Preparation and electrochemical properties of TiO2 hollow spheres as an anode material for lithium-ion batteries

TiO₂ hollow spheres are fabricated by a sol-gel process using carbon spheres as template. The diameter and the shell thickness of the TiO₂ hollow spheres are about 400-600 nm and 60-80 nm, respectively. The electrochemical properties of the hollow spheres are investigated by galvanostatic cycling and cyclic voltammetry (CV) measurements. The initial discharge capacity reaches 291.2 mAh g⁻¹ at a current density of 60 mA g⁻¹. The average discharge capacity loss is about 1.72 mAh g⁻¹ per cycle from the 2nd to the 40th cycles and the coulombic efficiency is approximately 98% after 40 cycles, indicating excellent cycling stability and reversibility.     

MnO/C core-shell nanorods as high capacity anode materials for lithium-ion batteries

MnO/C core-shell nanorods were synthesized by an in situ reduction method using MnO₂ nanowires as precursor and block copolymer F127 as carbon source. Field emission scanning electron microscopy and transmission electron microscopy analysis indicated that a thin carbon layer was coated on the surfaces of the individual MnO nanorods. The electrochemical properties were evaluated by cyclic voltammetry and galvanostatic charge-discharge techniques. The as-prepared MnO/C core-shell nanorods exhibit a higher specific capacity than MnO microparticles as anode material for lithium ion batteries.     

Synthesis of carbon coated Fe3O4/SnO2 composite beads and their application as anodes for lithium ion batteries

Abstract

Two metal oxide materials, namely, Fe₃O₄ and SnO₂, were combined into one specially designed nanostructure for lithium ion battery application. Hollow and porous Fe₃O₄ beads with an average size of ～700 nm were first synthesised through a one-step solvothermal route, followed by the decoration of SnO₂ nanoparticles via a hydrothermal method. A thin carbon layer was coated to further enhance the overall electrochemical performances. Under the current density of 100 mA g^?1, the first reversible capacity of such composite beads reached 834·7 mA h g^?1. While being tested at a higher current density of 500 mA g^?1, carbon coated Fe₃O₄/SnO₂ delivered steady reversible capacities with 569·5 mA h g^?1 at two hundredth cycle. Such performances were attributed to the high theoretical capacities of the metal oxides, desired morphology in nanoscale, carbon coating layer and the synergistic effect between Fe₃O₄ and SnO₂.     

Hollow SnNi@PEO nanospheres as anode materials for lithium ion batteries

Polyethylene oxide (PEO)-coated hollow SnNi nanospheres (SnNi@PEO) and hollow SnNi nanospheres were obtained by a galvanic replacement method using Ni nanospheres as the sacrificial template association with surfactant (sodium dodecyl sulfate, SDS). Compared with hollow SnNi nanospheres and solid Sn nanospheres, the obtained SnNi@PEO were applied for the first time in lithium ion batteries (LIBs) and showed better electrochemical properties (reversible capacity of 560 mAh g^?1 after 100 cycles with a coulomb efficiency above 98%). The excellent electrochemical performance of SnNi@PEO can be ascribed to hollow structure and PEO coating to alleviate volume expansion. To further comprehending of the mechanical stability, a diffusion-stress coupled model was solved numerically to simulate the diffusion-induced stress evolution of the single sphere during the lithiation process in LIBs.     

Carbon-coated SiO2 nanoparticles as anode material for lithium ion batteries

A simple approach is proposed to prepare C-SiO₂ composites as anode materials for lithium ion batteries. In this novel approach, nano-sized silica is soaked in sucrose solution and then heat treated at 900 °C under nitrogen atmosphere. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis shows that SiO₂ is embedded in amorphous carbon matrix. The electrochemical test results indicate that the electrochemical performance of the C-SiO₂ composites relates to the SiO₂ content of the composite. The C-SiO₂ composite with 50.1% SiO₂ shows the best reversible lithium storage performance. It delivers an initial discharge capacity of 536 mAh g⁻¹ and good cyclability with the capacity of above 500 mAh g⁻¹ at 50th cycle. Electrochemical impedance spectra (EIS) indicates that the carbon layer coated on SiO₂ particles can diminish interfacial impedance, which leads to its good electrochemical performance.     

Improving electrochemical properties and structural stability of lithium manganese silicates as cathode materials for lithium ion batteries via introducing lithium excess

The serious capacity decay caused by structural amorphization is still a major issue for polyanion-type lithium manganese silicates (Li₂MnSiO₄) as cathode material for lithium ion batteries. In this work, a new strategy for alleviating the structural instability via the introduction of excess lithium into the host crystal lattice is provided. A comprehensive study demonstrates that the required energy for the extraction/insertion of lithium ions into host crystal lattice was decreased as a result of changed local environment of cations in the compound after the excess lithium occupancy in lattice. Importantly, it was found that Li-rich samples deliver higher reversible capacity and increased average potential than pristine sample, indicating the improved energy density of polyanion-type Li_{2 + 2x}Mn_{1 − x}SiO₄/C_. Additionally, the structure of Li2.2 sample was kept intact, while the Li2.0 sample was transformed to amorphous state at 200 mA h g⁻¹ during the initial charging process by controlling the charge cut-off potential. As expected, the introduction of a certain amount of excess lithium into Li₂MnSiO₄ is explored as a route to achieving increased capacity with more movable lithium, while maintaining its structural stability and cyclic stability.     

Enhanced electrochemical performance of porous NiO-Ni nanocomposite anode for lithium ion batteries

The nickel foam-supported porous NiO-Ni nanocomposite synthesized by electrostatic spray deposition (ESD) technique was investigated as anodes for lithium ion batteries. This anode was demonstrated to exhibit improved cycle performance as well as good rate capability. Ni particles in the composites provide a highly conductive medium for electron transfer during the conversion reaction of NiO with Li⁺ and facilitate a more complete decomposition of Li₂O during charge with increased reversibility of conversion reaction. Moreover, the obtained porous structure is benefical to buffering the volume expansion/constriction during the cycling.     

Reduced graphene oxide/tin oxide composite as an enhanced anode material for lithium ion batteries prepared by homogenous coprecipitation

Reduced graphene oxide/tin oxide composite is prepared by homogenous coprecipitation. Characterizations show that tin oxide particles are anchored uniformly on the surface of reduced graphene oxide platelets. As an anode material for Li ion batteries, it has 2140 mAh g⁻¹ and 1080 mAh g⁻¹ capacities for the first discharge and charge, respectively, which is more than the theoretical capacity of tin oxide, and has good capacity retention with a capacity of 649 mAh g⁻¹ after 30 cycles. The simple synthesis method can be readily adapted to prepare other composites containing reduced graphene oxide as a conducting additive that, in addition to supporting metal oxide nanoparticles, can also provide additional Li binding sites to, perhaps, further enhance capacity.     

SnO2 nanocrystals deposited on multiwalled carbon nanotubes with superior stability as anode material for Li-ion batteries

We report a novel ethylene glycol-mediated solvothermal-polyol route for synthesis of SnO₂-CNT nanocomposites, which consist of highly dispersed 3-5 nm SnO₂ nanocrystals on the surface of multiwalled carbon nanotubes (CNTs). As anode materials for Li-ion batteries, the nanocomposites showed high rate capability and superior cycling stability with specific capacity of 500 mAh g⁻¹ for up to 300 cycles. The CNTs served as electron conductors and volume buffers in the nanocomposites. This strategy could be extended to synthesize other metal oxides composites with other carbon materials.     

The study of Mg2Si/carbon composites as anode materials for lithium ion batteries

The study of Mg₂Si/C composites as anode materials for lithium ion batteries is reported in this paper. Firstly, Mg₂Si was synthesized by mechanically activated annealing (MAA) technique and the preparing conditions for pure Mg₂Si alloy were investigated and optimized. Then the composite materials of Mg₂Si and carbon materials such as CNTs and CMS with different ratios were prepared by the followed ball-milling techniques. Their electrochemical performances were compared by the galvanostatically charge/discharge and EIS experiments. The pure Mg₂Si alloy delivers a large initial capacity, but the capacity decreases rapidly with cycling. In contrast, the composites show good cyclic stability and deliver a reversible capacity of about 400 mAh g⁻¹ with 40% carbon in the composite. The results of EIS indicate that the composite of Mg₂Si/CMS has better interface stability than that of pure Mg₂Si materials.     

Preparation and electrochemical characterization of tin/graphite/silver composite as anode materials for lithium-ion batteries

The tin/graphite/silver (Sn/G/Ag) composite was prepared by high-energy mechanical milling (HEMM) for the first time. The composite powders consisted of electrochemically active Sn, Ag₄Sn phases which were uniformly distributed on the surface of the graphite particles. The formation of Ag₄Sn alloy phase and the uniform distribution of the active particles could accommodate the large volume changes during cycling. X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM) and scanning electron microscopy (SEM) were used to determine the phases obtained and to observe the microstructure and dispersion of particles. In addition, cyclic voltammetry (CV) and galvanostatic discharge/charge tests were carried out to characterize the electrochemical properties of the composite. The composite electrodes exhibited an initial capacity of 1154 mAh g⁻¹ and maintained a reversible capacity of above 380 mAh g⁻¹ for more than 100 cycles.     

Porous NiO/poly(3,4-ethylenedioxythiophene) films as anode materials for lithium ion batteries

NiO/poly(3,4-ethylenedioxythiophene) (PEDOT) films are prepared by chemical bath deposition and electrodeposition techniques using nickel foam as the substrate. These composite films are porous, and constructed by many interconnected nanoflakes. As anode materials for lithium ion batteries, the NiO/PEDOT films exhibit weaker polarization and better cycling performance as compared to the bare NiO film. Among these composite films, the NiO/PEDOT film deposited after 2 CV cycles has the best cycling performance, and its specific capacity after 50 cycles at the current density of 2 C is 520 mAh g⁻¹. The improvements of these electrochemical properties are attributed to the PEDOT, a highly conductive polymer, which covers on the surfaces of the NiO nanoflakes, forming a conductive network and thus enhances the electrical conduction of the electrode.     

Exploration of amorphous hollow FeOOH@C nanosphere on energy storage for sodium ion batteries

Sodium ion batteries (SIBs) have enjoyed a high profile in recent years and gradually been commercialized to supplement the lithium-ion batteries system. However, the large volume expansion of anode materials within discharging and low electrical conductivity hinder the application of SIBs. In this work, a FeOOH@C composite was synthesized with the use of hydrothermal method and pyrolyzing of polydopamine. The amorphous FeOOH exhibits a hollow spherical structure to offer free space for buffering the volumetric variation. Furthermore, the outer carbon served as a protective shell could maintain the sphere integrity and enhance the electrical conductivity. Hence, benefiting from the achieved synergy of the hollow architecture, amorphous structure and carbon shell, the composite presented a long cycle life (316 mA h g^?1 after 500 cycles at a current density of 100 mA g^?1 and 234.5 mA h g^?1 after 400 cycles at 2 A g^?1) and high-rate performance (180 mA h g^?1 at 5 A g^?1), revealing a potential to be a promising candidate for electrode material of SIBs.     

Titanium-based materials as anode materials for sodium ion batteries

钛基材料具有环境友好、安全性好、稳定性好等优点而备受关注。但是钛基材料带隙宽,电子导电性差,比容量低限制了其在钠离子电池领域的发展与应用。本文主要综述了TiO2、Na2TinO2n+1、NaTi2(PO4)3三类钛基材料的结构、电化学性能、改性方法和相关储钠机理。评述了钛基材料存在的问题并展望了其发展前景。今后的研究可以从以下几方面开展：① 深入研究钛基负极材料储钠机理;② 研究多种阳、阴离子掺杂对钛基材料的电子结构的影响,从根本上提高钛基材料的电子导电性;③ 与高比容量负极材料复合,获得兼具稳定性与高比容量优点的复合材料;④ 设计合成具有多级、三维结构的钛基复合负极材料,进一步提高材料的循环稳定性、倍率性能;⑤ 开发新型结构的钛基负极材料。     

High performance silicon carbon composite anode materials for lithium ion batteries

Silicon and silicon containing compounds are attractive anode materials for lithium batteries because of their low electrochemical potential vs. lithium and high theoretical capacities. In this work the relationship between the electrochemical performance of silicon powders and their particle sizes was studied. It is found that the material with nano particle sizes gives the best performance. New silicon/carbon composite anode materials were synthesized and their structures and electrochemical performance were investigated. The results of these studies are reported in this paper.     

In situ electrochemical synthesis of lithiated silicon–carbon based composites anode materials for lithium ion batteries

Most composite anode systems research on lithium ion batteries to date focus on pristine unalloyed Si as the electrochemically active component combined with a suitable matrix component that is electrochemically inactive or relatively inactive to lithium ions. Herein, we report the generation of composites by electrochemical synthesis in situ, denoted as Li–Si/C based on Li–Si alloys synthesized as dispersoids in a carbon (C) matrix, as potential anode materials for lithium ion batteries. The electrochemical performance of the Li–Si/C composite of different compositions generated has been systematically studied in order to identify a suitable Li–Si–C composition that could be most effective as a lithium ion anode. The resultant alloy would also exhibit stable electrochemical capacities while expecting to deliver high energy density during discharge with suitable cathode systems. This study shows that the Li–Si/C composite of composition 64 at.% C–21.6 at.% Li–14.4 at.% Si, comprised of Li–Si alloy of compositions in the vicinity of Li–40 at.% Si dispersed in the C matrix cycled within the stable potential window of 0.02–0.5 V, has the potential characteristics of being a promising anode material displaying excellent capacity retention (0.13% loss per cycle) with high specific capacity (700 mA h g⁻¹), and also expected to deliver high energy density during discharge in the full cell configuration employing a suitable cathode.     

Electrochemical properties of carbon-coated Si/B composite anode for lithium ion batteries

Carbon-coated Si and Si/B composite powders prepared by hydrocarbon gas (argon + 10 mol% propylene) pyrolysis were investigated as the anodes for lithium-ion batteries. Carbon-coated silicon anode demonstrated the first discharge and charge capacity as 1568 mAh g⁻¹ and 1242 mAh g⁻¹, respectively, with good capacity retention for 10 cycles. The capacity fading rate of carbon-coated Si/B composite anode decreased as the amounts of boron increased. In addition, the cycle life of carbon-coated Si/B/graphite composite anode has been significantly improved by using sodium carboxymethyl cellulose (NaCMC) and styrene butadiene rubber (SBR)/NaCMC mixture binders compared to the poly(vinylidene fluoride, PVdF) binder. A reversible capacity of about 550 mAh g⁻¹ has been achieved at 0.05 mAm g⁻¹ rate and its capacity could be maintained up to 450 mAh g⁻¹ at high rate of 0.2 mAm g⁻¹ even after 30 cycles. The improvement of the cycling performance is attributed to the lower interfacial resistance due to good electric contact between silicon particles and copper substrate.     

Nitrogen/sulfur co-doped disordered porous biocarbon as high performance anode materials of lithium/sodium ion batteries

Nitrogen/sulfur co-doped disordered porous biocarbon was facilely synthesized and applied as anode materials for lithium/sodium ion batteries. Benefiting from high nitrogen (3.38 wt%) and sulfur (9.75 wt%) doping, NS_1-1 as anode materials showed a high reversible capacity of 1010.4 mA h g⁻¹ at 0.1 A g⁻¹ in lithium ion batteries. In addition, it also exhibited excellent cycling stability, which can maintain at 412 mAh g^-1 after 1000 cycles at 5 A g⁻¹. As anode materials of sodium ion batteries, NS_1-1 can still reach 745.2 mA h g⁻¹ at 100 mAg^-1 after 100 cycles. At a high current density (5 A g^-1), the reversible capacity is 272.5 mA h g⁻¹ after 1000 cycles, which exhibits excellent electrochemical performance and cycle stability. The preeminent electrochemical performance can be attributed to three effects: (1) the high level of sulfur and nitrogen; (2) the synergic effect of dual-doping heteroatoms; (3) the large quantity of edge defects and abundant micropores and mesopores, providing extra Li/Na storage regions. This disordered porous biocarbon co-doped with nitrogen/sulfur exhibits unique features, which is very suitable for anode materials of lithium/sodium ion batteries.     

Advances in tin-based nanoparticles and their nonocomposite anode for lithium ion batteries

锡基负极材料由于具有很高的储锂容量,较低的电压平台和较大的压实密度而得到广泛的研究,是最具应用潜力的下一代锂离子电池负极材料之一.然而,锡基负极材料在充放电过程中巨大的体积效应导致电极材料破碎粉化脱落,严重降低了电池的循环寿命和限制了其商业化应用.超细化和复合化是解决锡金负极材料缺陷的有效途径,本文论述了近年来在锡基负极材料研究方面的热点及最新成果,特别是超细SnO₂纳米颗粒及其与碳纳米管或石墨烯复合负极材料方面的研究进展.     

Hierarchical porous TiNb2O7@N-doped carbon microspheres as superior anode materials for lithium ion storage

TiNb₂O₇ is considered to be one of the ideal candidate anode materials for lithium-ion batteries (LIBs) because of its safe working potential and high theoretical capacity. However, its low intrinsic conductivity and poor ionic diffusion rate hinder its practical application. In this study, an ultrathin N-doped carbon coating was uniformly deposited onto hierarchical porous TiNb₂O₇ microspheres by combining a solvothermal route with a carbonization process using ionic liquid. The TiNb₂O₇@N-doped carbon microspheres exhibited an ultra-high rate performance (208 mA h g^?1 at 30 C) and excellent cycling stability (specific capacity retention of 79% after 500 cycles at 10 C), and showed excellent electrochemical performance in a full cell using LiNi_0·5Mn_0·3Co_0·2O₂ as a cathode. The superior performance can be attributed to the synergistic effects between the ultrathin N-doped carbon coating and unique microstructure. Therefore, TiNb₂O₇@N–C is a promising negative electrode for high-power LIBs.