One step "growth to spinning" of biaxially multilayered CNT web electrode for long cycling Li-O2 batteries

Li-O-2 batteries have attracted great attention because of their high theoretical energy density, which exceeds the highest possible value of currently used Li-ion batteries. The operation of Li-O-2 batteries include the formation and decomposition of Li2O2 at the cathode, and cell degradation occurs because such discharge products accumulate on the pores and cause pore clogging. For reversible charge-discharge process, in this study, a biaxially multilayered high crystalline carbon nanotube (CNT) web was designed and fabricated by a modified direct spinning method, which was the first demonstration that realize the biaxially multilayered structure in one-step process. The high crystallinity of the CNT surface reduced its decomposition and the biaxial alignment of CNT enabled the web to be opened for O-2 gas and electrolytes without pore clogging. The pore size distribution verified that effective pores were better developed in the biaxially multilayered CNT web, which facilitated the flow of O-2 gas and electrolytes. The use of this specially designed CNT as a cathode improved the cyclability by 75% and dramatically reduced the overpotential. For the practical use of Li-O-2 batteries, a 3D folded cell with biaxially multilayered CNT web electrode is fabricated and demonstrated 30 cycles at 100 W h/kg(cell) cutoff. (C) 2021 Elsevier Ltd. All rights reserved.