Stable and high-performance lithium metal battery via electrode-electrolyte interfacial engineering

Abstract

Rechargeable high-energy batteries are critical in the development of next-generation energy storage technologies and this leads to the revival of lithium metal anode. The ultrahigh capacity (3860 mAh g$^{-1}$) and low redox potential (-3.04 V vs. SHE) of metallic lithium make it an excellent anode for such technologies. However, its practical application is limited because of the challenges associated with lithiation and de-lithiation, such as the formation of dendrites, volume change, and parasitic reactions. To overcome these issues, regulation and uniform Li deposition is necessary. Further, Li deposition should be restricted below the solid electrolyte interphase for longer cycle life (SEI). In this thesis, comprehensive design methodologies for the electrode, electrolyte and their interfaces are investigated. Three-dimensional (3D) anodes with tuned interface using lithiophilic N-doped graphene quantum dots (N-GQDs) are employed as a host for storing the deposited Li beneath the anode's surface. With this interface-regulated structure, stable and high power performance is achieved. Also, an anode-free structure (AF), with no heavy and voluminous host material on the current collector, has been proposed and further studied to fulfill the increasing demand for low-cost and high-energy density batteries. This structure enables uniformly guided Li deposition on the copper surface with high capacity retention after cycling. Finally, the barrier against uncontrolled Li deposition is electrolyte engineering, which favors Li transport, regulates Li deposition, and suppresses dendrites. Typical organic liquid electrolytes, when paired with a Li metal anode, are prone to internal short circuits and catastrophic failure. Solid-polymer electrolyte (SPE) that use non-volatile components with N-GQD nanofillers with improved ionic conductivity are investigated. This work examines systematic ideas and solutions for controlling Li deposition below the interface, paving the path for safer lithium metal batteries to be manufactured.