Superior Sodium Storage Performance Research Articles

Engineering Metal Electron Spin Polarization to Regulate p‐Band Center of Se for Enhanced Sodium‐Ion Storage

AbstractSluggish ion diffusion of large sodium ions is one of the main drawbacks challenging the development of metal selenides‐based anode materials for sodium‐ion batteries (SIBs). A spin‐state regulating strategy is first proposed in this work to lift the p‐band center (ɛp) of Se for a fast Na+ transfer kinetic in (Co,Cu)Se2. By utilizing the electron transfer from Cu to Co, the π‐symmetry t2g of Co is fully occupied to decrease the spin polarization. The resultant electron repulsion between Co and Se weakens Co–Se bond to lift the ɛp of Se. The enhanced sodium adsorption energy effectively accelerates the ion transfer at the active material–electrolyte interface. As a result, the (Co,Cu)Se2/NC electrode exhibits an superior sodium storage performance with a capacity of 445 mAh g−1 at 0.2 A g−1, 312 mAh g−1 at 50 A g−1, and 363 mAh g−1 after 10 000 cycles at 10.0 A g−1. The insight into the working mechanism of regulating spin‐state of metals to lift the p‐band center of Se can provide guidelines for the development of both metal selenides‐based anode material and high‐performance SIBs.

One stone two birds: K2CO3 promoting the in-situ synthesis of K3PO4 coated Na3V2(PO4)3 attached on the porous carbon skeleton for superior sodium storage performance

Na3V2(PO4)3 (NVP) has attracted much attention because of its open 3D channel, high voltage platform and capacity, but its inherent low ionic and electronic conductivity limits further development. In this work, we successfully achieve the double modification effect by adding K2CO3 in situ for the first time. Firstly, the addition of K2CO3 induces the formation of porous carbon substrate, which can reduce the accumulation of Na3V2(PO4)3 particles, thus making the sample particles more dispersed and uniform. Meanwhile, NVP active particles can be uniformly attached to the porous carbon substrate, effectively promoting the electronic conductivity. Secondly, K2CO3 can be decomposed and react to produce K3PO4 in the sintering process, which is evenly coated on the periphery of NVP grains to form a double-layer conductive interface with excess amorphous carbon. This unique double-interface not only boost specific conductance but also play a protective role to prevent the side reaction in the electrolyte from destroying the cathode material. Moreover, the ex-situ XRD/XPS/SEM/TEM after cycling further demonstrate the stabilized porous skeleton and the existence of K3PO4 coatings. Comprehensively, the optimized NVP/C@1%K3PO4 sample behaves outstanding electrochemistry capability and cyclic performance. With a high capacity of 122.3 mAh g−1 at 0.1C, this material exhibits excellent cycling stability. At 60C, it delivers a high capacity of 85.1 mAh g−1 and retains 69.1 mAh g−1 after 7000 cycles. Even at 180C, it demonstrates a remarkable capacity of 79.97 mAh g−1 and maintains 49.8 mAh g−1 after 14,000 cycles. When integrated into a full battery, the assembled NVP/C@1%K3PO4//CHC battery exhibits a reversible capacity of 112.2 mAh g−1 at 0.1C and retains 70 mAh g−1 at 2C, highlighting its promising potential for commercial applications.

Encapsulating Sb/MoS2 Into Carbon Nanofibers Via Electrospinning Towards Enhanced Sodium Storage

AbstractMetallic antimony (Sb) and molybdenum disulfide (MoS2) are identified as promising anode materials for sodium ion batteries (SIBs) owing to their high theoretical capacities. Herein, both Sb and MoS2 are integrated and fully embedded into carbon nanofibers (CNFs) to form Sb/MoS2@CNFs nanocomposite via an electrospinning technique followed by heat treatment. When employed as anode material for SIBs, the Sb/MoS2@CNFs electrode presents a reversible capacity of 282.7 mAh g−1 after 300 cycles at 1 A g−1, and even 197.5 mAh g−1 after 1350 cycles at a high current density of 5 A g−1. The superior sodium storage performance of the Sb/MoS2@CNFs can be ascribed to the synergistic effect of the integrated Sb/MoS2 components and their full encapsulation into the one‐dimensional (1D) conductive carbon nanofibers. The well‐dispersed Sb/MoS2 nanoparticles ensure good Na+ ions accessibility and high storage capacity, while 1D nanostructure facilitates ion/electron transport, tolerates the volume expansion, and prevents the Sb/MoS2 nanoparticles from aggregating during cycling. This work provides a simple and efficient synthetic route of multicomponent anode materials in advanced SIBs.

Dual carbon modification of few-layered ReS2 nanosheets to retard polysulfide shuttling for long-cycling sodium-ion batteries

Rhenium disulfide (ReS2) is promising to work as a robust host for sodium storage, owing to the extremely weak interlayer van der Waals interactions and large interlayer spacing. However, the low electronic conductivity and huge volume expansion seriously restrict high-rate capability and cycling lifespan. In this work, few-layered ReS2 nanosheets with carbon coating (ReS2/C) grown on the hollow mesoporous carbon spheres (HMCS) are designed to form the HMCS@ReS2/C architectures that have several merits for the sodium storage, attributed to the dual carbon modification and the hollow structure. (i) HMCS provides a large interior void to relieve the volume change during discharge/charge processes and superior structural stability for long-term cycling. (ii) The large hetero-interfacial contact can enhance electron/Na+ transport in ReS2, enabling accelerated reaction kinetics. (iii) The outer carbon layer formed on ReS2 surface is capable of inhibiting dissolution of polysulfide ions and their corrosion to the copper current collector, preventing the “under-voltage failure” phenomenon. Consequently, HMCS@ReS2/C delivers superior sodium storage performance, yielding excellent high-rate capability (211 mAh g−1 at 10 A g−1), long lifespan (4000 cycles at 10 A g−1) and stable cycling stability with an extremely low capacity decay rate of 0.0096% per cycle. The high-rate cyclability surpasses the record of ReS2-based anodes reported previously. Furthermore, the fabricated Na3V2(PO4)3║HMCS@ReS2/C full cells can also exhibit outstanding cycling performance.

Dual Design on Hierarchically Hollow MoTe2/C with Ion/Electron Channel Engineering for High-Performance Sodium Storage.

Transition-metal tellurides have been investigated as novel anode materials for application in sodium-ion batteries (SIBs) due to their rich active sites and unique and controllable layered nanostructures. However, the weak structural strength and inferior intercalation/deintercalation kinetics inhibit the development of transition-metal tellurides. In this work, MoTe2/C composites with two different hollow nanostructures are designed and prepared. By adjustment of the precursor structure, MoTe2/C-2 exhibits superior sodium-storage performance because of its uniquely hollow nanostructure with self-assembled 2D flexible nanosheets grown on the external surface. MoTe2/C-2 delivers a higher specific capacity (276 mAh g-1 at 0.1 A g-1 after 300 cycles), much more than MoTe2/C-1 (201 mAh g-1 at 0.1 A g-1 after 300 cycles), and exhibits a long-time cycling performance (131 mAh g-1 at 1 A g-1 after 2000 cycles). The excellent sodium-storage performance derived from the rational structure design is beneficial for shortening the ion paths, facilitating the sodiation/desodiation process, and reinforcing the intrinsic structural stability, thus boosting the reaction kinetics and prolonging the cycling life. Meanwhile, the assembled full-cell maintains 101 mAh g-1 at 0.1 A g-1 after 50 cycles and lights an electric watch. The findings provide several new views for preparation of more transition-metal tellurides with multi-ion/electron migration channel engineering.

Phase engineering of Ni-Mn binary layered oxide cathodes for sodium-ion batteries

Nickel-manganese binary layered oxides with high working potential and low cost are potential candidates for sodium-ion batteries, but their electrochemical properties are highly related to compositional diversity. Diverse composite materials with various phase structures of P3, P2/P3, P2, P2/O3, and P2/P3/O3 were synthesized by manipulating the sodium content and calcination conditions, leading to the construction of a synthetic phase diagram for NaxNi0.25Mn0.75O2 (0.45 ≤ x ≤ 1.1). Then, we compared the electrochemical characteristics and structural evolution during the desodiation/sodiation process of P2, P2/P3, P2/O3, and P2/P3/O3-NaxNi0.25Mn0.75O2. Among them, P2/P3-Na0.75Ni0.25Mn0.75O2 exhibits the best rate capability of 90.9 mA h g−1 at 5 C, with an initial discharge capacity of 142.62 mA h g−1 at 0.1 C and a capacity retention rate of 78.25% after 100 cycles at 1 C in the voltage range of 2–4.3 V. The observed superior sodium storage performance of P2/P3 hybrids compared to other composite phases can be attributed to the enhanced Na+ transfer dynamic, reduction of the Jahn-teller effect, and improved reaction reversibility induced by the synergistic effect of P2 and P3 phases. The systematic research and exploration of phases in NaxNi0.25Mn0.75O2 provide new sights into high-performance nickel-manganese binary layered oxide for sodium-ion batteries.

Fe3Se4 decorating carbon nanotubes with superior sodium storage performance for sodium-ion batteries

Due to the ideal theoretical capacity, high initial coulombic efficiency, satisfactory electronic conductivity, and environmental friendliness, iron-based selenides have been intensively explored and developed as anodes for sodium-ion batteries (SIBs). However, they still face numerous obstacles in the commercialization process, such as large volume changes. In this work, a nanocomposite of Fe3Se4 decorated carbon nanotubes (Fe3Se4/CNTs) was designed and prepared through a simple solvothermal method and subsequent selenization process. SEM and TEM images manifest that the Fe3Se4 nanoparticles are well anchored to the two-dimensional CNTs. In the composite, Fe3Se4 can provide high sodium storage capacity, meanwhile, CNTs acts as a self-supporting framework, which effectively enhances the electronic conductivity and mitigates the drastic volume expansion of Fe3Se4/CNTs electrode during electrochemical process. Thus, the Fe3Se4/CNTs electrode presents satisfactory sodium storage capacity and cycling stability. At 1 A g−1, it delivers a high capacity of 424 mA h g−1 after 500 cycles, with a superior capacity retention of ~100 %. In addition, cyclic voltammetry (CV), galvanostatic intermittent titration (GITT), and ex-situ X-ray diffraction (XRD) were employed to analyze the sodium storage mechanism and sodium ion diffusion ability in the Fe3Se4/CNTs electrode. This work provides an effective method for developing high-performance anodes for SIBs.

An Na/TM-site Mg substituted P2-Na2/3[Fe1/3Mg1/12Mn7/12]O2 cathode with extremely high capacity for sodium-ion batteries

The well-designed Na/TM-site Mg substituted P2-Na2/3[Fe1/3Mg1/12Mn7/12]O2 exhibits extremely high energy density, highly reversible anionic redox reaction, robust crystal structure, and superior sodium storage performance.

Efficient sulfur atom-doped three-dimensional porous MXene-assisted sodium ion batteries.

Recently, it has been reported that MXene is a promising pseudocapacitive material for energy storage, primarily due to its intercalation mechanism. However, Ti3C2Tx MXenes face challenges, such as inadequate layer spacing and low specific capacity, which greatly hinder their potential as anode materials for sodium storage. In this study, MXene was doped with sulfur to create a three-dimensional porous structure that resulted in an increased layer spacing. The sulfur-doped porous MXene (SPM) demonstrated exceptional performance as sodium ion battery anodes, with a capacity of 335.2 mA h g-1 after 490 cycles at 2 A g-1 and a long-term cycling performance of 256.1 mA h g-1 even after 2480 cycles at 5 A g-1. It is worth noting that the porous structure formed after sulfur-doping exhibits superior sodium storage performance compared to previously reported MXene-based electrodes. This highlights the feasibility of the structural construction strategy, offering an effective solution for energy storage and conversion applications.

Interfacial built-in electric field and crosslinking pathways enabling WS2/Ti3C2Tx heterojunction with robust sodium storage at low temperature

Developing efficient energy storage for sodium-ion batteries (SIBs) by creating high-performance heterojunctions and understanding their interfacial interaction at the atomic/molecular level holds promise but is also challenging. Besides, sluggish reaction kinetics at low temperatures restrict the operation of SIBs in cold climates. Herein, cross-linking nanoarchitectonics of WS2/Ti3C2Tx heterojunction, featuring built-in electric field (BIEF), have been developed, employing as a model to reveal the positive effect of heterojunction design and BIEF for modifying the reaction kinetics and electrochemical activity. Particularly, the theoretical analysis manifests the discrepancy in work functions leads to the electronic flow from the electron-rich Ti3C2Tx to layered WS2, spontaneously forming the BIEF and “ion reservoir” at the heterogeneous interface. Besides, the generation of cross-linking pathways further promotes the transportation of electrons/ions, which guarantees rapid diffusion kinetics and excellent structure coupling. Consequently, superior sodium storage performance is obtained for the WS2/Ti3C2Tx heterojunction, with only 0.2% decay per cycle at 5.0 A g−1 (25 °C) up to 1000 cycles and a high capacity of 293.5 mA h g−1 (0.1 A g−1 after 100 cycles) even at −20 °C. Importantly, the spontaneously formed BIEF, accompanied by “ion reservoir”, in heterojunction provides deep understandings of the correlation between structure fabricated and performance obtained.

High-Capacity and High-Rate sodium storage of CoS2/NiS2@C anode material enabled by interfacial C-S covalent bond and Mott–Schottky heterojunction

In this paper, carbon-matrix-embedded Mott–Schottky (MS) heterojunction of CoS2/NiS2 (CoS2/NiS2@C) is prepared. The obtained CoS2/NiS2@C offers superior sodium storage performance such as large specific capacity (861.0 mAh/g at 2 A/g), extraordinary rate capability (649.2 mAh/g at 10 A/g, 371.4 mAh/g at 40 A/g) and excellent cycling stability (380.5 mAh/g after 3000 cycles at 10 A/g, and 298.5 mAh/g after 2000 cycles at 40 A/g). Electrochemical measurements and density functional theory (DFT) calculations as well as in/ex-situ characterization techniques are employed to reveal the underlying mechanisms. It is found that the outperforming sodium storage properties of CoS2/NiS2@C can be mainly attributed to the C-S bond and the MS heterojunction. The C-S bond formed at the interface between CoS2/NiS2 and the carbon matrix promotes the migration of the sodium ions in the carbon matrix to the embedded CoS2/NiS2, while the MS heterojunction accelerates the electrochemical reaction kinetics of CoS2/NiS2. Moreover, full-cell is assembled with CoS2/NiS2@C and Na3V2(PO4)3/C to validate the practical application of CoS2/NiS2@C. The full-cell achieves both high specific capacity and outstanding rate performance, demonstrating the great application potential of such CoS2/NiS2@C anode in high-performance sodium-ion batteries.

Double carbon modified Na3V2(PO4)3 with dual charge carriers and high performance synthesized in-situ in polypyrrole and chitosan quaternary ammonium hydrogel

Sodium-ion batteries (SIBs) are regarded as the most promising battery to replace lithium-ion batteries (LIBs) in the future. Na3V2(PO4)3 (NVP), as an ideal positive electrode material for SIBs, is limited by poor electronic conductivity and low reversible capacity. In this paper, the double carbon resources of chitosan quaternary ammonium hydrogel (CHACC) and Polypyrrole (PPy) were introduced into NVP. Through the construction of double charge carriers, the high conductivity and the high reversible capacity of NVP which broke the theoretical limit were achieved. The introduction of CHACC brings the second charge carrier, ClO4−, in addition to Na+ in NVP system. Furthermore, the conductive network and defect-rich carbon coatings formed by CHACC and PPy significantly improve the electronic conductivity and kinetics of the electrode. Comprehensively, the detailed functional mechanism of dual carriers in NVP is deeply investigated by ex-situ FTIR and XPS, revealing that ClO4− utilizes the N+ in the carbonized substrate of CHACC and PPy as the binding sites to reversibly inserted/extracted from the carbon layer to provide additional capacities. Notably, the optimized CHACC-PPy-NVP submits superior sodium storage performance. It delivers a capacity of 148.3 and 139.3 mAh g−1 at 0.1 and 1C, significantly exceeding the theoretical capacity (117.6 mAh g−1). Even at 140C, it still maintains a capacity value of 88.9 mAh g−1 with 75.7 mAh g−1 remaining after 2000 cycles, corresponding to a low decay rate of 0.007 % per cycle.

Defect regulation of Co2+ substituting V3+ in Na3V2(PO4)3 for superior sodium storage performance: Experimental and theoretical study

Na3V2(PO4)3 (NVP), possessing stabilized framework and high voltage platform, has attracted extensive attentions in the field of energy storage. However, the low conductivity restricts its further development. Herein, a novel strategy of defect regulation by Co2+ substitution is proposed. Co2+ doping not only generates beneficial hole carries resulting from the p-type doping to accelerate the electronic conductivity, but also favors to expand the interplanar spacing in the internal bulk of NVP system to enhance the ionic transportation. Moreover, theoretical calculation indicates the beneficial Co2+ substitution modifies the electronic structure of NVP to reduce the band gap, as well as decline the energy barrier. Distinctively, the Co0.07-NVP/C composite delivers a high value of 114.4 mA h g−1 at 0.1 C, almost close to its theoretical value (117.6 mA h g−1). It submits a reversible capacity of 104.6 mA h g−1 at 1 C and keeps 100.1 mA h g−1 after 200 cycles with a retention value of 95.70%. Even at 10 C, it also can reveal a capacity of 101.6 mA h g−1 and remains 81.8 mA h g−1 after 1000 cycles.

Interface Engineering of Fe7S8/FeS2 Heterostructure in situ Encapsulated into Nitrogen-Doped Carbon Nanotubes for High Power Sodium-Ion Batteries

HighlightsIron sulfide-based heterostructure in situ hybridized with nitrogen-doped carbon nanotubes was prepared through a successive pyrolysis and sulfidation approach.The as-prepared Fe7S8/FeS2/NCNT electrode exhibits superior sodium storage performance in both ester and ether-based electrolytes.The structure advantages of the electrode contribute to high electrochemical performance in the ester-based electrolyte, while fast ionic diffusion and favorable capacitive behavior result in the robust sodium storage performance in the ether-based electrolyte.

A Versatile Sulfur‐Assisted Pyrolysis Strategy for High‐Atom‐Economy Upcycling of Waste Plastics into High‐Value Carbon Materials

With the overconsumption of disposable plastics, there is a considerable emphasis on the recycling of waste plastics to relieve the environmental, economic, and health-related consequences. Here, a sulfur-assisted pyrolysis strategy is demonstrated for versatile upcycling of plastics into high-value carbons with an ultrahigh carbon-atom recovery (up to 85%). During the pyrolysis process, the inexpensive elemental sulfur molecules are covalently bonded with polymer chains, and then thermally stable intermediates are produced via dehydrogenation and crosslinking, thereby inhibiting the decomposition of plastics into volatile small hydrocarbons. In this manner, the carbon products obtained from real-world waste plastics exhibit sulfur-rich skeletons with an enlarged interlayer distance, and demonstrate superior sodium storage performance. It is believed that the present results offer a new solution to alleviate plastic pollution and reduce the carbon footprint of plastic industry.

Boosting sodium-ion storage performance by tailoring intragranular porous WS2/C nanocomposites anode

Two-dimensional layered semiconducting materials, such as tungsten disulfide, have attracted significant research interest over the past few decades. With rational optimization of their chemical constitutions and regulation of electronic configurations, these materials can achieve commercial viability. Herein, the WS2/C hybrid was constructed by organic amine intercalation and in-situ pyrolysis. Intraparticle porous WS2/C was successfully synthesized by dissolving and etching. The specific surface area of the obtained WS2/C was significantly enhanced on the removal of WO3 through alkali etching, which facilitated the Na-insertion/extraction. Therefore, the obtained porous WS2/C composite delivered a high reversible capacity and improved cycle stability with 346.3 mAh g−1 over 80 cycles at 100 mA g−1. This work proposes an intragranular porous WS2/C composite electrode design which shows a superior sodium storage performance, improved electronic conductivity and enhanced reversible specific capacity. It is expected to present a novel insight for designing other high-capacity sodium-ion and other alkaline ion battery electrode materials.

Bi nanoparticles confined in N,S co-doped carbon nanoribbons with excellent rate performance for sodium-ion batteries.

Bismuth (Bi) has emerged as a promising candidate for sodium-ion battery anodes because of its unique layered crystal structure, superior volumetric capacity, and high theoretical gravimetric capacity. However, the large volume expansion and severe aggregation of Bi during the alloying/dealloying reactions are extremely detrimental to cycling stability, which seriously hinders its practical application. To overcome these issues, we propose an effective synthesis of composite materials, encapsulating Bi nanoparticles in N,S co-doped carbon nanoribbons and composites with carbon nanotubes (N,S-C@Bi/CNT), using Bi2S3 nanobelts as templates. The uniform distribution of Bi nanoparticles and the structure of carbon nanoribbons can reduce the diffusion path of ions/electrons, efficiently buffer the large volume change and prevent Bi from aggregating during cycles. As expected, the N,S-C@Bi/CNT electrode shows superior sodium storage performance in half cells, including a high specific capacity (345.3 mA h g-1 at 1.0 A g-1), long cycling stability (1000 cycles), and superior rate capability (336.0 mA h g-1 at 10.0 A g-1).

In situ Cu doping of ultralarge CoSe nanosheets with accelerated electronic migration for superior sodium-ion storage.

The progress of sodium-ion batteries is currently confronted with a noteworthy obstacle, specifically the paucity of electrode materials that can store large quantities of Na+ in a reversible fashion while maintaining competitiveness. Herein, ultrafast and long-life sodium storage of metal selenides is rationally demonstrated by employing micron-sized nanosheets (Cu-CoSe@NC) through electron accumulation engineering. The nanosheet structure proves to be effective in reducing the transport distance of sodium ions. Furthermore, the addition of Cu ions enhances the electron conductivity of CoSe and accelerates charge delocalization. As an anode for sodium-ion batteries, Cu-CoSe@NC exhibits a noticeably enhanced specific capacity of 527.2 mA h g-1 at 1.0 A g-1 after 100 cycles. Additionally, Cu-CoSe@NC maintains a capacity of 428.5 mA h g-1 at 5.0 A g-1 after 800 cycles. It is possible to create sodium-ion full batteries with a high energy density of 101.1 W h kg-1. The superior sodium storage performance of Cu-CoSe@NC is attributed to the high pseudo-capacitance and diffusion control mechanisms, as evidenced by theoretical calculations and ex situ measurements.

Nickel cobalt selenides on black phosphorene with fast electron transport for high-energy density sodium-ion half/full batteries

The BP@Ni3Se4/CoSe2heterostructure delivers superior sodium storage performance with long cycling stability and high energy density.

Pre-engineering artificial solid electrolyte interphase for hard carbon anodes for superior sodium storage performance.

A 5-nm-thick artificial solid electrolyte interface (SEI) was engineered for the hard carbon anodes of sodium-ion batteries. Benefiting from the artificial SEI, the hard carbon anode shows a significantly improved initial Coulombic efficiency of 94% and superior rate performance with a reversible capacity of 247 mA h g-1 after 800 cycles at 1C, 220 mA h g-1 after 400 cycles at 6C.