A sodiophilic carbon cloth decorated with Bi-MOF derived porous Bi@C nanosheets for stable Na metal anode

Sodium (Na) metal anode has been considered as the promising candidate for next generation high-energy-density rechargeable batteries such as Na-S, Na-O-2 and Na-CO2, owing to its high specific capacity, low electrode potential and low cost. Unfortunately, some intractable problems hinder the practical application, including volume change and dendrite formation induced by inhomogeneous Na nucleation. Herein, 3D carbon cloth (CC) supporting Bi-MOF derived carbon nanosheets containing Bi nanoparticles and carbon shells (CC@Bi@C) were prepared to serve as Na deposition/dissolution hosts, integrating high surface area and favorable sodiophilicity. Due to the existence of Bi sodiophilic sites, Na nucleation and deposition can be induced, rendering uniform and dendrite-free morphology. Moreover, the 3D carbon framework can effectively reduce the current density and uniform distribution of Na+ flux, solving the uncontrolled Na dendrite growth. As a result, the CC@Bi@C parallel to Na half cell operating at 1 mA cm(-2) for 1 mA h cm(-2) exhibits 99.85% Coulombic efficiency for nearly 500 cycles. The symmetric cell maintains stable cycle for more than 300 h at 2 mA cm(-2) for 2 mA h cm(-2) with low overpotential. When paired a full cell with Na3V2 (PO4)(3) cathode, CC@Bi@C anode exhibits a stable capacity of 103.4 mA h g(-1) at 1C (1 C = 117 mA h g(-1)) over 150 cycles for 95.5% capacity retention with high CE of 99.0%. This work provides a facile strategy to inhibit dendrite growth and uniform Na deposition.

Automated summary

The study developed a 3D carbon cloth supporting Bi-MOF derived carbon nanosheets to inhibit dendrite growth and uniform sodium deposition in sodium metal batteries, achieving enhanced cycling stability and Coulombic efficiency.