A new nanocomposite formulation of the FeS-based anode for lithium-ion batteries is proposed, where FeS nanoparticles wrapped in reduced graphene oxide (RGO) are produced via a facile direct-precipitation approach. The resulting nanocomposite FeS@RGO structure has better lithium ion storage properties, exceeding those of FeS prepared without RGO sheets. The enhanced electrochemical performance is attributed to the robust sheet-wrapped structure with smaller FeS nanoparticles and synergetic effects between FeS and RGO sheets, such as increased conductivity, shortened lithium ion diffusion path, and the effective prevention of polysulfide dissolution.
Crosslinked polyacrylate is self-healed and reprocessed through rearrangement of networks based on catalyst-free dynamic exchange of aromatic Schiff base bonds.
Traditional interpenetrating polymer networks (IPNs) are not adaptable materials because the topological structure of the macromolecules cannot be changed, which limits their structural rearrangement, reprocessing, and recycling. Here in this work we present a strategy for preparing reversibly interlocking networks (RILNs) from two preformed immiscible polymer networks based on dynamic covalent chemistry. The frequently opening and closing of the single networks enabled by the exchange reactions of the embedded orthogonal dynamic covalent bonds and stronger intercomponent interaction mainly account for the formation of the interlocking topology architecture of the RILNs. The resultant RILNs are rather homogeneous, which not only possess stimulus-responsive adaptive performance like self-healing but also exhibit nonlinear improvement in static and dynamic mechanical properties. By taking advantage of the reversible bonding, more importantly, the RILNs can be unlocked reproducing the pristine single networks, and the relocking/unlocking cycling is allowed to proceed for multiple times, which are not available for IPNs as defined by their chemical nature. It is anticipated that the proposed methodology provides a new idea for producing multifunctional cross-linked polymers capable of repeated controlled degradation and regeneration.
Unlike most conventional anode materials, the newly developed TiNb2O7 (TNO) does not form a solid electrolyte interface (SEI) layer, which makes it safe for high power requiring lithium-ion batteries. In this paper, we demonstrated an SBA-15 confined synthetic approach to prepare TNO nanoparticles (S-TNO) with a small particle size around 10 nm and a large BET surface area of 79.5 m(2) g(-1). It is worth mentioning that this is the smallest size reported so far for TNO. In contrast, the TNO (L-TNO) synthesized without SBA-15 has a particle size above 100 nm and a BET surface area of only 4.3 m(2) g(-1). The S-TNO shows better lithium-ion storage properties than L-TNO. The excellent electrochemical performance of S-TNO is attributed to its small crystalline size, which not only provides a larger effective area for better contact between the electrode material and the electrolyte, but also reduces the rate-limiting Li diffusion path. Moreover, S-TNO shows a high Coulombic efficiency (above 98% over 300 cycles) and negligible increase of impedance after cycling, which confirms no SEI layer formation in the operational voltage (1-3 V) of TNO.
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