Sputtered Titanium Nitride Catalysts on Sulfur Hosts and Current Collectors for Lithium–Sulfur Batteries

Abstract

Lithium–sulfur batteries (LSBs) offer high theoretical capacities (1675 mAh g−1) and are a strong prospect for next-generation energy storage, but their performance is heavily limited by the polysulfide shuttle effect and slow redox kinetics. In this study, ultrathin layers of titanium nitride (TiN) were deposited by physical vapor deposition (PVD) onto multi-walled carbon nanotubes (MWCNTs) and aluminum current collectors to evaluate their effectiveness as a catalytic coating. The cells fab ricated with TiN-coated current collectors delivered superior discharge capacities of 1261.8 and 920.3 mAh g−1 at 0.1 and 0.5 C, respectively, significantly outperforming the reference cells (1010.1 and 770.8 mAh g−1), indicating enhanced interfacial con ductivity and sulfur utilization. Modification of the MWCNT sulfur host material with TiN coatings also improved electrochemical performance, with TiN@MWCNT cathodes showing increased initial discharge capacities of 1088.9 mAh g−1 for a ∼3 nm TiN layer and 1183.1 mAh g−1 for a ∼6 nm layer at 0.1 C, compared to the uncoated MWCNT reference (1010.1 mAh g−1 ), and consistently delivering higher capacities throughout extended cycling. An initial voltage decay was observed only in the TiN-modified MWCNT electrodes, after which the voltage profiles gradually stabilized over subsequent cycles, indicating an activation period associated with the TiN@MWCNT architecture. While PVD proved effective for both the planar aluminum current collector and the nanoscale MWCNT host, the fabrication of uniform TiN coatings was considerably more straightforward on the flat current col lector surface, suggesting that nanotube–based architectures warrant further study using PVD-optimized or alternative coating strategies. Overall, the results highlight TiN as a promising interfacial modifier for LSBs.