Preparation of hard carbon/carbon nitride nanocomposites by chemical vapor deposition to reveal the impact of open and closed porosity on sodium storage

Closed Pores can store Sodium

Konstantin was able to synthetically switch the porosity of hard carbons. By using CVD, he could intentionally close open pores to create closed pore materials - thus revealing the impact on sodium storage within batteries.
Preparation of hard carbon/carbon nitride nanocomposites by chemical vapor deposition to reveal the impact of open and closed porosity on sodium storage
Foto: ©2021 The Author(s). Published by Elsevier Ltd.
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The sodium-ion battery is a promising successor for the lithium-ion battery. Its energy density is limited by the anode, where sodium ideally is stored at low potentials vs. Na/Na+. The understanding of the fundamental relationships between material properties and sodium storage is often lagging behind materials development. There is a discord regarding the involvement of so-called “closed pores” in carbons in sodium storage. To investigate their influence, a chemical vapor deposition (CVD) process to deposit polymeric carbon nitride (p-C3N4) on hard carbon fibres of both, open and closed microporosity, is developed. High storage capacity at a low potential is only possible, when suitable, sealed pores are present. In fibers without notable gas-accessible surface, p-C3N4 is deposited on the external area, whereas in open-microporous samples the p-C3N4 phase grows in micropores. Consequently, except for the untreated fibres with closed pores, the composite with a pore gradient along the fibers is the only one in the study that is able to accommodate sodium at low potentials. Neither the remaining graphitic domains, nor the introduced p-C3N4 are able to accommodate sodium in a quasimetallic state. Finally, not only the sodium storage but also the solid-electrolyte interphase (SEI) build-up is influenced by the additional p-C3N4 layer.

Preparation of hard carbon/carbon nitride nanocomposites by chemical vapor deposition to reveal the impact of open and closed porosity on sodium storage

https://www.sciencedirect.com/science/article/pii/S0008622321009428Externer Link