The lithium–sulfur (Li–S) battery is an appealing choice for the next-generation high-energy-density energy storage systems . However, side reactions between lithium polysulfides (LiPSs) and Li metal anode cause the growth of Li dendrites, loss of active materials, and safety issues, which severely hinders the practical application of Li–S batteries. Constructing a protection layer on the surface of Li anode is an effective strategy to shield LiPSs and regulate lithium uniform deposition in Li–S batteries. Herein, we design and fabricate a lithiated Nafion protective layer to alleviate the side reactions between LiPSs and the Li anode and guide uniform deposition of Li, in which, their mechanism is investigated. The optimal protective layer effectively protects the Li anode from the detrimental side reactions, which boosts the stability of the Li anode. Li–Li and Li-stainless steel cells with 4 M [S] Li 2 S 8 electrolyte can last for more than 400 cycles and 100 cycles at current density of 1 mA cm −2 . A Li–S full cell also exhibits a high reversible capacity of 791.5 mA h g −1 after 250 cycles at 0.5 C. This work reveals the vital role of the artificial protective layer in enhancing the stability of the Li anode in Li–S batteries.
XinLong Zhang,HaiYan Zhang,Yuan Geng,ZhangQin Shi,Sheng Zhu,QunJie Xu,YuLin Min
Lithium–sulfur (Li–S) batteries are considered as very promising energy storage systems due to their higher theoretical performance and lower active material cost. However, the notorious shuttle effect and lithium dendrite growth have severely restricted the industrial production of Li–S batteries. In this study, we used polyethylene oxide (PEO) as the matrix and added multifunctional nanofillers (nano In 2 O 3 ) to effectively inhibit the shuttle effect caused by the dissolution of lithium polysulphides (LiPSs) in Li–S batteries. As a multifunctional filler, nano-In 2 O 3 not only improves the ionic conductivity of the PEO electrolyte, but also forms a Li–In alloy layer in situ at the polymer/anode interface, which can cause the rapid diffusion of lithium ions and prevent the side reactions between lithium metal anode and the electrolyte. Achieving the effect of stabilizing the lithium metal anode and suppressing the shuttle effect. Multiple problems in the system are solved by introducing a single component with multiple functions. The symmetrical lithium battery based on the PEO/LiTFSI/In 2 O 3 solid polymer electrolyte (PEO/LiTFSI/In 2 O 3 SPE) has higher cycle stability (over 1200 h) because it is more stable to the lithium metal anode. The Li–S full battery also exhibits excellent electrochemical performance. After 500 cycles at 1C, its capacity can be maintained at 570 mAh g −1 , the capacity decay rate is 0.038%. The coulombic efficiency (CE) during the cycle is also close 100%.
Lithium metal is a promising anode material for rechargeable batteries with high energy density . However, the uncontrollable dendrite growth severely hinders the commercialization of Li metal anode . Inspired by the “leveling” mechanism in traditional electroplating, we demonstrate that boron nitride nanosheets (BNNSs) as a liquid electrolyte additive can level out Li protrusions and enable dendrite-free Li metal anodes. 2D BNNSs can automatically and continuously flatten Li deposits and accommodate volume changes during Li plating/stripping. B atoms in BNNS as Lewis acid sites interact with Lewis basic anions in electrolyte, reducing Li + concentration gradient and unifying Li deposition. The collect effects of BNNS additive give rise to dendrite-free Li anodes over 400 h and deep plating/stripping up to 35 mAh cm −2 , as well as potential application in sub-zero temperature batteries (−20 °C). Li–S full cells using BNNS electrolyte also exhibit improved performance. This simple and effective strategy is applicable to develop dendrite-free Li or other metal anodes in high-performance energy storage devices.
The interplay between solid electrolytes and electrodes is of vital importance to the performance of all-solid-state Li batteries. Recently, halide superionic conductors have emerged as a new family of high-performance solid electrolytes, but their compatibility with Li metal, i.e., the anode with the highest theoretical capacity, has not been systematically studied. Here, we investigate the interaction between Li metal and two representative halide solid electrolytes: Li 3 YCl 6 and Li 3 YBr 6 . Both materials are found to form interphases with Li, similar to most solid electrolytes. However, the interphases observed here contain electronic conducting components, which are detrimental to their compatibility with Li. By elucidating this phenomenon, the present study provides guiding principles for improving the Li compatibility of halide solid electrolytes.
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