Robert C. Massé

Beyond Li-ion: electrode materials for sodium- and magnesium-ion batteries

The need for economical and sustainable energy storage drives battery research today. While Li-ion batteries are the most mature technology, scalable electrochemical energy storage applications benefit from reductions in cost and improved safety. Sodium- and magnesium-ion batteries are two technologies that may prove to be viable alternatives. Both metals are cheaper and more abundant than Li, and have better safety characteristics, while divalent magnesium has the added bonus of passing twice as much charge per atom. On the other hand, both are still emerging fields of research with challenges to overcome. For example, electrodes incorporating Na+ are often pulverized under the repeated strain of shuttling the relatively large ion, while insertion and transport of Mg2+ is often kinetically slow, which stems from larger electrostatic forces. This review provides an overview of cathode and anode materials for sodium-ion batteries, and a comprehensive summary of research on cathodes for magnesium-ion batteries. In addition, several common experimental discrepancies in the literature are addressed, noting the additional constraints placed on magnesium electrochemistry. Lastly, promising strategies for future study are highlighted.中文摘要对于经济和可持续能源存储设备的需求促进了当今电池的研究. 锂离子电池是目前最成熟的技术, 但是电化学储能的应用 可通过降低成本和提高安全性进一步扩大. 钠和镁离子电池有可能成为两种可行的替代技术. 这两种金属比锂更便宜、储量更丰富, 并具有更好的安全特性, 而且二价镁还有一个附加优势, 即每个原子可以传输二倍的电荷. 另一方面, 钠和镁离子电池都还是新兴的研 究领域, 仍有很多挑战需要克服. 例如, 因较大的离子穿梭而造成的重复形变使结合Na+的电极容易粉末化, 而镁离子的插入和传输由 于较大的静电作用力普遍显示出较慢的动力学特性. 本文综述了钠离子电池阴极和阳极材料的概况, 并对镁离子电池阴极的研究进行 了全面总结. 此外, 本综述还讨论了文献中常见的一些实验差异, 指出了镁离子电化学研究的其他限制, 最后, 对未来研究提出了有价 值的观点和策略.

Novel Carbon-Encapsulated Porous SnO2 Anode for Lithium-Ion Batteries with Much Improved Cyclic Stability

Porous SnO2 submicrocubes (SMCs) are synthesized by annealing and HNO3 etching of CoSn(OH)6 SMCs. Bare SnO2 SMCs, as well as bare commercial SnO2 nanoparticles (NPs), show very high initial discharge capacity when used as anode material for lithium-ion batteries. However, during the following cycles most of the Li ions previously inserted cannot be extracted, resulting in considerable irreversibility. Porous SnO2 cubes have been proven to possess better electrochemical performance than the dense nanoparticles. After being encapsulated by carbon shell, the obtained yolk-shell SnO2 SMCs@C exhibits significantly enhanced reversibility for lithium-ions storage. The reversibility of the conversion between SnO2 and Sn, which is largely responsible for the enhanced capacity, has been discussed. The porous SnO2 SMCs@C shows much increased capacity and cycling stability, demonstrating that the porous SnO2 core is essential for better lithium-ion storage performance. The strategy introduced in this paper can be used as a versatile way to fabrication of various metal-oxide-based composites.

Design of coherent anode materials with 0D Ni3S2 nanoparticles self-assembled on 3D interconnected carbon networks for fast and reversible sodium storage

There has been tremendous progress in development of nanomaterials for energy conversion and storage, with sodium-ion batteries (SIBs) attracting attention because of the high abundance of raw materials and low cost. However, inferior cycling stability, sluggish reaction kinetics, and poor reversibility hinder their practical applications. In the present study, Ni3S2/carbon nanocomposites with coherent nanostructures were successfully used as anodes in half- and full-cells. Outstanding cycling and rate performances are attributed to a synergistic effect between the Ni3S2 nanoparticles and interconnected carbon networks. The coherent porous framework effectively alleviated volume changes of Ni3S2, shortened the Na+ diffusion path, and accelerated electron transport and ionic diffusion during the electrochemical reaction. More importantly, conversion reaction products can be confined by the entangled carbon networks, leading to reversible redox reactions as demonstrated in ex situ XRD studies. The coherent Ni3S2/C nanocomposites demonstrated a highly reversible charge capacity of 453 and 430 mA h g−1 at a current density of 0.1 and 0.4 A g−1 over 100 cycles, respectively. At a current density of 2.0 A g−1, high rate capacities of 408 mA h g−1 can be attained over 200 cycles. The high performance of Na3V2(PO4)3/Ni3S2 full-cells enrich prospects for future practical applications.

A three layer design with mesoporous silica encapsulated by a carbon core and shell for high energy lithium ion battery anodes

A novel C/SiO2 composite with a carbon–silica–carbon (C-mcms) three layer structure was synthesized and evaluated as an anode material for high-energy lithium ion batteries. The C-mcms exhibits an excellent capacity of about 1055 mA h g−1 at a current density of 500 mA g−1 after 150 cycles without detectable decay, and high-rate capability, which is superior to other similar composites without the carbon core or the carbon shell. The results indicate the structural effect on the enhancement of the electrochemical properties: the SiO2 nanoparticles are completely confined between the carbon shell and the carbon core; the two carbon parts work together to keep the structural integrity and to keep the electrode highly conductive and active during cycling, which guarantees high capacity and cycle stability; the interior pores and voids among the SiO2 nanoparticles can provide free space to accommodate the volume change and buffer the volume effect of the electrode during lithiation/delithiation.

A comparison of ZnS and ZnSe passivation layers on CdS/CdSe co-sensitized quantum dot solar cells

The design and synthesis of passivation materials are of significant importance to reducing surface charge recombination in quantum dot-sensitized solar cells (QDSCs). In this study, the systematic characterization and comparison of the optical and electrochemical properties of ZnS and ZnSe passivation layers and their impacts on the performance of the resulting QDSCs have been investigated. The ZnS and ZnSe passivation layers were all deposited via a reproducible and controlled successive ionic layer adsorption and reaction method. QDSCs with a ZnSe passivation layer demonstrated strongly inhibited interfacial charge recombination and greatly enhanced light harvesting, resulting in a power conversion efficiency of up to 6.4%, which is appreciably higher than 4.9% for the solar cells with a ZnS passivation layer and 3.4% for the solar cells without a passivation layer.