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SnS 2 /reduced graphite oxide (rGO) composite materials show great potential as high-performance anode candidates in sodium-ion batteries (SIBs) owing to their high specific capacities and power densities. However, the repeated formation/decomposition of the solid electrolyte interface (SEI) layer around composite anodes usually consumes additional sodium cations, resulting in poor Coulombic efficiency and decreasing specific capacity upon cycling. Therefore, in order to compensate for the large irreversible sodium loss of the SnS 2 /rGO anode, this study has proposed a facile strategy by implementing organic solutions of sodium-biphenyl/tetrahydrofuran (Na-Bp/THF) and sodium-naphthylamine/dimethoxyethane (Na-Naph/DME) as chemical presodiation reagents. Particularly, the storage stability of Na-Bp/THF and Na-Naph/DME in ambient air accompanied by their presodiation behavior on the SnS 2 /rGO anode has been investigated, and both reagents exhibited desirable ambient air-tolerant storage stability with favorable sodium supplement effects even after 20 days of storage. More importantly, the initial Coulombic efficiency (ICE) of SnS 2 /rGO electrodes could be controllably increased by immersing in a presodiation reagent for different durations. Consequently, with a facile chemical presodiation strategy of immersion in Na-Bp/THF solution for only 3 min in ambient air, the presodiated SnS 2 /rGO anode has exhibited an outstanding electrochemical performance with a high ICE of 95.6% as well as an ultrahigh specific capacity of 879.2 mAh g -1 after 300 cycles (83.5% of its initial capacity), highly superior to the pristine SnS 2 /rGO anode. This efficient and scalable presodiation strategy provides a new avenue for the prevailing application of other anode candidates in high-energy SIBs.

The development of high-efficiency, robust, and available electrode materials for oxygen evolution reaction (OER) and lithium-ion batteries (LIBs) is critical for clean and sustainable energy system but remains challenging. Herein, a unique yolk-shell structure of Fe 2 O 3 nanotube@hollow Co 9 S 8 nanocage@C is rationally prepared. In a prearranged sequence, the fabrication of Fe 2 O 3 nanotubes is followed by coating of zeolitic imidazolate framework (ZIF-67) layer, chemical etching of ZIF-67 by thioacetamide, and eventual annealing treatment. Benefiting from the hollow structures of Fe 2 O 3 nanotubes and Co 9 S 8 nanocages, the conductivity of carbon coating and the synergy effects between different components, the titled sample possesses abundant accessible active sites, favorable electron transfer rate, and exceptional reaction kinetics in the electrocatalysis. As a result, excellent electrocatalytic activity for alkaline OER is achieved, which delivers a low overpotential of 205 mV at the current density of 10 mA cm -2 along with the Tafel slope of 55 mV dec -1 . Moreover, this material exhibits excellent high-rate capability and excellent cycle life when employed as anode material of LIBs. This work provides a novel approach for the design and the construction of multifunctional electrode materials for energy conversion and storage., (© 2021 The Authors. Small published by Wiley-VCH GmbH.)

In this work, we demonstrate an interesting structural phase transition from SnS2/reduced graphene oxide to SnS/sulfur-doped graphene at a moderate calcination temperature of 500 °C under an inert atmosphere. It is discovered that SnS2 chemically bound to rGO with a weakened C-S bond is easier to break and decompose into SnS, whereas it is difficult for pure-phase crystalline SnS2 to experience phase transformation at this temperature. Moreover, the thin-layered structure of SnS2 and rGO is an important factor for the effective doping of the dissociated Sx into graphene. Density functional theory calculations also reveal the feasibility of the structural phase transition process. Morphology characterization shows that partial SnS maintains the original nanosheet structure (∼100 nm) and the others are decomposed into tiny nanoparticles (10-20 nm). A high S-doping amount reduces the irreversible lithium storage sites on graphene, and the first coulombic efficiency is as high as 81.7%. In addition, thin-layered and small-sized SnS can alleviate the structural damage caused by volume expansion and shrinkage; therefore, a high specific capacity of 893.9 mA h g-1 is retained after 100 cycles.

Materials with a low coefficient of thermal expansion (CTE) are extremely demanded in many fields, varying from microelectronics to space technology. Here we report a novel method to achieve low CTE, which differs essentially from the conventional way that uses additives with negative thermal expansion (NTE) to compensate for the positive CTE of the matrix. The stoichiometric Hf 0.87 Ta 0.13 Fe 2+ x ( x = 0) shows a giant NTE, which is gradually suppressed with increasing x and finally changed to near-zero thermal expansion (ZTE) at x ≈ 0.4. The excess Fe was suggested to form anti-site defects by occupying the 4f sites. As revealed by electron spin resonance (ESR) spectra, the weakened NTE is closely related to a slower ferromagnetic (FM) ordering process than observed at x = 0. In addition, the CTE can be further tuned by introducing an extra α-Fe phase to achieve a low CTE (e.g., 3.3 ppm/K for x = 1.0) with markedly enhanced mechanical properties, beneficial to applications.