Freestanding graphitic carbon nitride‐based carbon nanotubes hybrid membrane as electrode for lithium/polysulfides batteries

Abstract

Summary Lithium sulfur batteries have drawled worldwide attention in recent years, which benefit of its high‐density energetic, low cost, and environmental benignity. Nevertheless, the shuttle effect of polysulfides and resulting self‐discharge lead to capacity fade loss and poor electrochemical performance. Herein, graphitic‐carbon nitride/carbon nanotubes (g‐C3N4/CNTs) hybrid membrane is fabricated by the flow‐direct vacuum filtration process. The as‐prepared 3‐D freestanding g‐C3N4/CNTs membrane employed as positive current collector containing Li2S6 catholyte solution for lithium/polysulfides batteries. The fabricated g‐C3N4/CNTs provide a physical barriers and chemisorption resist polysulfide shuttling. Moreover, the conductive network constructed by CNTs can empower sulfur to be evenly distributed in the cathode and accelerates electron transport. Thus, to further prove the cooperative effect of g‐C3N4 and CNTs, the freestanding g‐C3N4/CNTs/Li2S6 electrode exhibits more stable electrochemical performance than CNTs/Li2S6 electrode, deliver the first discharge capacity of 876 mAh g−1 at 0.5 C and maintained at 633 mAh g−1 after 300 cycles. The sulfur mass in electrode was increased to 7.11 mg, and the g‐C3N4/CNTs/Li2S6 electrode also possess a high capacity retention of 75.5%. Meanwhile, g‐C3N4 modified CNTs can not only trap polysulfides by strong adsorption but also effectively inhibit the self‐discharge behavior of lithium/polysulfides batteries. As a consequence, the g‐C3N4/CNTs composites for lithium/polysulfides batteries are indicating an excellent electrochemical stability with a long‐term storage without obvious capacity degradation.

Designing conductive networks of hybrid carbon enables stable and long-lifespan cotton-fiber-based lithium–sulfur batteries

“…In recent years, researchers have employed various approaches to address these intractable problems, among which carbon-based conductive host materials provide a path to effectively promote the electrochemical performance of Li-S batteries. [16][17][18] For example, Cao et al 19 utilized an interconnected mesoporous carbon (MPC-1300) with a large surface area as a cathode additive. The effectiveness of the sulfur-conned technique has been exemplied in reports of graphene, graphene oxide, and other analogous nano-sized carbon materials.…”

Synergistic effect of titanium‐oxide integrated with graphitic nitride hybrid for enhanced electrochemical performance in lithium‐sulfur batteries

“…The cell with TOCN@S cathode delivers discharge capacities of 963, 907, 843, 804, 731, and 630 mAh g −1 at 0.1, 0.2, 0.3, 0.5, 1, and 2°C, respectively. And when the charge‐discharge rate is returned to 0.1°C, a reversible capacity of 953 mAh g −1 is recovered, showing the superior stability of TOCN@S. As schematic illustration of Figure 4E, the nitrogen groups of CN and polar structure TiO 2 could effectively suppress the dissolution of polysulfide and leading to restrain shuttle effect 35,47‐49 . In view of the synergy of advantages, TOCN exhibits superior electrochemical performance, especially ultra‐long cycling stability with high sulfur loading 50 .…”

“…And when the chargedischarge rate is returned to 0.1 C, a reversible capacity of 953 mAh g −1 is recovered, showing the superior stability of TOCN@S. As schematic illustration of Figure 4E, the nitrogen groups of CN and polar structure TiO 2 could effectively suppress the dissolution of polysulfide and leading to restrain shuttle effect. 35,[47][48][49] In view of the synergy of advantages, TOCN exhibits superior electrochemical performance, especially ultra-long cycling stability with high sulfur loading. 50 Moreover, as shown in Table 2, compared with other CN or various dimensional structures of TiO 2 to modify sulfur electrodes, the TOCN@S electrode has outstanding cycle life, which also illustrates the synergistic effect of chemisorption polysulfide by TOCN.…”

Confine sulfur in double-hollow carbon sphere integrated with carbon nanotubes for advanced lithium–sulfur batteries

“…2d). The characteristic peaks at 26° and 43° are attributed to the graphitic carbon [23], resulted due to the carbonization of the material at high temperatures. The characteristic peaks of the sublimed sulfur (PDF # 78-1889) can be observed in the S-DHCS/CNTs, confirming the presence of sulfur in the material.…”