Tungsten Nitride/Carbon Cloth as Bifunctional Electrode for Effective Polysulfide Recycling

Abstract

The inevitable dissolution, diffusion, and migration of polysulfides cause an irreversible loss of active material, leading to poor cyclic performance in lithium sulfur batteries. Herein, a freestanding tungsten nitride nanorod/carbon cloth (WN/CC) interlayer is prepared by hydrothermal growth to function as both current collector and physicochemical barrier to soluble lithium polysulfides (Li2S x ). The cells containing a dual-functional interlayer deliver a significantly improved initial discharge capacity of 1337 mAh g–1 with a reversible capacity of 814.2 mAh g–1 after 500 cycles at 100 mA g–1. The enhanced electrochemical performance is attributed to the highly adsorptive WN nanorods grown on conductive CC to entrap polysulfides, leading to effective recycling of active materials. The density functional theory (DFT) calculations prove important roles of the WN (200) surface in entrapping polysulfides through their strong adsorption energies (3.21–4.67 eV) with Li2S x and S8. The potential of the dual-functional WN/CC composite interlayer in improving the electrochemical performance of lithium sulfur batteries has not been reported previously.

Sandwiched Cathodes Assembled from CoS2‐Modified Carbon Clothes for High‐Performance Lithium‐Sulfur Batteries

“…The higher binding energy indicates the stronger chemical anchoring of soluble Li 2 S n . [61,72] The calculations match well with the visual adsorption test in Figure 2a, confirming the improved adsorption capability by coating CoS 2 on CC. The charge density of soluble Li 2 S n absorbed on CoS 2 and carbon are quite different owing to their diverse electrostatic affinities.…”

Hierarchically Porous Ti3C2 MXene with Tunable Active Edges and Unsaturated Coordination Bonds for Superior Lithium–Sulfur Batteries

“…The two cathodic peaks at 2.04 and 2.30 V of the 3D S/e-Ti 3 C 2 -2 cathode can be assigned to the conversion from S 8 to high-order soluble Li 2 S x and further reduction to insoluble Li 2 S 2 /Li 2 S. The anodic peaks at 2.32 and 2.37 V correspond to the multistep conversion of Li 2 S/Li 2 S 2 to LiPS and S 8 . 43 Compared with other electrodes, the S/e-Ti 3 C 2 -2 electrode displays the smallest polarizations and highest redox peaks, which indicates that they expedite sulfur kinetics. In order to demonstrate the improved Li + diffusion dynamics of different electrodes, the CV curves of S/3D e-Ti 3 C 2 -1, S/3D e-Ti 3 C 2 -2, S/3D e-Ti 3 C 2 -3, S/Ti 3 C 2 , and S/3D Ti 3 C 2 electrodes were measured at different scan rates (Figures S14a−c and S15a,b).…”

“…The CV curves of different cathodes were obtained in 1.7–2.8 V at 0.1 mV s –1 (Figure a). The two cathodic peaks at 2.04 and 2.30 V of the 3D S/e-Ti 3 C 2 -2 cathode can be assigned to the conversion from S 8 to high-order soluble Li 2 S x and further reduction to insoluble Li 2 S 2 /Li 2 S. The anodic peaks at 2.32 and 2.37 V correspond to the multistep conversion of Li 2 S/Li 2 S 2 to LiPS and S 8 . Compared with other electrodes, the S/e-Ti 3 C 2 -2 electrode displays the smallest polarizations and highest redox peaks, which indicates that they expedite sulfur kinetics.…”

Three-Dimensionally Ordered Macroporous ZnO Framework as Dual-Functional Sulfur Host for High-Efficiency Lithium–Sulfur Batteries

“…CV curves of both electrodes have two cathodic peaks and one anodic peak, corresponding to the conversion of S 8 to Li 2 S n (4 ≤ n ≤ 8), Li 2 S n to Li 2 S 2 /Li 2 S, followed by the reverse reaction with the formation of S 8 , respectively. According to the calculated slope of peak current vs. ν 0.5 , it is clear that S/3DOM ZnO has the higher Li + diffusivity, which further proves that 3DOM ZnO has high catalytic activity ( Figure 5 c,d) [ 38 ].…”