The long-standing issue of lithium dendrite growth during repeated deposition or dissolution processes hinders the practical use of lithium-metal anodes for high-energy density batteries. Here, we demonstrate a promising lithiophilic–lithiophobic gradient interfacial layer strategy in which the bottom lithiophilic zinc oxide/carbon nanotube sublayer tightly anchors the whole layer onto the lithium foil, facilitating the formation of a stable solid electrolyte interphase, and prevents the formation of an intermediate mossy lithium corrosion layer. Together with the top lithiophobic carbon nanotube sublayer, this gradient interfacial layer can effectively suppress dendrite growth and ensure ultralong-term stable lithium stripping/plating. This strategy is further demonstrated to provide substantially improved cycle performance in copper current collector, 10 cm 2 pouch cell and lithium–sulfur batteries, which, coupled with a simple fabrication process and wide applicability in various materials for lithium-metal protection, makes the lithiophilic–lithiophobic gradient interfacial layer a favored strategy for next-generation lithium-metal batteries.
Cai Zuo,Hongping Li,Gong Chen,Jun Yang,Zhixin Xu,Zhigang Xue
Lithium metal batteries with liquid electrolytes usually suffer from the growth of lithium dendrites and safety issues such as leaking and volatilization. Solid polymer electrolytes (SPEs) can relieve these problems due to their chemical and electrochemistry stability. However, PEO-based SPEs are still too brittle to endure bending, stretching, and shearing. Herein, highly elastic cyclodextrin-based triblock polymer electrolytes (CDTPEs) were fabricated via the ring-opening polymerization and initiator-free thiol–ene reaction. The rubbery PTMC segment endows the CDTPEs excellent elasticity to suffer from bending, stretching, and complicated conditions. This CDTPE integrates an excellent elongation (580%) and favorable ionic conductivity (1.5 × 10–3 S cm–1 at 100 °C). More importantly, the stable lithium stripping/plating process for over 2200 h was achieved due to the uniform lithium electrodeposition. The cyclodextrin component is verified to be beneficial for the uniform lithium electrodeposition. The LiFePO4/CDTPE/Li cells exhibit stable cycling performance and reversible specific discharge capacity. Our work may provide a method for stabilizing lithium metal batteries.
Yuanzhou Yao,Xiaohui Zhao,Amir Abdul Razzaq,Yuting Gu,Xietao Yuan,Rahim Shah,Yuebin Lian,Jinxuan Lei,Qiaoqiao Mu,Yong Ma,Yang Peng,Zhao Deng,Zhongfan Liu
The passivation of lithium metal anodes to mitigate an unstable solid electrolyte interface and parasitic dendrite growth is the key premise for their successful implementation in lithium metal batteries. Herein, aiming to simultaneously reduce the interfacial resistance and to suppress lithium dendrites, we coated lithium metal anodes with two-dimensional (2D) rGO layers prepared via a solvent-evaporation-assisted self-assembly. Upon lithiation/delithiation, the rGO coating cracked into mosaic-like flakes, in between which the interconnected gaps served as the passage for uniform lithium plating/stripping. Half cells composed of a sandwich Cu/Li/rGO electrode vs. Cu foils revealed much improved Li usage and coulombic efficiencies. Through ex situ SEM imaging and XPS depth profiling, a comprehensive view of Li intercalation, deposition, and dendrite suppression on the rGO coating was obtained. As a result of the improved kinetics of Li transportation, excellent electrochemical performances were demonstrated in symmetric gLi‖gLi cells with a stabilized overpotential of only 87.9 mV at 5 mA cm−2 over 600 cycles, and in Li–S batteries with a stabilized capacity of 1200 mA h g−1 at 1C near 1000 cycles.
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