The practical use of lithium−sulfur battery (LSB) is impeded by the excessive growth of Li dendrite in the anode and the dissolution of soluble intermediates (shuttle effect) in the cathode. In spite of efforts to overcome these issues, separate research in the anode and cathode fields could not tackle the problems of both electrodes simultaneously, limiting the realization of LSB. Herein, a bifunctional separator is fabricated by coating morphology-controlled NbN on a Celgard separator. The large surface area (67 m 2 g −1 ) and strong adsorptive surface of NbN effectively suppress the crossover of soluble intermediates to the anode side, and the captured sulfur species can be reactivated on the electrical conductive NbN surface to enhance the capacity. Most importantly, the improved mechanical strength and electrolyte wettability of separator by NbN functional layer suppress the growth of Li dendrite in anode. Consequently, even with sulfur loading of 4 mg cm −2 , the capacity decay per cycle reaches only 0.061% during 300 cycles at 1 C rate.
For practical use of Li metal anode, developing the stabilization method with simple fabrication steps is necessary. Here, biopolymer-based hybrid film with simple preparation steps extended the cycle life (>1000 h) under additive-free condition.
Traditionally, the manipulation of contact mechanisms has been adopted as the primary strategy to tailor the friction properties of surfaces. On the contrary, the detaching process involving the local deformation and failure at the interface has been considered relatively less important. Here, we present a new approach toward the friction control of amorphous carbon through the plasticity and resultant transition of deformation mode on nanopatterned surfaces. Depending on the topography of the nanopatterns, the mechanical responses of the surfaces alter from elastic fracture to plastic flow, through which the friction coefficient changes by a factor of 5 without manipulation of the intrinsic structure of the material.
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