Design Of High-performance Anode Materials Research Articles

Polar Molecule Intercalation to Weaken P2─S Bonding in MnPS3 Toward Ultrahigh-Capacity Sodium Storage.

Layered transition metal trithiophosphates (TMPS3, TM = Mn, Fe, Co, etc.) with high theoretical capacity (>1300 mAh g-1) are potential anode materials for sodium-ion batteries (SIBs). However, the strong bonding between P2 dimers and S atoms in TMPS3 hinders the efficient alloying reaction between P2 dimers and Na+, resulting in practical capacities much lower than theoretical values. Herein, a polar molecule diisopropylamine (DIPA) is intercalated into MnPS3 for the first time to improve the sodium storage performance effectively. Theoretical calculations show that the electron transfer between DIPA and MnPS3 induces more delocalized S p states and weaker P─S bonds, significantly enhancing the electrochemical activity and sodiation/desodiation reaction kinetics. Moreover, the expanded interlayer spacing from 6.48 to 10.75 Å enables faster Na+ diffusion and more active sites for Na+ adsorption. As expected, the DIPA-MnPS3 exhibits an ultrahigh capacity of 1,023 mAh g-1 at 0.2 A g-1 and excellent cycling performance (≈100% capacity retention after 4200 cycles at 10 A g-1), far outperforming those metal thiophosphates anodes reported for SIBs. Interestingly, in situ and ex situ characterizations reveal a quasi-topological intercalation mechanism of DIPA-MnPS3. This work provides a novel strategy for the design of high-performance anode materials for SIBs.

Unveiling the effects of different component ratios on the structure and electrochemical properties of MoS2/TiO2 composites

In this study, a composite material comprising of MoS2 and TiO2 was designed, and the TiO2 content in the composite was systematically varied to enhance the rate capability and cycling performance of MoS2. The optimized composite structure (MT-3 with a mass ratio of MoS2 to TiO2 of 8:1) ensures stable connections between the flower-like MoS2 and TiO2 nanosheets through robust covalent Ti–O–S bonds, effectively enhancing the electrochemical reaction kinetics and thus improving lithium storage performance. Additionally, the incorporation of an appropriate amount of TiO2 alleviates the stacking of MoS2, increasing the number of electrochemically active sites. The specific capacities of MT-3 at current densities of 0.1, 0.5, 1, 2, and 5 A g−1 are 1172.9, 1039.3, 921.6, 864.9, and 696.5 mA h g−1, respectively. Furthermore, even after 100 cycles at 2 A g−1, it still maintains a high specific capacity of 694 mA h g−1, indicating excellent lithium storage performance. This synergistic strategy between MoS2 and TiO2 holds promise for the rational design of high-performance anode materials for LIBs.

Microporous Sulfur-Carbon Materials with Extended Sodium Storage Window.

Developing high-performance carbonaceous anode materials for sodium-ion batteries (SIBs) is still a grand quest for a more sustainable future of energy storage. Introducing sulfur within a carbon framework is one of the most promising attempts toward the development of highly efficient anode materials. Herein, a microporous sulfur-rich carbon anode obtained from a liquid sulfur-containing oligomer is introduced. The sodium storage mechanism shifts from surface-controlled to diffusion-controlled at higher synthesis temperatures. The different storage mechanisms and electrode performances are found to be independent of the bare electrode material's interplanar spacing. Therefore, these differences are attributed to an increased microporosity and a thiophene-rich chemical environment. The combination of these properties enables extending the plateau region to higher potential and achieving reversible overpotential sodium storage. Moreover, in-operando small-angle X-ray scattering (SAXS) reveals reversible electron density variations within the pore structure, in good agreement with the pore-filling sodium storage mechanism occurring in hard carbons (HCs). Eventually, the depicted framework will enable the design of high-performance anode materials for sodium-ion batteries with competitive energy density.

First principles study of a triazine-based covalent organic framework as a high-capacity anode material for Na/K-ion batteries.

The rational design of high-performance anode materials is crucial for the development of rechargeable Na-ion batteries (NIBs) and K-ion batteries (KIBs). In this study, based on density functional theory (DFT) calculations, we have systematically investigated the possibility of a bilayer triazine-based covalent organic framework (bilayer TCOF) as an anode for NIBs and KIBs. The calculation of the electronic band structure shows that the bilayer TCOF is a direct band gap semiconductor with a band gap of 2.01 eV. After the adsorption of Na/K at the most favorable sites, the bilayer TCOF transitions from a semiconductor to a metal state, guaranteeing good electronic conductivity. The low diffusion barriers of the bilayer TCOF are 0.45 and 0.26 eV, respectively, indicating a fast diffusion rate of Na/K ions. In addition, the bilayer TCOF has a theoretical storage capacity of up to 628 mA h g-1. Finally, it is found that the average voltage of the bilayer TCOF for NIBs and KIBs is 0.53 and 0.48 V, respectively. Based on these results, we can conclude that the bilayer TCOF may be a suitable anode material for NIBs and KIBs.

Interlayer-Expanded MoS2 Enabled by Sandwiched Monolayer Carbon for High Performance Potassium Storage.

Potassium-ion batteries (PIBs) have aroused a large amount of interest recently due to the plentiful potassium resource, which may show cost benefits over lithium-ion batteries (LIBs). However, the huge volume expansion induced by the intercalation of large-sized potassium ions and the intrinsic sluggish kinetics of the anode hamper the application of PIBs. Herein, by rational design, nano-roses assembled from petals with a MoS2/monolayer carbon (C-MoS2) sandwiched structure were successfully synthesized. The interlayer distance of ultrathin C-MoS2 was expanded from original MoS2 of 6.2 to 9.6 Å due to the formation of the MoS2-carbon inter overlapped superstructure. This unique structure efficiently alleviates the mechanical strain, prevents the aggregation of MoS2, creates more active sites, facilitates electron transport, and enhances the specific capacity and K+ diffusion kinetics. As a result, the prepared C-MoS2-1 anode delivers a high reversible specific capacity (437 mAh g-1 at 0.1 A g-1) and satisfying rate performance (123 mAh g-1 at 6.4 A g-1). Therefore, this work provides new insights into the design of high-performance anode materials of PIBs.

Bi@C sandwiched carbon nanolayers enables remarkable cyclability at high current density for lithium-ion batteries

Large designs are devoted to decrease the volume fluctuation and pulverization of bismuth anodes. However, further advances in cycling stability at higher current density remain challenging. Herein, we skillfully designed a unique sandwich structure composed of bismuth nanoparticles coated with carbon nanolamella (Bi@C) and carbon nanolayers (C NL) via a simple pyrolysis method. Benefiting from the synergistic effect of the unique interlayer hybrid structure, the Bi@C composite material has an interconnected electron transportation pathway, which effectively alleviates the volume expansion during alloying/dealloying and reduces the agglomeration of the Bi particles during cycling. In addition, the Bi@C embedded in the double carbon layers structure (Bi@C/C NL) not only serve as highly conductive networks for Li+, but also provide a large surface area for electrolyte penetration and storage, which will enhance the charge transfer reaction kinetics process. As a result, the Bi@C/C NL-700 anode revealed a superior capacity (427.5 mAh g−1 at 500 mA g−1 after 300 cycles), excellent long cycling stability (373 mAh g−1 at 3 A g−1 after 1500 cycles) and improved rate performance, outperforming the most reported Bi-based anode materials for lithium-ion batteries. This work will lay an experimental foundation for the rational design of high-performance anode materials in rechargeable batteries with layered hybrid structures.

Cation doping constructed vacancy engineering for designing Sn3Se5@PPy heterostructures toward lithium/sodium-ion batteries

SnSe/SnSe2 heterostructure composites with polypyrrole (PPy) coating layer and selenium (Se) vacancies are prepared by solvothermal and subsequent liquid-phase surface coating methods, and first reported as anode for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). Results indicate that PPy coating can effectively stabilize the structure and improve the electronic conductivity of the material, the heterostructure formed by SnSe and SnSe2 can reduce the reaction barrier and promote charge transfer, and the Se vacancies can provide more active sites for electron transfer and relieve structural strain. In addition, adjusting the molar ratio of SnSe and SnSe2 proves that the as-prepared Sn3Se5@PPy composite has the best rate and excellent cycle performance. Attributed to the difference in alloying between lithium-ion storage and sodium-ion storage, the Sn3Se5@PPy composite deliverers a higher specific capacity as anode for LIBs. It has a higher capacity retention and better rate performance for SIBs. The engineering design of cation doping-induced defects provides a new method for the structural design of high-performance anode materials.

Rational design of intrinsic and defective BGe monolayer as the anode material for Li-ion batteries

The rational design of high-performance anode materials is an effective strategy to expedite the development of next-generation lithium-ion rechargeable batteries (LIBs). In this work, the first-principles calculation method is applied to systematically investigate the adsorption and diffusion behaviors of Li ions on the intrinsic and defective BGe monolayer, as well as the application prospects of such materials acting as anode materials for LIBs. Our results show that intrinsic planar BGe monolayer has the advantages of high structural stability, distinct metallic feature and strong interaction with Li. In addition, Li migration on the BGe surface shows a low diffusion barrier (0.32 ​eV), which could guarantee a rapid charging/discharging capability. Interestingly, the presence of the single B vacancy defect weakens the adsorption strength of Li ion in the defective regions due to the charge redistribution. Correspondingly, the defect slightly impedes the diffusion performance, resulting in an increased energy barrier for Li ion (0.44 ​eV) to escape the defective regions. On the other hand, the intrinsic BGe monolayer could be lithiated into BGeLi3 with a theoretical specific capacity of 1927 ​mA ​h ​g−1. The moderate open-circuit voltage and the flexible structural stability with negligible volume change further enhance the reversibility of BGe anode materials. All these results provide a robust foundation for the rational design of BGe monolayer as an efficient anode material for LIBs.

TEA driven C, N co-doped superfine Fe3O4 nanoparticles for efficient trifunctional electrode materials

Poor conductivity is an obstacle that restricts the development of the electrochemistry performance of Fe3O4. In this work, a novel carbon and nitrogen co-doped ultrafine Fe3O4 nanoparticles (CN-Fe3O4) have been synthesized by triethylamine (TEA) induction and subsequent calcination. The addition of TEA could not only regulate the size of Fe3O4 nanoparticles, but also promote the formation of amorphous carbon layer. Well-designed CN-Fe3O4 heterostructures provide a highly interconnected porous conductive network, large heterogeneous interface area, large specific surface area and a large number of active sites, which greatly improve conductivity and promote electron transfer and electrolyte diffusion. The prepared CN-Fe3O4 electrode exhibits a high specific capacitance of 399.3 mF cm−2 and good cycling stability. Meanwhile, CN-Fe3O4 catalyst exhibits excellent oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activities, with overpotentials of 136 and 281 mV at the current density of 10 mA cm−2, respectively. This work provides a promising approach for the design of high-performance anode materials for supercapacitors and provides profound implications for the development of catalysts with bifunctional catalytic activity.

Facile and efficient synthesis of binary FeOOH/Fe2O3 composite as a high-performance anode material for lithium-ion batteries

Compared with single-component electrode materials, multi-component composite materials are more capable to promote the electrochemical performance of electrode materials because of the synergistic effect of different components. In this work, a binary FeOOH/Fe2O3 composite is fabricated by a facile and low-cost hydrothermal method with FeCl3•6 H2O and CO(NH2)2 as raw materials. The microstructure and composition of the as-prepared sample is characterized by XRD, SEM, TEM, FT-IR, and XPS. The electrochemical performance of the binary FeOOH/Fe2O3 composite is investigated by CV, EIS, charge-discharge test, and GITT measurement. Compared to single-component FeOOH or Fe2O3, this binary FeOOH/Fe2O3 composite exhibits outstanding high-rate capability (645 mA h g-1 at 1 A g-1) and superior long-term cycling stability (779 mA h g-1 after 300 cycles at 0.5 A g-1) due to the synergetic effect between FeOOH and Fe2O3. EIS analysis reveals that the electrochemical reaction resistance in binary FeOOH/Fe2O3 composite is lower than that in single-component FeOOH or Fe2O3. CV analysis demonstrates that the binary FeOOH/Fe2O3 composite has a certain pseudocapacitive behavior during discharge and charge processes. The lithium ion diffusion coefficient of the binary FeOOH/Fe2O3 composite derived from GITT data ranges from 4.0 × 10-12 to 1.0 × 10-14 cm2 s-1. Ex-situ SEM observations revealed that the binary FeOOH/Fe2O3 composite has good structural integrity upon cycling, which partially accounts for the superior electrochemical performance of the electrode. The reported method could provide a facile avenue for the ingredient design of high-performance anode materials for next-generation lithium-ion batteries (LIBs).

Structural engineering of sulfur-doped carbon encapsulated bismuth sulfide core-shell structure for enhanced potassium storage performance

Owing to the high theoretical capacity, metal sulfides have emerged as promising anode materials for potassium-ion batteries (PIBs). However, sluggish kinetics, drastic volume expansion, and polysulfide dissolution during charge/discharge result in unsatisfactory electrochemical performance. Herein, we design a core-shell structure consisting of an active bismuth sulfide core and a highly conductive sulfur-doped carbon shell (Bi2S3@SC) as a novel anode material for PIBs. Benefiting from its unique core-shell structure, this Bi2S3@SC is endowed with outstanding potassium storage performance with high specific capacity (626 mAh·g−1 under 50 mA·g−1) and excellent rate capability (268.9 mAh·g−1 at 1 A·g−1). More importantly, a Bi2S3@SC//KFe[Fe(CN)6] full cell is successfully fabricated, which achieves a high reversible capacity of 257 mAh·g−1 at 50 mA·g−1 over 50 cycles, holding great potentials in practical applications. Density functional theory (DFT) calculations reveal that potassium ions have a low diffusion barrier of 0.54 eV in Bi2S3 due to the weak van der Waals interactions between layers. This work heralds a promising strategy in the structural design of high-performance anode materials for PIBs.

Exploring n‐type SiC film with ultralow work function Cs coating surface for solar cell anode

In this study, the Cs adsorption behavior on n-type 3C-SiC (0001)-(2 × 1) and -(3 × 2) reconstructed surfaces are investigated via first-principles calculations. The potentiality of 3C-SiC as the anode material of solar cell based on photon-enhanced thermionic emission (PETE) is discussed. Various doping configurations are considered for the determination of an optimum n-type doping structure. Cs-covered (3 × 2) surface exhibits stronger stability compared with (2 × 1) surface. The charge transfer caused by Cs adsorption produces a [Cs+-SiC] dipole moment directing from Cs adatom to reconstructed surface, resulting in an effective declination of work function. Specifically, 0.5 ML Cs coverage surface provides an ultralow work function with 0.9 eV, demonstrating its potential application in PETE devices. Combining with a photoemission model, the maximum conversion efficiency can attain 30% utilizing SiC as an anode. Moreover, the Mulliken charge analysis provides the details of surface charge transfer and implies the inner mechanism of work function alteration. This study provides guiding significance for the synthesis of SiC material with low work function and an effective theoretical method for the design of high-performance anode materials in application of PETE devices. The adsorption mechanism of Cs on n-type doped 3C-SiC(0001)-(2 × 1) and -(3 × 2) reconstructed surfaces and its application as the anode material of solar cell are systematically investigated. For one Cs adatom adsorption, Cs-covered (3 × 2) surfaces present stronger stability compared with (2 × 1) surfaces. Cs-decorated (3 × 2) surface with 0.5 ML coverage exhibits an ultralow work function as low as 0.9 eV. Based on the photoemission model, the maximum conversion efficiency of PETE devices with SiC anode can reach 30%. Highlights Cs-decorated SiC surfaces with ultralow work function are suitable as PETE anode materials. Cs adsorption mechanism on 3C-SiC(0001)-(2 × 1) and -(3 × 2) surfaces are explored. The optimum n-type doped (2 × 1) and (3 × 2) surfaces are, respectively, determined. 0.5 ML Cs-adsorbed (3 × 2) surfaces show an ultralow work function of 0.9 eV. Cs adsorption induces a [Cs+-SiC] dipole moment on (2 × 1) and (3 × 2) surfaces.

Nonsolvent-induced phase separation-derived TiO2 nanotube arrays/porous Ti electrode as high-energy-density anode for lithium-ion batteries

TiO2 nanotube arrays, growing on three-dimensional (3D) porous Ti membrane, were synthesized using a facile nonsolvent-induced phase separation and anodization process. The length of those three-dimensional nanotube arrays could be tuned by prolonging the anodizing time. When the anodizing time is 8 h, the three-dimensional TiO2 nanotube arrays/porous Ti electrode exhibits well cycling stability and ultra-high specific capacity, which is used in lithium-ion batteries, attributed to the high utilization rate of the substrate and the high growth intensity of the active materials. Three-dimensional TiO2 nanotube arrays/porous Ti electrode, at 100 μA·cm−2 with 8 h anodizing time, shows a typical discharge plateau at 1.78 V and exhibits the specific capacity with 2126.7 μAh·cm−2. The novel nanotube arrays@3D porous architecture effectively shortens the electron/ion transmission path, which could pave way for optimizing the design of high-performance anode materials for next-generation energy storage system.

Graphene/Amorphous Carbon Restriction Structure for Stable and Long-Lifespan Antimony Anode in Potassium-Ion Batteries.

Sb-based materials have attracted much attention owing to their ability to undergo a multi-electron alloy reaction with K+ . However, there are still the serious problems of volume change and aggregation of particles, which lead to rapid capacity fading and a limited lifespan. In this work, a graphene/amorphous carbon restriction structure is proposed, in which the amorphous carbon layer on the surface of Sb nanoparticles can protect the particles from pulverization, and the graphene can buffer the volume change of the material. In addition, the conductive network formed by the dual carbon structure effectively improves the rate performance of the material. Thus, the material delivers a high capacity of 550 mA h g-1 at 100 mA g-1 , a rate capability of 370 mA h g-1 at 2000 mA g-1 , and a long lifespan of 350 cycles without significant capacity fading. The dual carbon strategy proposed offers a reference for the design of high-performance anode materials.

MoS2/N-doped graphene aerogles composite anode for high performance sodium/potassium ion batteries

Three-dimensional porous MoS2/nitrogen-doped graphene aerogels (MoS2/NGA) with different MoS2 loading masses were synthesized by a simple hydrothermal method. The unique structure can provide more Na+ (K+) transport channels and the three-dimensional porous morphology could greatly absorb the volume expansion of MoS2 during charging and discharging process. As the anode of sodium-ion batteries (SIBs), this material provides a specific capacity of 673 mAh g−1 at a current density of 100 mA g−1 with long cycle stability. In addition, the composite shows a specific capacity of 305 mAh g−1 at 2000 mA g−1 and exhibits excellent capacity reversibility after rate performance test, indicating that it is a promising anode choice for SIB. As the anode material of potassium-ion batteries (KIBs), it provides a reversible specific capacity of 349 mAh g−1 at a current density of 100 mA g−1. It has a specific capacity of 72 mAhg−1 at 5000 mAg−1 and exhibits excellent capacity reversibility after rate performance test as well. Therefore, this work provides some insights into the fabrication of MoS2/graphene composites and is helpful for the design of high-performance anode materials of metal ion batteries.

Facile method for adjustable preparation of nano-Fe7S8 supported by carbon as the anode for enhanced lithium/sodium storage properties in Li/Na-ion batteries

Iron sulfide (FeSx), as an anode material for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), has attracted special attention in recent years. In this paper, an extremely facile calcination method for the synthesized of Fe7S8@C nanocomposites with different morphologies and sizes is described. The Fe7S8@C anode provides an ultrahigh charge capacity of 1042 mAh g−1 after 100 cycles at a current density of 100 mA g−1 for LIBs and 524 mAh g−1 after 150 cycles at a current density of 200 mA g−1 for SIBs. It is impressive that the material shows super-long cycle stability with a reversible capacity of 789 mAh g−1 after 1000 cycles and 370 mAh g−1 after 500 cycles at a high current density of 1000 mA g−1 and 500 mA g−1 for LIBs and SIBs, respectively. Nanosized particles, in situ generated carbon and the porous structure of the materials are beneficial for the storage of lithium/sodium ions. Importantly, the preparation of the Fe7S8@C anode provides a very simple method for the structural design of high-performance anode materials, and may be practical in various applications such as catalysis and sensors.

Biomass-derived nanostructured porous carbons for sodium ion batteries: a review

ABSTRACTSodium-ion batteries (SIBs) have been considered one of the optimal the large scale and low cost energy storage systems for smart grid system owing to the abundant sodium resource. Among various anode materials, the biomass-derived nanostructured porous carbons (BDNPCs) show some promising in SIBs due to obvious advantages of abundant resource, low cost, nontoxicity and high safety. In this review, the recent progress of the sodium storage performance of the biomass derived nanostructured porous carbons is summarized. Moreover, the dependent of SIB performances on the porous structures from BDNPCs is discussed. It is expected that this review may provide an in-depth understanding and guide rational design of high-performance anode materials by using low-cost, sustainable and natural biomass precursors.

Dual phase enhanced superior electrochemical performance of nanoporous bismuth-tin alloy anodes for magnesium-ion batteries

Magnesium-ion batteries (MIBs) have recently received great concerns, but are restrained by the challenge of exploring advanced anode materials with superior capacity and fast diffusion kinetics. Herein, for the first time we proposed a dual phase alloying strategy to address this issue, and developed novel high-performance bismuth (Bi)-tin (Sn) alloys with a unique nanoporous structure and high density of phase boundaries. As an anode for MIBs, the dual phase Bi-Sn alloys exhibit excellent Mg storage properties as compared to their single phase counterparts. Specially, the Bi6Sn4 electrode can deliver large discharge specific capacity (434 mA h g−1 at 50 mA g−1), good cycling stability (280 mA h g−1 after 200 cycles), greatly improved rate capability (362 mA h g−1 at 1000 mA g−1) and high Coulombic efficiency (close to 99% after 30 cycles). Ex situ X-ray diffraction and transmission electron microscopy further clarify the phase and structural evolution during the first discharge/charge processes of the Bi6Sn4 anode. The superior electrochemical performance of the Bi-Sn alloys is attributed to the increased phase/grain boundaries which can provide more channels for fast Mg2+ transport as well as unique nanoporous structure which can accommodate large volume changes and shorten diffusion lengths. The present strategy provides useful information on design of high-performance anode materials for MIBs.

Facile synthesis of carbon coated MoO3 nanorods decorated with WO2 nanoparticles as stable anodes for lithium-ion batteries

Elaborate design of high-performance anode materials is of vital significance for lithium-ion batteries (LIBs). Herein, carbon-coated MoO3 nanorods decorated with WO2 nanoparticles (MoO3/WO2@C), a novel structured nanohybrid in which MoO3 nanorods are encapsulated by the amorphous carbon layer and decorated with ultrasmall WO2 nanoparticles, have been successfully synthesized via a facile one-step hydrothermal method. When evaluated as the anode materials for LIBs, the effects of different carbon contents in the as-obtained MoO3/WO2@C nanomaterials on the lithium-ion storage properties are investigated. Results show that the MoO3/WO2@C nanocomposite with the optimized carbon content delivers a high reversible capacity of 815 mAh·g−1 after 100 cycles at 0.05 C and an ultrastable capacity of 80 mAh·g−1 at least 5000 cycles at the current density of 1 C.

Preparation and Lithium-Storage Performance of a Novel Hierarchical Porous Carbon from Sucrose Using Mg-Al Layered Double Hydroxides as Template

Novel hierarchical porous carbons (NHPCs) containing 3D carbon nanosheets and slit-mesopores are prepared in this work, using MgAl-layered double hydroxides as template and sucrose as carbon source, and their electrochemical performances as anodes of lithium-ion batteries are also investigated. Owing to the existence of abundant carbon nanosheets and slit-mesopores, the NHPCs electrode exhibits the specific reversible capacity of 1151.9mA h/g at the current density of 50mA/g, which is significantly higher than other hierarchical porous carbons reported in previous literatures. The contributions of carbon nanosheets and mesopores to the electrochemical performance are further clarified by nitrogen adsorption-desorption test, electrochemical impedance spectroscopy, cyclic voltammograms and galvanostatic charge/discharge test. This work not only provides an easy and effective method to prepare hierarchical porous carbon materials, but also is beneficial for the design of high-performance anode materials for lithium ion batteries.