Engineering of Siloxanes for Stabilizing Silicon Anode Materials.

Silicon (Si) is considered the most promising anode material for the next generation of lithium-ion batteries (LIBs) because of its high theoretical specific capacity and abundant reserves. However, the volume expansion of silicon in the cycling process causes the destruction of the electrode structure and irreversible capacity loss. As a result, the commercial application of silicon materials is greatly hindered. In recent years, siloxane-based organosilicon materials have been widely used in silicon anode of LIBs because of their unique structure and physical and chemical properties, and have shown excellent electrochemical properties. The comprehensive achievement of siloxanes in silicon-based LIBs can be understood better through a systematic summary, which is necessary to guide the design of electrodes and achieve better electrochemical performance. This paper systematically introduces the unique advantages of siloxane materials in electrode, surface/interface modification, binder, and electrolyte. The challenges and future directions for siloxane materials are presented to enhance their performance and expand their application in silicon-based LIBs.

Flexible aqueous supercapacitors with excellent cycling performance and high-energy density based on mesocrystalline NiCo-LDHs.

Flexible aqueous supercapacitors are promising candidates as safe power sources for wearable electronic devices (WEDs). However, the absence of advanced electrode materials with high structural stability has become the most critical factor hindering the development, which is closely related to the poor interface combination between the active substances and flexible collectors. Herein, a unique rigid layered double hydroxide (LDH) nanorod array with the mesocrystalline feature is created using the NiO-Ni layer as the inducer by the electrodeposition strategy. Differing from the traditional NiCo-LDH nanosheets directly grown on a carbon cloth, an elaborately designed NiO-Ni buffer can simultaneously and effectively improve the bidirectional combination with active substances and collectors, also the mesocrystalline LDH showed enhanced intrinsic stability through the reinforcing effect of grain boundaries. Benefiting from these, the assembled supercapacitor exhibited pre-eminent cycle stability (increased from 64% of the initial capacity after 10 000 cycles to no significant attenuation after 50 000 cycles) and ultrahigh energy density. When it was used as a flexible device, a remarkable energy density of 70.4 W h kg-1 could be harvested and processed with high flexibility in the bending state and good temperature adaptability. This study provides an excellent design strategy for the development of next-generation flexible supercapacitors with the goal of better comprehensive performances.

Achieving Ultrahigh Energy-Density Aqueous Supercapacitors via a Novel Acidic Radical Adsorption Capacity-Activation Mechanism in Ni(SeO3 )/Metal Sulfide Heterostructure.

Transitional metal chalcogenide (TMC) is considered as one promising high-capacity electrode material for asymmetric supercapacitors. More evidence indicates that TMCs have the same charge storage mechanism as hydroxides, but the reason why TMC electrode materials always provide higher capacity is rare to insight. In this work, a Nix Coy Mnz S/Ni(SeO3 ) (NCMS/NSeO) heterostructure is prepared on Ni-plated carbon cloth, validating that both NCMS and NSeO can be transformed into hydroxides in electrochemical process as accompanying with the formation of SeO3 2- and SOx 2- in confined spaces of NCMS/NSeO/Ni sandwich structure. Based on density functional theory calculation and experimental results, a novel space-confined acidic radical adsorption capacity-activation mechanism is proposed for the first time, which can nicely explain the capacity enhancement of NCMS/NSeO electrode materials. Thanks to the unique capacity enhancement mechanism and stable NCMS/NSeO/Ni sandwich structure, the optimized electrodes exhibit a high capacity of 536 mAh g-1 at 1 A g-1 and the impressive rate capability of 140.5 mAh g-1 at the amazing current density of 200 A g-1 . The assembled asymmetric supercapacitor achieves an ultrahigh energy density of 141 Wh Kg-1 and an impressive high-rate capability and cyclability combination with 124% capacitance retention after 10 000 cycles at a large current density of 50 A g-1 .