Freestanding TiO₂ Nanoparticle-Embedded High Directional Carbon Composite Host for High-Loading Low-Temperature Lithium–Sulfur Batteries

Abstract

Improving the low-temperature performance of lithium–sulfur batteries is significant for future applications. Meanwhile, a low temperature often leads to sluggish charge transfer kinetics and low energy output. Herein, we designed a thick freestanding TiO2 nanoparticle-embedded three-dimensional carbon composite (TiO2@C@CSC) host with high directional channels, aiming at achieving a high-performance low-temperature lithium–sulfur battery. The carbon-coated TiO2 nanoparticles (TiO2@C) are derived from polyimide-coated TiO2 nanoparticles and embedded in the channels. The chitosan-foam-derived carbon framework (CSC) has vertically aligned channels, which kinetically accelerates ion/electron transport and precisely confines sulfur/polysulfides within its channels. TiO2@C nanoparticles could facilitate the adsorption and conversion of polysulfides. The combination of vertically aligned channels and TiO2@C nanoparticles further provides a chemical gradient that prevents the diffusion of polysulfides and enhances the reaction kinetics at low temperatures. The designed host also has enough accommodation space, which is beneficial to improving the mass loading and utilization efficiency of active sulfur. Finally, the energy storage performance of TiO2@C@CSC as a sulfur host was investigated under 30, −20, and −40 °C. Under 30 °C, the initial discharge capacity of TiO2@C@CSC is 679 mAh g–1 at 1C with 4.0 mg cm–2 sulfur, and an initial capacity of 969 mAh g–1 could be obtained at 0.1C with the sulfur loading mass of 10.0 mg cm–2. Under −20 °C, the performance of TiO2@C@CSC with loading masses of 2.5, 5.0, 10.0, and 20.0 mg cm–2 was investigated, and the corresponding initial capacities at 0.05C were 1573, 924, 242, and 13 mAh g–1, respectively. As the temperature drops to −40 °C, the efficiency becomes lower but the charge–discharge process can still be complete. This work presents a promising direction for developing high-energy low-temperature lithium–sulfur batteries.

Design of Thick Electrodes with Vertical Channels for Aqueous Batteries: Experimental and Numerical Analysis

“…The design of thick electrodes has been extensively investigated in lithium-ion batteries. , Various template methods have been applied to construct ion transport channels for specific structures, including ice templating, − magnetic templating, , wood templating, , and templated phase inversion methods . For instance, Li et al utilized the ice template method to prepare a low-tortuosity thick electrode with fast lithium-ion transport kinetics, which greatly reduced the concentration polarization, delivering a superior area capacity of up to 14.8 mAh cm –2 at a high mass loading of 99.56 mg cm –2 .…”

Empowering Low-Temperature Lithium–Sulfur Batteries: Unlocking the Potential of Transition Metal Alloy-Based Cathode Materials

“…The consequences include a rise in internal resistance, a diminution in discharge capacity, and the detrimental electrical insulation of both elemental sulfur (S 8 ) and lithium polysulfides (LiPSs), further stifling operational efficiency. Furthermore, these batteries exhibit an inferior rate capability when subjected to low temperatures, a shortcoming linked to sluggish chemical kinetics during the iterative charging and discharging phases . Compounding these issues, substantial volumetric changes take place as a result of lithium sulfide (Li 2 S) deposition on the cathode surface, which not only diminishes the solubility but also leads to structural instability .…”