Polypyrrole-S-coated MWCNT composites as cathode materials for lithium-sulfur batteries
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ORIGINAL PAPER
Polypyrrole-S-coated MWCNT composites as cathode materials for lithium-sulfur batteries Shaojun Huang 1,2 & Xuri Wang 3 & Renwen Hu 3 & Xinming Wang 3 & Xuexian Yang 1 & Nie Zhao 3 & Weixin Lei 3 & Ling Zhu 1 & Jinfeng Peng 4 Received: 30 July 2020 / Revised: 5 August 2020 / Accepted: 6 August 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract A composite of MWCNTs@S-PPy with excellent electrical conductivity and good restriction on polysulfide has been prepared for lithium-sulfur batteries. In this composite, sulfur particles confined to polypyrrole (PPy) are uniformly distributed on the surface of carbon nanotubes. The MWCNTs@S-PPy composite with a sulfur content of 48.8 wt% delivers a high initial discharge capacity of 1304.9 mAh g−1 at 0.2 C and remains a stable capacity of 986.3 mAh g−1 after 300 cycles. The significant improvement in the electrochemical performance can be attributed to the core-shell structure supported by the multiwalled carbon nanotubes (MWCNTs) and S-PPy composite, which own excellent electronic conductivity and alleviate the “shuttle effect” of lithium polysulfide. These results suggest that the MWCNTs@S-PPy composite is a promising cathode material for high-performance lithium-sulfur batteries. Keywords Lithium-sulfur battery . Cathode material . Carbon nanotubes . Polypyrrole-S coating
Introduction With the rapid development of the new generation of portable electronic devices and pure electric vehicles, the enhancement of energy density for lithium-ion battery (LIB) is urgently needed to meet the escalating application requirements. Amongst the next-generation battery systems, lithium-sulfur batteries (LSBs) are considered to be highly competitive for the high energy storage density [1–4]. Elemental sulfur has a high theoretical capacity of 1675 mAh g−1 and an energy density of 2600 Wh kg−1, which are much higher than those
* Ling Zhu [email protected] * Jinfeng Peng [email protected] 1
School of Physics and Electromechanical Engineering, Jishou University, Jishou 416000, China
2
Ningde Amperex Technology Limited, Ningde 352100, China
3
National-Provincial Laboratory of Special Function Thin Film Materials, Xiangtan University, Xiangtan 411105, Hunan, China
4
School of Mechanical Engineering, Xiangtan University, Xiangtan 411105, China
of the conventional cathode materials (capacity of ∼ 250 mAh g−1 and energy density of ∼ 400 Wh kg−1) for lithium-ion battery [5–8]. Moreover, sulfur is abundant, low cost, and environmentally friendly. However, there are also several stumbling blocks on the way of commercial application for lithium-sulfur batteries. Firstly, the electronic and ionic insulating natures of sulfur (5 × 10−30 S cm−1 at room temperature) lead to a poor electrochemical performance and the low utilization of the sulfur cathode [9–11]. Secondly, the large volume expansion of sulfur in LSBs is as high as about 80% during cycling, resulting in the poor cycling performance. Thirdly, the high dissolution of lithium polysulfid
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