Unveiling the Working Mechanism of g-C₃N₄ as a Protection Layer for Lithium- and Sodium-Metal Anode

Abstract

The practical application of lithium-/sodium-metal batteries is currently hindered by severe safety issues caused by uncontrolled continuous dendrite growth. Semiconductive nanoporous g-C3N4 film has been demonstrated to be an effective protection layer for lithium-/sodium-metal anode, which can suppress the growth of dendrite. However, the underlying mechanism of how this semiconductive flexible thin film works to suppress dendrite growth remains unclear. In this work, we investigate the detailed working mechanism of g-C3N4 protection layer employing both density functional theory calculations and ab initio molecular dynamics simulations. The calculation results indicate that g-C3N4 layers show strong adhesion toward the lithium-/sodium-metal surface. When contacting with lithium/sodium metal, the intrinsic triangular nanopores of g-C3N4 will be quickly filled with lithium/sodium atoms, turning the semiconductive g-C3N4 into a metallic material. Lithium/sodium atoms can migrate through the triangular nanopores of stacked g-C3N4 layers via a vacancy-mediated approach with moderate energy barriers of 0.42 and 0.61 eV, respectively. With a low current density, the newly deposited lithium/sodium atoms can permeate through the g-C3N4 protection layers, therefore resulting in a flat electrode surface with no dendrite; with a high current density, however, the newly deposited lithium/sodium atoms cannot transport across the protection layer timely, which will result in the aggregation of lithium/sodium atoms on the surface of the g-C3N4 protection layer.

Conformal carbon nitride thin film inter-active interphase heterojunction with sustainable carbon enhancing sodium storage performance

“…In these regards, carbon nitride (CN) is a promising material for artificial interphase due to its low electrical conductivity, high thermal stability, and ionic conductivity, as previously reported. [24][25][26][27][28][29][30][31] Moreover, CN itself is not an active material for sodium storage, 32 making it an even better candidate to be employed as a passivation layer. The in-plane structural pores (0.68 nm) might enable the diffusion of sodium ions while simultaneously blocking the negative counter ions.…”

Interaction Mechanisms Between Nitrogen‐Containing Groups and Alkali Metals with Molecular Model System of HATCN**

“…[3b,19] Nano-porous and highly lithiophilic/sodiophilic g-C 3 N 4 has emerged as an effective artificial protective layer in this context. [20] Moreover, flexible and mechanically stable polymers containing nitrogen functional groups are also favored, such as polythiourea, [21] and polyacrylonitrile. [22] While recent studies have shown significant improvements in battery performance using nitrogen-containing materials, the relevant studies are still rare and result-oriented which primarily concentrate on battery performance, giving less emphasis to comprehending the fundamental interactions between AMAs and those protective materials.…”

Au NP-Decorated g-C3N4-Based Photoelectochemical Biosensor for Sensitive Mercury Ions Analysis

“…Choosing appropriate photoelectric materials is the key to constructing a highly sensitive PEC sensing platform. Among numerous photoelectric materials, graphitic-like carbon nitride (g-C 3 N 4 ) has a band gap of 2.7 eV, which has attracted wide attention due to g-C 3 N 4 ’s excellent chemical stability, adjustable electronic structure, low price, convenient synthesis, and lack of toxicity. − Unfortunately, the photoelectric performance of g-C 3 N 4 is limited by the quick recombination rate of photogenerated electron–hole pairs and its low specific surface area. In order to improve the photoelectric performance of g-C 3 N 4 , many researchers have focused on modifying g-C 3 N 4 to boost the charge separation through element doping, sensitization, and semiconductor coupling. , In particular, a semiconductor modified with metal nanoparticles (NPs) could effectively improve the photoelectric performance of the semiconductor for two reasons.…”