共查询到20条相似文献,搜索用时 15 毫秒
1.
A tin antimony based electrode has been synthesized in the form of nanometric particles housed into the pores of a protective, amorphous carbon matrix. Electrochemical results, obtained using this material as the working electrode in a lithium cell, suggested that the electrochemical process involves both SnSb intermetallic and Sn metal, present in the carbon matrix. Moreover, the results demonstrated that the optimized nanostructure prevents the mechanical drawbacks, associated with the volume changes during the alloying processes, which normally affect this class of materials. Finally, a lithium ion battery based on the SnSb-C electrode as the anode and lithium iron phosphate, LiFePO4, as the cathode, showed very promising performance. 相似文献
2.
LiFePO4/C composites were synthesized by two methods using home-made amorphous nano-FePO4 as the iron precursor and soluble starch, sucrose, citric acid, and resorcinol-formaldehyde (RF) polymer as four carbon precursors, respectively. The crystalline structures, morphologies, compositions, electrochemical performances of the prepared powders were investigated with XRD, TEM, Raman, and cyclic voltammogram method. The results showed that employing soluble starch and sucrose as the carbon precursors resulted in a deficient carbon coating on the surface of LiFePO4 particle, but employing citric acid and RF polymer as the carbon precursors realized a uniform carbon coating on the surface of LiFePO4 particle, and the corresponding thicknesses of the uniform carbon films are 2.5 nm and 4.5 nm, respectively. When RF polymer was used as the carbon precursor, the material showed the highest initial discharge capacity (138.4 mAh g− 1 at 0.2 C at room temperature) and the best rate performance among the four materials. 相似文献
3.
4.
Hui Xie 《Electrochimica acta》2006,51(10):2063-2067
The Li0.98Al0.02FePO4/C (2.0 wt.%) mix-doped composite had been synthesized by adding aluminum stearate to the react precursors through solid-state reaction. The mix-doping method does not affect the olivine structure of the cathode but greatly improves its kinetics in terms of capacity delivery, cycle life and rate capability. Such an enhancement of the electrochemical properties has been ascribed to the increase of intra- and inter-crystal electronic conductivity and the reduction of the particle size, these two effects being promoted by the co-existence of the lattice doping element (Al3+) and the non-lattice doping element (C). Overcharge test indicates that this composite has excellent safety performances. 相似文献
5.
Caixian Chang 《Electrochimica acta》2008,54(2):623-627
A novel hydrothermal synthesis was developed to prepare carbon-coated lithium vanadium phosphate (Li3V2(PO4)3) powders to be used as cathode material for Li-ion batteries. The structural, morphological and electrochemical properties were investigated by means of X-ray powder diffraction (XRD), thermogravimetry (TG), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and constant current charge-discharge cycling. This material exhibits high initial discharge capacity of 178, 173 and 172 mAh g−1 at 0.1, 0.2 and 0.5 C between 3.0 and 4.8 V, respectively. Moreover, it displays good fast rate performance, which discharge capacities of 136, 132 and 127 mAh g−1 can be delivered after 100 cycles between 3.0 and 4.8 V versus Li at a different rate of 1, 2 and 5 C, respectively. For comparison, the electrochemical properties of carbon-coated lithium vanadium phosphate prepared by traditional solid-state reaction (SSR) method are also studied. 相似文献
6.
Recent research results confirm the importance of structural surface features of cathode materials for their electrochemical performance. Modification by coating is an important method to achieve improved electrochemical performance, and the latest progress was reviewed here. When the surface of cathode materials including LiCoO2, LiNiO2, LiMn2O4 and LiMnO2 is coated with oxides such as MgO, Al2O3, SiO2, TiO2, ZnO, SnO2, ZrO2, Li2O·2B2O3-glass and other materials, the coatings prevent the direct contact with the electrolyte solution, suppress phase transition, improve the structural stability, and decrease the disorder of cations in crystal sites. As a result, side reactions and heat generation during cycling are decreased. Accompanying actions such as suppression of Mn2+ dissolution, increase in conductivity and removal of HF in electrolyte solutions have been observed. Consequently, marked improvement of electrochemical performance of electrode materials including reversible capacity, coulomb efficiency in the first cycle, cycling behavior, rate capability and overcharge tolerance has been achieved. In conclusion, further directions are suggested for the surface modification of electrode materials. With further understanding of the effects of the surface structure of cathode materials on lithium intercalation and de-intercalation, better and/or cheaper cathode materials from surface modification will come up in the near future. 相似文献
7.
Electrochemical stability of silicon/carbon composite anode for lithium ion batteries 总被引:2,自引:0,他引:2
Silicon/carbon composite anode materials were prepared by pyrolyzing the phenol-formaldehyde resin (PFR) mixed with silicon and graphite powders. Scanning electron microscopic (SEM) observation showed that the morphology stability of the composite electrodes can be retained during cycling. A structure evolution mechanism is proposed to illuminate the enhancement of cycleability of the composite electrode. The composite used as anode material for lithium ion batteries possesses a reversible capacity of over 700 mAh/g. 相似文献
8.
Highly ordered porous Cu2O film is electrodeposited on copper foil through a self-assembled polystyrene sphere template. Compared with the dense Cu2O film and the octahedral Cu2O powder, the ordered porous Cu2O film exhibits an improved electrochemical cycling stability. The capacity of the porous Cu2O film can maintain 336 mAh g−1 and 213 mAh g−1 after 50 cycles at the rate of 0.1 C and 5 C, respectively. The reversible capacity holds 63.4% as the discharge-charge rate even increases by 50 times. The enhanced high rate properties of the ordered porous film should be attributed to the sufficient contact surface of Cu2O/electrolyte and the short diffusion length of Li+. Moreover, the direct contact between Cu2O and current collector and the decreasing inactive interfaces of Cu2O/polymer binder are also suggested as being responsible for the enhanced high rate property. 相似文献
9.
Zhichao Liu Ruisong Guo Mei Zheng Fuyun Li Baoyu Wang Tingting Li Yani Luo 《Ceramics International》2018,44(10):11757-11764
As one of the novel two-dimensional metal carbides, Ti3C2Tx has received intense attention for lithium-ion batteries. However, Ti3C2Tx has low intrinsic capacity due to the fact that the surface functionalization of F and OH blocks Li ion transport. Herein a novel “plane-line-plane” three-dimensional (3D) nanostructure is designed and created by introducing the carbon nanotubes (CNTs) and SnO2 nanoparticles to Ti3C2Tx via a simple hydrothermal method. Due to the capacitance contribution of SnO2 as well as the buffer role of CNTs, the as-fabricated sandwich-like CNTs@SnO2/Ti3C2Tx nanocomposite shows high lithium ion storage capabilities, excellent rate capability and superior cyclic stability. The galvanostatic electrochemical measurements indicate that the nanocomposite exhibits a superior capacity of 604.1 mAh g?1 at 0.05?A?g?1, which is higher than that of raw Ti3C2Tx (404.9 mAh g?1). Even at 3?A?g?1, it retains a stable capacity (91.7 mAh g?1). This capacity is almost 5.6 times higher than that of Ti3C2Tx (16.6 mAh g?1) and 58 times higher than that of SnO2/Ti3C2Tx (1.6 mAh g?1). Additionally, the capacity of CNTs@SnO2/Ti3C2Tx for the 50th cycle is 180.1 mAh g?1 at 0.5?A?g?1, also higher than that of Ti3C2Tx (117.2 mAh g?1) and SnO2/Ti3C2Tx (65.8 mAh g?1), respectively. 相似文献
10.
Nanoflower-like CuO/Ni film was prepared by electrodeposition method in an alkaline nickel electroplating solution, and the nanoflower-like CuO film was obtained by direct oxidation on copper substrate. The nanoflower-like CuO was crystalline with space group of C2/c, and the amorphous Ni particle layer on the surface of film contacted well with the nanoflower-like CuO. The electrochemical properties of CuO/Ni film were investigated by cyclic voltammetry (CV) and galvanostatic charge-discharge tests. Since the metallic Ni can act as conductor and catalyst, the CuO/Ni film exhibits higher initial coulombic efficiency (72.1%) than the pure CuO film (57.0%), and better capacity retention (96.3% of the 2nd cycle) than the pure CuO film (67.8% of the 2nd cycle) at the current density of 0.1 mA cm−2. 相似文献
11.
《Ceramics International》2017,43(3):3190-3195
Three-dimensional (3D) olivine LiMn0.8Fe0.2PO4 nanoflowers constructed by two-dimensional (2D) nanoflakes have been successfully synthesized through an easy liquid phase method. Hierarchical LiMn0.8Fe0.2PO4/C could be easily formed via a liquid coating technology and subsequent calcination treatment. When acting as cathode materials for lithium ion batteries, the LiMn0.8Fe0.2PO4/C nanoflowers show excellent rate performance and cycle stability. The unique flower-like hierarchical structured LiMn0.8Fe0.2PO4 and thin carbon coating outside make this composite a promising candidate as cathode materials for lithium ion batteries. 相似文献
12.
LiFePO4作为新一代首选的正极材料,具有材料来源广泛、价格便宜、热稳定性好、比能量高、无吸湿性、对环境友好等优点。笔者综述了LiFePO4的结构特征、充放电机理、合成方法及改性研究。 相似文献
13.
Dawei SuHyun-Soo Kim Woo-Seong KimGuoxiu Wang 《Microporous and mesoporous materials》2012,149(1):36-45
Tuneable porous α-Fe2O3 materials were prepared by using a selective etching method. The structure and morphology of the as-prepared porous hematites have been systematically characterised by X-ray diffraction, field emission scanning electron microscope, and transmission electron microscope. We found that the pore size and pore volume can be controlled by adjusting the etching time during the synthesis process. The porous hematites have been applied for gas sensing and lithium storage in lithium ion cells. The porous α-Fe2O3 materials demonstrated a reversible lithium storage capacity of 1269 mAh/g. When used as a sensing material in gas sensors, porous α-Fe2O3 exhibited a superior sensitivity towards toxic and flammable gases. 相似文献
14.
A Si thin film of thickness 275 nm was deposited on rough Cu foil by magnetron sputtering for use as lithium ion battery anode
material. X-ray diffraction (XRD) and TEM analysis revealed that the Si thin film was completely of amorphous structure. The
electrochemical performance of the Si thin film was investigated by cyclic voltammetry and constant current charge/discharge
test. The film exhibited a high capacity of 3,134 mAh g−1 at 0.025 C rate. The capacity retention was 61.3% at 0.5 C rate for 500 cycles. An island structure formed on the Cu foil
substrate after cycling adhered to the substrate firmly and provided electrical connection. This is the possible reason for
the long cycling life of Si thin film anode. Moreover, the cycling performance was further improved by annealing at 300 °C.
The Li+ diffusion coefficients (D
0) of Si thin film, measured by cyclic voltammetry, are 1.47 × 10−9 cm2 s−1 and 2.16 × 10−9 cm2 s−1 for different reduced peaks. 相似文献
15.
Spinel LiMn2O4 is a promising cathode due to its advantages of low-cost, nontoxicity and thermal stability. However, the dissolution of manganese and the phase transformation induce the rapid capacity fade. Surface coating is an effective method to improve its electrochemical performance. In this work, spinel LiMn2O4 modified with perovskite LaCoO3 was prepared using a novel molten salt method. The resulted samples were characterized by X-ray diffraction (XRD), transmission/scanning electron microscopy (TEM/SEM), Fourier transformation infrared (FT-IR), Raman, and X-ray photoelectronic spectroscopy. The content of Mn3+ increased with the LaCoO3 coating accompanied by the increased concentration of oxygen vacancy. LiMn2O4 modified with 2% LaCoO3 shows a higher capacity and cycling stability than others at 0.2 C, while the cathode with 4% LaCoO3 shows the best rate performance at a larger current at 2 and 5 C. This enhanced performance can be attributed to improved interfacial conductivity between the cathode and electrolyte and the protective effects of coating. 相似文献
16.
G.X. Wang L. Yang Y. Chen J.Z. Wang Steve Bewlay H.K. Liu 《Electrochimica acta》2005,50(24):4649-4654
A series of polypyrrole-LiFePO4 (PPy-LiFePO4) composites were synthesised by polymerising pyrrole monomers on the surface of LiFePO4 particles. AC impedance measurements show that the coating of polypyrrole significantly decreases the charge-transfer resistance of LiFePO4 electrodes. The electrochemical reactivity of polypyrrole and PPy-LiFePO4 composites for lithium insertion and extraction was examined by charge/discharge testing. The PPy-LiFePO4 composite electrodes demonstrated an increased reversible capacity and better cyclability, compared to the bare LiFePO4 electrode. 相似文献
17.
Nacer Badi Abhinay Reddy Erra Francisco C Robles Hernandez Anderson O Okonkwo Mkhitar Hobosyan Karen S Martirosyan 《Nanoscale research letters》2014,9(1):360
The specific energy of the existing lithium ion battery cells is limited because intercalation electrodes made of activated carbon (AC) materials have limited lithium ion storage capacities. Carbon nanotubes, graphene, and carbon nanofibers are the most sought alternatives to replace AC materials but their synthesis cost makes them highly prohibitive. Silicon has recently emerged as a strong candidate to replace existing graphite anodes due to its inherently large specific capacity and low working potential. However, pure silicon electrodes have shown poor mechanical integrity due to the dramatic expansion of the material during battery operation. This results in high irreversible capacity and short cycle life. We report on the synthesis and use of carbon and hybrid carbon-silicon nanostructures made by a simplified thermo-mechanical milling process to produce low-cost high-energy lithium ion battery anodes. Our work is based on an abundant, cost-effective, and easy-to-launch source of carbon soot having amorphous nature in combination with scrap silicon with crystalline nature. The carbon soot is transformed in situ into graphene and graphitic carbon during mechanical milling leading to superior elastic properties. Micro-Raman mapping shows a well-dispersed microstructure for both carbon and silicon. The fabricated composites are used for battery anodes, and the results are compared with commercial anodes from MTI Corporation. The anodes are integrated in batteries and tested; the results are compared to those seen in commercial batteries. For quick laboratory assessment, all electrochemical cells were fabricated under available environment conditions and they were tested at room temperature. Initial electrochemical analysis results on specific capacity, efficiency, and cyclability in comparison to currently available AC counterpart are promising to advance cost-effective commercial lithium ion battery technology. The electrochemical performance observed for carbon soot material is very interesting given the fact that its production cost is away cheaper than activated carbon. The cost of activated carbon is about $15/kg whereas the cost to manufacture carbon soot as a by-product from large-scale milling of abundant graphite is about $1/kg. Additionally, here, we propose a method that is environmentally friendly with strong potential for industrialization. 相似文献
18.
19.
CuO/C microspheres as anode materials for lithium ion batteries 总被引:1,自引:0,他引:1
CuO/C microspheres are prepared by calcining CuCl2/resorcinol-formaldehyde (RF) gel in argon atmosphere followed by a subsequent oxidation process using H2O2 solution. The microstructure and morphology of materials are characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and transition electron microscopy (TEM). Carbon microspheres have an average diameter of about 2 μm, and CuO particles with the sizes of 50–200 nm disperse in these microspheres. The electrochemical properties of CuO/C microspheres as anode materials for lithium ion batteries are investigated by galvanostatic discharge–charge and cyclic voltammetry (CV) tests. The results show that CuO/C microspheres deliver discharge and charge capacities of 470 and 440 mAh g−1 after 50 cycles, and they also exhibit better rate capability than that of pure CuO. It is believed that the carbon microspheres play an important role in their electrochemical properties. 相似文献
20.
《Ceramics International》2017,43(4):3915-3918
A lithium-vanadium-molybdenum-oxide composite has been prepared by a soft chemical route with mechanical activation assistance followed by low-temperature heat treatment in argon atmosphere. The X-ray diffraction reveals that the synthesized sample is made up of Li3V(MoO4)3 and LiVOMoO4 crystal phases. The SEM images show the fine particles ~300 nm in size. HRTEM image shows a clear crystal boundary between the two phases. The composite possesses good electrochemical performance as anode material. Particularly, it delivers an initial charge capacity of 927 mAh g−1 at 50 mA g−1 with a high initial coulombic efficiency of 81.2% and maintains 87.8% of its initial capacity after 50 cycles. Even if tested at 1000 mA g−1, it can deliver a reversible capacity of 542 mA h g−1. 相似文献