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Study On The Positive Electrode Material Of High Temperature Lithium Sulfur Battery With Fast Charge And Discharge

- Jan 02, 2019 -

The research team of "advanced energy materials and devices" led by professor jin zhong and professor liu jie from the school of chemistry and chemical engineering of nanjing university has made progress in the research of lithium sulfur batteries with high magnification and high tolerance. Related achievements: "self-templated Formation of interlace Carbon Nanotubes Threaded Hollow Co3S4 Nanoboxes for high-rate and heat-resistant lithium-sulfur Batteries", published in the Journal of the American Chemical Society, 2017, 139, 12710-2017. Chen tao is the first author of the thesis, and zhang zewen, a senior undergraduate, is the second author.

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Schematic diagram of structural advantages comparison between s-cnts/co3s4-nbs positive pole and 

s-co3s4-nbs positive pole

The obtained cathode filled with sulfur CNT/co3s4-nbs (s-cnts/co3s4-nbs) can provide high discharge capacity, significant rate performance and impressive cycle stability, far superior to the control sample of Co3S4 filled with sulfur。

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Uv absorption curve and cycling performance

(a) uv absorption curve obtained by immersing the circulating electrode in the electrolyte

(b) S @ CNTs/Co3S4 - NBs anode under 50 ° C, 0.2 C cycle performance

(c, d) under 50 ° c, S @ CNTs/Co3S4 - the positive ratio of NBs performance

At present, the traditional ether electrolyte commonly used in li-sulfur batteries has a low boiling point and flash point, which cannot meet the working requirements of the battery at high temperature. At the same time, high temperature working environment will also accelerate the dissolution of lithium polysulfide in the electrolyte, thus causing a serious "shuttle effect". To address these key issues, the team designed a self-template synthesis method, which nucleated the zif-67 in the crosslinked network of carbon nanotubes (CNTs) to form nano-cubes, and then transformed the precursor of CNTs/ zif-67 into a hollow nano-box of carbon nanotubes /Co3S4 (CNTs/ co3s4-nbs). The structure design has the following advantages:

A microzoned and integrated three-dimensional conductive network (especially the active sulfur inside the Co3S4 hollow nano-box) is provided, which can significantly improve the utilization rate and efficiency of the active sulfur. It can accelerate electron transport and shorten the diffusion path of lithium ions, thus promoting the kinetic behavior of electrochemical REDOX process. Increased electrode/electrolyte contact area (especially active sulfur at depth inside) and provided more open channels for electrolyte penetration.

The results show that this s-cnts/co3s4-nbs anode material has excellent high magnification performance. In addition, the electrode in the ethers electrolyte and 50 ° C and 0.2 C to charge and discharge cycle after 300 times, its discharge specific capacity can still be maintained at 718 mAh/g, for the research and development and design of high temperature resistant lithium battery cathode material provides a new train of thought.

In the past two years, the research group has conducted in-depth studies on anode materials of li-sulfur batteries (Nano letters, 2016, 17, 437). Nano Energy, 2017, 38, 239; ACS Nano, 2017, 11, 7, 7274). The research work has been supported by the thousand talents program for young people, the 973 program, the national key research and development program, the national natural science foundation of China and the natural science foundation of jiangsu province.