In Situ Embedment of ZnS Nanocrystals in High Porosity Carbon Fibers as an Advanced Anode Material for Efficient Lithium Storage

ZnS is a promising material for lithium-ion battery anodes due to its abundant natural resources, simplicity of synthesis, and high theoretical lithium storage capacity. However, it needs to be optimized for its low conductivity and volume effect during the charge-discharge process. The traditional method of combining with carbonaceous materials is usually laborious, and the required sulfuration process may possibly result in the destruction of materials morphology. In this study, hybrid materials formed by the combination of ZnS nanocrystals and high porosity carbon fibers were synthesized by one-step electrospinning using zinc diethyldithiocarbamate and polyacrylonitrile as raw materials and poly (ethylene glycol)—block-poly (propylene glycol)—block-poly (ethylene glycol) as template. The method is simple and avoids the influence of sulfuration process on the morphology of materials. The composite presents a specific capacity of 592.2 mAh g⁻¹ under a current density of 1 A g⁻¹ after 1000 cycles. The porous structure significantly decreases the diffusion mean-free path of Li⁺ and inhibits the volume effect associated with the lithium storage process of ZnS. In addition, the 3D cross-linked carbon fibers improve the conductivity of materials. This study can serve as an inspiration for the development of other lithium storage composites.     

Construction of Na2Li2Ti6O14@LiAlO2 Composites as Anode Materials of Lithium-Ion Battery with High Performance

In this work, we construct Na₂Li₂Ti₆O₁₄@LiAlO₂ (NLTO-L) composites by a simple ball milled process and post-calcination in air atmosphere to improve the electrochemical performance. The thickness of the LiAlO₂ coating layer is approximate 2 nm. The morphology and particle size of Na₂Li₂Ti₆O₁₄ are not dramatically altered after LiAlO₂ coating. All samples display similar particles with a size range from 150 to 500 nm. The LiAlO₂ coating can supply fast charge transmission paths with good insertion/extraction dynamics of lithium ions and provide an excellent rate performance and cycle performance of as-prepared Na₂Li₂Ti₆O₁₄@LiAlO₂ anodes. Therefore, LiAlO₂ coating efficiently enhances the rate performance and cycle performance of Na₂Li₂Ti₆O₁₄ anode, even at large current densities. As a result, Na₂Li₂Ti₆O₁₄@LiAlO₂ (5 wt%) reveals remarkable rate properties with reversible charge capacity of 238.7, 214.7, 185.8, 168.5 and 139.8 mAh g⁻¹ at 50, 100, 200, 300 and 500 mA g⁻¹, respectively. Na₂Li₂Ti₆O₁₄@LiAlO₂ (5 wt%) also possesses a good cycle performance with a de-lithiation capacity of 166.5 mAh g⁻¹ at 500 mA g⁻¹ after 200 cycles. Nonetheless, the corresponding de-lithiation capacity of pure Na₂Li₂Ti₆O₁₄ is only 140.1 mAh g⁻¹. Consequently, LiAlO₂ coating is an efficient approach to enhance the electrochemical performances of Na₂Li₂Ti₆O₁₄.     

Facile Preparation of NiO@graphene Nanocomposite with Superior Performances as Anode for Li-ion Batteries

Transition metal oxides gain considerable research attentions as potential anode materials for lithium ion batteries, but their applications are hindered due to their poor electronic conductivity, weak cycle stability and drastic volume change. Here, a NiO@graphene composite with a unique 3D conductive network structure is prepared through a simple strategy. When applied as anode material for Li-ion batteries, at 50 mA g^-1, the NiO@graphene displays a high reversible capacity of 1366 mAh g^-1 and a stable cyclability of 205 mAh g^-1 after 500 cycles. Even at a high rate of 10 A g^-1, it displays a favorable reversible capacity of 711 mAh g^-1. Remarkably, when it recovers back to 0.05 A g^-1, a reversible capacity of 1741 mAh g^-1 is achieved. Thus, the NiO@graphene composite with 3D structure shows good application prospects as an alternative anode for advanced lithium ion batteries.     

In-situ Synthesis of Coral-Like Molybdenum Phosphide (MOP) Microspheres for Lithium-Ion Battery

Molybdenum phosphide (MoP) has attracted extensive attention as promising anode candidates for lithium-ion batteries owing to its high specific capacity,low potential range and low polarization.However,severe volume changes and intrinsic low conductivity are major challenges for further application of MoP electrode materials.In this work,a coral-like MoP microsphere encapsulated by N-doped carbon (MoP@NDC) was successfully prepared through annealing the precursor derived from self-polymerization of dopamine with phosphomolybdic acid.The introduction of carbon framework not only serves as matrix to confine MoP nanocrystals from aggregations,but also improves the electrochemical conductivity and facilitates lithium ion or electron transport on the surface of MoP.Such hierarchical structure delivered high discharge capacity of 495 mAh g-1 after 300 cycles with 90.1％ capacity retention,which could be attributed to the synergistic effects of MoP nanoparticles and conductive carbon network.This design strategy shows MoP@NDC electrode with applicable application as anode in lithium-ion battery.     

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。     

氧化镍柔性自支撑电极材料的电化学性能研究

制备具有优异界面结构和电子/离子传质能力的柔性电极材料是解决高性能电化学活性物质由体积膨胀引起材料粉化和从集流体剥落难题的关键。一种独特的工艺实现了高性能过渡金属氧化物（氧化镍）内嵌碳纤维柔性织物电极的一步制备,所制备的活性物质免于使用导电剂、粘结剂和集流体直接用于锂离子电池负极材料的组装。得益于氧化镍超高的理论比容量,活性碳纤维基体材料低维特性和良好的内应力分散率,制备的复合织物电极展现出良好的电化学性能,一维氧化镍/碳纳米纤维（NiO-CNF）复合柔性电极较纯氧化镍（NiO NF）纤维电极材料具有更卓越的循环耐久性和倍率性能,NiO-CNF和NiO NF在0.5C倍率循环200次分别具有418 mAh·g-1和242 mAh·g-1的可逆容量,良好的电化学性质归因于复合柔性电极的交联结构提供的优异扩散动力学和应力缓冲。     

Effect of Different Calcination Temperatures on the Structure and Properties of Zirconium-Based Coating Layer Modified Cathode Material Li1.2Mn0.54Ni0.13Co0.13O2

Lithium-rich manganese-based oxides have the advantages of high discharge specific capacity, so they are potential candidates for advanced lithium battery cathode materials. However, they also have drawbacks to be solved such as serious irreversible loss of capacity and voltage decay in the cycling process. Surface coating method was used in this paper to modify the lithium-rich manganese-based oxide (LRMO, Li_1.2Mn_0.54Ni_0.13Co_0.13O₂) to improve its electrochemical properties. Zirconium-based compounds coated LRMO materials (ZBC@LRMO) were obtained via the reaction of lithium hydroxide with zirconium n-butanol and subsequent thermal treatment at different temperatures. The results of X-ray diffraction and transmission electron microscopy confirm that the crystal structure and composition of the ZBC coating layer vary with the calcination temperature. The coating layer obtained at 600 ℃ is composed of tetragonal ZrO₂ and Li₂ZrO₃. The ZBC@LRMO sample with tetragonal ZrO₂ and Li₂ZrO₃ composite exhibits the best electrochemical performance: the discharge capacity of ZBC@LRMO can reach 296 mAh g^-1 at 0.1 C and 120 mAh g^-1 at high rate of 5 C.     

Controllable Morphology Tailoring with Solvothermal Method Toward LiMnPO4/C Cathode Materials for Improved Performance and Favorable Thermostability

An environmentally friendly method for the synthesis of LiMnPO₄/C anode material for lithium-ion batteries by solvothermal method is introduced. The modification of the morphology of this precursor is altered by changing the ratio of the conditioning solvent (water-ethylene glycol solution) and the order of material addition. Ethylene glycol (EG) exerts a considerable influence on synthesizing LiMnPO₄/C flake-like nanocrystal, which benefits the extraction/insertion reaction of lithium ions and improves the electrochemical activity and electrochemical performance of LiMnPO₄/C material. When the solvent composition is H₂O:EG = 1:3, exhibiting exceptional charge/discharge performance and rate capability, the specific discharge capacities are 155.8, 153.7, 148.8, 141.4, 129.5, and 112.6 mAh g^-1 at the 0.1, 0.2, 0.5, 1, 2, and 5 C rates, respectively. When the charge-discharge rate returns to 0.1 C, the LiMnPO₄/C material shows a reversible discharge specific capacity of 153.7 mAh g^-1. Differential scanning calorimetry (DSC) tests verify that the thermodynamic stability of the prepared LiMnPO₄/C(LMP) and commercial LiFePO₄ (LFP)materials is better than that of commercial nickel-cobalt-aluminum (NCA) ternary materials. These prepared LiMnPO₄/C composites have high electrochemical capacity and cycle stability.     

Electrochemical characteristics of single crystalline nanowires and their driven mechanism

The electrochemical characteristics of single crystalline SnO₂, ZnO and Si nanowires and their driven mechanism are reported as nanostructural anode materials. As intercalation and deintercalation of Li, Si nanowires are converted to amorphous phases of shorter wire shapes caused by the lattice expansion of the single crystalline Si, resulting in the fading of discharge capacity, although the reversible capacity (2500 mAh/g) in the first cycle is very high. However, oxide nanowries (SnO₂ and ZnO) are transformed from a single crystalline structure into a polycrystalline form consisting of nano-sized metallic particles and Li₂O crystals within the wires, which maintain their discharge capacity. The results of this study imply that the large surface area and high electrochemical activity of nanowires and nano-sized polycrystalline particles can provide a method to develop a new class of one-dimensional anode nanostructures in lithium-ion rechargeable batteries.     

锂一次电池正极材料CFx-Cu的高倍率性能研究

本文采用一种简单新颖的原位化学改性方法制备了锂电池用CF_x-Cu复合正极材料。采用XRD、SEM、EDS、TGA、EIS、CV和恒电流放电对正极材料的结构、形貌、反应机理和电化学性能进行了表征。CuO与分布在CF_x边缘或表面的非活性基团反应原位生成纳米铜,有效地提高了材料的电子导电性和锂离子扩散率,从而使改性材料显示出优异的比容量、倍率性能及功率密度。CF_x-Cu复合材料在5 C的高倍率下,其放电比容量高达546 mAh/g,最大功率密度为8393 w/kg,放电电压平台为2.0 V。     

Facile Synthesis of Yolk-Shell Bi@C Nanospheres with Superior Li-ion Storage Performances

Recently,exploring appropriate anode materials for current commercial lithium-ion batteries(LIBs) with suitable operating potential and long cycle life has attracted extensive attention.Herein,a novel anode of Bi nanoparticles fully encapsulated in carbon nanosphere framework with uniform yolk-shell nanostructure was prepared via a facile hydrothermal method.Due to the special structure design,this anode of yolk-shell Bi@C can effectively moderate the volume exchange,avoid the aggregation of active Bi nanoparticle and provide superior kinetic during discharge/charge process.Cycling in the voltage of 0.01-2.0 V,yolk-shell Bi@C anode exhibits outstanding Li+storage performance(a reversible capacity over 200 mAh g~(-1)after 400 cycles at 1.25 A g~(-1)) and excellent rate capability(a capacity of 404,347,304,275,240,199 and 163 mAh g~(-1) at0.05,0.1,0.25,0.5,1.0,1.8 and 3.2 A g~(-1),respectively).This work indicates that rational design of nanostructured anode materials is highly applicable for the next-generation LIBs.     

PPy-Encapsulated Na2Li2Ti6O14 Composites as High-Performance Anodes for Li-Ion Battery

Na₂Li₂Ti₆O₁₄ as a reliable anode material is becoming a hopeful candidate for Li-ion battery. Nevertheless, the pristine Na₂Li₂Ti₆O₁₄ usually suffer from bad rate performance and poor cycling stability under high current due to limited diffusion kinetics and poor electrical conductivity. Here, the PPy-coated Na₂Li₂Ti₆O₁₄ composites are successfully obtained via the solid-state method and followed by chemical oxidation process in the first time. The results of tests prove that the Na₂Li₂Ti₆O₁₄@PPy composites have better electrochemical performance than the bare Na₂Li₂Ti₆O₁₄ because of the excellent electrical conductivity and the special macromolecular architecture of PPy. In particular, the Na₂Li₂Ti₆O₁₄@PPy (4 wt%) exhibits excellent charge capacities of about 223.2, 218.0, 200.8, 184.3 and 172.6 mAh g^-1 at 50, 100, 200, 300 and 500 mA g^-1, respectively, revealing the best rate capability of all electrode materials. The Na₂Li₂Ti₆O₁₄@PPy(4 wt%) not only has the highest charge capacity under 0.5 mA g^-1, but also has the highest capacity retention of 85.12% among all samples after 100 loops. Hence, the PPy coating is known as a promising way to improve the electrochemical property of Na₂Li₂Ti₆O₁₄. The PPy-coated Na₂Li₂Ti₆O₁₄ demonstrates the great prospect as promising negative materials for Li-ion batteries.     

Synthesis of Co_3O_4 Nanoparticles Wrapped Within Full Carbon Matrix as an Anode Material for Lithium Ion Batteries

A facile polyol-assisted pyro-synthesis method was used to synthesize Co_3O_4 nanoparticles embedded into carbon matrix without using any conventional carbon source. The surface analysis by scanning electron microscopy showed that the Co_3O_4 nanoparticles(~20 ± 5 nm) are tightly enwrapped within the carbon matrix. CHN analysis determined the carbon content was only 0.11% in the final annealed sample. The Co_3O_4@carbon exhibited high capacities and excellent cycling performance as an anode at various current rates(such as 914.4 and 515.5 mAh g~(-1) at 0.25 and1.0 C, respectively, after 50 cycles; 318.2 mAh g~(-1) at a high current rate of 5.0 C after 25 cycles). This superior electrochemical performance of the electrode can be attributed to the various aspects, such as,(1) the existence of carbon matrix, which acts as a flexible buffer to accommodate the volume changes during Li~+ion insertion/deinsertion and facilitates the fast Li~+and electron transfer and(2) the anchoring of Co_3O_4 nanoparticles within the carbon matrix prevents particles agglomeration.     

高性能锂离子电池负极材料CoO/石墨烯纳米复合结构的超声法制备(英文)

以羰基钴为原料,采用简易超声法制备氧化亚钴和石墨烯纳米复合结构。通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)及光电子能谱(XPS)对该纳米复合结构进行表征。结果表明:粒径为3~5nm的氧化亚钴纳米颗粒均匀分布于石墨烯表面。将氧化亚钴/石墨烯纳米复合结构用作锂离子电池负极材料,电化学测试结果表明,该复合结构具有高电容量(50次循环后电容量为650mA·h/g,约是商用石墨电极的2倍)、高库伦效率(高于95%)以及很好的循环稳定性。该优异的电化学性能源于氧化亚钴/石墨烯纳米复合结构的特点:纳米尺寸的氧化亚钴颗粒分散于导电的石墨烯衬底上,有利于锂离子的嵌入和脱嵌,缩短了锂离子的扩散路径,提高了氧化物的导电性,从而改善了材料的电性能。     

钇掺杂LiFePO4锂离子电池正极材料的制备与性能

用固相法合成LiFe1-xYxPO4 (x=0, 0.01, 0.02, 0.03, 0.04)锂离子电池正极材料,采用X射线衍射仪、扫描电子显微镜、粉末比电阻法和充放电性能测试表征材料的晶体结构、微观形貌、电子电导率和电化学性能。结果表明,少量的钇掺杂并未改变材料的晶体结构,但改善了材料的微观结构,提高其电子电导率,改善可逆容量和电化学性能。在10 mA/g的电流密度下,LiFe0.97Y0.03PO4首次放电容量可达146.54 mAh/g。     

锂离子电池Sn薄膜电极厚度对其电化学性能的影响

用电沉积方法在铜集流体上分别制备出不同厚度(2,0.5,0.25,0.12μm)的锡薄膜电极。用扫描电镜观察其表面形貌、以充放电实验比较其性能。结果表明,减小Sn薄膜厚度可改善电极的循环性能,但首次容量损失也增大。0.5μm厚的Sn薄膜具有最高的放电容量和较好的循环稳定性;其首次放电比容量为749mAh/g,40次循环时放电比容量仍保持578mAh/g。     

Improving anode performances of lithium-ion capacitors employing carbon-Si composites

The lithium-ion capacitor is a promising energy storage system with a higher energy density than traditional supercapacitors.However,its cycling and rate performances,which depend on the electrochemical properties of the anode,are still required to be improved.In this work,soft carbon anodes reinforced using carbon-Si composites of various compositions were fabricated to investigate their beneficial influences on the performance of lithium-ion capacitors.The results showed that the specific capacities of the anodes increased significantly by 16.6 mAh g~(-1) with 1.0 wt% carbon-Si composite,while the initial discharge efficiency barely changed.The specific capacity of the anode with a 10.0 wt% carbon-Si composite reached 513.1 mAh g~(-1),and the initial discharge efficiency was 83.79%.Furthermore,the anodes with 7.5 wt% or lower amounts of carbon-Si composite demonstrated reduced charge transfer resistances,which caused an improvement in the rate performance of the lithium-ion capacitors.Moreover,the use of the optimized amount(7.5 wt%) of carbon-Si composite in the anode could significantly improve the cycling performance of the lithium-ion capacitor by compensating the consumption of active lithium.The capacity retention of the lithium-ion capacitor reached 95.14% at 20 C after 10,000 cycles,while the anode potential remained below 0.412 V,which is much lower than that of a soft carbon anode.     

Cobalt-free over-stoichiometric Laves phase alloys for Ni–MH batteries

The charge–discharge cycling behavior of the over-stoichiometric Laves phase alloy Zr_0.75Ti_0.25V_0.9Mn_0.4Cr_0.3Ni_1.4 as hydride electrode has been studied in a negative electrode-limited sealed cell. This cobalt-free alloy shows a maximum discharge capacity C_max=373 mAh g⁻¹ at 160 mA g⁻¹ discharge current and a high rate dischargeability of 285 mAh g⁻¹ at 1500 mA g⁻¹ discharge rate. After 600 cycles the discharge capacity is 81% of the C_max; the alloy also shows good charging efficiency (98%) and low temperature discharge rate.     

快速充电锂离子电池LiEuTiO4负极材料研究进展

随着电动车产业的快速发展,锂离子电池的安全问题和快速充电问题越来越受到关注。石墨作为商业化已久的锂离电池负极材料,因其析锂平台近乎于零,而存在因负极析锂而短路的巨大安全隐患,因而不适用于快速充电的锂离子电池负极材料。具有层状钙钛矿结构LiEuTiO₄,其脱/嵌锂平台约为0.8V,实际比容量高于200 mAh/g,既可以避免析锂的发生, 又不会导致电池能量密度过低,且倍率性能良好,利用该材料有望发展出一种电动车用安全的快速充电动力电池。本工作总结了钛酸铕锂(LiEuTiO₄)负极材料的研究现状,包括分子结构、储锂机制、制备方法及亟待解决的问题,指出进一步的研究方向。     

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.