Multiple heterostructures of Co and derivatives decorated high N-doped biochar host accelerating polysulfide redox kinetics for lithium sulfur batteries

Abstract

Simultaneously improving the anchoring of polysulfides and the interconversion of polysulfides is an urgent problem to be solved to improve the redox kinetics of lithium-sulfur batteries. In this work, a multiple heterostructures of Co and derivatives decorated high N-doped biochar are fabricated. With the special synergistic effect, the anchoring of polysulfide compounds is enhanced through chemical adsorption (Co, O, N), and the excellent catalytic ability of Co and derivatives particles can speed up the electrochemical reaction process. After the injection of sulfur, The Co-N@PC@S electrode achieves a stable reversible capacity of 416.02 mAh g−1 after 1000 cycles at 0.5 C. And it also gets a reversible capacity of 334.10 mAh g−1 after 500 cycles at 5.0 C, with a specific capacity decay rate for a single turn of only 0.043%. When the sulfur loading reaches 3.2 mg cm−1, the reversible specific capacity can still reach 600.87 mAh g−1 at 0.2 C after 400 cycles and maintain a reversible specific capacity of 429.50 mAh g−1 after 400 cycles 0.5 C. This work provides a fresh idea to facilitate the process of commercialization of lithium-sulfur batteries in the industry.