N,O Co-Doped Carbon Spheres Enable Stable Anode-Less Sodium Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Anode-less sodium metal batteries (SMBs) offer high energy density and low cost but face challenges with sodium dendrite formation and inactive sodium.
• Developing stable and efficient nucleation strategies is crucial for practical SMB applications.

Purpose of the Study:

• To engineer a stable, sodiophilic nucleation layer for anode-less SMBs to promote uniform sodium deposition.
• To investigate the role of heteroatom doping in enhancing sodium nucleation and guiding deposition.

Main Methods:

• Scalable synthesis of N,O co-doped carbon spheres (NOCS) via polymerization and pyrolysis.
• Electrochemical measurements, including plating/stripping cycling in symmetric and asymmetric cells.
• Sodium deposition morphology observation and density functional theory (DFT) calculations.

Main Results:

• NOCS layer significantly enhances Na+ adsorption and reduces nucleation overpotential, promoting homogeneous sodium deposition.
• NOCS-coated Cu electrodes demonstrate excellent cycling stability (>1000 cycles) in asymmetric and symmetric cells.
• Anode-less full cells with NOCS-modified Cu foil exhibit high initial capacity and good capacity retention.

Conclusions:

• N,O co-doping of carbon spheres provides an effective strategy for creating a stable nucleation layer in anode-less SMBs.
• This approach paves the way for the practical application of high-performance, low-cost anode-less sodium metal batteries.