Sulfur–Carbon Electrode with PEO‐LiFSI‐PVDF Composite Coating for High‐Rate and Long‐Life Lithium–Sulfur Batteries

Abstract

To address the problem of the serious capacity fading in lithium–sulfur batteries, a multi‐functional PEO(polyethylene oxide)/LiFSI (lithium bis(fluorosulfonyl)imide)/PVDF (polyvinylidene fluoride) (PLP) gel polymer electrolyte is exploited by coating PLP on a carbon nanotubes (CNTs) based sulfur cathode (PLP‐S/CNTs) with a controlled thermal annealing process. The annealing process leads to the conformal infusion of PLP through the matrix of S/CNTs with retaining the amorphous phase of the PLP, which enhance the rate performance compared to the bare S/CNTs. The PLP coating drives the transformation of more elemental sulfur to Li2S2/Li2S without forming intermediary product by restraining soluble‐polysulfides formation. Furthermore, the PLP coating successfully inhibits the dissolution of Li2Sx (x > 4) in PEO and prevents the loss of active material in the cathode, which is confirmed by density functional theory calculations. Comprehensively, the PLP coating applied to the surface of the S/CNTs cathode exhibit significantly suppressed shuttle effect and greatly improve long‐term cycle stability of the lithium–sulfur battery. The synthesized PLP‐coated S/CNTs composite cathode demonstrates a high specific capacity of 573.6 mAh g−1 at a current density of 0.5 C after 1 000 cycles, even achieving 318.1 mAh g−1 at an extremely high C‐rate (6 C). which is unprecedented performance among the reported studies on coating technology.

Tailoring a multi-system adaptable gel polymer electrolyte for the realization of carbonate ester and ether-based Li-SPAN batteries

“…Therefore, competitive solvation potential (Δ P = Δ E SE − Δ E CE ) is applied to compare the adsorption energy and cohesion strength of Li 2 S x to evaluate the adsorption ability and stability. According to previous studies, 62–64 the value of Δ E CE increases with the number of cluster aggregates ((Li 2 S n ) x , n = 2, 4, 6, 8, and x = 1, 2, 6), and Δ E CE of ((Li 2 S n ) 6 , n = 2, 4, 6, 8) are 1.80398, 1.0063, 0.96771 and 1.0063, respectively. The negative Δ P indicates that the Li 2 S n molecule is facile to aggregate, resulting in a sluggish conversion reaction.…”

Mechanism of Bilayer Polymer-Based Electrolyte with Functional Molecules in Enhancing the Capacity and Cycling Stability of High-Voltage Lithium Batteries

“…It was notable that the σ i values of CSEs were lower than those of ASEs at the same temperature resulting from the high crystallinity of the PVDF substrate in CSEs. 31 Moreover, PVDF retained its crystal structure while PEO was in molten state at 60 °C, 33,34 which limited the σ i of the heterogeneous double-layer SPE. As the PEO matrix turns to be semimolten state above the glass transition temperature (60 °C), the subsequent electrochemical measurements would be conducted at 60 °C for high σ i values and desirable mechanical strength of the solid-state electrolyte.…”

Sorghum-derived porous carbon for outstanding green supercapacitors

“…Bamboo possesses excellent flexibility and mechanical durability owing to its well-connected microtexture and multichannel structure, which could be applied to synthesizing carbon with interconnected, multichannel and porous structures. 27,28 However, it is still necessary to search for new precursors, which are cheap, accessible and economically valuable.…”