Abstract
Abstract Fast charge transfer and lithium-ion transport in the electrodes are necessary for high performance Li–S batteries. Herein, a N-doped carbon-coated intercalated-bentonite (Bent@C) with interlamellar ion path and 3D conductive network architecture is designed to improve the performance of Li–S batteries by expediting ion/electron transport in the cathode. The interlamellar ion pathways are constructed through inorganic/organic intercalation of bentonite. The 3D conductive networks consist of N-doped carbon, both in the interlayer and on the surface of the modified bentonite. Benefiting from the unique structure of the Bent@C, the S/Bent@C cathode exhibits a high initial capacity of 1,361 mA h g−1 at 0.2C and achieves a high reversible capacity of 618.1 m Ah g−1 at 2C after 500 cycles with a sulfur loading of 2 mg cm−2. Moreover, with a higher sulfur loading of 3.0 mg cm−2, the cathode still delivers a reversible capacity of 560.2 mA h g−1 at 0.1C after 100 cycles.
Highlights
Fast charge transfer and lithium-ion transport in the electrodes are necessary for high performance Li–S batteries
A N-doped carbon-coated intercalated-bentonite composite sulfur host with efficient ion transport pathways and interconnected three-dimensional (3D) conductive networks can be controllably constructed. This strategy delivers the following advantages: (i) Through regulating the interlayer distance of bentonite by simple inorganic/organic intercalation, a fast lithium-ion transport pathway can be constructed (ii) The organic intercalation agent-derived carbon in the interlayer combines with PDA-derived carbon (PDA-C) on the surface, endowing Bent@C with an interconnected 3D conductive network which effectively improves the conductivity of this composite bentonite host (iii) The alumina-silicate components of bentonite clay and abundant N-doping of the carbon conductive networks provide a strong chemical adsorption of LiPSs (iv) This synthetic route is both facile and economical, and highly suitable for large-scale production
Once the current rate increases to 3C (Figure S5a), the galvanostatic charge/discharge profiles of S/Li-Bent cathode exhibit distinct distortion and overpotential and the charge and discharge platform effect even disappears. These phenomena confirm that the free ion/electron transport, induced by the efficient ion transport pathways in the interlayer of bentonite combined with the high electronic conductivity of the interconnected 3D conductive carbon networks, confers fast redox kinetics and high sulfur utilization to the S/Bent@C cathode [41]
Summary
Abstract: Fast charge transfer and lithium-ion transport in the electrodes are necessary for high performance Li–S batteries. The organic intercalation agent and PDA are simultaneously carbonized for in situ synthesis of nano conductive carbon materials on the surface, and in the interlayers of bentonite Through this approach, a N-doped carbon-coated intercalated-bentonite composite sulfur host (denoted as Bent@C) with efficient ion transport pathways and interconnected three-dimensional (3D) conductive networks can be controllably constructed. (i) Through regulating the interlayer distance of bentonite by simple inorganic/organic intercalation, a fast lithium-ion transport pathway can be constructed (ii) The organic intercalation agent-derived carbon in the interlayer combines with PDA-derived carbon (PDA-C) on the surface, endowing Bent@C with an interconnected 3D conductive network which effectively improves the conductivity of this composite bentonite host (iii) The alumina-silicate components of bentonite clay and abundant N-doping of the carbon conductive networks provide a strong chemical adsorption of LiPSs (iv) This synthetic route is both facile and economical, and highly suitable for large-scale production. This work provides an economical and effective strategy for the construction of efficient ion transport pathways and conductive networks in high sulfur loading cathodes by using 2D layered clay materials
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