Selenium-Doped Sulfurized Poly(acrylonitrile) Composites as Ultrastable and High-Volumetric-Capacity Cathodes for Lithium–Sulfur Batteries

Abstract

Lithium−sulfur (Li−S) batteries, despite their superior gravimetric energy density, are inferior to lithium-ion (Li-ion) batteries in terms of volumetric energy density because of the intrinsic low density of sulfur and the lightweight carbon host. Here, a new strategy is proposed to improve the volumetric capacity of sulfur cathode with selenium-doped sulfurized poly(acrylonitrile) (SPAN) as the electrode material. The introduction of Se not only accelerates the redox kinetics of sulfur conversion but also leads to dramatically enhanced active materials content and higher tap density of the electrode material. Consequently, the Se 0.4 SPAN composite delivers an impressive volumetric capacity of 1185 mAh cm −3 at 0.1 C, a high rate capability of 850 mAh cm −3 at 4 C, and excellent long-term stability over 500 cycles at 1 C. Self-discharge behavior and the shuttle effect are completely avoided due to the absence of soluble intermediates. Moreover, a remarkable volumetric energy density of 1537 Wh L cathode −1 is achieved based on the densification effect with a high cathode density (1.51 g cm −3 ), which is comparable to the metal oxide cathode of Li-ion batteries. This study demonstrates a promising way to overcome the bottlenecks of current Li−S technologies for high volumetric-energy-density rechargeable batteries.

Flower-Shaped Sulfurized Polyacrylonitrile Nanostructures as Cathode Materials for High-Performance Lithium–Sulfur Batteries

“…After cycling for 200 cycles, both the SPAN-P and SPAN-F cathodes exhibit significantly reduced R ct , suggesting the presence of the electrochemical activation process in the cathodes. A similar situation is also observed on other SPAN-based cathodes in the previous literature. ,, Moreover, the W 0 of SPAN-F3 after cycling is 65.4 Ω, which is very close to the value of the pristine SPAN-F3 cathode. In contrast, the W 0 of SPAN-P increases from 72.9 to 248.6 Ω after cycling, implying that SPAN-F is conducive to the formation of stable electrochemical interfaces during long-term cycling.…”

“…After coheating with sulfur at 330 °C, all four SPAN-F can retain their 3D configuration. Compared with the PAN-F precursor, SPAN-F exhibits thicker petals and larger particle size, attributing to the infiltration of sulfur species. − No agglomerated sulfur particles are discovered on the surfaces of SPAN-F, indicating that sulfur is well dispersed in the carbon skeleton rather than adhering to the surface. The sulfur contents of SPAN-F1, SPAN-F2, SPAN-F3, and SPAN-F4 are 48.12, 51.23, 52.80, and 50.87%, respectively (Table S1).…”

Sulfurized polyacrylonitrile as cathodes for advanced lithium–sulfur batteries: advances in modification strategies

“…Subsequently, from the angle of raising the volumetric energy density of the battery, they optimized the density of the cathode materials by doping Se into SPAN, and the Se 0.4 SPAN prepared exhibited a high volumetric energy density of 1537 W h L −1 . 71…”