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

Abstract

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 ≈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.

Tailored Electrolytes Enabling Practical Lithium–Sulfur Full Batteries via Interfacial Protection

“…Recently, academia’s awareness of devising Li–S full cells has been gradually raised. Research interests are mainly focused on the design of electrode frameworks (e.g., catalyst-modified carbon fabrics − and lithiophilic 3D metal skeletons − ), but the introduction of porous hosts will intensify the compromise of E v . More importantly, the N/P ratio is rarely explicitly controlled, which does not satisfy the eligibility criteria of Li–S full cells.…”

Achieving Uniform Li Plating/Stripping at Ultrahigh Currents and Capacities by Optimizing 3D Nucleation Sites and Li2Se‐Enriched SEI

“…It is noteworthy that such remarkable cycling performances are superior to those of previously reported LMAs based on 3D frameworks (Figure 5d ; Table S1 , Supporting Information). [ 28 , 34 , 36 , 37 , 51 , 52 , 53 , 54 , 55 ] To investigate the cycling performance of the Li/CoSe 2 –C@CFC anode under a higher capacity, the executed capacity was further enhanced to 20 mAh cm –2 . As shown in Figure 5e , at a current density of 5 mA cm –2 , the symmetric Li/CoSe 2 –NC@CFC cell exhibited a stable voltage platform that remained for over 1600 h. Moreover, the symmetric cell of the Li/CoSe 2 –NC@CFC can be cycled for over 280 h at 10 mA cm –2 (Figure 5f ), representing its superiority as a high‐energy‐density LMA.…”

“…More recently, the use of three‐dimentional (3D) conductive frameworks to accommodate Li plating/stripping has achieved remarkable results. [ 26 , 27 , 28 ] Owing to their light mass, high conductivity, predominant flexibility, and robust structure, carbon‐based frameworks are promising high‐energy‐density Li hosts among numerous frameworks, as well as in the area of flexible energy storage. [ 29 , 30 ] The introduction of lithiophilic materials into carbon‐based frameworks is a representative strategy for promoting Li storage performance.…”

Dual‐Functional MgO Nanocrystals Satisfying Both Polysulfides and Li Regulation toward Advanced Lithium−Sulfur Full Batteries

“…[43] The long-term cycling performances at high current densities and under a large areal capacity are proved to be essential for practical Li anodes applied to high-energy-density and highpower-density LSBs. [44] Its reported that the nucleation process of Li is heavily dependent on the current density, where the high current density causes serious deterioration of lithium dendrite, which is difficult to meet the demand of rapid charging/discharging in practical application. [42] In Figure 3e, when the current density increases to 3 mA cm −2 , the Li@MCG-2@Cu based symmetric cell still delivers outstanding stability of Li stripping/plating electrochemistry and low voltage hysteresis (nearly 17.9 mV for 760 h), demonstrating the tremendous potential for stable circulation under large current.…”