Internally enhanced conductive 3D porous hierarchical biochar framework for lithium sulfur battery

Due to the insulation of S8 and its discharge product Li2S, the stability of the conductive network in the positive electrode of lithium-sulfur batteries (LSBs) becomes critical. So, an internally enhanced high strength conductive three-dimensional (3D) biochar framework composite of high porosity biochar and carbon nanotube (HPBC/CNTs) is synthesized in this paper. The framework has a reinforced concrete structure , HPBC as concrete and CNTs as reinforcement to promote the strength of the matrix and maintain structural stability, thus improving the cyclic stability of the cathode material. In the designed composite, HPBC is interconnected and can effectively strengthens the physical constraints and traps soluble polysulfides; the CNTs buried in HPBC provides a highly reliable conductive pathway to facilitate electron/ion transport. As a result, the HPBC/CNTs/S composite exhibits good electrochemical performances. It has a high specific capacity of 1227, 1039, 739 and 639 mAh g(-1) at 0.5, 1.0, 2.0 and 4.0C, respectively. In long-life cycles, the composite has an initial discharge capacity of 988.41 mAh g(-1 )at 1.0C, and it is still able to maintain a reversible specific capacity of 482.42 mAh g(-1) after 1000 cycles, with a capacity decay rate of 0.051% per cycle. (C) 2022 Elsevier Ltd. All rights reserved.

Automated summary

In this paper, an internally enhanced high strength conductive three-dimensional (3D) biochar framework composite of high porosity biochar and carbon nanotube (HPBC/CNTs) is synthesized to improve the cyclic stability and electrochemical performances of the cathode material in lithium-sulfur batteries (LSBs).