Multifunctional Effects of Sulfonyl-Anchored, Dual-Doped Multilayered Graphene for High Areal Capacity Lithium Sulfur Batteries

Abstract

Li–S batteries (LSBs) require a minimum 6 mAh cm–2 areal capacity to compete with the state-of-the-art lithium ion batteries (LIBs). However, this areal capacity is difficult to achieve due to a major technical issue—the shuttle effect. Nonpolar carbon materials limit the shuttle effect through physical confinement. However, the polar polysulfides (PSs) only provide weak intermolecular interactions (0.1–0.7 eV) with these nonpolar carbon materials. The physically encapsulated PSs inside the nonpolar carbon scaffold eventually diffuses out and starts shuttling. Chemically interactive hosts are more effective at interacting with the PSs due to high binding energies. Herein, a multifunctional separator coating of nitrogen-doped multilayer graphene (NGN) and −SO3– containing Nafion (N-NGN) is used to mitigate PS shuttling and to produce a high areal capacity LSB. The Nafion is used as a binder instead of PVDF to provide an additional advantage of −SO3– to chemically bind the PS. The motive of this research is to investigate the effect of highly electronegative N and −SO3– (N-NGN) in comparison with the −OH, −COOH, and −SO3– groups from a hydroxyl graphene and Nafion composite (N-OHGN) to mitigate PS shuttling in LSBs. The highly conductive doped graphene architecture (N-NGN) provides efficient pathways for both electrons and ions, which accelerates the electrochemical conversion at high sulfur loading. Moreover, the electron-rich pyridine N and −SO3– show strong chemical affinity with the PS through polar–polar interactions, which is proven by the superior electrochemical performance and density functional theory calculations. Further, the N-NGN (5 h) produces a maximum areal capacity of 12.0 and 11.0 mAh cm–2, respectively, at 15 and 12 mg cm–2 sulfur loading. This areal capacity limit is significantly higher than the required areal capacity of LSBs for commercial application, which shows the significant strength of N-NGN as an excellent separator coating for LSBs.

Novel Lithium‐Sulfur Polymer Battery Operating at Moderate Temperature

“…[55] Furthermore, both DOL and DME solvents suffer from marked volatility which may be promoted by the challenging temperature value, whilst the target performance of this liquid electrolyte is achieved at 25 °C. [45][46][47]55] These data suggest the poor applicability of the DOL:DME solutions at high temperature, which, on the other hand, improves the performance of the PEGDME_CPE electrolyte.…”

“…To better evaluate the differences between the various electrolyte configurations, Figure 1 reports a comparison between solid PEO_PE [41] and PEGDME_CPE, and a DOL:DME_LE solution in terms of Li + transference number (t + ) measured at the optimal operative temperature of each medium (Figure 1a) and ionic conductivity at 50 °C (Figure 1b). In this work, the "optimal operative temperature" refers to the most adequate temperature value for allowing efficient operation in a LiÀ S cell depending on the employed solvent, that is, 25 °C for DOL:DME solutions, [23,[45][46][47] 50 °C for the PEGDME2000, [42] and 80 °C for PEO. [41] The DOL:DME_LE exhibits a significantly higher t + at room temperature compared to that of PEGDME_CPE at 50 °C, that is, 0.67 vs. 0.23 (Figure 1a, and Figure S1a and Table S1 in Supporting Information), [42] while the PEO_PE has a t + of 0.22 at 80 °C.…”

Progress study on the development of lithium-sulfur batteries

“…This area capacity limit is significantly higher than the area capacity of Li-S batteries required for commercial applications, suggesting a clear advantage of N-NGN as an excellent separation coating for Li-S batteries. [4] Fig. 4 N-NGN coated Celgard PP separator and their mechanism to chemically bind the PS through multifunctional effects.…”

Sea Urchin-like Si@MnO2@rGO as Anodes for High-Performance Lithium-Ion Batteries

“…The low conductivity of transition metal oxides and Si nanospheres can be compensated by rGO. MnO 2 wraps the Si nanosphere to avoid the agglomeration of the Si nanosphere, increase the contact area with the rGO sheet, ensure the interface strength between MnO 2 and rGO, and improve the structural stability of the material [29][30][31][32].…”