Route to sustainable lithium-sulfur batteries with high practical capacity through a fluorine free polysulfide catholyte and self-standing Carbon Nanofiber membranes

Du-Hyun Lim,Marco Agostini,James Manuel,Jou-Hyeon Ahn,Florian Nitze,Aleksandar Matic

doi:10.1038/s41598-017-06593-2

Du-Hyun Lim, Marco Agostini + Show 4 more

Open Access

https://doi.org/10.1038/s41598-017-06593-2

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Abstract

We report on a new strategy to improve the capacity, reduce the manufacturing costs and increase the sustainability of Lithium-Sulfur (LiS) batteries. It is based on a semi-liquid cathode composed of a Li2S8 polysulphide catholyte and a binder-free carbon nanofiber membrane with tailored morphology. The polysulphides in the catholyte have the dual role of active material and providing Li+-conduction, i.e. no traditional Li-salt is used in this cell. The cell is able to deliver an areal capacity as high as 7 mAh cm−2, twice than that of commercial Lithium-ion batteries (LiBs) and 2–4 times higher than that of state-of-the-art LiS cells. In addition, the battery concept has an improved sustainability from a material point of view by being mainly based on sulfur and carbon and being completely fluorine-free, no fluorinated salt or binders are used, and has potential for upscaling and competitive price. The combination of these properties makes the semi-liquid LiS cell here reported a very promising new concept for practical large-scale energy storage applications.

Highlights

The recent increased demand for electric vehicles and for the development of renewable energy systems has put focus on the generation energy storage systems[1, 2]
We demonstrate that by tailoring the morphology of the Carbon Nanofiber (CNF) membrane, by increasing porosity and pore size distribution, we can build a semi-liquid Lithium-Sulfur batteries (LiS)-cell that can deliver a capacity as high as 7 mAh cm−2, a value twice as high as that of commercial Lithium-Batteries (LiBs) and 2–3 times higher than Li-S systems commonly reported as state-of-the-art[17,18,19,20,21,22,23,24,25,26,27]
The results show that the capacity of the LiS-cell based on this concept delivers an areal capacity of up to 7 mAh cm−2 which is 2 times higher than that of the commercial Lithium-ion batteries (LiBs) and 2–3 times higher than LiS cells based on state-of-the-art solid-state cathodes[18,19,20,21,22,23,24,25,26,27, 29,30,31]

Summary

Introduction

The recent increased demand for electric vehicles and for the development of renewable energy systems has put focus on the generation energy storage systems[1, 2]. Sulfur-based cathodes are characterized by a very higher theoretical energy density, i.e. 2600 Whkg−1, and by the use of abundant, non-toxic and cheap raw materials, i.e. sulfur and carbon These characteristics has put the spotlight on Lithium-Sulfur batteries (LiS) as one of the most promising alternatives to replace the conventional Li-ion technology in high capacity energy storage systems[8, 9]. We demonstrate that by tailoring the morphology of the CNF membrane, by increasing porosity and pore size distribution, we can build a semi-liquid LiS-cell that can deliver a capacity as high as 7 mAh cm−2 (corresponding to a specific capacity of 1200 mAh gs−1 and with a sulfur loading of 6.5 mg cm−2), a value twice as high as that of commercial Lithium-Batteries (LiBs) and 2–3 times higher than Li-S systems commonly reported as state-of-the-art[17,18,19,20,21,22,23,24,25,26,27]

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Results

Conclusion