Enhancing electrochemical performance of SnO2 anode with humic acid modification

Humic acid (HA) was studied as a modifier in the SnO₂ anode preparation for the electrochemical performance improvement. Scanning electron microscopy, 180° peel test, and nanoindentation experiment were used to examine the influence of the HA on electrode. The results showed that the addition of HA could improve the dispersion uniformity of all particles. The components were tightened, increasing the difficulty of peeling off the film from the current collector. The deformation resistance of the electrode was greatly enhanced by the HA modification. The electrochemical test results showed that the anode from the normal micron-sized SnO₂ particles with the HA modifier exhibited significant progress in electrochemical performance compared with those without HA. The reversible specific capacity of the SnO₂ anode can be maintained as high as 733.4 mA·h/g at a current density of 100 mA/g after 50 cycles. Therefore, HA is a promising modifier for anode preparation of lithium-ion batteries.     

改进溶剂热法制备锂离子电池负极材料用多级孔Co3O4微球

将溶剂热法与高温煅烧法相结合制备多级孔Co3O4微球,采用XRD、SEM、TEM和电化学测试等技术研究该多级孔Co3O4微球的结构和性能.结果表明:当煅烧温度为700℃时,所合成的Co3O4(Co3O4-700)是由丰富的纳米颗粒(50～200 nm)和大量孔洞(～100 nm)构成的微米级微球(1～2μm);该Co3...     

3D MoS2/graphene nanoflowers as anode for advanced lithium-ion batteries

Vertical MoS₂ nanosheets were controllably patterned onto graphene as nanoflowers through a two-step hydrothermal method. The interconnected network and intimate contact between MoS₂ nanosheets and graphene by vertical channels enabled a high mechanical integrity of electrode and cycling stability. In particular, MoS₂/graphene nanoflowers anode delivered an ultrahigh specific capacity of 901.8 mA·h/g after 700 stable cycles at 1000 mA/g and a corresponding capacity retention as 98.9% from the second cycle onwards.     

Preparation and electrochemical performance of nitrogen-doped carbon-coated Bi2Mn4O10 anode materials for lithium-ion batteries

To inhibit rapid capacity attenuation of Bi₂Mn₄O₁₀ anode material in high-energy lithium-ion batteries, a novel high-purity anode composite material Bi₂Mn₄O₁₀/ECP-N (ECP-N: N-doped Ketjen black) was prepared via an uncomplicated ball milling method. The as-synthesized Bi₂Mn₄O₁₀/ECP-N composite demonstrated a great reversible specific capacity of 576.2 mA·h/g after 100 cycles at 0.2C with a large capacity retention of 75%. However, the capacity retention of individual Bi₂Mn₄O₁₀ was only 27%. Even at 3C, a superior rate capacity of 236.1 mA·h/g was retained. Those remarkable electrochemical performances could give the credit to the introduction of ECP-N, which not only effectively improves the specific surface area to buffer volume expansion and enhances conductivity and wettability of composites but also accelerates the ion transfer and the reversible conversion reaction.     

Synthesis and characterization of ɛ-VOPO4 nanosheets for secondary lithium-ion battery cathode

Vanadium (III) phosphate monoclinic VPO₄·H₂O was synthesized hydrothermally. The ?-VOPO₄ nanosheets, formed by the oxidative de-intercalation of protons from monoclinic VPO₄·H₂O, can reversibly react with more than 1 mol lithium atoms in two steps. Crystal XRD analysis revealed that the structure of the ?-VOPO₄ nanosheets is monoclinic with lattice parameters of α=7.2588(4) Å, b=6.8633(2) Å and c=7.2667(4) Å. The results show that the ?-VOPO₄ nanosheets have a thickness of 200 nm and uniform crystallinity. Electrochemical characterization of the ?-VOPO₄ monoclinic nanosheets reveals that they have good electrochemical properties at high current density, and deliver high initial capacity of 230.3 mA·h/g at a current density of 0.09 mA/cm². Following the first charge cycle, reversible electrochemical lithium extraction/insertion at current density of 0.6 mA/cm² affords a capacity retention rate of 73.6% (2.0–4.3 V window) that is stable for at least 1000 cycles.     

Ascorbic Acid-Assisted Eco-friendly Synthesis of NiCo<Subscript>2</Subscript>O<Subscript>4</Subscript> Nanoparticles as an Anode Material for High-Performance Lithium-Ion Batteries

We have synthesized NiCo₂O₄ nanoparticles (NCO NPs) using an ascorbic acid-assisted co-precipitation method for the first time. When NCO NPs are used as an anode material for lithium-ion batteries, the cell exhibits superior lithium storage properties, such as high capacity (700 mA h g^?1 after 300 cycles at 200 mA g^?1), excellent rate capabilities (applied current density range 100–1200 mA g^?1), and impressive cycling stability (at 1200 mA g^?1 up to 650 cycles). The enhanced electrochemical properties of NCO NPs are due to the nanometer dimensions which not only offers a smooth charge-transport pathway and short diffusion paths of the lithium ions but also adequate spaces for volume expansion during Li storage. Hence, this eco-friendly synthesis approach will provide a new strategy for the synthesis of various nanostructured metal oxide compounds, for energy conversion and storage systems applications.     

Preparation and characterization of spinel LiMn2O4 nanorods as lithium-ion battery cathodes

The hydrothermal synthesis of single-crystallineβ-MnO2 nanorods and their chemical conversion into single-crystalline LiMn2O4 nanorods by a simple solid-state reaction were reported.This method has the advantages of producing pure,single-phase and crystalline nanorods.The LiMn2O4 nanorods have an diameter of about 300 nm.The discharge capacity and cyclic performance of the batteries were investigated.The LiMn2O4 nanorods show better cyclic performance with a capacity retention ratio of 86.2% after 100 cycles.Battery cyclic studies reveal that the prepared LiMn2O4 nanorods have high capacity with a first discharge capacity of 128.7 mA·h/g.     

Nano-SnO_2 Decorated Carbon Cloth as Flexible,Self-supporting and Additive-Free Anode for Sodium/Lithium-Ion Batteries

In this study,nano-sized SnO_2 decorated on carbon cloth(SnO_2/CC) is prepared through a simple and facile solid method.The nano-sized SnO_2 is uniformly distributed on the surface of carbon fibers in carbon cloth,providing sufficient free space to relieve volume expansion and reduce electrode pulverization during cycling.The as-prepared SnO_2/CC as a flexible,self-supporting and additive-free anode electrode for sodium-ion/lithium-ion batteries(SIBs/LIBs) can demonstrate outstanding electrochemical performance.SnO_2/CC after annealing at 350℃(SC-350) as an anode for SIBs can deliver a reversible capacity of 0.587 mA h cm~(-2) at the current density of 0.3 mA cm~(-2) after 100 cycles.In addition,when cycling at 1.5 mA cm~(-2),SC-350 can maintain 1.69 mA h cm~(-2) after 500 cycles when used as LIB anode.These results illustrate that the as-prepared SnO_2/CC can be a promising flexible anode material for flexible SIBs/LIBs and provide a simple and practical method for designing new flexible electrode materials.     

三维泡沫状结构生物质碳/MoS2复合材料的电化学储锂性能

以废弃油茶籽粕作为碳源,将MoS2负载于生物质碳上,再涂覆聚多巴胺盐酸盐构建复合型生物质碳/MoS2电极材料。研究不同MoS2含量复合电极材料的电化学储锂性能。SEM观察结果表明,该复合材料具有以MoS2作为夹层的三维泡沫状结构。XRD和HRTEM测试结果表明MoS2的层间距增大。XPS分析结果显示,活性材料中已形成Mo—N键。电化学性能测试结果表明,MoS2含量为63%的活性材料在100 mA/g电流密度下具有较高的初始比容量(1434 mA·h/g)。在大电流、长循环条件下此电极材料呈良好的循环稳定性,其容量保持率接近100%,在电化学动力学过程中具有较好的锂离子脱嵌能力。     

水热电沉积法生长Co9S8薄膜电极

采用水热电沉积法在泡沫镍基体上原位沉积Co_9S_8薄膜,并对其形貌、组成、结构和电化学性能进行表征和测试。结果表明,镍基Co_9S_8薄膜呈花瓣片状,并具有优异的电化学性能,其在电流密度为10mA/cm~2时,比电容可高达2538.7 F/g。即使电流密度扩大至50 mA/cm~2时,比电容依然可达1930.7 F/g。经过1000次循环(电流密度为20 mA/cm2),比电容仍可达为1825.2 F/g,电容保有率72.8%,经过1500次循环后,电容保有率61.4%。     

微乳液法制备锂离子电池用ZnMn2O4/Mn3O4亚微米棒及其转化反应机理

采用油包水微乳液法再经煅烧制备分级ZnMn2O4/Mn3O4复合亚微米棒。ZnMn2O4/Mn3O4电极在550次连续放电/充电循环中,在500 mA/g充放电电流条件下,其比容量从440 mA·h/g增加到910 mA·h/g,并在100 mA/g下提供1276 mA·h/g的超高比容量,远高于ZnMn2O4或Mn3O4的理论比容量。采用循环伏安法和微分容量分析法研究这种现象的潜在机制,两者均揭示在充放电循环过程中新的可逆氧化还原反应的产生和增强。这种新的可逆转化反应可能是由于电极材料在循环过程中的活化过程引起的,从而解释电极材料容量在循环过程中不断上升的现象;而容量超过理论值表明还有其他因素对容量的增长起作用。     

Electrochemical performance of aluminum niobium oxide as anode for lithium-ion batteries

AlNbO_4,as lithium-ion batteries(LIBs) anode,has a high theoretical capacity of 291.5 m Ah g~(-1).Here,AlNbO_4 anode materials were synthesized through a simple solid-state method.The structure,morphology and electrochemical performances of AlNbO_4 anode were systematically investigated.The results show that AlNbO_4 is monoclinic with C2/m space group.The scanning electron microscopy(SEM) and transmission electron microscopy(TEM) characterizations reveal the AlNbO_4 particles with the size of 100 nm~(–2) lm.As a lithium-ion batteries anode,AlNbO_4 delivers a high reversible capacity and good rate capability.The discharge capacity is as high as 151.0 m Ah g~(-1)after 50 charge and discharge cycles at 0.1 C corresponding to capacity retention of 90.7 %.When the current density increases to 5.0C,AlNbO_4 anode displays reversible discharge capacity of 73.6 m Ah g~(-1)at the50 th cycle.     

Preparation and properties of transition metal nitrides caged in N-doped hollow porous carbon sphere for oxygen reduction reaction

A series of transition metal nitrides (M_xN_y, M=Fe, Co, Ni) nanoparticle (NP) composites caged in N-doped hollow porous carbon sphere (NHPCS) were prepared by impregnation and heat treatment methods. These composites combine the high catalytic activity of nitrides and the high-efficiency mass transfer characteristics of NHPCS. The oxygen reduction reaction results indicate that Fe₂N/NHPCS has the synergistic catalytic performance of higher onset potential (0.96 V), higher electron transfer number (~4) and higher limited current density (1.4 times as high as that of commercial Pt/C). In addition, this material is implemented as the air catalyst for zinc-air battery that exhibits considerable specific capacity (795.1 mA·h/g) comparable to that of Pt/C, higher durability and maximum power density (173.1 mW/cm²).     

Preparation of Sb2O3/Sb2S3/FeOOH composite photoanodes for enhanced photoelectrochemical water oxidation

A novel Sb₂O₃/Sb₂S₃/FeOOH photoanode was fabricated via a simple solution impregnation method along with chemical bath deposition and post-sulfidation. The X-ray diffractometry, Raman measurement, and X-ray photoelectron spectroscopy show that the Sb₂O₃/Sb₂S₃/FeOOH thin films are successfully prepared. SEM−EDS analyses reveal that the surface of Sb₂O₃/Sb₂S₃ thin films becomes rough after the immersion in the FeCl₃ solution. The optimized impregnation time is found to be 8 h. The FeOOH co-catalyst loaded Sb₂O₃/Sb₂S₃ electrode exhibits an enhanced photocurrent density of 0.45 mA/cm² at 1.23 V versus RHE under simulated 1 sun, which is approximately 1.41 times compared to the photocurrent density of the unloaded one. Through the further tests of UV−Vis spectroscopy, the electrochemical impedance spectra, and the PEC measurements, the enhancement can result from the increased light-harvesting ability, the decreased interface transmission impedance, and the remarkably enhanced carrier injection efficiency.     

通过水热法合成的纳米铁酸镍/石墨复合阳极材料具有优异的电化学性能

作为锂离子电池阳极材料的铁酸镍及其相关材料,由于其具有较高的理论比容量,近来受到广泛关注。为了克服在充放电过程中的较低导电性与较大的体积膨胀等不良因素,本文通过水热法合成了纳米铁酸镍钉扎在石墨表面而形成的复合物。该纳米铁酸镍/石墨复合物表现出了较高的比容量以及优异的循环性能。其初始放电容量接近1478mAh g-1,并且在100 mA g-1的电流密度下循环50周之后,其可逆容量依然高达1109 mAh g-1。在1000 mA g-1的充电电流情况下,该复合材料的充电容量也能保持750 mA g-1。这优异的电化学性能主要归功于纳米铁酸镍能够稳定的钉扎在石墨表面上,这种特殊的结构增强了材料的导电性同时也增大了材料的表面比容量。     

Enhancement of lithium storage capacity and rate performance of Se-modified MnO/Mn3O4 hybrid anode material via pseudocapacitive behavior

To improve rate and cycling performance of manganese oxide anode material, a precipitation method was combined with thermal annealing to prepare the MnO/Mn₃O₄/SeO_x (x=0, 2) hybrid anode by controlling the reaction temperature of Mn₂O₃ and Se powders. At 3 A/g, the synthesized MnO/Mn₃O₄/SeO_x anode delivers a discharge capacity of 1007 mA·h/g after 560 cycles. A cyclic voltammetry quantitative analysis reveals that 89.5% pseudocapacitive contribution is gained at a scanning rate of 2.0 mV/s, and the test results show that there is a significant synergistic effect between MnO and Mn₃O₄ phases.     

Performance of carbon-coated nano-ZnO prepared by carbonizing gel precursor as anodic material for secondary alkaline Zn batteries

Although carbon coating can improve the cycle life of anode for alkaline Zn batteries, the specific capacity reported is still lower compared with nanosized ZnO. Herein, carbon-coated nanosized ZnO (nano-ZnO@C) was synthesized by one-step heat treatment from a gel precursor in N₂. Commercial ZnO and homemade ZnO prepared similarly in air atmosphere were studied for comparison. Structure analysis displayed that both nano-ZnO@C and homemade ZnO had a porous hierarchical agglomerated architecture produced from primary nanoparticles with a diameter of approximately 100 nm as building blocks. Electrochemical performance measurements showed that nano-ZnO@C displayed the highest electrochemical activity, the lowest electrode resistance, the highest discharge capacity (622 mA·h/g), and the best cyclic stability. These properties were due to the combination of nanosized ZnO and the physical capping of carbon, which maintained the high utilization efficiency of nano-ZnO, and simultaneously prevented dendrite growth and densification of the anode.     

A simple physical mixing method for MnO2/MnO nanocomposites with superior Zn2+ storage performance

MnO₂/MnO cathode material with superior Zn²⁺ storage performance is prepared through a simple physical mixing method. The MnO₂/MnO nanocomposite with a mixed mass ratio of 12:1 exhibits the highest specific capacity (364.2 mA·h/g at 0.2C), good cycle performance (170.4 mA·h/g after 100 cycles) and excellent rate performance (205.7 mA·h/g at 2C). Analysis of cyclic voltammetry (CV) data at various scan rates shows that both diffusion- controlled insertion behavior and surface capacitive behavior contribute to the Zn²⁺ storage performance of MnO₂/MnO cathodes. And the capacitive behavior contributes more at high discharge rates, due to the short paths of ion diffusion and the rapid transfer of electrons.     

Preparation and Lithium Storage Performance of NiO/ C@CNT Anode Material

将核壳的聚吡咯基的碳@碳纳米管(C@CNT)与纳米片组装的氧化镍 (NiO) 微球结合,制备了一种多孔的锂离子电池负极材料(NiO/C@CNT),该材料 (NiO/C@CNT) 与纯的 NiO和 NiO/CNT 相比,其容量值和循环稳定性能明显提高。在 50 mA·g-1的电流密度下,经过20次循环后,其可逆容量达到573 mA·g-1,容量保持率为68.6%。这些性能的提高是由于核壳结构的C@CNT的导电缓冲性引起的。C@CNT具有诸如多孔结构、大比表面积、高电化学活性、高电子导电性和良好的浸润性等许多优点,这些优点有利于避免电极材料显著的体积变化,因此在锂嵌入和脱出过程中可减少电极容量衰减并提高传质速率。     

Thermodynamic and kinetic analysis for carbothermal reduction process of CoSb alloy powders used as anode for lithium ion batteries

Thermodynamic calculation and kinetic analysis were performed on the carbothermal reduction process of Co₃O₄-Sb₂O₃-C system to clarify the reaction mechanism and synthesize pure CoSb powder for the anode material of secondary lithium-ion batteries. The addition of carbon amount and thus the purity of CoSb powders were critical to the electrochemical property of CoSb anode. It was revealed that in an inert atmosphere, Co₃O₄ was preferentially reduced to CoO, followed by the reduction of Sb₂O₃ and CoO. CO₂ was the gas product for the reduction of Co₃O₄ and Sb₂O₃, while CO was the gas product for that of CoO. Based on the analysis result, pure CoSb powder without any oxides and residual carbon was synthesized, which showed a higher specific capacity and a lower initial irreversible capacity loss, compared to CoSb sample with residual carbon. This work can be a reference for other carbothermal reduction systems.