Bifunctional 3D Hierarchical Hairy Foam toward Ultrastable Lithium/Sulfur Electrochemistry

The dendrite formation resulting from the irregular lithium deposition and the infinite volume expansion in lithium anodes significantly impede their commercialization for high energy applications. Herein, it is demonstrated that carbon nanofibers (CNFs) grown in situ on a nickel foam (CNF@Ni) can locally change the Li stripping/plating behavior by reducing the nucleation overpotential and regulating the electric field distribution. The 3D conductive hairy foam with a hierarchical structure can provide sufficient active sites for lithium nucleation. In addition, the numerous CNFs with protuberant tips can act as the charge centers and significantly increase the electrochemically active surface area, resulting in the locally reduced and uniformly distributed current density. The symmetric cells using CNF@Ni-Li electrodes can achieve ultralong lifespan with low voltage hysteresis up to 1000 h. More remarkably, the CNF@Ni hairy foam can simultaneously enable reliable sulfur electrochemistry. The corresponding Li-S full cell shows excellent cycle stability with a high capacity of approximate to 400 mAh g(-1)at 5 C after 800 cycles. This work provides an exemplary way to concurrently address the challenges in lithium and sulfur electrodes toward the development of high-performance Li-S batteries.