Dual Functionalities of Carbon Nanotube Films for Dendrite-Free and High Energy-High Power Lithium-Sulfur Batteries.

As a promising Li-metal battery, Li-S battery has an ultrahigh theoretical energy density of 2600 Wh kg-1. However, most of the previous work has mainly focused on tackling the "polysulfide shuttle" originating from the S cathode, while the dendrite problem coming from the Li-metal anode has often been overlooked. Herein, to solve the issues arising from both the cathode and anode simultaneously, we propose a novel cell configuration for the first time by inserting CNT films on both sides of the separator in Li-S batteries, in which the cathode-side CNT film works as a shield to suppress the "polysulfide shuttle" and the anode-side CNT film acts as a powerful shield to prevent the Li dendrite growth. In the new cell configuration, the S/rGO cathode with a high S loading of about 4.0 mg cm-2 displays a high specific capacity (1336 mAh g-1 at 0.2 C), excellent rate ability (1070, 833, 656, and 444 mAh g-1 at 0.5, 1, 2, and 5 C, respectively), and sustainable cycling stability for 150 cycles with high Coulombic efficiency (>99%) at 1 C, while the Li metal anode displays an ultrasmooth surface. We believe this work will aid in developing other metal-based (e.g., Na, K, Zn, and Al) batteries.