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Rechargeable sodium-sulfur batteries able to operate stably at room temperature are sought-after platforms as they can achieve high storage capacity from inexpensive electrode materials. Here, the authors use rationally selected cathode and electrolyte materials to design a room temperature Na-S battery.

Carbon materials have been ubiquitously applied in energy conversion and storage devices owing to their high conductivity, excellent stability, and flexible structure. Conventional functionalization of carbon materials typically involves complex chemical treatment or long-term thermal and hydrothermal modifications. Here, a one-step universal strategy for the rapid surface engineering of carbon materials by microwave-induced carbothermal shock is reported. The temperature of carbon-fiber clothes (CC) quickly ramps to 1500 K within 5 s and maintains it for 2 s to complete the surface engineering process. At elevated temperatures, salt precursors decompose rapidly to form the catalytic nanoparticles, which simultaneously facilitate the oxidation of neighboring carbon sites, resulting in an activated CC with multiscale defects, oxygen-containing functional groups, and nanoparticles based on metal/metal oxide. In this process, both high temperatures from carbothermal shock and metal salt precursors are indispensable, as the former ensures effective carbon oxidation reaction while the latter provides the catalytic substance. The authors' method can be extended to many carbon materials, thereby offering a facile, efficient, and universal strategy for surface engineering toward a range of applications. [ABSTRACT FROM AUTHOR]

Solid-state electrolytes (SSEs) have been widely considered as enabling materials for the practical application of lithium metal anodes. However, many problems inhibit the widespread application of solid state batteries, including the growth of lithium dendrites, high interfacial resistance, and the inability to operate at high current density. In this study, we report a three-dimensional (3D) mixed electron/ion conducting framework (3D-MCF) based on a porous-dense-porous trilayer garnet electrolyte structure created via tape casting to facilitate the use of a 3D solid state lithium metal anode. The 3D-MCF was achieved by a conformal coating of carbon nanotubes (CNTs) on the porous garnet structure, creating a composite mixed electron/ion conductor that acts as a 3D host for the lithium metal. The lithium metal was introduced into the 3D-MCF via slow electrochemical deposition, forming a 3D lithium metal anode. The slow lithiation leads to improved contact between the lithium metal anode and garnet electrolyte, resulting in a low resistance of 25 O cm2. Additionally, due to the continuous CNT coating and its seamless contact with the garnet we observed highly uniform lithium deposition behavior in the porous garnet structure. With the same local current density, the high surface area of the porous garnet framework leads to a higher overall areal current density for stable lithium deposition. An elevated current density of 1 mA/cm2 based on the geometric area of the cell was demonstrated for continuous lithium cycling in symmetric lithium cells. For battery operation of the trilayer structure, the lithium can be cycled between the 3D-MCF on one side and the cathode infused into the porous structure on the opposite side. The 3D-MCF created by the porous garnet structure and conformal CNT coating provides a promising direction toward new designs in solid-state lithium metal batteries. [ABSTRACT FROM AUTHOR]

The increasing demands for efficient and clean energy-storage systems have spurred the development of Li metal batteries, which possess attractively high energy densities. For practical application of Li metal batteries, it is vital to resolve the intrinsic problems of Li metal anodes, i.e., the formation of Li dendrites, interfacial instability, and huge volume changes during cycling. Utilization of solid-state electrolytes for Li metal anodes is a promising approach to address those issues. In this study, we use a 3D garnet-type ion-conductive framework as a host for the Li metal anode and study the plating and stripping behaviors of the Li metal anode within the solid ion-conductive host. We show that with a solid-state ion-conductive framework and a planar current collector at the bottom, Li is plated from the bottom and rises during deposition, away from the separator layer and free from electrolyte penetration and short circuit. Owing to the solid-state deposition property, Li grows smoothly in the pores of the garnet host without forming Li dendrites. The dendrite-free deposition and continuous rise/fall of Li metal during plating/stripping in the 3D ion-conductive host promise a safe and durable Li metal anode. The solid-state Li anode shows stable cycling at 0.5 mA cm-2for 300 h with a small overpotential, showing a significant improvement compared with reported Li anodes with ceramic electrolytes. By fundamentally eliminating the dendrite issue, the solid Li metal anode shows a great potential to build safe and reliable Li metal batteries. [ABSTRACT FROM AUTHOR]

The synthesis of nanoscale metal compound catalysts has attracted much research attention in the past decade. The challenges of preparation of the metal compound include the complexity of the synthesis process and difficulty of precise control of the reaction conditions. Herein, we report an in situ synthesis of nanoparticles via a high-temperature pulse method where the bulk material acts as the precursor. During the process of rapid heating and cooling, swift melting, anchoring, and recrystallization occur, resulting in the generation of high-purity nanoparticles. In our work, the cobalt boride (Co2B) nanoparticles with a diameter of 10-20 nm uniformly anchored on the reduced graphene oxide (rGO) nanosheets were successfully prepared using the high temperature pulse method. The as-prepared Co2B/rGO composite displayed remarkable electrocatalytic performance for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). We also prepared molybdenum disulfide (MoS2) and cobalt oxide (Co3O4) nanoparticles, thereby demonstrating that the high-temperature pulse is a universal method to synthesize ultrafine metal compound nanoparticles. [ABSTRACT FROM AUTHOR]

Lithium metal anode with the highest capacity and lowest anode potential is extremely attractive to battery technologies, but infinite volume change during the Li stripping/plating process results in cracks and fractures of the solid electrolyte interphase, low Coulombic efficiency, and dendritic growth of Li. Here, we use a carbonized wood (C-wood) as a 3D, highly porous (73% porosity) conductive framework with well-aligned channels as Li host material. We discovered that molten Li metal can infuse into the straight channels of C-wood to form a Li/C-wood electrode after surface treatment. The C-wood channels function as excellent guides in which the Li stripping/plating process can take place and effectively confine the volume change that occurs. Moreover, the local current density can be minimized due to the 3D C-wood framework. Therefore, in symmetric cells, the as-prepared Li/C-wood electrode presents a lower overpotential (90 mV at 3 mA⋅cm-2), more-stable stripping/plating profiles, and better cycling performance (~150 h at 3 mA⋅cm-2) compared with bare Li metal electrode. Our findings may open up a solution for fabricating stable Li metal anode, which further facilitates future application of high-energy-density Li metal batteries. [ABSTRACT FROM AUTHOR]

The article offers information on a study which examined anisotropic thermal management capabilities of cellulose nanofibrils fabricated nanowood. It mentions that a simple approach is developed for preparation of thermally insulating bulk material through direct chemical treatment of nanowood. It shows that the thermal management, low mass density, and high mechanical strength of the nanowood make the material attractive for thermal insulation applications.