“Room-like” TiO<sub>2</sub> Array as a Sulfur Host for Lithium-Sulfur Batteries: Combining Advantages of Array and Closed Structures
Junling Guo, Siyuan Zhao, Yonglong Shen, Guosheng Shao, Fengxiang Zhang
Abstract
Polar oxides (POs) with array structures are widely utilized to enhance the performance of the sulfur cathode. However, the array structures with extensive open spaces are not able to trap as much lithium polysulfide species (LPSs) as closed structures, thus seriously limiting their sulfur-loading capacities. Consequently, it is highly desirable to identify alternative sulfur trapping architectures that can facilitate combined advantages of array and closed structures. Herein, we have designed a sulfur cathode based on a “room-like” TiO2 array (RTA) structure, which can not only provide an electron transport path similar to that in the array structures but also adsorb LPSs as efficient as closed structures. As a result, this cathode with a significant sulfur loading of 2.8 mg cm–2 was shown to enable remarkable utilization of sulfur together with an excellent cycle life. We also confirm that the inferior adsorption of LPSs in the array structure is not caused by insufficient adsorption sites but derives from the optimized direction of the concentration difference, which can make LPSs to exist for a longer time near host materials leading to reabsorption of dissociative LPSs. Our work offers a new avenue in enabling high sulfur loading essentials for realization of high energy density Li-S batteries.