Regulating Sodium Deposition through Gradiently‐Graphitized Framework for Dendrite‐Free Na Metal Anode

Abstract

Na metal anode (NMA) is one of the most promising candidate materials for next‐generation low‐cost sodium metal batteries. However, the preferred deposition of Na metal at the anode/separator interface increases the risk of dendrite penetration of the separator, consequently, reduces safety and life of batteries with NMA. In this study, a Na deposition‐regulating strategy is shown by designing a gradiently graphitized 3D carbon fiber (CF) framework as host (grad‐CF), whereby Na is guided to deposit preferentially at the bottom of the anode, safely away from the separator. The obtained Na anode significantly reduces the probability of dendrite‐induced short circuits. The grad‐CF host enables NMA stable cycling at a high current density of 6 mA cm−2. When the Na@grad‐CF is applied as anode in full cells pared with Na3V2(PO4)3 (NVP) cathode, it exhibits a reversible capacity of 73 mA h g−1 after 500 cycles with a low decay rate of 0.13%.

A simple and effective host for sodium metal anode: a 3D-printed high pyrrolic-N doped graphene microlattice aerogel

“…4h and i show the comparison between our work and the representative graphene-based 7,25,43,44,57,67–69 and other hosts for Na metal anodes. 26,60,63,70–79 It is clear to see that our specially designed 3DP-NGA electrode exhibits relatively good cycle performance, including high CE and long cycle stability even at high areal current densities with large areal capacities.…”

Gradient Designs for Efficient Sodium Batteries

“…Figure 6c,d gives such a case where a gradient 3D carbon framework has been used to form a "bottom-up" gradient of conductivity. 75 This electrode induces the preferential deposition of Na at the electrode bottom. With such a gradient, Na// NVP full cells sustain stable performance up to 500 cycles, demonstrating its great potential in regulating sodium metal electrochemistry.…”

“…(e) Discharge capacities of Na@PRST-CF||NVP, Na@homo-CF||NVP, and Na@G-CF||NVP batteries at a current density of 1 mA cm –2 for 500 cycles. Reproduced with permission from ref . Copyright 2022 Wiley-VCH.…”

“…Under the influence of an electric field, sodium would preferentially deposit at the bottom of the electrode as it is more electrically conductive. Figure c,d gives such a case where a gradient 3D carbon framework has been used to form a “bottom-up” gradient of conductivity . This electrode induces the preferential deposition of Na at the electrode bottom.…”

3D Carbon Materials for High-Performance Electric Energy Storage Facilities

“…The composite anode, CNT@grad-Ag/Na, demonstrated a high cyclic stability of more than 1000 h at a high charging/discharging current density of 8 mA cm –2 . Inspired by the successful attempt of a gradient buffer layer, our groups proposed another gradient CCC for the Na metal anode with the special controlling factor of graphitization degree . The precusor of the host was specially designed as polyacrylonitrile cloths with gradiently distributed Co salts alongside its thickness, which was prepared by a step-spinning process.…”