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991.
992.
二次离子电池商业化负极石墨的比容量已接近理论比容量. 合金型负极和金属负极因具有高比容量而受到广泛关注, 但其循环性能差和安全性问题限制了实际应用, 据此提出载体设计策略. 碳材料具有来源广泛、 易于调控等特性, 常用作二次离子电池高比容量负极的载体. 本文从碳载体的孔结构、 比表面积、 电子导电率、 离子导电率、 杂原子掺杂和界面修饰的角度出发, 综述了其在硅基、 磷基、 锗基、 锡基负极以及金属锂、 钠等负极中的研究进展, 展望了碳载体的发展前景和方向. 相似文献
993.
硅氧化物(SiOx, 0<x≤2)具有高的比容量和低的嵌锂电位, 且体积膨胀率显著低于纯硅负极, 因而被认为是替代传统石墨负极材料的理想选择之一. 然而SiOx负极在首次嵌锂过程中表面形成的固体电解质界面膜(SEI)以及大量的不可逆产物, 造成其首次库伦效率偏低, 严重阻碍了SiOx负极的实际应用. 本文从SiOx的结构模型出发, 系统阐述了SiOx负极的嵌锂机理以及首次库伦效率低的原因; 归纳了SiOx负极首次库伦效率的提升策略及其研究进展; 并对提升SiOx负极首次库伦效率的未来发展方向进行了展望. 相似文献
994.
建立了自动快速燃烧(AQF)-离子色谱联用测定铜精矿中氟的方法。将 AQF 的自动化特性和离子色谱的灵敏度高、准确性好的特点结合起来,能够实现操作过程的连续自动化。结果表明,线性范围内(1.0?50.0 μg )校准曲线相关系数 r >0. 999,氟的检出限为0.0004%。按照实验方法测定铜精矿样品中氟,结果的相对标准偏差( RSD ,n =6)为2.14 % ?4.24 %。将实验方法用于铜精矿标准样品氟含量测定,测定值与认定值吻合较好;方法对照试验表明,实验方法对氟含量的测定值与国家标准 GB/T 3884. 12—2010的测定值基本一致。 相似文献
995.
锌具有原料丰富、质量轻便、金属导电性与延展性好以及理论比容量高等优势,可以作为绿色可充电电池的理想电极材料。其中,以中性或弱酸性水溶液为电解质、锌为负极的锌基水系电池具有安全性高、电池材料廉价无毒、制备工艺简单、环境友好等特点,在储能和动力电池领域具有极高的应用价值和发展前景。但电池充放电过程中伴随的锌枝晶、析氢、腐蚀、钝化等问题限制了其实际应用。本文综述了锌基水系电池负极存在的问题及当前的解决策略,并对其负极研究发展方向进行了展望。 相似文献
996.
以镍钴氢氧化物、异丙醇铝为原料,采用水解法合成三元前驱体Ni_(0.88)Co_(0.07)Al_(0.05)O_2,再与锂盐混合烧结得到正极材料(TEM)、X射线光电子能谱(XPS)、能量色散X射线谱(EDS)和恒电流充放电测试等对样品的晶体结构、微观形貌、元素价态以及电化学性能进行表征。研究表明,料液比1∶25、水洗3次、600℃回烧2 h合成的LiNi_(0.88)Co_(0.07)Al_(0.05)O_2具有较优的综合电化学性能,其在0.2C的放电比容量达207.6 mAh·g~(-1),首次充放电效率为84.8%,1C放电比容量为192.0 mAh·g~(-1),循环100周后,材料的放电比容量仍有148.0 mAh·g~(-1),容量保持率达到77.1%。 相似文献
997.
《中国化学快报》2021,32(9):2914-2918
The silicon-based materials are promising candidates for lithium-ion batteries owing to their high energy density. However, achieving long lifespan under realistic conditions remains a challenge because of the volume expansion and low conductivity. In this work, the highly elastic cobweb-like composite materials consisted by SiO and nanofibers are designed and fabricated for high-efficient lithium storage by ball-milling & electrostatic spinning method. The reconstructed heterostructure and highly elastic nanofibers can simultaneously increase the conductivity and inhibit the “expansion effect” of silicon-based materials. The constructed electrode of n-SiO/CNF delivers an initial capacity of 1700 mAh/g, and maintains the capacities over 1000 mAh/g after 100 cycles at the current density of 500 mA/g. Meanwhile, this electrode can give an initial coulombic efficiency over 85% and maintains at 98% in the following charge/discharge processes. Furthermore, it exhibits efficient long-term electrochemical performance, maintaining the capacity at about 1000 mAh/g at a high current density of 1000 mA/g after 1000 cycles. This work could provide a promising strategy for enhancing the performance of silicon-based composite materials for practical application in lithium-ion batteries. 相似文献
998.
Dr. Marwa Abdelmouleh Dr. Mathieu Lalande Edith Nicol Dr. Gilles Frison Prof. Dr. Guillaume van der Rest Dr. Jean-Christophe Poully 《Chemphyschem》2021,22(12):1243-1250
These last decades, it has been widely assumed that 18-crown-6-ether (CE) plays a spectator role during the chemical processes occurring in isolated host-guest complexes between peptides or proteins and CE after activation in mass spectrometers. Our present experimental and theoretical results challenge this hypothesis by showing that CE can abstract a proton or a protonated molecule from protonated peptides after activation by collisions in argon or electron capture/transfer. Furthermore, thanks to comparison between experimental and calculated values of collision cross-sections, we demonstrate that CE can change binding site after electron transfer. We also propose detailed mechanisms for these processes. 相似文献
999.
Yuanqi Gui Baian Ji Gaoyi Yi Xiuju Li Kailian Zhang Qifeng Fu 《Molecules (Basel, Switzerland)》2021,26(6)
Herein, a novel L-arginine (L-Arg)-modified polydopamine (PDA)-coated capillary (PDA/L-Arg@capillary) was firstly fabricated via the basic amino-acid-induced PDA co-deposition strategy and employed to constitute a new chiral ligand exchange capillary electrochromatography (CLE-CEC) method for the high-performance enantioseparation of D,L-amino acids (D,L-AAs) with L-Arg as the immobilized chiral ligand coordinating with the central metal ion Zn(II) as running buffer. Assisted by hydrothermal treatment, the robust immobilization of L-Arg on the capillary inner wall could be facilely achieved within 1 h, prominently improving the synthesis efficiency and simplifying the preparation procedure. The successful preparation of PDA/L-Arg coatings in the capillary was systematically characterized and confirmed using several methods. In comparison with bare and PDA-functionalized capillaries, the enantioseparation capability of the presented CLE-CEC system was significantly enhanced. Eight D,L-AAs were completely separated and three pairs were partially separated under the optimal conditions. The prepared PDA/L-Arg@capillary showed good repeatability and stability. The potential mechanism of the greatly enhanced enantioseparation performance obtained by PDA/L-Arg@capillary was also explored. Moreover, the proposed method was further utilized for studying the enzyme kinetics of L-glutamic dehydrogenase, exhibiting its promising prospects in enzyme assays and other related applications. 相似文献
1000.
In atomic and many-particle physics, Green functions often occur as propagators to formally represent the (integration over the) complete spectrum of the underlying Hamiltonian. However, while these functions are very crucial to describing many second- and higher-order perturbation processes, they have hardly been considered and classified for complex atoms. Here, we show how relativistic (many-electron) Green functions can be approximated and systematically improved for few- and many-electron atoms and ions. The representation of these functions is based on classes of virtual excitations, or so-called excitation schemes, with regard to given bound-state reference configurations, and by applying a multi-configuration Dirac-Hartree-Fock expansion of all atomic states involved. A first implementation of these approximate Green functions has been realized in the framework of Jac, the Jena Atomic Calculator, and will facilitate the study of various multi-photon and/or multiple electron (emission) processes. 相似文献