用于锂硫电池高效硫载体的Co-N-C@KB复合材料的规模化制备策略

硫正极较差的性能严重阻碍了锂硫电池的商业化进程,这些因素包括较低的导电能力以及在促进多硫化物转化方面较差的催化活性。我们开发了一种基于配体调控合成和低温热解的规模化策略来制备高效的正极复合材料（Co-N-C@KB）,这种材料由富含Co-N-C活性位点的科琴黑（KB）组成。原子级分散的Co-N-C活性位点被证明有利于多硫化物在正极的转化,因而可以提高锂硫电池的容量和循环寿命。基于此,Co-N-C@KB作为正极可以使锂硫电池获得高达1 442 mAh·g^-1的初始放电容量,并且该电池在长时间的稳定性测试中具有出色的容量保持能力。     

Two-dimensional MgSiP_2 with anisotropic electronic properties and good performances for Na-ion batteries

Using the global particle-swarm optimization method and density functional theory,we predict a new stable two-dimensional layered material:MgSiP_2 with a low-buckled honeycomb lattice.Our HSE06 calculation shows that MgSiP_2 is an indirect-gap semiconductor with a band-gap of 1.20 eV,closed to that of bulk silicon.More remarkably,MgSiP2 exhibits worthwhile anisotropy along with electron and hole carrier mobility.A ultrahigh electron mobility is even up to 1.29 × 104 cm~2 V ~1 s ~1.while the hole mobility is nearly zero along the a direction.The large difference of the mobility between electron and hole together with the suitable band-gap suggest that MgSiP_2 may be a good candidate for solar cell or photochemical catalysis material.Furthermore,we explore MgSiP2 as an anode for sodium-ion batte ries.Upon Na adsorption,the semiconducting MgSiP2 transforms to a metallic state,ensuring good electrical conductivity.A maximum theoretical capacity of 1406 mAh/g,a small volume change(within 9.5%),a small diffusion barrier(～0.16 eV) and low average open-circuit voltages(～0.15 V) were found fo r MgSiP2 as an anode for sodium-ion batteries.These results are helpful to deepen the understanding of MgSiP2 as a nanoelectronic device and a potential anode for Na-ion batteries.     

Sulfone-based high-voltage electrolytes for high energy density rechargeable lithium batteries:Progress and perspective

Further enhancement in the energy density of rechargeable lithium batteries calls for high-voltage cathode materials and stable anodes,as well as matched high-voltage electrolytes without compromising the overall property of batteries.Sulfone-based electrolytes have aroused great interest in recent years owing to their wide electrochemical window and high safety.However,significant challenges such as the complexity of synthesis,high melting point(typically above room temperature),high viscosity,and their poor compatibility with graphite-based anodes have drastically impeded their practical applications.In this review,recent progress of sulfone solvents in high energy density rechargeable lithium batteries is summarized theoretically and experimentally.More importantly,general improvement methods of sulfone-based electrolytes,such as adding additives and cosolvents,structural modifications of sulfo ne,superconcentrated salt strategy are briefly discussed.We expect that this review provides inspiration for the future developments of sulfone-based high-voltage electrolytes(SHVEs) and their widespread applications in high specific energy lithium batteries.     

Booting the electrochemical properties of Fe-based anode by the formation multiphasic nanocomposite for lithium-ion batteries

Fe-based compounds with good environmental friendliness and high reversible capacity have attracted considerable attention as anode for lithium-ion batteries.But,similar to other transition metal oxides(TMOs),it is also affected by large volume changes and inferior kinetics during redox reactions,resulting in the destruction of the crystal structure and poor electrochemical performance.Here,Fe_3O_4/C nanospheres anchored on the two-dimensional graphene oxide as precursors are phosphated and sintered to build the multiphasic nanocomposite.XRD results confirmed the multiphasic nanocomposite composed of Fe_2O_3,Fe_3O_4 and Fe_3PO_7,which will facilitate the Li~+ diffusion.And the carbonaceous matrix will buffer the volume changes and enhance electron conduction.Consequently,the multiphasic Febased anode delivers a large specific capacity of 1086 mAh/g with a high initial Coulombic efficiency of 87% at 0.1 C.It also has excellent cycling stability and rate property,maintaining a capacity retention of～87% after 300 cycles and a high reversible capacity of 632 mAh/g at 10 C.The proposed multiphasic structure offers a new insight into improving the electrochemical properties of TMO-based anodes for advanced alkali-ion batteries.     

Copper-cobalt-nickel oxide nanowire arrays on copper foams as self-standing anode materials for lithium ion batteries

Numerous scientists are in the pursuit of energy storage materials with high energy and high power density by assembly of electrochemically active materials into conductive scaffolds, owing to the emerging need for next-generation energy storage devices. In this architectures, the active materials bonded to the conductive scaffold can provide a robust and free-standing structure, which is crucial to the fabrication of materials with high gravimetric capacity. Thus, hierarchical copper-cobalt-nickel ternary oxide (CuCoNi-oxide) nanowire arrays grown from copper foam were successfully fabricated as free-standing anode materials for lithium ion batteries (LIBs). CuCoNi-oxide nanowire arrays could provide more active sites owing to the hyperbranched structure, leading to a better specific capacity of 1191 mAh/g, cycle performance of 73% retention in comparison to CuO nanowire structure, which exhibited a specific capacity of 1029 mAh/g and capacity retention of 43%, respectively.     

电动汽车与锂离子电池

文章简要介绍了混合动力汽车、插电式混合动力汽车、纯电动汽车和锂离子动力电池及其关键材料。发展电动汽车可以大幅度降低人们对石油的依赖和改善城市空气质量。锂离子电池性能优越,为电动汽车的发展提供了支撑。近期,新一代锂离子动力电池正极材料即将走向应用,可使电动汽车里程增加一倍,材料选择和电池设计及制造工艺与电池储存能量、寿命、安全等密切相关,尊道而重德,可做出“好”电池。     

Synthesis,characterization and electrochemical performances of LiFePO4/graphene cathode material for high power lithium-ion batteries

LiFePO₄/graphene (LiFePO₄/G) cathode with exciting electrochemical performance was successfully synthesized by liquid phase method. LiFePO₄ nanoparticles wrapped with multi-layered grapheme can be fabricated in a short time. This method did not need external heating source. Heat generated by chemical reaction conduct the process and removed the solvent simultaneously. The LiFePO₄/G were analyzed by X-ray diffraction (XRD) analysis, scanning electron microscope (SEM), transmission electron microscopy (TEM), magnetic properties analysis and electrochemical performance tests. The LiFePO₄/G delivered a capacity of 160 mAh g⁻¹ at 0.1C and could tolerate various dis-charge currents with a capacity retention rate of 99.8%, 99.2%, 99.0%, 98.6%, 97.3% and 95.0% after stepwise under 5C, 10C, 15C, 20C, 25C and 30C, respectively.     

Metal Oxide‐Coated Three‐Dimensional Graphene Prepared by the Use of Metal–Organic Frameworks as Precursors

A simple method for the preparation of metal‐oxide‐coated three‐dimensional (3D) graphene composites was developed. The metal–organic frameworks (MOFs) that served as the precursors of the metal oxides were first synthesized on the 3D graphene networks (3DGNs). The desired metal oxide/3DGN composites were then obtained by a two‐step annealing process. As a proof‐of‐concept application, the obtained ZnO/3DGN and Fe₂O₃/3DGN materials were used in a photocatalytic reaction and a lithium‐ion battery, respectively. We believe this method could be extended to the synthesis of other metal oxide/3DGN composites with 3D structures simply through the appropriate choice of specific MOFs as precursors.     

A Rechargeable Hydrogen Battery Based on Ru Catalysis

Apart from energy generation, the storage and liberation of energy are among the major problems in establishing a sustainable energy supply chain. Herein we report the development of a rechargeable H₂ battery which is based on the principle of the Ru‐catalyzed hydrogenation of CO₂ to formic acid (charging process) and the Ru‐catalyzed decomposition of formic acid to CO₂ and H₂ (discharging process). Both processes are driven by the same catalyst at elevated temperature either under pressure (charging process) or pressure‐free conditions (discharging process). Up to five charging–discharging cycles were performed without decrease of storage capacity. The resulting CO₂/H₂ mixture is free of CO and can be employed directly in fuel‐cell technology.     

Facile Mechanochemical Synthesis of Nano SnO2/Graphene Composite from Coarse Metallic Sn and Graphite Oxide: An Outstanding Anode Material for Lithium‐Ion Batteries

A facile method for the large‐scale synthesis of SnO₂ nanocrystal/graphene composites by using coarse metallic Sn particles and cheap graphite oxide (GO) as raw materials is demonstrated. This method uses simple ball milling to realize a mechanochemical reaction between Sn particles and GO. After the reaction, the initial coarse Sn particles with sizes of 3–30 μm are converted to SnO₂ nanocrystals (approximately 4 nm) while GO is reduced to graphene. Composite with different grinding times (1 h 20 min, 2 h 20 min or 8 h 20 min, abbreviated to 1, 2 or 8 h below) and raw material ratios (Sn:GO, 1:2, 1:1, 2:1, w/w) are investigated by X‐ray diffraction, X‐ray photoelectron spectroscopy, field‐emission scanning electron microscopy and transmission electron microscopy. The as‐prepared SnO₂/graphene composite with a grinding time of 8 h and raw material ratio of 1:1 forms micrometer‐sized architected chips composed of composite sheets, and demonstrates a high tap density of 1.53 g cm^?3. By using such composites as anode material for LIBs, a high specific capacity of 891 mA h g^?1 is achieved even after 50 cycles at 100 mA g^?1.