Self-supporting titanium carbide and nitride modified electrodes for lithium metal batteries

Abstract

Lithium metal batteries are currently at the forefront of global research, driven by their remarkable attributes such as an incredibly low redox potential and an exceptionally high theoretical energy density. However, their widespread commercialization is impeded by persistent issues surrounding poor cycle stability and safety concerns, primarily arising from the unregulated growth of lithium dendrites. Lithiophilic titanium carbide and nitride modified threedimensional frameworks are herein constructed and tested as lithium metal scaffolds. A TiC-modified 3D carbon network has been designed and prepared via a simple and lowcost carbonisation method as a lithium metal host to suppress the formation of lithium dendrites in lithium metal batteries. The lithiophilic TiC can effectively increase the affinity between the entire 3D carbon electrode and lithium, reducing the local current density and providing a large number of lithium metal nucleation sites to induce a uniform distribution and deposition of lithium metal. Consequently, well-distributed TiN nanoparticles, with higher conductivity than that of TiC, on the same carbon skeleton was designed as a self-supporting lithiophilic 3D host via a facile nitriding method. The obtained TiN@C hosts have a dual-functional intrinsic advantage of incorporating the homogenously distributed lithophilic nucleation sites and formation of a favourable Li3N-rich SEI layer with high ionic conductivity. Firstly, there is an abundance of strongly bound TiN nanoparticles on the surface of carbon skeleton, which enhances the affinity to Li, explained by first-principles calculations, thus ensuring a well-regulated Li nucleation/growth. Meanwhile, a Li3N-rich SEI layer can be formed in situ in the TiN@C system via electrochemically converting TiN into Li3N, thus improving its Li ionic conductivity. Benefiting from the synergistic effect of both the 3D skeleton and TiN modification, the assembled TiN@C electrodes achieve a dendrite-free morphology even at a really high capacity of 20 mA h cm-2 and effectively accommodate the volume expansion. To further advance the scalability and explore the utilization of TiN in lithium metal electrodes, the TiN modification was maintained in subsequent work, while substituting the carbon substrate with lighter and thinner MXene films to further improve the energy density of the whole lithium metal anode. As expected, the distribution of TiN nucleation seeds within the MXene framework effectively reduces the Li nucleation overpotential and enables uniform and dense lithium deposition.

More information

Identifiers

ORCID for Andrew Hector: orcid.org/0000-0002-9964-2163

ORCID for Andrea Russell: orcid.org/0000-0002-8382-6443

Catalogue record

Export record