Lithium Ion Storage Performance Research Articles

Engineering a hierarchical carbon supported magnetite nanoparticles composite from metal organic framework and graphene oxide for lithium-ion storage

Fe based metal organic framework (MOF) materials are being extensively investigated as a precursor sample for engineering carbon supported iron containing nanoparticles composites. Rational design and engineering Fe-containing MOFs with optimized structures using economic and eco-friendly methods is a challenging task. In this work, 1,3,5-benzenetricarboxylic acid (C9H6O6, trimesic acid, H3BTC) and metal Fe are employed to synthesize a MOF sample Fe-BTC in a mild hydrothermal condition. Moreover, with the addition of a small quantity of graphene oxide (GO) as dispersant, a redox coprecipitation reaction has taken place where small Fe-BTC domains well dispersed by reduced graphene oxide (RGO). The Fe-BTC/RGO intermediate sample is finally converted to the hierarchical Fe3O4@C/RGO composite, which delivers an ultrahigh specific capacity of 1262.61 mAh·g−1 at 200 mA·g−1 after 150 cycles and a superior reversible capacity of 910.65 mAh·g−1 at 1000 mA·g−1 after 300 cycles in half cells. The full cell performance for the Fe3O4@C/RGO composite have been studied. It is also revealed that the improved structural stability, high pseudocapacitive contribution and enhanced lithium-ion and electron transportation conditions jointly guarantee the outstanding lithium-ion storage performances for the Fe3O4@C/RGO composite over long-time cycling. The synthesized samples have good potential for wider application.

Ti–Cl bonds decorated Ti2NT x MXene towards high-performance lithium-ion batteries

Transition metal carbides or nitrides, collectively known as MXenes, are burgeoning two-dimensional materials for energy conversion and storage. The surface chemistry of MXenes could be specially tuned by the modified surface terminations, which directly influences their physicochemical properties. However, the in-depth study and understanding of the specific microstructure and the influence on the electrochemical performance of these terminations remain lacking. Herein, we present an accordion layered Ti2NT x MXene with –Cl and –O terminations obtained from copper chloride molten salt etching at a relatively low temperature. X-ray absorption fine structure and x-ray photoelectron spectroscopy analyses reveal the formation of Ti–Cl and Ti–O bonds on the surface of Ti2NT x MXene. Density functional theory calculations further suggest that the surface terminations tend to be replaced by –O terminations after Ti–Cl decoration, which implies promising lithium-ion storage performance due to the high lithium affinity of –O terminations. As a result, the Ti2NT x MXene based electrode delivers a high reversible capacity (303.4 mAh g−1 at 100 mA g−1), stable cycling capability (1200 cycles without capacity attenuation), and fast Li+ storage (52% capacity retention at 32 C). This work provides a new vision for MXene surface chemistry and an effective avenue to prepare high-performance nitride electrodes, expanding the diversity and controllability of the MXenes family.

Tailoring interfacial interaction in GaN@NG heterojunction via electron/ion bridges for enhanced lithium-ion storage performance

In this paper, gallium nitride (GaN) nanoparticles is synthesized on the nitrogen-doped graphene (NG) (GaN@NG). X-ray absorption fine structure (XAFS) shows the distinct interfacial interaction (Ga–N/NC). This well-designed GaN@NG shows good reversible capacity (793.2 mAh/g at 0.1 A/g) and cycling durability with 98.5 % capacity retention at 2.0 A/g after 2000 cycles. Both DFT analysis and electrochemical kinetic analysis reveal that the configuration of intriguing electron and ion bridges is able to control and tailor the interfacial interaction via the interfacial coupled chemical bonds in GaN@NG heterojunction. Such electron/ion bridges can enhance the interfacial charge transfer kinetics and prevent pulverization/aggregation via the ion/electron channel during the cycling. As expected, the lithium-ion full cell (LiFePO4/C//GaN@NG) exhibits impressive energy and power densities and maintains superior cycling stability. This electron/ion bridges-related structural engineering strategy can open opportunities for the traditional electrode material to achieve the high-performance lithium ion storage and beyond.

Facile fabrication of Si-embedded amorphous carbon@graphitic carbon composite microspheres via spray drying as high-performance lithium-ion battery anodes

Silicon-nanoparticle-embedded amorphous carbon-graphitic carbon composite microspheres (denoted as Si/AC@GC) with numerous empty voids are synthesized using a spray drying process. Spray dried composite microspheres consisting of Si nanopowders, dextrin, and iron salt are transformed to uniquely structured Si/AC@GC microspheres via one-step carbonization followed by acid etching. The in situ formation of graphitic carbon with high electrical conductivity within the Si-C composite at a low carbonization temperature (700 °C) is achieved by applying a metallic Fe nanocatalyst. The Si/AC@GC microspheres exhibit higher electrochemical properties than bare Si nanopowders and Si/amorphous carbon composite microspheres (denoted as Si/AC) with filled structures. The synergistic effects of structural merits owing to the spherical morphology with empty nanovoids for liquid electrolyte penetration and a graphitic carbon layer with high electrical conductivity result in the superior lithium-ion storage performances of Si/AC@GC microsphere. The composite-based electrode delivers a high reversible capacity of 803 mA h g−1 after 200 cycles at 1.0 A g−1, indicating long-term cycling stability. Even at 5.0 A g−1, the electrode exhibits stable reversible discharge capacity of 589 mA h g−1 without significant capacity loss.

Hybridization of Ti2SnC with carbon nanofibers via electrospinning for improved lithium ion storage performance

As the precursor of MXenes (2D transition metal carbides, carbon nitrides and nitrides), MAX phase materials have attracted ever-increasing attention in electrochemical applications. In this work, we have successfully hybridized a MAX phase, Ti2SnC, with various ratios of carbon nanofibers (CNFs) via electrospinning. The results show that the Ti2SnC/CNFs compounds possess a stable lithium ion storage ability as an anode material, reaching a stable specific capacity of up to 367.5 mAh·g−1 after 500 charge/discharge cycles at the current density of 1.0 A g−1, which are drastically better than some other MAX phase materials such as Ti3SiC2 and Nb2SnC. This strategy provides a new pathway for the improvement of the electrochemical stability of MAX phase, which has a wide application prospect.

Hollow Tubular Biomass-Derived Carbon Loaded NiS/C for High Performance Lithium Storage

Transition Metal Sulfides (TMSs) have received broadly research and application in the Lithium-ion Batteries (LIBs) field owing to their rare physical/chemical characteristics. Unfortunately, the fundamental flaws of volume expansion and poor electrical conductivity hampered its future practical implementation. Herein, a carbonization/activation procedure coupled with a facile solvothermal method and post-annealing strategy were developed to synthesize hollow tubular biomass-derived carbon (HBC) loaded NiS/C composite. The HBC serves a dual functional by providing highly active surface sites for NiS/C particles loading and naturally existing micron-level pores that can accommodate the volume variation. As a consequence, the HBC-NiS/C anode displayed strong lithium-ion storage performances with a high specific capacity (652 mAh g−1 at 0.2 A g−1 over 100 cycles), favorable rate capability, and exceptional structural durability.

Self-assembly synthesis of petal-like MoS2/Co9S8/carbon nanohybrids for enhanced lithium storage performance

Transition metal sulfides are favored as anode materials for the next generation of lithium-ion batteries because of their high theoretical capacities and abundant natural resources. However, serious volume changes during charging and discharging pose great challenges to their stability. In this work, petal-like MoS2/Co9S8/C nanohybrids were synthesized via the immobilization of molybdyl acetoacetonate MoO2(acac)2 in ZIF-67 and subsequent combined vulcanization and thermolysis process. Benefiting from the homogeneous bimetallic sulfide and highly conductive carbon layer, the as-obtained MoS2/Co9S8/C nanohybrids exhibited a high initial discharge capacity of 988.3 mAh g−1 at 200 mA g−1 and a capacity retention > 99.9% after 50 cycles. Even at a high current density of 1000 mA g−1, the reversible capacity of MoS2/Co9S8/C is still as high as 754.6 mAh g−1, revealing extraordinary rate ability. This work can provide a general approach to design and synthesize other advanced bimetallic chalcogenides for boosting lithium-ion batteries storage performance.

Controllable engineering magnetite nanoparticles dispersed in a hierarchical amylose derived carbon and reduced graphene oxide framework for lithium-ion storage

A straightforward and eco-friendly method is demonstrated to engineer magnetite (Fe3O4) nanoparticles well dispersed by an amorphous amylose-derived carbon (AMC) and reduced graphene oxide (RGO) framework. Naturally available amylose (AM) serves as both reducing agent for few-layered graphene oxide (GO) in the first mild redox coprecipitation system and precursor for small-sized pyrolytic AMC in the following thermal treatment. In particular, the presence of the AM molecules effectively limits the crystal growth kinetics for the akaganeite (FeOOH) in the intermediate FeOOH@AM/RGO sample, which contributes to the transformation to Fe3O4 nanoparticles with significantly controlled size in the final Fe3O4@AMC/RGO composite. As a result, both Fe3O4 nanoparticles and AMC domains are adjacently anchored on the larger sized RGO sheets, and a unique hierarchical structure has been engineered in the Fe3O4@AMC/RGO sample. Compared with the controlled Fe3O4@RGO sample, the Fe3O4@AMC/RGO composite exhibits remarkably enhanced initial coulombic efficiency, superior cycling stability and rate performance for lithium-ion storage. The mechanisms of the interaction between GO sheets and AM molecules as well as the inspiring electrochemical behaviors of the Fe3O4@AMC/RGO electrode have been revealed. The Fe3O4@AMC/RGO sample possesses good potential for scaling-up and finding applications in wider fields.

Rationally engineering a hierarchical porous carbon and reduced graphene oxide supported magnetite composite with boosted lithium-ion storage performances

Ferric gallate (Fe-GA), an ancient metal–organic framework (MOF) material, has been recently employed as an eco-friendly and cost-effective precursor sample to synthesize a porous carbon confined nano-iron composite (Fe/RPC), and the Fe element in the Fe/RPC sample could be further oxidized to Fe3O4 nanocrystals in a 180 °C hydrothermal condition. On this foundation, this work reports an optimized approach to engineering a hierarchical one-dimensional porous carbon and two-dimensional reduced graphene oxide (RGO) supporting framework with Fe3O4 nanoparticles well dispersed. Under mild hydrothermal condition, the redox reaction between metal iron atoms from Fe/RPC and surface functional radicals from few-layered graphene oxide sheets (GO) is triggered. As a result, reinforced microstructure and improved atomic efficiency have been achieved for the Fe3O4@RPC/RGO sample. The homogeneously dispersed Fe3O4 nanoparticles with controlled size are anchored on the surface of the larger sized RGO coating layers while the smaller sized RPC domains are embedded between the RGO sheets as spacer. Challenges including spontaneous aggregation of RPC, over exposure of Fe3O4 nanoparticles and excessive restacking of RGO have been significantly inhibited. Furthermore, micro-sized carbon fiber (CF) is chosen as a structural reinforcement additive during electrode fabrication, and the Fe3O4@RPC/RGO sample delivers a good specific capacity of 1170.5 mAh·g−1 under a current rate of 1000 mA·g−1 for 500 cycles in the half cell form. The reasons for superior electrochemical behaviors have been revealed and the lithium-ion storage performances of the Fe3O4@RPC/RGO sample in the full cell form have been preliminarily investigated.

Pseudo-capacitive and kinetic enhancement of metal oxides and pillared graphite composite for stabilizing battery anodes

Nanostructured TiO2 and SnO2 possess reciprocal energy storage properties, but challenges remain in fully exploiting their complementary merits. Here, this study reports a strategy of chemically suturing metal oxides in a cushioning graphite network (SnO2[O]rTiO2-PGN) in order to construct an advanced and reliable energy storage material with a unique configuration for energy storage processes. The suggested SnO2[O]rTiO2-PGN configuration provides sturdy interconnections between phases and chemically wraps the SnO2 nanoparticles around disordered TiO2 (SnO2[O]rTiO2) into a cushioning plier-linked graphite network (PGN) system with nanometer interlayer distance (~ 1.2 nm). Subsequently, the SnO2[O]rTiO2-PGN reveals superior lithium-ion storage performance compared to all 16 of the control group samples and commercial graphite anode (keeps around 600 mAh g−1 at 100 mA g−1 after 250 cycles). This work clarifies the enhanced pseudo-capacitive contribution and the major diffusion-controlled energy storage kinetics. The validity of preventing volume expansion is demonstrated through the visualized image evidence of electrode integrity.

Preparation of D-A-D conjugated polymers based on [1,2,5]thiadiazolo[3,4-c]pyridine and thiophene derivatives and their electrochemical properties as anode materials for lithium-ion batteries

Based on the fact that D-A-D CPs (donor-acceptor-donor conjugated polymers) can significantly improve the lithium-ion storage performance of anode materials, three D-A-D CPs (PMTP, PMOTP, and PDOTP) were prepared by simple chemical polymerization reactions with [1,2,5] thiadiazole [3,4-c] pyridine as the acceptor unit and methylthiophene (MTh), methoxythiophene (MOTh), and 3,4-ethylenedioxythiophene (EDOT) as the donor unit, respectively. Each polymer was compounded in situ with the carbon nanotubes (CNTs) to prepare the PMTP@CNT, PMOTP@CNT, and PDOTP@CNT, respectively, all of which were used as the anode materials for the lithium-ion batteries. The capacities of PMTP, PMOTP, and PDOTP were 762.6, 933.4, and 1351.4 mAh g−1 after 160 cycles at 0.1 A g−1, respectively. The order of magnitude of the specific capacity of the three polymers was PDOTP > PMOTP > PMTP, which was due to the fact that with the increasing electron-donating ability of the donor unit of the polymer, the LUMO energy level gradually decreased, the HOMO energy level gradually increased, and the Eg gradually decreased, resulting in an increase in its redox ability and conductivity. The Galvanostatic intermittent titration technique (GITT) showed that the lithium-ion diffusion coefficients of the three electrodes were comparable. XPS demonstrated that lithium ions were mainly stored on the CC and CN of the three polymers (PMTP, PMOTP, and PDOTP). The b-values showed that their electrochemical reactions were controlled by both the internal solid-phase diffusion process and capacitive process. The CV, GCD, cycling stability performance, and rate capability tests showed that all the three electrodes had good electrochemical performance, among which PDOTP@CNT had the best performance and was well suited as the anode material for the Li-ion battery. D-A-D CP provides a new pathway for the development of electrode materials for high-capacity lithium-ion batteries.

Interface engineering of high entropy Oxide@Polyaniline heterojunction enables highly stable and excellent lithium ion storage performance

High-Entropy Oxide (HEO) is a new material system for lithium-ion battery (LIB) electrode materials; however, the poor electrical conductivity and instability of the electrode structure limit the further improvement of their electrochemical performance. In this work, we demonstrate that a highly stable and excellent Li-ion storage performance can be achieved by interfacial engineering of surface-chemically modified HEO@polyaniline heterojunctions. Polyaniline-coated HEO (HEO-MP) was prepared by polymerization of aniline on the surface of ball-milled micrometer-sized HEO (HEO-M). HEO-MP anodes exhibit high rate performance (325 mA h g−1 at 10 A g−1) and extremely long cycling stability (261 mA h g−1 at 4.0 A g−1 after 3200 cycles), both representing the best results so far. The improved electrochemical performance can be attributed to the conductive PANI coating, which buffers volume changes and maintains structural integrity during cycling, prevents side reactions between electrolyte and electrode materials, suppresses overproduction of SEI, and enhances ionic/electronic transport. This work demonstrates that surface interface engineering is a key step to significantly improve the performance of HEO anodes in LIBs, which can be progressed on the road to its practical applications.

Preparation and electrochemical properties of benzothiadiazole-benzotriazole donor-acceptor conductive polymer lithium-ion anode materials

The specific capacity of conventional conducting polymer composite electrodes is small. Based on the characteristics of donor-acceptor (D-A) conducting polymers with a wide range of π-electron leaving domains, narrow band gap, high conductivity and excellent electrochemical properties, D-A polymer monomers OTTBT (4, 8-Bis(3,4-ethylenedioxythiophene-2-yl)-6-(2-ethylhexyl)-[1,2,5]thiadiazolo[3,4-f] benzotriazole) and TTBT (4, 8-Bis(thiophen-2-yl)-6-(2-ethylhexyl)-[1,2,5]thiadiazolo[3,4-f] benzotriazole) were synthesized by Stille cross-coupling reaction using benzothiadiazole-benzotriazole as the acceptor unit and EDOT (3,4-ethylenedioxythiophene) or thiophene as the donor unit. Each monomer was polymerized in situ on the surface of activated carbon (AC) to obtain POTTBT@AC and PTTBT@AC composite electrode materials, respectively. The results showed that the charge storage behavior of both composites was controlled by the pseudocapacitance process. POTTBT@AC had better specific capacity, rate performance and cycling stability than PTTBT@AC. The lithium-ion storage performance of POTTBT was significantly higher than that of PTTBT, probably due to the former's higher electron supply capacity, rigidity and co-planarity. Both electrode materials had good specific capacity and rate performance and were suitable as anode materials for lithium batteries. D-A conductive polymer provides a new idea for the synthesis of electrode materials for high-capacity lithium batteries.

Defect-engineered TiO2 nanocrystals for enhanced lithium-ion battery storage performance

TiO2 nanocrystals containing oxygen defects were successfully prepared by a hydrothermal method with reductive sintering in a 5% H2 + 95% Ar mixed atmosphere. The high-resolution transmission electron microscopy and X-ray diffraction results showed that the prepared samples were all anatase TiO2. X-ray photoelectron spectroscopy analysis showed that the reductive sintering converted Ti4+ to Ti3+. The Ti3+/Ti4+ molar ratio of the TiO2 nanocrystals increased with increasing sintering time. The results of the electron paramagnetic resonance spectroscopy analysis showed that the reduced and sintered TiO2 nanocrystals produced strong signals at g = 2.0010 and 1.9478, corresponding to the presence of oxygen defects and Ti3+, respectively. Furthermore, stronger signals were generated with increasing sintering time, indicating a progressively higher concentration of oxygen defects. The TiO2 nanocrystalswere used as anode materials for lithium-ion batteries. One sample, H-TiO2-5, containing a moderate concentration of oxygen defects, presented a higher lithium ion diffusion coefficient (D = 5.1 × 10-13 cm2s−1) compared to the other TiO2 samples. This sample had a Ti3+/Ti4+ molar ratio of 0.179 and excellent cycling stability after 100 cycles. The discharge capacity was 124 mAh.g−1 after 500 cycles at a current density of 1C, which means that it has good cyclic stability.

V-substituted pyrochlore-type polyantimonic acid for highly enhanced lithium-ion storage

Pyrochlore-structured polyantimonic acid (PAA) is a potential high-capacity electrode material, but its innately poor electroconductivity (∼10−10 S/cm) seriously impairs its electrochemical reversibility for lithium-ion storage. Herein, we report design and synthesis of a novel V-substituted PAA (PAA-V), where V5+ are introduced to partially replace Sb5+. Owing to identical valence and close ionic radius relative to Sb5+, the V5+ cation can constitute the covalent VO6 octahedra framework without changing the pyrochlore crystal structure of PAA. As a result, the V5+-substitution is capable to modulate the electronic structure of PAA with significantly improved electrical conductivity (∼10−6 S/cm for PAA-V) and meanwhile decreases the size of crystals with reduced diffusion length for Li+-ions. With varying the ratio of V5+-substitution, the PAA-V with optimized substitution molar ratio (18%) exhibits the best lithium-ion storage performance, delivering a long cycling life with high reversible capacity (731 mAh/g after 1200 cycles at 1 A/g) and outstanding rate capability (279 mAh/g at 15 A/g). More importantly, by pairing the PAA-V as anode and commercial LiFePO4 as cathode, the full cell with a limited negative/positive capacity ratio of 1.2 exhibits decent cycling stability at 1 C after 150 cycles with 85.5% capacity retention.

Facile synthesis of porous iron oxides heterostructural nanosheets as an enhanced anode material for lithium ion battery

To solve the common problems of intrinsically poor electrical conductivity and drastic volume expansion of the Fe2O3 anode in lithium-ion batteries, we synthesized porous Fe2O3 heterostructural nanosheets with β-Fe2O3/α-Fe2O3 by simple pyrolyzing of iron(III) ethylene diamine tetra acetate (Fe-EDTA) precursor and subsequently washing to remove NaCl particles formed in situ. Porous Fe2O3 nanosheets combining the advantages of large-area porous structure and β-Fe2O3/α-Fe2O3 heterostructure as an anode showed improved lithium ion storage performance. The porous nanosheets exhibited a high reversible capacity (1131.1 mA h g−1 at a current density of 1.0 A g−1 after 300 cycles), and a remarkable rate capability of 505 mA h g−1 at 10 A g−1.

Simultaneous interfacial interaction and built-in electric field regulation of GaZnON@NG for high-performance lithium-ion storage

Interfacial interaction and built-in electric field regulation strategy is developed to construct (Ga1−xZnx)(N1−xOx) (GaZnON) nanoparticles coupled with nitrogen-doped graphene (NG) (GaZnON@NG) via a simple and facile method. Advanced structural characterization and density functional theory (DFT) analysis reveals the strong bridging bonds (Ga–N/N–C) and the interfacial charge transfer in GaZnON@NG. This interfacial interaction can subtly regulate the interfacial electronic state and improve the surface electron density and charge transport kinetics for efficient lithium-ion storage. As a proof-of-concept study, this well-designed GaZnON@NG heterostructure anode shows an enhanced lithium-ion storage performance of 1073.6 mA h g−1 at 0.1 A g−1 after 200 cycles. Even at 5.0 A g−1, the reversible capacity is still maintained at 338.6 mA h g−1 after 2000 cycles. Electrochemical kinetic analysis corroborates the enhanced pseudocapacitive contribution and lithium-ion reaction kinetics in the GaZnON@NG anode. Furthermore, XRD and XPS analysis of the GaZnON@NG heterostructure reveals good structural stability and reversible lithium-ion intercalation mechanism. DFT analysis further reveals that this GaZnON@NG heterostructure anode possesses lower lithium-ion adsorption energy and higher charge and discharge rates. This interfacial interaction strategy can open opportunities for advanced energy storage applications and beyond.

A Spinel Tin Ferrite with High Lattice-Oxygen Anchored on Graphene-like Porous Carbon Networks for Lithium-Ion Batteries with Super Cycle Stability and Ultra-fast Rate Performances.

A new type of nano-SnFe2O4 with stable lattice-oxygen and abundant surface defects anchored on ultra-thin graphene-like porous carbon networks (SFO@C) is prepared for the first time by an interesting freezing crystallization salt template method. The functional composite has excellent rate performance and long-term cycle stability for lithium-ion battery (LIB) anodes due to the stable structure, improved conductivity, and shortened migrating distance for lithium-ions, which are derived from the higher lattice-oxygen of SnFe2O4, abundant porous carbon networks and surface defects, and smaller nanoparticles. Under the ultra-high current density of 10, 15, and 20 A g-1 cycling for 1000 times, the SFO@C can provide high reversible capacities of 522.2, 362.5, and 361.1 mAh g-1, respectively. The lithium-ion storage mechanism of the composite was systematically studied for the first time by in situ X-ray diffraction (XRD), ex situ XRD and scanning electron microscopy (SEM), and density functional theory (DFT) calculations. The results indicate that the existence of Li2O and metallic Fe during the lithiation/delithiation process is a key reason for reducing the initial lithium-ion storage reversibility but increasing the rate performance and capacity stability in the subsequent cycles. DFT calculations show that lithium-ions are more easily adsorbed on the (111) crystal plane with a much lower adsorption energy of -7.61 eV than other planes, and the Fe element is the main acceptor of electrons. Moreover, the kinetics investigation indicates that the lithium-ion intercalation and deintercalation in SFO@C are mainly controlled by the pseudocapacitance behavior, which is favorable to enhancing the rate performance. The research provides a new strategy for designing LIB electrode materials with a stable structure and outstanding lithium-ion storage performance.

Insights into the enhanced Lithium-Ion storage performance of CoSx/Carbon polyhedron hybrid anode

In this work, the 3D cobalt sulfide/carbon polyhedral (CoSx/CP) hybrids (x = 1, 2) have been fancily prepared by employing the ZIF-67 as template. The as-prepared CoSx/CP inherit the structure of ZIF-67, realizing the polyhedral structure where the CoSx nanoparticles are well embedded. The battery performance measurements demonstrate that the CoS2 has played a significant role contributing to the lithium ions batteries (LIBs) performance of CoSx/CP. As a result, the capacity of the optimized CoSx/CP is 562 mAh g−1 after 300 cycles at 0.5 A g−1. When cycled at 10 A g−1, it delivers a reversible specific capacity of 131 mAh g−1. The electrochemical analysis points out that the optimized CoSx/CP possesses diverse electrochemical reactions and the lowest charge transfer resistance. Moreover, the insertion mechanism and structural evolution process of CoSx/CP are examined by the in-situ XRD. Beyond that, the unique nanoarchitecture of CoSx/CP guarantees the high specific surface area which enables the large electrode–electrolyte contract area, fast ions diffusion/electron transfer and robust structural stability. Meanwhile, the carbon skeleton is deductive to confine the huge volume expansion of CoSx as well.

A variety of carbon-coated FeS2 anodes: FeS2@CNT with excellent lithium-ion storage performance

Pyrite FeS2, which has abundant reserves, is widely regarded as an excellent anode material for lithium-ion batteries. However, FeS2 is prone to volume expansion and low conductivity during charging and discharging, resulting in poor electrochemical performance. In this paper, a fast non-hydrogel method was used to synthesize the precursor of FeS2 @C (carbon nanotubes, graphene, crab shell carbon, and sucrose carbon), and the obtained FeS2@CNT has a relatively best electrochemical performance. Benefiting from its structural advantages, FeS2@CNT exhibits a good rate performance (1200, 1125, 1020, 920 and 820 mA h g−1 at five levels of the current density of 100–2000 mA g−1). And it has an excellent cycle performance (1200 mA h g−1 after 100 cycles at 100 mA g−1). It shows that this method has considerable advantages in the process of preparing composites.