Sodiophilic three-dimensional carbon skeleton derived from polyacrylonitrile@zeolitic imidazolate framework fiber for dendrite-free sodium metal anode

Albeit with natural abundance, appealing theoretical capacity and low electrode potential merits, infinite volume expansion and notorious Na dendrite still hamper the implementation of sodium metal batteries (SMBs) based on Na metal anode chemistry. Herein, we prepare a 3D sodiophilic polyacrylonitrile@zeolitic imidazolate framework (PAN@ZIF) derived carbon fiber (PZC) host, targeting at enhancing Na ion deposition kinetics and reversibility. Asymmetric cell with PZC electrode yields a low nucleation potential and impressive rate capability. Symmetric cell based on Na@PZC electrode is able to achieve a superior cycling life over 4600 h at 1 mA cm(-2), 1 mAh cm(-2). Even at 5 mA cm(-2), 5 mAh cm(-2), a remarkable cycling life over 2500 h is obtained for the Na@PZC electrode. In addition, sodiophilic characteristics of the PZC host are well uncovered by the electrochemical and DFT analyses. Meanwhile, in-situ optical microscopy and SEM results clearly unravel a stable Na ion dynamic deposition process on the Na@PZC electrode surface, thereby leading to a nearly dendrite-free morphology. Assembled with a 3D printed NVP cathode (similar to 16.3 mg cm(-2)), Na@PZC anode demonstrates a high reliability in SMBs, thus making 3D PZC host a promising strategy for regulating Na metal interface stability.

Automated summary

Volume expansion and dendrite formation remain challenges for sodium metal batteries. However, a 3D carbon fiber host with sodiophilic characteristics can enhance sodium ion deposition kinetics and reversibility, leading to improved performance.