An in-situ generated Bi-based sodiophilic substrate with high structural stability for high-performance sodium metal batteries

Sodium (Na) metal anode exhibits a potential candidate in next-generation rechargeable batteries owing to its advantages of high earth abundance and low cost. Unfortunately, the practical development of sodium metal batteries is inherently plagued by challenges such as the side reactions and the growth of Na dendrites. Herein we report a highly stable Bi-based sodiophilic substrate to stabilize Na anode, which is created by in-situ electrochemical reactions of 3D hierarchical porous Bi2MoO6 (BMO) micro spheres. BMO is initially transformed into the Bi nanoseeds embedded in the Na-Mo-O matrix. Subsequently, the Bi nanoseeds working as preferential nucleation sites through the formation of Bi-Na alloy enable the non-dendritic Na deposition. The asymmetric cells based on such BMO-based substrate can deliver a long-term cycling for 600 cycles at a large capacity of 4 mAh cm(-2) and for 800 cycles at a high current density of 10 mA cm(-2). Even at a high depth of discharge (66.67%), the Na-predeposited BMO (Na@BMO) electrodes can cycle for more than 1600 h. The limited Na@BMO anodes coupled with the Na3V2(PO4)(3) cathodes (N/P ratio of 3) in full cells also show excellent electrochemical performance with a capacity retention of about 97.4% after 1100 cycles at 2 C. (C) 2022 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

In this study, a highly stable Bi-based sodiophilic substrate is reported to stabilize the sodium metal anode, effectively addressing challenges associated with side reactions and dendrite growth. The experimental results demonstrate that the asymmetric cells based on this substrate exhibit excellent electrochemical performance.