2D P-doped carbon nitride as an effective artificial solid electrolyte interphase for the protection of Li anodes

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Metallic lithium is crucial for advanced batteries but suffers from dendrite growth, limiting its use as an anode.
• A stable solid electrolyte interphase (SEI) is essential for controlling dendrite formation and improving the stability and cyclability of lithium metal anodes.

Purpose of the Study:

• To propose and evaluate an artificial protective layer of P-doped carbon nitride (CNP) for lithium metal anodes.
• To investigate the effect of this CNP layer on dendrite suppression, SEI stability, and battery performance.

Main Methods:

• A thin film of synthesized P-doped carbon nitride (CNP) was applied to the lithium anode surface via a drop-casting method to create an artificial SEI.
• Symmetric Li/Li cells were tested for cyclability and overpotential.
• Cycled electrodes were analyzed to understand anode degradation and SEI composition.
• CNP-modified anodes were integrated into Li-S coin cell batteries.

Main Results:

• CNP-modified Li/Li cells demonstrated excellent cyclability with low overpotentials (around 40 mV) over 500 cycles at 3 mA cm^-2.
• The modified anodes showed high capacity and retention in Li-S coin cells at a 1C current density.
• First-principles calculations confirmed that P-doping enhances lithium surface diffusion and promotes uniform lithium plating.

Conclusions:

• P-doped carbon nitride serves as an effective artificial SEI, significantly improving the stability and performance of lithium metal anodes.
• The CNP layer successfully suppresses lithium dendrite growth and enhances the cyclability of lithium metal batteries.
• This approach offers a promising strategy for developing next-generation high-energy-density batteries.