Shuai Ran,Ji Qi,Xufeng Dong,Hao Huang,Min Qi,Wenjing Dong,Penghui Zhao,Zenghui Zhao,Jingyuan Yang
Controllable preparation of cross-linked mesoporous carbon materials on a large scale remains challenging. In the present work, a simple NaCl-assisted pyrolysis strategy is proposed here to efficiently convert closed pores into open pores in the pyrolysis products of 2-methylimidazole zinc salt nanoparticles/polyacrylonitrile (ZIF-8/PAN) electrospun fibers to prepare 1D cross-linked mesoporous N-rich carbon-based oxygen reduction reaction (ORR) electrocatalyst. The total specific surface area of micropores and mesopores was significantly increased from 162 m 2 /g to 1069 m 2 /g (mesopores: 704 m 2 /g). The ORR catalytic activity of open pore was superior to that of closed pore with more positive onset potential (0.96 vs . 0.85 V) and half-wave potential (0.79 vs . 0.72 V), larger limiting current density (5.23 vs . 3.62 mA cm −2 ) and electron transfer number (3.89 vs . 3.15). Such enhanced performance was attributed to the transformation from closed to open pores which greatly improved the mass transfer performance and the number of active sites.
It is a huge challenge to develop safe and stable lithium metal batteries with high energy density owing to the growth of Li dendrites. Herein, for the first time, an oxidized ZIF-8/polyacrylonitrile (OZPAN) fiber film is designed as a multifunctional interlayer for constructing a novel Li metal battery with superior performance. The excellent lithophilicity and uniform porous structure of the OZPAN interlayer could anchor and regulate Li-ion flux with high ionic conductivity (2.22 mS cm−1), high Li+ transference number (0.78) and homogeneous Li deposition. Therefore, the Li//Li symmetric cell exhibits ultralow overpotential (11 mV) with long-term cycling stability and dendrite-free Li deposition. Moreover, Li//LiFePO4 (LFP) full cell has an extremely high capacity (162 mA h g−1 at 1C, close to the theoretical specific capacity of LFP), outstanding rate performance and high coulombic efficiency (more than 94%) during 500 cycles. This study demonstrates a promising interlayer strategy for developing high-performance Li metal batteries.
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