Preparation and characterization of SnO2/carbon nanotube composite for lithium ion battery applications

SnO₂/multi-walled carbon nanotube (MWCNT) composite was prepared via a diffusion method. Firstly the MWCNT was sonicated in a filtrate which was derived from a tin dichloride solution mixed with AgNO₃ solution. Then the SnO₂/MWCNT composite was prepared whereby, after calcination in N₂ atmosphere, the salts inside the MWCNT decomposed to SnO₂. The resulting composite was characterized by transmission electron microscopy, Raman spectroscopy and X-ray diffraction, which indicated that SnO₂ had infiltrated into the MWCNT and filled the interior. The subsequent evaluation of the electrochemical performance in lithium ion batteries showed that the SnO₂/MWCNT composite had a reversible discharge capacity of 505.9 mAh?g^− 1 after 40 cycles, as compared to 126.4 mAh?g^− 1 for pure nano-SnO₂.     

Preparation of porous SnO2 helical nanotubes and SnO2 sheets

We report a surfactant-free chemical solution route for synthesizing one-dimensional porous SnO₂ helical nanotubes templated by helical carbon nanotubes and two-dimensional SnO₂ sheets templated by graphite sheets. Transmission electron microscopy, X-ray diffraction, cyclic voltammetry, and galvanostatic discharge–charge analysis are used to characterize the SnO₂ samples. The unique nanostructure and morphology make them promising anode materials for lithium-ion batteries. Both the SnO₂ with the tubular structure and the sheet structure shows small initial irreversible capacity loss of 3.2% and 2.2%, respectively. The SnO₂ helical nanotubes show a specific discharge capacity of above 800 mAh g⁻¹ after 10 charge and discharge cycles, exceeding the theoretical capacity of 781 mAh g⁻¹ for SnO₂. The nanotubes remain a specific discharge capacity of 439 mAh g⁻¹ after 30 cycles, which is better than that of SnO₂ sheets (323 mAh g⁻¹).     

In situ synthesis of SnO2/graphene nanocomposite and their application as anode material for lithium ion battery

SnO₂/graphene nanocomposite was prepared via an in situ chemical synthesis method. The nanocomposite was characterized by X-ray diffraction, filed emission scanning electron microscope and transmission electron microscope, which revealed that tiny SnO₂ nanoparticles could be homogeneously distributed on the graphene matrix. The electrochemical performance of the SnO₂/graphene nanocomposite as anode material was measured by galvanostatic charge/discharge cycling. The SnO₂/graphene nanocomposite showed a reversible capacity of 665 mAh/g after 50 cycles and an excellent cycling performance for lithium ion battery, which was ascribed to the three-dimensional architecture of SnO₂/graphene nanocomposite. These results suggest that SnO₂/graphene nanocomposite would be a promising anode material for lithium ion battery.     

SnO2@C core-shell spheres: synthesis, characterization, and performance in reversible Li-ion storage

The nanostructured SnO₂@C spheres with tin oxide cores and carbon shells were prepared by a facile one-pot solvothermal method followed by a subsequent calcination at 600 °C in a high-purity nitrogen atmosphere. The resulting samples were characterized with thermogravimetric analysis (TGA), X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and charge-discharge test. Electrochemical performance test showed that these SnO₂@C core-shell spheres exhibited an initial discharge specific capacity of 667.4 mAh/g in the potential range of 1.2–0.01 V. After 18 cycles, the capacity of the SnO₂@C core-shell spheres anode stabilized reversibly at about 370 mAh/g. This improved cycling performance could be attributed to the carbon shells, which can enhance the conductivity of SnO₂ and suppress the aggregation of active particles to increase their structure stability during cycling. These SnO₂@C core-shell spheres are promising anodes for lithium ion batteries. This study provides a facile way to improve the cycle ability of transition oxides for reversible lithium-ion storage.     

表面活性剂对纳米SnO2负极材料形貌结构及电化学性能的影响

为了提高SnO_2负极材料的电化学性能,本文以锡酸钠为原料、聚乙烯吡咯烷酮(PVP)、尿素、十二烷基硫酸钠(SDS)分别作为表面活性剂,采用水热法制备了具有纳米结构的SnO_2负极材料.利用扫描电子显微镜(SEM)、X射线衍射(XRD)、电化学测试仪测试了材料的形貌、结构和电化学性质.结果表明,使用不同表面活性剂,可获得不同形貌的纳米结构,并且对材料的电化学性能有较大的影响.当尿素作表面活性剂时,获得了分散较好的球形材料,在0.01~3.0 V,以200 mA/g进行充放电测试,首次放电容量2 256.6 mAh/g,经过50次循环后,放电容量保持在440 mAh/g,表现了较好的循环性能.     

Polycrystalline SnO2 nanowires coated with amorphous carbon nanotube as anode material for lithium ion batteries

One-dimensional (1D) SnO₂ nanowires, coated by in situ formed amorphous carbon nanotubes (a-CNTs) with a mean diameter of ca. 60 nm, were synthesized by annealing the anodic alumina oxide (AAO) filled with a sol of SnO₂. X-ray diffraction (XRD) and selected area electron diffraction (SAED) patterns revealed that the prepared SnO₂ nanowires exist in polycrystalline rutile structure. The coating of carbon nanotubes has some defects on the wall after the internal SnO₂ nanoparticles were removed. The 1D SnO₂ nanowires present a reversible capacity of 441 mAh/g and an excellent cycling performance as an anode material for lithium ion batteries. This suggests that 1D nanostructured materials have great promise for practical application.     

Preparation and electrochemical performance of manganese oxide/carbon nanotubes composite as a cathode for rechargeable lithium battery with high power density

Manganese oxide/carbon nanotubes (MO/CNTs) composite was prepared by hydrothermally reducing KMnO₄ with CNTs, where the used CNTs are of dual role, i.e., they serve as reductant during reaction and the remaining CNTs act as conducting agent in the composite. This composite was characterized by X-ray diffraction and scanning electron microscopy techniques. In addition, the electrochemical performances of the composite were investigated, which suggested an excellent rate-capability of this material; e.g., it delivered a high discharge capacity as 131 mAh g^− 1 at a high current density of 4 A g^− 1 (20 C), and high capacity at low discharge current density, e.g., about 209 mAh g^− 1 at 0.2 C rate. Therefore, such a MO/CNTs composite is promising in high power application of lithium battery and electrochemical capacitor.     

Carbon nanotubes anchored with SnO2 nanosheets as anode for enhanced Li-ion storage

The carbon nanotubes (CNTs) anchored with SnO₂ nanosheets were prepared using a hydrothermal method. The as-prepared products were characterized by X-ray diffraction, fourier transform infrared spectroscopy, thermogravimetric analyses, field emission scanning electron microscope and transmission electron microscope. The electrochemical performances of SnO₂ nanosheets/CNTs composite were measured by galvanostatic charge/discharge cycling, cyclic voltammetry and electrochemical impedance spectroscopy. The results show that the SnO₂ nanosheets/CNTs composite maintains high lithium storage capacity and good cycling stability. The designed structure plays key role in improving electrochemical performance. The CNTs anchored with SnO₂ nanosheets will be an ideal candidate of anode material for lithium ion batteries.     

Interface Chemistry Engineering of Protein‐Directed SnO2 Nanocrystal‐Based Anode for Lithium‐Ion Batteries with Improved Performance

A novel uniform amorphous carbon‐coated SnO₂ nanocrystal (NCs) for use in lithium‐ion batteries is formed by utilizing bovine serum albumin (BSA) as both the ligand and carbon source. The SnO₂–carbon composite is then coated by a controlled thickness of polydopamine (PD) layer through in situ polymerization of dopamine. The PD‐coated SnO₂–carbon composite is finally mixed with polyacrylic acid (PAA) which is used as binder to accomplish a whole anode system. A crosslink reaction is built between PAA and PD through formation of amide bonds to produce a robust network in the anode system. As a result, the designed electrode exhibits improved reversible capacity of 648 mAh/g at a current density of 100 mA/g after 100 cycles, and an enhanced rate performance of 875, 745, 639, and 523 mAh/g at current densities of 50, 100, 250, and 500 mA/g, respectively. FTIR spectra confirm the formation of crosslink reaction and the stability of the robust network during long‐term cycling. The great improvement of capacity and rate performance achieved in this anode system is attributed to two stable interfaces built between the active material (SnO₂–carbon composite) and the buffer layer (PD) and between the buffer layer and the binder (PAA), which effectively diminish the volume change of SnO₂ during charge/discharge process and provide a stable matrix for active materials.     

Effect of Cu-doping on the electrochemical performance of FeS2

FeS₂ reportedly has a high specific capacity of 893 mAh/g; however, its poor cyclic performance limits its commercialization. To circumvent this limitation, strategies such as preparation of high-purity FeS₂ and Ni-doping were adopted to modify the electrochemical properties of FeS₂. Nevertheless, these approaches resulted only in limited improvements in the electrochemical properties. Therefore, in this study, we synthesized Cu-doped FeS₂ via a solvothermal process, aiming at improved electrochemical properties. Systematic studies indicated that Cu doping changed the morphology of FeS₂ from larger irregular particles to smaller spherical ones. The charge–discharge measurements indicated that the Cu-doped FeS₂ exhibited two discharge plateaus, at 1.6 V and 1.4 V. The initial specific discharge capacity of Cu-doped FeS₂ was about 866 mAh/g at a current density of 90 mA/g, which is approximately 11% higher than that of the undoped FeS₂. The initial discharge capacity of the Cu-doped FeS₂ at a current density of 2700 mA/g was 518 mAh/g, and its cyclic discharge capacity exceeded 105 mAh/g at the 20th cycle. Cyclic voltammetry and resistance measurements revealed that Cu-doping reduces both the internal resistance and polarization of Li/FeS₂ batteries.     

The effect of ZnO coating on LiMn2O4 cycle life in high temperature for lithium secondary batteries

The surface of the spinel LiMn₂O₄ was modified with zinc oxide by a chemical process to improve its electrochemical performance at high temperatures. The physical properties of the prepared products have been investigated by thermogravimetry (TG), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-rays analysis (EDAX). The charge/discharge of the materials was carried at 1 mA/cm² in the range of 3.0 and 4.4 V at 55 °C. The discharge capacity of ZnO-coated LiMn₂O₄ (117 mAh/g) showed only 3% loss of the initial capacity (121 mAh/g) over 60 cycles. The cycle ability improvement of the spinel LiMn₂O₄ coated with ZnO is demonstrated at high temperatures. From the analysis of electrochemical impedance spectroscopy (EIS), the improvement of cycle ability may be attributed to the suppression on the formation of the passivation film and the reduction of Mn dissolution, which result from the modifying the surface of the spinel LiMn₂O₄ with zinc oxide.     

Electrochemical characteristics of LiNiO2 films prepared for charge storable electrode application

In this paper, electrochemical investigation of LiNiO₂ films prepared by molten salt synthesis (MSS) method was performed to develop a storage electrode of solar cell energy. The preferred orientation constantly indicates (111), (012), (110) and (113). The microstructures confirmed the size of the LiNiO₂ particles in a narrow range of ~ 200 nm. Cyclic voltammogram (CV) profiles have broad cathodic peak at 3.7 V and three anodic peaks at 3.4, 3.1 and 1.9 V. For the charge and discharge range of 2.5-4.4 V, the discharge capacity was 159 mAh/g at first, and slowly decreased to 148 mAh/g during the 30th cycles.     

Partially-crystallized carbon material obtained by the reducing reactions from alkalis carbonate and its electric performance

We report here a new sort of partially-crystallized carbon materials obtained from the reducing reactions between alkalis carbonate (M₂CO₃ M = Li, K, Na) and active metals such as Li, Mg, Al and Ga. The chemical reactions are carried out at the temperature range of 600-900 °C and under the argon ambience. The typical reaction can be represented as follows: K₂CO₃ + 4Li = 2Li₂O + K₂O + C. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and energy-dispersive X-ray fluorescence (EDAX) characterizations reveal evidently that the obtained final black powder products are carbon materials with partially-crystallized structure. In addition, we also investigate the electric performance of the obtained carbon materials; the initial discharge capacity and initial charge capacity have been measured respectively as high as 1267 mAh/g and 736 mAh/g.     

SnO2-reduced graphene oxide nanoribbons as anodes for lithium ion batteries with enhanced cycling stability

A nanocomposite material of SnO2-reduced graphene oxide nanoribbons has been developed. In this composite, the reduced graphene oxide nanoribbons are uniformly coated by nanosized SnO2 that formed a thin layer of SnO2 on the surface. When used as anodes in lithium ion batteries, the composite shows outstanding electrochemical performance with the high reversible discharge capacity of 1,027 mAh/g at 0.1 A/g after 165 cycles and 640 mAh/g at 3.0 A/g after 160 cycles with current rates varying from 0.1 to 3.0 A/g and no capacity decay after 600 cycles compared to the second cycle at a current density of 1.0 A/g. The high reversible capacity, good rate performance and excellent cycling stability of the composite are due to the synergistic combination of electrically conductive reduced graphene oxide nanoribbons and SnO2, The method developed here is practical for the large-scale development of anode materials for lithium ion batteries.     

Enhancing the Sequential Conversion‐Alloying Reaction of Mixed Sn–S Hybrid Anode for Efficient Sodium Storage by a Carbon Healed Graphene Oxide

To date, the possible depletion of lithium resources has become relevant, giving rise to the interest in Na‐ion batteries (NIBs) as promising alternatives to Li‐ion batteries. While extensive investigations have examined various transition metal oxides and chalcogenides as anode materials for NIBs, few of these have been able to utilize their high specific capacity in sodium‐based systems because of their irreversibility in a charge/discharge process. Here, the mixed Sn–S nanocomposites uniformly distributed on reduced graphene oxide are prepared via a facile hydrothermal synthesis and a unique carbothermal reduction process, producing ultrafine nanoparticle with the size of 2 nm. These nanocomposites are experimentally confirmed to overcome the intrinsic drawbacks of tin sulfides such as large volume change and sluggish diffusion kinetics, demonstrating an outstanding electrochemical performance: an excellent specific capacity of 1230 mAh g^?1, and an impressive rate capability (445 mAh g^?1 at 5000 mA g^?1). The electrochemical behavior of a sequential conversion‐alloying reaction for the anode materials is investigated, revealing both the structural transition and the chemical state in the discharge/charge process. Comprehension of the reaction mechanism for the mixed Sn–S/rGO hybrid nanocomposites makes it a promising electrode material and provides a new approach for the Na‐ion battery anodes.     

Sn/SnO2/Mwcnt composite anode and electrochemical impedance spectroscopy studies for Li-ion batteries

Tin/tinoxide/multi-walled carbon nanotube (Sn/SnO₂/MWCNT) core-shell structure nanocomposite anode is produced by thermal evaporation and subsequent plasma oxidation with using MWCNT buckypaper. Metallic tin is evaporated onto free-standing and flexible MWCNT buckypaper having controlled porosity and subsequent RF plasma oxidized in Ar:O₂(1:1) gas mixture. X-ray diffraction and scanning electron microscopy are used to determine the structure and morphology of the obtained nanocomposite. The electrochemical characteristics of the nanocomposite anode are examined by using electrochemical impedance spectroscopy and galvanostatic charge–discharge experiments. Family of Nyquist plots during first discharge process are obtained and studied at different voltage values.     

Preparation of graphene nanosheets/SnO2 composites by pre-reduction followed by in-situ reduction and their electrochemical performances

The Graphene nanosheets/SnO₂ composites were synthesized using stannous chloride to restore the semi-reduction graphene oxide (SRGO) under a simple hydrothermal reduction procedure. First graphene oxide was pre-reduced by glucose for a certain time to get SRGO, which keeps the good water-solubility of graphite oxide (GO) and has a good conductivity like graphene nanosheets. The higher electrostatic attraction between SRGO and Sn²⁺ makes SnO₂ nanoparticles tightly anchor on the graphene sheets in the hydrothermal reduction process. The formation mechanism of the composite was investigated by SEM, TEM, XRD, AFM and Raman. Moreover, the electrochemical behaviors of the Graphene nanosheets/SnO₂ nanocomposites were studied by cyclic voltammogram, electrical impedance spectroscopy (EIS) and chronopotentiometry. Results showed that the Graphene nanosheets/SnO₂ composites have excellent supercapacitor performances: the specific capacitance reached 368 F g⁻¹ at a current density of 5 mA cm⁻², and the energy density was much improved to 184 Wh kg⁻¹ with a power density of 16 kW kg⁻¹, and capacity retention was more than 95% after cycling 500 cycles with a constant current density of 50 mA cm⁻². The experimental results and the thorough analysis described in this work not only provide a potential electrode material for supercapacitors but also give us a new way to solve the reunification of the graphene sheets.     

SnO2‐Based Nanomaterials: Synthesis and Application in Lithium‐Ion Batteries

The development of new electrode materials for lithium‐ion batteries (LIBs) has always been a focal area of materials science, as the current technology may not be able to meet the high energy demands for electronic devices with better performance. Among all the metal oxides, tin dioxide (SnO₂) is regarded as a promising candidate to serve as the anode material for LIBs due to its high theoretical capacity. Here, a thorough survey is provided of the synthesis of SnO₂‐based nanomaterials with various structures and chemical compositions, and their application as negative electrodes for LIBs. It covers SnO₂ with different morphologies ranging from 1D nanorods/nanowires/nanotubes, to 2D nanosheets, to 3D hollow nanostructures. Nanocomposites consisting of SnO₂ and different carbonaceous supports, e.g., amorphous carbon, carbon nanotubes, graphene, are also investigated. The use of Sn‐based nanomaterials as the anode material for LIBs will be briefly discussed as well. The aim of this review is to provide an in‐depth and rational understanding such that the electrochemical properties of SnO₂‐based anodes can be effectively enhanced by making proper nanostructures with optimized chemical composition. By focusing on SnO₂, the hope is that such concepts and strategies can be extended to other potential metal oxides, such as titanium dioxide or iron oxides, thus shedding some light on the future development of high‐performance metal‐oxide based negative electrodes for LIBs.     

Morphology effect on the performances of SnO2 nanorod arrays as anodes for Li-ion batteries

Ni foam suppported-SnO₂ nanorod arrays with controllable diameter were prepared via a template-free growth method, which was a convenient route for the large-scale growth of pure-phase metal oxide nanorod arrays on metal substrates. The relationship between electrochemical behavior and the shape of SnO₂ nanorod arrays has been investigated in detail. SnO₂ nanorod arrays with diameter of about 25 nm, as anode materials for Li-ion batteries revealed a capacity of 607 mAh g⁻¹ (at 0.2 C) up to 50 cycles. The superior performance of the SnO₂ nanorods can be mainly attributed to small size of nanorods which reduce volume expansion and lithium diffusion length.     

利用碳纳米管增强Li/CFx一次电池的性能

以碳纳米管(Multi-walled carbon nanotubes)为导电添加剂,对锂/氟化石墨(Li/CFx)一次电池正极活性材料氟化石墨进行改性。采用TGA、Raman、SEM、TEM对氟化石墨和碳纳米管进行表征分析。采用恒流放电和电化学阻抗频谱对电池进行检测。结果表明,添加碳纳米管能够有效改善电池的综合性能。碳纳米管添加量为5%(质量分数),在1C放电倍率时,电池的放电比容量达到900mAh/g,并具有2.2V放电电压平台,对比超级炭黑导电剂598.5mAh/g的放电比容量和2V的放电平台,电池放电比容量和电压平台分别提高50.2%和10%,电池的倍率性明显改善。电化学阻抗频谱也显示,添加碳纳米管能有效减小电池的内阻,改善放电性能。