Lithium-sulfur (Li-S) batteries have attracted considerable attention as a promising alternative to current state-of-the-art lithium-ion batteries (LIBs), however, their practical use remains elusive, which becomes more serious upon application to flexible/wearable electronics. Here, we demonstrate a new class of nanomat Li-S batteries based on all-fibrous cathode-separator assemblies and conductive nonwoven-reinforced Li metal anodes as an unprecedented strategy toward ultrahigh energy density and mechanical flexibility. Sulfur cathodes, which are fibrous mixtures of sulfur-deposited multi-walled carbon nanotubes and single-walled carbon nanotubes, are monolithically integrated with bi-layered (pristine cellulose nanofiber (CNF)-anionic CNF) paper separators, resulting in metallic foil current collector-free, all-fibrous cathode-separator assemblies. The cathode-separator assemblies, driven by their all-fibrous structure (contributing to three-dimensional bi-continuous electron/ion conduction pathways) and anionic CNFs (suppressing the shuttle effect via electrostatic repulsion), improve redox kinetics, cyclability and flexibility. Nickel-/copper-plated conductive poly(ethylene terephthalate) nonwovens are physically embedded into Li foils to fabricate reinforced Li metal anodes with dimensional/electrochemical superiority. Driven by the structural uniqueness and chemical functionalities, the nanomat Li-S cells provide exceptional improvements in electrochemical performance (the (cell-based) gravimetric/volumetric energy density = 457 W h kg cell -1 /565 W h L cell -1 and the cycling performance (over 500 cycles) under 110% capacity excess of the Li metal anode) and mechanical deformability (they even can be crumpled).
Bibliographical noteFunding Information:
This work was supported by the Basic Science Research Program (2017M1A2A2087810 and 2018R1A2A1A05019733) and Wearable Platform Materials Technology Center (2016R1A5A1009926) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and future Planning. This work was also supported by the Industry Technology Development Program (10080540) funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea) and the National Institute of Forest Science (FP 0400-2016-01).
All Science Journal Classification (ASJC) codes
- Environmental Chemistry
- Renewable Energy, Sustainability and the Environment
- Nuclear Energy and Engineering