Crystal engineering of the nbo metal-organic framework (MOF) platform MOF-505 with a custom-designed azamacrocycle ligand (1,4,7,10-tetrazazcyclododecane-N,N',N'',N'''-tetra-p-methylbenzoic acid) leads to a high density of well-oriented Lewis active sites within the cuboctahedral cage in MMCF-2, [Cu2(Cu-tactmb)(H2O)3(NO3)2]. This MOF demonstrates high catalytic activity for the chemical fixation of CO2 into cyclic carbonates at room temperature under 1 atm pressure.

Si has been considered as a promising alternative anode for next-generation lithium ion batteries (LIBs), but the commercial application of Si anodes is still limited due to their poor cyclability. In this paper, we propose a new strategy to enhance the long-term cyclability of Si anode by embedding nano-Si particles into a Li(+)-conductive polymer to form a Si/polymer composite with core-shell structure, in which nano-Si cores act as active Li-storage phase and the polymeric matrix serves not only as a strong buffer to accommodate the volume change, but also as a protection barrier to prevent the direct contact of Si surface with electrolyte, so as to maintain the mechanical integrity of Si anode and suppress the repeated destruction and construction of solid electrolyte interphase (SEI) on the Si surface. To realize this strategy, we synthesize a Si/PPP (polyparaphenylene) composite simply by ball-milling the Si nanoparticles with PPP polymer that has n-doping activity. Our experimental results demonstrate that the thus-prepared Si/PPP composite exhibits a high capacity of 3184 mA h g(-1) with an initial coulombic efficiency of 78%, an excellent rate capability with a considerably high capacity of 1670 mA h g(-1) even at a very high rate of 16 A g(-1), and a long-term cyclability with 60% capacity retention over 400 cycles, showing a great prospect for battery application. In addition, this structural design could be adopted to other Li-storable metals or alloys for developing cycle-stable anode materials for Li-ion batteries.

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