锂离子电池负极用多孔碳包覆Li4Ti5O12复合材料的制备及电化学性能

利用水热合成和高温活化处理对Li₄Ti₅O₁₂进行多孔碳包覆复合改性实验,制备了Li₄Ti₅O₁₂@porous-C复合材料,研究了复合材料微观结构和电化学性能。结果表明:Li₄Ti₅O₁₂完全被包覆在多孔碳层中,同时,Li₄Ti₅O₁₂@porous-C复合材料表面碳层孔洞分布均匀,碳层厚度约为（8.5±3.6） nm。其首次放电比容量为363 m Ah/g,约为纯Li₄Ti₅O₁₂放电比容量的2倍;交流阻抗值降低,仅为纯Li₄Ti₅O₁₂的阻抗值的一半;Li₄Ti₅O₁₂@porous-C复合材料在循环200周后的放电比容量为2...     

锂离子电池高镍三元正极材料LiNi0.9Co0.05Mn0.05O2的制备与改性

采用La掺杂和固态电解质Li_1.3Al_0.3Ti_1.7(PO4)₃包覆对LiNi_0.9Co_0.05Mn_0.05O₂进行改性，研究掺杂和包覆对LiNi_0.9Co_0.05Mn_0.05O₂结构与性能的影响。结果表明：适量的La掺杂可以降低LiNi_0.9Co_0.05Mn_0.05O₂材料的离子迁移阻抗，提高Li⁺扩散系数，稳定材料的结构，从而提高材料的放电比容量及循环性能，当La掺杂量为0.1 wt%时，首次放电比容量为180.1 mAh·g^-1，经过100次循环后的容量保持率高达93.34%，远高于未掺杂样品的86.20%。Li_1.3Al_0.3Ti_1....     

Li2ZrO3包覆LiNi0.8Co0.1Mn0.1O2的复合材料及其电化学性能

以Zr（NO₃）₄·5H₂O和CH₃COOLi·2H₂O为原料,采用湿化学法,将Li₂ZrO₃包覆在LiNi_0.8Co_0.1Mn_0.1O₂锂离子电池正极材料的表面,研究Li₂ZrO₃不同包覆比例对LiNi_0.8Co_0.1Mn_0.1O₂电化学性能的影响。SEM、TEM、EDS谱图分析表明,Li₂ZrO₃层均匀地包覆在LiNi_0.8Co_0.1Mn_0.1O₂表面,其厚度约为8 nm。与纯相相比,1%（质量分数） Li₂ZrO₃包覆的LiNi_0.8Co_0.1Mn_0.1O₂复合材料在1.0 C下首次放电比容量为184.7 mA·h·g^-1、100次循环之后放电比容量为169.5 mA·h·g^-1,其容量保持率达到91.77%,表现出良好的循环稳定性。循环伏安（CV）和电化学阻抗（EIS）测试结果表明,Li₂ZrO₃包覆层抑制了正极材料与电解液之间的副反应,减小了材料在循环过程中的电荷转移阻抗,从而提高了材料的电化学性能。     

Cr掺杂对富锂锰基正极材料Li1.2Ni0.2Mn0.6O2结构和电化学性能的影响

采用共沉淀-高温固相合成法制备锂离子电池正极材料Li_1.2Ni_0.2Mn_0.2-x/2Mn_0.6-x/2Cr_xO₂（x=0,0.04,0.08,0.12）。利用X射线衍射（XRD）、扫描电镜（SEM）、恒电流充放电测试和电化学交流阻抗谱（EIS）对掺杂不同Cr含量的正极材料的结构、形貌和电化学性能进行分析测试。结果表明：制备出的Li_1.2Ni_0.2Mn_0.2-x/2Mn_0.6-x/2Cr_xO₂正极材料均具备层状固溶体结构。Cr掺杂不会改变材料的结构,而且能够有效抑制循环过程中材料由层状向尖晶石结构转变的过程。当Cr的掺杂量为8%（即x=0.08）时,得到的正极材料Li_1.2Ni_0.16Mn_0.56Cr_0.08O₂具有最好的电化学性能。0.1C的首次放电比容量由未掺杂的230.4 mA·h·g^-1增加到246.6 mA·h·g^-1,在0.2C电流下50次循环后的容量保持率由93.5%提高至95.36%,5C的放电比容量由91.5 mA·h·g^-1增加到104.2 mA·h·g^-1。而且x=0.08时制备的样品具有最小的电荷转移阻抗。     

无人机用锂离子电池正极材料Li1.20Mn0.54Ni0.13Co0.13O2的Mo6+掺杂改性研究

采用碳酸盐共沉淀法和高温烧结工艺将一定量的Mo⁶⁺掺杂到Li_1.20Mn_0.54Ni_0.13Co_0.13O₂正极材料中。利用XRD、SEM、EDS和恒流测试仪研究Mo⁶⁺掺杂对Li_1.20Mn_0.54Ni_0.13Co_0.13O₂正极材料的晶体结构、微观形貌和电化学性能的影响。结果显示,Li_1.20Mn_0.52Ni_0.13Co_0.13Mo_0.02O₂表现出更低的阳离子混排和优异的电化学性能。经过Mo⁶⁺掺杂后的正极,由于Li⁺高速的迁移速率,使得首次不可逆容量损失降低,并展现出更好的高倍率性能和优异的循环稳定性。在0.5C倍率下循环100周后,Li_1.20Mn_0.52Ni_0.13Co_0.13Mo_0.02O₂的容量保持率达到92.2%,远远大于Li_1.20Mn_0.54Ni_0.13Co_0.13O₂的87.5%。另外,当放电倍率增大到5C时,Li_1.20Mn_0.54Ni_0.13Co_0.13O₂的放电比容量要比Li_1.20Mn_0.52Ni_0.13Co_0.13Mo_0.02O₂低21.0 mA·h/g。因此,采用Mo⁶⁺掺杂改性Li_1.20Mn_0.54Ni_0.13Co_0.13O₂正极材料,可以有效提高锂电池的循环保持率和高倍率放电性能。     

多孔FeF2正极材料的制备及电化学性能研究

利用分解反应中大比例质量损失和大量气体产生,制备出具有40.369m²·g^-1大比表面积的多孔FeF₂材料。多孔结构为FeF₂材料构建了优异的离子和电子导电通路,表现出优秀的倍率性能和循环性能。在2C、5C和15C的倍率下分别表现出589.21mAh·g^-1、406.95mAh·g^-1和83.53mAh·g^-1的高放电比容量。在0.5C和2C下,循环100次后放电比容量分别为502.5mAh·g^-1和267.9mAh·g^-1。该结果为电池正极材料提升倍率性能提供了新思路。     

K2Ti4O9制备TiO2-B纤维快速嵌锂负极材料

以四钛酸钾(K₂Ti₄O₉)经离子交换得到的四钛酸(H₂Ti₄O₉·xH₂O)为前驱体,经过不同温度热处理得到不同结晶度的氧化钛纤维。对样品进行XRD、Raman、FE-SEM及TEM等结构形貌表征,发现600℃烧结可得到纯相、高结晶度的TiO₂-B材料。并考察了其作为锂离子电池负极材料的容量、倍率和稳定性。嵌锂性能测试发现,TiO₂-B相材料的首放容量可以达到225 mA·h·g^-1,比相近结构的锐钛矿(anatase)相材料高50 mA·h·g^-1,即22.5%的容量。与相似结构anatase材料的倍率结果对比发现,TiO₂-B纤维倍率性能更高,主要是TiO₂-B纤维的开放结构使其锂离子扩散系数达到1.92×10^-7 cm²·s^-1,是anatase相材料的8倍。1 C稳定性测试发现循环80次后容量仍然高于anatase,且最终容量稳定在159 mA·h·g^-1,比anatase材料的64 mA·h·g^-1高1.5倍。     

Cr掺杂对Li1.2Ni0.2Mn0.6O2结构和电化学性能的影响

采用共沉淀法制备了锂离子电池正极材料Li_1.2Mn_0.6Ni_0.2O₂和Li_1.2Ni_0.18Mn_0.58Cr_0.04O₂,并利用X射线衍射（XRD）、扫描电镜（SEM）和电化学性能测试对材料的晶体结构、形貌和电化学性能进行了表征。结果表明:掺Cr³⁺后材料的阳离子混排程度降低,层状结构更为规整,电化学性能明显优于Li_1.2Mn_0.6Ni_0.2O₂,其0.2C和1C首次放电容量分别为262.2 mAh/g和241.7 mAh/g,1C倍率下循环50次的容量保持率为95.5%。     

Ga掺杂FeNb11O29材料的制备及其电化学性能

FeNb₁₁O₂₉由于其高的理论充电容量(400 mAh·g^-1),作为锂离子电池(LIBs)负极材料具有很大的应用前景。然而,目前报道的FeNb₁₁O₂₉实际容量仅有168~273 mAh·g^-1。因此,有必要进一步提高其电化学性能。本文介绍了一种制备Ga掺杂FeNb₁₁O₂₉材料的方法,成功合成了Ga_xFe_1-xNb₁₁O₂₉(x=0.1,0.2)。结果表明,Ga_0.2Fe_0.8Nb₁₁O₂₉的电导率比FeNb₁₁O₂₉提高了两个数量级。X射线衍射结果显示,Ga掺杂不会改变FeNb₁₁O₂₉的正交剪切ReO₃晶体结构。扫描电镜结果显示,材料的微观形貌没有发生明显改变。电化学实验表明,Ga_0.2Fe_0.8Nb₁₁O₂₉具有较好的电化学性能,在电流密度为0.1 C时,Ga_0.2Fe_0.8Nb₁₁O₂₉充电容量为290 mAh·g^-1,当电流密度达到5 C时容量仍能保持145 mAh·g^-1,此外,Ga_0.2Fe_0.8Nb₁₁O₂₉具有良好的循环稳定性,在电流密度为5 C时循环1 000圈之后,容量保持率为91.0%,而不掺杂的FeNb₁₁O₂₉的充电容量仅有107 mAh·g^-1,容量保持率仅为55.9%。利用Ga掺杂改善FeNb₁₁O₂₉负极材料的电化学性能在锂离子电池中具有广阔的应用前景。     

喷雾干燥法制备球形Li3V2(PO4)3/C正极材料及其电化学性能

从控制Li₃V₂(PO₄)/C的形貌入手,旨在提高其作为锂离子电池正极材料的电化学性能。以葡萄糖为碳源,CTAB为表面活性剂,利用喷雾干燥法制备了粒径约为1μm的正球形Li₃V₂(PO₄)/C活性材料,颗粒尺寸均匀,振实密度较高。葡萄糖热解碳所形成的包覆层有效提高了材料的导电性,对材料的形貌控制则改善了锂离子扩散能力,因此本文所合成的Li₃V₂(PO₄)/C具良好的电化学性能,材料的锂离子扩散系数相对纯相提升约2个数量级,低于1C倍率下放电比容量均大于115mA?h/g,10C和15C大倍率下放电比容量为85mA?h/g和75mA?h/g左右,5C下循环50次,其库仑效率为96.2%。充放电平台的电位平稳,电位差较小,电化学反应阻抗值小,说明极化现象得到了有效控制。     

原位合成的介孔TiO2-B/锐钛微粒:改善的锂离子电池阳极材料（英文）

Mesoporous TiO2-B/anatase microparticles have been in-situ synthesized from K2Ti2O5 without template. The TiO2-B phase around the particle surface accelerates the diffusion of charges through the interface, while the anatase phase in the core maintains the capacity stability. The heterojunction interface between the main polymorph of anatase and the trace of TiO2-B exhibits promising lithium ion battery performance. This trace of 5%(by mass) TiO2-B determined by Raman spectra brings the first discharge capacity of this material to 247 mA·h·g?1, giving 20%improvement com-pared to the anatase counterpart. Stability testing at 1 C reveals that the capacity maintains at 171 mA·h·g?1, which is better than 162 mA·h·g?1 for single phase anatase or 159 mA·h·g?1 for TiO2-B. The mesoporous TiO2-B/anatase microparticles also show superior rate performance with 100 mA·h·g?1 at 40 C, increased by nearly 25%as compared to pure anatase. This opens a possibility of a general design route, which can be applied to other metal oxide electrode materials for rechargeable batteries and supercapacitors.     

Facile synthesis of spinel LiNi0.5Mn1.5O4 as 5.0 V-class high-voltage cathode materials for Li-ion batteries

LiNi_0.5Mn_1.5O₄ and LiMn₂O₄ with novel spinel morphology were synthesized by a hydrothermal and post-calcination process. The synthesized LiMn₂O₄ particles (5-10 μm) are uniform hexahedron, while the LiNi_0.5Mn_1.5O₄ has spindle-like morphology with the long axis 10-15 μm, short axis 5-8 μm. Both LiMn₂O₄ and LiNi_0.5Mn_1.5O₄ show high capacity when used as cathode materials for Li-ion batteries. In the voltage range of 2.5-5.5 V at room temperature, the LiNi_0.5Mn_1.5O₄ has a high discharge capacity of 135.04 mA·h·g^-1 at 20 mA·g^-1, which is close to 147 mA·h·g^-1 (theoretical capacity of LiNi_0.5Mn_1.5O₄). The discharge capacity of LiMn₂O₄ is 131.08 mA·h·g^-1 at 20 mA·g^-1. Moreover, the LiNi_0.5Mn_1.5O₄ shows a higher capacity retention (76%) compared to that of LiMn₂O₄ (61%) after 50 cycles. The morphology and structure of LiMn₂O₄ and LiNi_0.5Mn_1.5O₄ are well kept even after cycling as demonstrated by SEM and XRD on cycled LiMn₂O₄ and LiNi_0.5Mn_1.5O₄ electrodes.     

Lithium Storage Performance of Hollow and Core/Shell TiO2 Microspheres Containing Carbon☆

TiO2 microspheres containing carbon have been synthesized viaa one-pot hydrothermal process using CTAB as the mesoporous template and nanoparticle stabilizer and Ti(SO4)2 and sucrose as titanium and ca...     

响应面法优化碳热还原合成LiFePO4/C的工艺参数（英文）

A statistically based optimization strategy is used to optimize the carbothermal reduction technology for the synthesis of LiFePO4/C using LiOH,FePO4 and sucrose as raw materials.The experimental data for fitting the response are collected by the central composite rotatable design(CCD).A second order model for the discharge ca-pacity of LiFePO4/C is expressed as a function of sintering temperature,sintering time and carbon content.The ef-fects of individual variables and their interactions are studied by a statistical analysis(ANOVA).The results show that the linear effects and the quadratic effects of sintering temperature,carbon content and the interactions among these variables are statistically significant,while those effects of sintering time are insignificant.Response surface plots for spatial representation of the model illustrate that the discharge capacity depends on sintering temperature and carbon content more than sintering time.The model obtained gives the optimized reaction parameters of sinter-ing temperature at 652.0 ℃,carbon content of 34.33 g?mol-1 and 8.48 h sintering time,corresponding to a dis-charge capacity of 150.8 mA·h·g-1.The confirmatory test with these optimum parameters gives the discharge ca-pacity of 147.2 and 105.1 mA·h·g-1 at 0.5 and 5 C,respectively.     

Effective enhancement of the electrochemical properties for Na2FeP2O7/C cathode materials by boron doping

In recent years, the composite materials based on polyanionic frameworks as secondary sodium ion battery electrode material have been developed in large-scale energy storage applications due to its safety and stability. The Na₂FeP₂O₇/C (theoretical capacity 97 mA·h·g^-1) is recognized as optimum Na-storage cathode materials with a trade-off between electrode performance and cost. In the present work, The Na₂FeP₂O₇/C and boron-doped Na₂FeP_2-BO₇/C composites were synthesized via a novel method of liquid phase combined with high temperature solid phase. The non-metallic element B doping not only had positive influence on the crystal structure stability, Na⁺ diffusion and electrical conductivity of Na₂FeP₂O₇/C, but also contributed to the high-value recycling of B element in waste borax. The structure and electrochemical properties of the cathode material were investigated via X-ray diffraction (XRD), scanning electron microscopy (SEM), The X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and charge/discharge cycling. The results showed that different amounts of boron doping had positive effects on the structure and electrochemical properties of the material. The initial charge/discharge performances of born doped materials were improved in comparison to the bare Na₂FeP₂O₇/C. The cycle performance of the Na₂FeP_1.95B_0.05O₇/C showed an initial reversible capacity of 74.8 mA·h·g^-1 and the high capacity retention of 91.8% after 100 cycles at 1.0 C, while the initial reversible capacity of the bare Na₂FeP₂O₇/C was only 66.2 mA·h·g^-1. The improvement of apparent Na⁺ diffusion and electrical conductivity due to B doping were verified by the EIS test and CVs at various scan rate. The experimental results from present work is useful for opening new insight into the contrivance and creation of applicable sodium polyanionic cathode materials for high-performance.     

Enhanced electrochemical performance of garnet-based solid-state lithium metal battery with modified anodic and cathodic interfaces

Due to high ionic conductivity and wide electrochemical window, the garnet solid electrolyte is considered as the most promising candidate electrolyte for solid-state lithium metal batteries. However, the high contact impedance between metallic lithium and the garnet solid electrolyte surface seriously hampers its further application. In this work, a Li-(ZnO)_x anode is prepared by the reaction of zinc oxide with metallic lithium and in situ coated on the surface of Li_6.8La₃Zr_1.8Ta_0.2O₁₂(LLZTO). The anode can be perfectly bound to the surface of LLZTO solid electrolyte, and the anode/electrolyte interfacial resistance was reduced from 2319 to 33.75 Ω·cm². The Li-(ZnO)_0.15|LLZTO|Li-(ZnO)_0.15 symmetric battery exhibits a stable Li striping/plating process during charge-discharging at a constant current density of 0.1 mA·cm^-2 for 100 h at room temperature. Moreover, a Li-(ZnO)_0.15|LLZTO-SPE|LFP full battery, comprised of a polyethylene oxide-based solid polymer electrolyte (SPE) film as an interlayer between LiFePO₄ (LFP) cathode and LLZTO solid electrolyte, presents an excellent performance at 60 ℃. The discharge capacity of the full battery reaches 140 mA·h·g^-1 at 0.1 C and the capacity attenuation is less than 3% after 50 cycles.     

Hybrid CuO-Co3O4 nanosphere/RGO sandwiched composites as anode materials for lithium-ion batteries

Hybrid CuO-Co₃O₄ nanosphere building blocks have been embedded between the layered nanosheets of reduced graphene oxides with a three dimensional (3D) hybrid architecture (CuO-Co₃O₄-RGO), which are successfully applied as enhanced anodes for lithium-ion batteries (LIBs). The CuO-Co₃O₄-RGO sandwiched nanostructures exhibit a reversible capacity of~847 mA·h·g^-1 after 200 cycles' cycling at 100 mA·g^-1 with a capacity retention of 79%. The CuO-Co₃O₄-RGO compounds show superior electrochemical properties than the comparative CuO-Co₃O₄, Co₃O₄ and CuO anodes, which may be ascribed to the following reasons:the hybridizing multicomponent can probably give the complementary advantages; the mutual benefit of uniformly distributing nanospheres across the layered RGO nanosheets can avoid the agglomeration of both the RGO nanosheets and the CuO-Co₃O₄ nanospheres; the 3D storage structure as well as the graphene wrapped composite could enhance the electrical conductivity and reduce volume expansion effect associated with the discharge-charge process.     

Self-assembled MoS2/C nanoflowers with expanded interlayer spacing as a high-performance anode for sodium ion batteries

Two-dimensional (2D) MoS₂ nanomaterials have been extensively studied due to their special structure and high theoretical capacity, but it is still a huge challenge to improve its cycle stability and achieve superior fast charge and discharge performance. Herein, a facile one-step hydrothermal method is proposed to synthetize an ordered and self-assembled MoS₂ nanoflower (MoS₂/C NF) with expanded interlayer spacing via embedding a carbon layer into the interlayer. The carbon layer in the MoS₂ interlayer can speed the transfer of electrons, while the nanoflower structure promotes the ions transport and improves the structural stability during the charging/discharging process. Therefore, MoS₂/C NF electrode exhibits exceptional rate performance (318.2 and 302.3 mA·h·g^-1 at 5.0 and 10.0 A·g^-1, respectively) and extraordinary cycle durability (98.8% retention after 300 cycles at a current density of 1.0 A·g^-1). This work provides a simple and feasible method for constructing high-performance anode composites for sodium ion batteries with excellent cycle durability and fast charge/discharge ability.     

Influence of synergistic effect of LiNi0.8Co0.15Al0.05O2@Cr2O5 composite on the electrochemical properties

LiNi_(0.8)Co_(0.15)Al_(0.05)O_2@Cr_2O_5(NCA)@Cr_2 O_5 composite electrode combines the high rate-capability characteristics of NCA with the stability of Cr_2 O_5, playing a synergistic role in improving the cyclic stability, initial discharge capacity and the security of low cut-off voltage(2.0 V). When the mass ratio of Cr_2 O_5 in NCA is 45%(mass), the capacity retention rate increases from 58.5% without Cr_2 O_5 to 69.3% in the range of 2.0–4.3 V.The initial discharge capacity of NCA@Cr_2 O_5 composite material is 211.4 m A·h·g~(-1), its first coulombic efficiency is 94.2%, and the charging capacity remains approximately constant when mixed with 15%(mass)Cr_2 O_5. The reason for the improvement of the initial charge–discharge efficiency(ICDE) was explained.Impedance and cyclic voltammetry analysis reveal more detailed reasons of the observed improvements.Compared with NCA cathode material, the NCA@Cr_2 O_5 composite material can provide not only additional stable sites and channels for Li+insertion/extraction to make up for the loss of active Li+sites and prevent the accumulation of Li+in the circulation process, but also protect the NCA electrode from the corrosion of the electrolyte decomposition by the Cr_2 O_5 nanoparticles adhering to NCA interface.     

FeS2@TiO2 nanorods as high-performance anode for sodium ion battery

Sodium-ion battery (SIB) is an ideal device that could replace lithium-ion battery (LIB) in grid-scale energy storage system for power because of the low cost and rich reserve of raw material. The key challenge lies in developing electrode materials enabling reversible Na⁺ insertion/desertion and fast reaction kinetics. Herein, a core-shell structure, FeS₂ nanoparticles encapsulated in biphase TiO₂ shell (FeS₂@TiO₂), is developed towards the improvement of sodium storage. The diphase TiO₂ coating supplies abundant anatase/rutile interface and oxygen vacancies which will enhance the charge transfer, and avoid severe volume variation of FeS₂ caused by the Na⁺ insertion. The FeS₂ core will deliver high theoretical capacity through its conversion reaction mechanism. Consequently, the FeS₂@TiO₂ nanorods display notable performance as anode for SIBs including long-term cycling performance (637.8 mA·h·g^-1 at 0.2 A·g^-1 after 300 cycles, 374.9 mA·h·g^-1 at 5.0 A·g^-1 after 600 cycles) and outstanding rate capability (222.2 mA·h·g^-1 at 10 A·g^-1). Furthermore, the synthesized FeS₂@TiO₂ demonstrates significant pseudocapacitive behavior which accounts for 90.7% of the Na⁺ storage, and efficiently boosts the rate capability. This work provides a new pathway to fabricate anode material with an optimized structure and crystal phase for SIBs.