanding functionality and durability remains challenging. Herein, we report the preparation of homogeneously scattered dual Fe−Ni atomic pairs stabilized in porous N-doped carbon matrix with a hierarchically porous nanoarchitecture (denoted as FeNi-NHC), wherein the atomically isolated bimetallic configuration is verified by combinative investigation of microscopy, spectroscopy, and theoretical computations. As an oxygen electrocatalyst in a basic electrolyte, FeNi-NHC exhibits an exceptional activity, achieving an outstanding half-wave potential (0.934 V vs. RHE) for oxygen reduction reaction, and a small overpotential for oxygen evolution reaction (254 mV at 10 mA cm-2). Furthermore, the zinc–air battery constructed with FeNi-NHC catalyst delivers an excellent functionality featuring a high maximum power density (126 mW cm-2) and insignificant activity decay after 200 charge−discharge cycles. Theoretical computations further reveal that the interaction effect of neighboring metal atoms in the bimetallic Fe−Ni sites energetically promotes the catalytic process by reducing the overall reaction barriers via optimization of adsorption−desorption behaviors.

Tailoring hierarchically porous nanoarchitectured N-doped carbon decorated with FeIIN4 moiety and encapsulated Fe/Fe3C nanoparticles as a synergistic catalyst for ORR in Zn-air battery

Rational designing and exploiting non-noble metal electrocatalysts with desirable nanoarchitecture and abundant active sites are crucial but challenging requirements for the development of fuel cells and Zn-air batteries (ZABs). Herein, a highly efficient carbonous hybrid is developed using a facile and effective synthesis strategy via template-assisted and optimized post-pyrolysis processes. The optimized electrocatalyst (denoted as Fe@NC-700) has extremely large specific surface area (1262.8 m2 g–1), and presents a desirable hierarchically porous nanoarchitecture, including plenty micro-/meso-pores, which endows the catalyst with the enhanced mass transfer for the reaction species. More importantly, Fe@NC-700 possesses not only numerous FeIIN4 moiety uniformly dispersed in N-doped carbon matrix, but also encapsulated Fe/Fe3C nanoparticles, synergistically boosting the electrocatalytic activity towards oxygen reduction reaction (ORR) verified by density functional theory (DFT) calculation. Due to the beneficial microstructure and rich active sites, the catalyst has a positive half-wave potential (E1/2) of 0.865 V for ORR in alkaline electrolyte, intrinsic 4e– reaction path and robust stability (only 14 mV negative shift of E1/2 after 10,000 potential cycles), outperforming the Pt/C. Impressively, the aqueous and quasi-solid-state primary ZABs assembled with Fe@NC-700 as cathode catalyst demonstrate superior discharge performance and excellent durability, holding promising potential in practical application of energy conversion devices.

Hollow engineering of sandwich NC@Co/NC@MnO2 composites toward strong wideband electromagnetic wave attenuation

Multiple hetero-interfaces would strengthen interfacial polarization and boost electromagnetic wave absorption, but still remain the formidable challenges in decreasing filler loadings. Herein, sandwich NC@Co/NC@MnO2 composites with hollow cavity, multiple hetero-interfaces, and hierarchical structures have been fabricated via the cooperative processes of self-sacrifice strategy and sequential hydrothermal reaction. In the sandwich composites, middle magnetic components (Co/NC) are wrapped by inner N-doped carbon (NC) matrix and outer hierarchical MnO2 nanosheets. Importantly, hollow engineering of sandwich composites with multiple hetero-interfaces greatly facilitates the enhancement of absorption bandwidth without sacrificing the absorption intensity. The maximum reflection loss of sandwich NC@Co/NC@MnO2 composites reaches -44.8 dB at 2.5 mm and the effective bandwidths is achieved as wide as 9.6 GHz at 2.3 mm. These results provide us a new insight into preparing efficient electromagnetic wave absorbers by interface engineering and hollow construction.

Achieving High Pseudocapacitance Anode SnP2O7@C By an in Situ Self-Nanocrystallization Method for Ultrastable Sodium Storage

Title: High Pseudocapacitance Anode SnP2O7@C by In Situ Self-Nanocrystallization Method for Ultrastable Sodium StorageThe rich resource and cheap price of Na have attracted attention in energy storage research and the market, becoming an optional choice for Li-ion batteries. The large radius of sodium-ion leads to a high diffusion barrier that restricted the development of sodium-ion batteries. Therefore, anodes with high capacity and stable cyclability are urgently addressed before further utilization.The mechanism of sodium-ion batteries can be classified into three categories: intercalation, alloying and conversion. Anode based on alloying and conversion mechanism became a research hotspot due to superior theoretical capacity. In pursuit of surpassing capacity, recent studies concentrated on anode with mixed mechanism, which had the potential to marriage the benefit of alloying and conversion mechanisms. However, the large volume expansion and short lifetime hindered the application in batteries.Here, we demonstrated an ultrastable sodium battery based on a novel anode, pomegranate-like SnP2O7 nanoparticles with a mixed mechanism homogeneously dispersed in the N-doped carbon matrix. Without the constraint of the grinding method, in situ self-nanocrystallization method has been first used to generate ultra-fine SnP2O7 particles.The results of the Ex-situ transmission electron microscope (TEM) characterization exhibited that the size range of SnP2O7 particles was efficiently decreased by the new fabrication method, from 66 to 20nm. During cycling tests, the nanostructure SnP2O7 particles remained well distributed in the N-doped carbon matrix rather than aggregation under long cycling tests. The self-nanocrystallization SnP2O7 nanoparticles ameliorated the diffusion of sodium-ion, which attained the acceleration of reaction kinetics. The N-doped carbon matrix contributed to the conductivity of composite material and meanwhile form strong adhesion with the carbon matrix to maintain the nanostructure SnP2O7 particles active during charge and discharge cycling. The pomegranate-like SnP2O7@C nanomaterial enhanced the pseudocapacitance to attain higher capacity and fast-charging storage. Under the capacitive-controlled behaviour test at 0.4mVs-1, the calculated capacitive showed a dominant contribution of total capacity, made up 75.7% of all. The participation of capacitive promoted avert the slow diffusion of sodium ion and obviate the destruction of the structure. The SnP2O7 carbon matrix anode exhibited superior specific capacity 403 mAh g-1 at 200 mA g-1 and cycling stability (185 mAh g-1 at 1000 mA g-1). The cycling stability of SnP2O7 nanomaterial has been ameliorated by the protection of N-doped carbon. The coulombic efficiency of SnP2O7@C showed no obvious changes and maintained around 100%, while the CE of SnP2O7 had appreciable variation. A new fabrication route of conversion and alloying anode nanomaterial was introduced in this work and has the potential to be utilized in large-scale manufacture. Figure 1