From Understanding to Performance: Interface Design of Anode-Free Batteries
Abstract
Lithium-ion batteries (LIBs) have become the ubiquitous energy storage technology from long range electric vehicles to portable consumer electronics. However due to their limited volumetric and gravimetric energy density, other battery chemistries and geometries must be investigated. One promising alternative is the use of anode-free batteries, which plate lithium metal directly onto or into a current collector, with the entire lithium source coming from the cathode. However, these anode-free systems face some key challenges including 1) the formation of lithium dendrites and poor cycling efficiency; 2) the construction of a robust and stable solid electrolyte interphase (SEI) on the current collector; and 3) the significant volume change of lithium plating and stripping.
This thesis focuses on the design of multiple strategies for the stabilization of the anode-free current collector and plated/stripped lithium and extending the life cycle and performance of the cell. The first part of the thesis demonstrates the use of a lithiated niobium oxide atomic layer deposition (ALD) coating to stabilize lithium deposition through the suppression of dendrite formation, extending the cycle life of the cell. Herein the total energy delivered over the life of the cell is improved by a factor of 10. In the second research chapter, an atomic/molecular layer deposition (MLD) bilayer coating is used as an artificial solid electrolyte interphase (SEI) to facilitate lithium deposition and improve the cycle life of the cell. The MLD/ALD bilayer structure is proven to act as a protective overlayer, rather than nucleation layer. In the third section, a lithiophilic nanowire mesh is utilized as an anode-free current collector to effectively host plated lithium metal and significantly improves the cycling efficiency and cycle life, while demonstrating exceptional capacity even at 12-minute charge and discharge. Finally, the last chapter investigates the relationship between the physicochemical and electrochemical properties of various SEI components generated homogeneously via a gas exposure method as a way to guide future SEI design.