锂离子电池锡氧化物基负极材料的湿化学合成与电化学性质

采用新兴的湿化学方法合成了锡氧化物基粉末材料。用X-射线衍射、扫描电镜和电化学方法对材料的微观结构、形貌和电化学性能进行了详细的研究。结果表明，经400 ℃热处理4 h的锡氧化物基材料的颗粒大小均匀，平均粒径约为200 nm。这种材料的可逆充电容量超过570 mAh·g^-1，30次循环后平均每次循环的容量衰减只有0.15%。良好的电化学性能表明锡氧化物基材料有望作为新一代锂离子电池的负极材料。     

锂离子蓄电池正极材料LiFePO4研究进展

锂离子电池正极材料正在向着高比能量、长寿命、低成本、环境友好的方向发展,而具有橄榄石结构的LiFePO_4正极材料以其结构稳定、成本低、无污染等优点成为21世纪最理想的绿色电源,但自身也存在缺点。综述了锂离子电池正极材料LiFePO_4的研究进展。系统地阐述了LiFePO_4的晶体结构特征及性能、多种合成方法以及掺杂多种导电材料和控制晶体生长制备纳米粉体对材料性能的影响。对该材料的应用前景进行了展望,并提出了下一步可能的研究趋势。     

酞菁类化合物对MH/Ni电池性能的影响

针对MH/Ni电池充电过程中氧的产生和不恰当的消除方式带来的内压升高和热量聚集使电池总体性能衰减很快的问题, 提出采用降低化学催化氧还原的比例, 提高热量产生少的电催化氧还原比例的方法加以解决.金属酞菁类化合物是一种电催化氧还原剂.添加酞菁的MH/Ni电池与对比电池进行容量衰减、内压、大电流放电等特性比较, 其性能均有显著提高.     

Novel siloxane polymers as polymer electrolytes for high energy density lithium batteries

A variety of disubstituted (double-comb) polysiloxane polymers have been prepared containing linear, branched, and cyclic oligoethyleneoxide units, –(OCH₂CH₂)_n–, in the side chains and as part of the siloxane backbone. Copolymers, using mixtures of linear ethylene oxide side chains, were also synthesized. These polymers were doped with LiN(SO₂CF₃)₂ (LiTFSI, 1) and conductivities of the polymer-salt complexes were determined as a function of temperature and doping level. The maximum conductivity of these polymers at 25 ° C was 2.99 ×10^–4, for a copolymer containing equimolar amounts of side chains with n = 5 and 6.     

Microwave assisted hydrothermal synthesis of tin niobates nanosheets with high cycle stability as lithium-ion battery anodes

SnNb₂O₆ and Sn₂Nb₂O₇ nanosheets were synthetized via microwave assisted hydrothermal method, and innovatively employed as anode materials for lithium-ion battery. Compared with Sn₂Nb₂O₇ and the previously reported pure Sn-based anode materials, the SnNb₂O₆ electrode exhibited outstanding cycling performance.     

Electrostatic Interactions Leading to Hierarchical Interpenetrating Electroconductive Networks in Silicon Anodes for Fast Lithium Storage

Recently, the frequency of combining MXene, which has unique properties such as metal-level conductivity and large specific surface area, with silicon to achieve excellent electrochemical performance has increased considerably. There is no doubt that the introduction of MXene can improve the conductivity of silicon and the cycling stability of electrodes after elaborate structure design. However, most exhaustive contacts can only improve the electrode conductivity on the plane. Herein, a MXene@Si/CNTs (HIEN-MSC) composite with hierarchical interpenetrating electroconductive networks has been synthesized by electrostatic self-assembly. In this process, the CNTs are first combined with silicon nanoparticles and then assembled with MXene nanosheets. Inserting CNTs into silicon nanoparticles can not only reduce the latter‘s agglomeration, but also immobilizes them on the three-dimensional conductive framework composed of CNTs and MXene nanosheets. Therefore, the HIEN-MSC electrode shows superior rate performance (high reversible capacity of 280 mA h⁻¹ even tested at 10 A g⁻¹), cycling stability (stable reversible capacity of 547 mA h g⁻¹ after 200 cycles at 1 A g⁻¹) and applicability (a high reversible capacity of 101 mA h g⁻¹ after 50 cycles when assembled with NCM622 into a full cell). These results may provide new insights for other electrodes with excellent rate performance and long-cycle stability.     

Effect of Dy3+‐doping on Electrochemical Properties of LiFePO4/C Cathode for Lithium‐Ion Batteries

Dy doping and carbon coating are adopted to synthesize a LiFePO₄ cathode material in a simple solution environment. The samples were characterized by X‐ray diffraction (XRD) and scanning electron microscopy (SEM). Their electrochemical properties were investigated by cyclic voltammetry (CV) and galvanostatic charge‐discharge tests. An initial discharge capacity of 153 mAh/g was achieved for the LiDy_0.02Fe_0.98PO₄/C composite cathode with a rate of 0.1 C. In addition the electronic conductivity of Dy doped LiFePO₄/C was enhanced to 1.9 × 10^?2 Scm^?1. The results suggest that the improvement of the electrochemical properties are attributed to the dysprosium doping and carbon coating which facilitates the phase transformation between triphylite and heterosite during cycling. XRD data indicate that doping did not destroy the lattice structure of LiFePO₄. To evaluate the effect of Dy substitution, cyclic voltammetry was used at room temperature. prepared. From Cv measurement a more symmetric curve with smaller interval between the cathodic and anodic peak current was obtained by Dy substitution. This denoted a decreasing of polarization with Dy substitution, which illustrated an enhancement of electrochemical performances.     

Presodiation Strategies for the Promotion of Sodium-Based Energy Storage Systems

Nowadays sodium-based energy storage systems (Na-based ESSs) have been widely researched as it possesses the possibility to replace traditional energy storage media to become next generation energy storage system. However, due to the irreversible loss of sodium ions in the first cycle, development of Na-based ESSs is limited. Presodiation, as a strategy of adding excess sodium ions to the system in advance, accomplishes the enhancement of electrochemical performance. In this minireview, different presodiation strategies applied in sodium-based energy storage systems will be summarized in detail, their functions and corresponding mechanisms will be discussed as well. Furthermore, the current novel application of presodiation method in other aspects of Na-based ESSs will be mentioned additionally. At last, in the view of present research status of presodiation, issues that can be mitigated are put forward and guidelines are given on how to deliberate in-depth presodiation technology in the future, dedicating to promote the further development of Na-based ESSs.