Spherical Metal Oxides with High Tap Density as Sulfur Host to Enhance Cathode Volumetric Capacity for Lithium–Sulfur Battery

Abstract

Effective hosts of sulfur are essential for the application of lithium–sulfur batteries. However, various refined nanomaterials or carbon-based hosts possess low density, high surface area, and large porosity, leading to undesirable reduction on both gravimetric and volumetric energy densities. Herein, spherical metal oxides with high tap density are introduced as carbon-free hosts of sulfur for the first time. The ternary oxides show a superior synergistic effect of adsorption and electrocatalytic conversion of soluble intermediate polysulfides. Besides, oxide microspheres can build stable conductive frameworks and open channels in porous electrodes for fast transport of electrons and active diffusion of electrolyte. Such a synergistic effect and unique structural feature of porous electrodes are favorable for achieving good utilization and stable cycle performance of the sulfur cathode. Typically, the S/LiNi0.8Co0.1Mn0.1O2 composite exhibits good cycle stability with a low capacity decay rate (0.057% per cycle) during 500 cycles at 0.1 C. Importantly, due to the high tap density (1.81 g cm–3), the S/LiNi0.8Co0.1Mn0.1O2 composite delivers a larger volumetric capacity (1601.9 mAh cm–3 –composite), almost 2.3 times of S/carbon composite (689.4 mAh cm–3 –composite). Therefore, this work provides a feasible strategy to reach long life and high volumetric capacity of cathode based on metal oxides as sulfur hosts.

Strategy of Enhancing the Volumetric Energy Density for Lithium–Sulfur Batteries

“…More recently, heavy and catalytic metal compounds are introduced into carbon-free host materials to enhance the W V for Li-S battery, including NiFe 2 O 4 , [83] NiCo 2 O 4 , [31a] CoOOH, [82] LiNi 0.8 Co 0.1 Mn 0.1 O 2 , [62] RuO 2 , [84] La 0.8 Sr 0.2 MnO 3 , [31b] and Nb 18 W 16 O 93 ( Figure 5). [85] These heavy metal oxides not only benefit the fabrication of the compact cathode, but also help to supress the shuttle of soluble lithium polysulfides (LiPS) through the superior catalytic feature or adsorption ability.…”

“…[31c] Copyright 2019, American Chemical Society. e) Tap density of different sulfur-based composites with porous carbon, compact carbon, and carbon-free host materials: S/Ketjen black, [65b] S/Super P, [28] S/CNT, [83] S/Graphene sheet, [55] S/Spherical carbon, [28] S/Dense graphene, [66] S/NCM 811, [62] S/NiCo 2 O 4 , [31a] S/La 0.8 Sr 0.2 MnO 3 , [31b] S/CoOOH, [82] and S/rGO/VS 2 . [57] www.advmat.de www.advancedsciencenews.com sulfur-rich materials refer to sulfur compounds or derivatives that have a high percentage of sulfur atom in the molecules and simultaneously possess a similar electrochemical behavior to that of sulfur.…”

“…[ 31c ] Copyright 2019, American Chemical Society. e) Tap density of different sulfur‐based composites with porous carbon, compact carbon, and carbon‐free host materials: S/Ketjen black, [ 65b ] S/Super P, [ 28 ] S/CNT, [ 83 ] S/Graphene sheet, [ 55 ] S/Spherical carbon, [ 28 ] S/Dense graphene, [ 66 ] S/NCM 811, [ 62 ] S/NiCo 2 O 4 , [ 31a ] S/La 0.8 Sr 0.2 MnO 3 , [ 31b ] S/CoOOH, [ 82 ] and S/rGO/VS 2 . [ 57 ] f) Comparison of W V and W G between S/La 0.8 Sr 0.2 MnO 3 and sulfur/aligned carbon nanotubes (S/A‐CNT) cathodes.…”

Applications of transition-metal sulfides in the cathodes of lithium–sulfur batteries

“…In order to increase the sulfur loading and inhibit the dissolution of LiPSs into the electrolyte, carbon materials with meso-or micro-pores and multi-channel morphology were once used to physically limit the movements of LiPSs but failed to obtain satisfactory performance. Then, the polar nature of LiPSs was further utilized by constructing a polar surface on cathode materials to improve the adsorption of LiPSs, with additives or matrixes such as metal oxides [40][41][42][43], noble metals [44,45], metal carbides [46,47], N-doped carbon [48][49][50], polymers [51][52][53] and TMSs.…”

Synergy between Interconnected Porous Carbon-Sulfur Cathode and Metallic MgB2 Interlayer as a Lithium Polysulfide Immobilizer for High-Performance Lithium-Sulfur Batteries

“…Transition-metal oxide, carbide, nitrides, and sulfides are mainly identified as polar materials, which can easily adsorb the LPS on their surface by the Lewis acid–base reaction, unlike nonpolar carbonaceous materials. 11 , 12 The shuttle mechanism is only partially limited by chemical interactions using transition-metal oxides, nitrides, carbides and sulfides due to the less number of available sites for these materials, which therefore hamper the cycling capability of the Li-S battery. To improve the performance of the Li-S battery, new materials/chemistry should be explored.…”