Title : Approaching Ultrastable High-Rate Li–SBatteries through Hierarchically Porous Titanium Nitride Synthesized by Multiscale PhaseSeparation

Author : Won-Gwang Lim, Changshin Jo, AraCho, Jongkook Hwang, Seongseop Kim, Jeong Woo Han, and Jinwoo Lee

Journal : Adv. Mater. 2019, 31, 1806547 

Abstract : Porousarchitectures are important in determining the performance oflithium–sulfur batteries (LSBs). Among them,multiscale porous architecuturesare highly desired to tackle the limitations of single-sized porousarchitectures, and to combine the advantages of different pore

scales. Althougha few carbonaceous materials with multiscale porosity are employed in LSBs,their nonpolar surface properties cause the severe dissolution of lithiumpolysulfides (LiPSs). In this context, multiscale porous structure design ofnoncarbonaceous materials is highly required, but has not been exploited in LSBs yet because of the absence of a facile method to control themultiscale porous inorganic materials. Here, a hierarchically porous titaniumnitride (h-TiN) is reported as a multifunctional sulfur host, integrating theadvantages of multiscale porous architectures with intrinsic surface propertiesof TiN to achieve high-rate and long-life LSBs. The macropores accommodate thehigh amount of sulfur, facilitate the electrolyte penetration andtransportation of Li+ ions, while the mesopores effectively prevent the LiPS dissolution. TiN strongly adsorbs LiPS, mitigates the shuttle effect, and promotes the redox kinetics. Therefore, h-TiN/S shows a reversible capacity of557 mA h g−1 evenafter 1000 cycles at 5 C rate with only 0.016% of capacity decay per cycle.