Rational Design of Composite Cathodes and Functional Electrolytes for High-Energy Lithium-Metal Batteries

Download or read book Rational Design of Composite Cathodes and Functional Electrolytes for High-Energy Lithium-Metal Batteries written by Panpan Dong and published by . This book was released on 2020 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metallic lithium has been considered one of the most attractive anode materials for high-energy batteries because it has a low density (0.53 g cm8́23), the lowest reduction potential (8́23.04 V vs. the standard hydrogen electrode), and a high theoretical specific capacity (3,860 mAh g8́21). Chalcogen elements, such as sulfur and selenium, have been widely reported as promising cathode candidates for next-generation lithium-metal batteries (LMBs) that demonstrate much higher energy density than current lithium-ion batteries. However, lithium0́3chalcogen batteries still suffer from the loss of cathode active materials and the degradation of lithium metal anode owing to the shuttle effects of intermediate products (e.g., polysulfides and polyselenides), leading to fast capacity fading and poor cyclability. Moreover, for lithium metal anodes, the cracking of solid electrolyte interphase (SEI) layer during long cycling results in dead lithium formation and lithium dendrite growth, leading to poor Coulombic efficiency and potential safety issues. The abovementioned challenges hinder the commercialization of LMBs. To address these problems, various strategies have been developed to mitigate the dissolution/diffusion of redox intermediates and stabilize metallic lithium anodes. In this dissertation, sulfur- and selenium-based nanocomposites were synthesized and employed as advanced cathode materials for high-energy LMBs. The correlations between syntheses, properties, and performances of such chalcogen cathode materials were established by various characterization methods such as microstructural analyses, solid-state nuclear magnetic resonance, X-ray photoelectron spectroscopy, and nanoscale X-ray computed tomography. Additionally, the interfacial electrochemistry of lithium metal anodes and ionic liquid0́3based electrolytes is comprehensively investigated, revealing the effective stabilization and protection of lithium anode via the formation of an in situ SEI layer with specific compositions. Moreover, strategies for achieving novel solid polymer electrolytes with improved lithium-ion transference number were demonstrated, paving the way toward safe LMBs by mitigating lithium dendrite growth. This dissertation provides a combined strategy of advanced cathode design, electrolyte engineering, and lithium anode stabilization to develop high-energy LMBs for practical applications.