ENABLING STABLE LITHIUM NUCLEATION AND GROWTH VIA CROSSLINKED POLYMER ELECTROLYTES AND ELECTRODE/ELECTROLYTE INTERPHASES

Stalin, Sanjuna

ENABLING STABLE LITHIUM NUCLEATION AND GROWTH VIA CROSSLINKED POLYMER ELECTROLYTES AND ELECTRODE/ELECTROLYTE INTERPHASES

Abstract

The rapid rise of electric drive vehicles has accelerated research aimed at developing energy storage technologies with high gravimetric and volumetric energy densities. Lithium metal batteries (LMBs) are considered particularly important in this aspect but are not available today primarily because the lithium metal anode poses multiple challenges. Among them, the most difficult include the metal’s propensity to form an undesirable and dynamic corrosion layer known as the solid electrolyte interphase (SEI) that results in rough, non-planar electrodeposits at all current densities. These challenges arise from coupling of chemical reactivity of Li, highly reducing potentials during battery charge, and the out-of-equilibrium transport phenomena that drive morphological instabilities at the metal/electrolyte interface. In this thesis, crosslinked polymers are used as a powerful platform to develop design principles for electrolytes and electrode/electrolyte interphases that enable planar deposition in lithium metal anodes. The design principles are based on guidelines from a theoretical linear stability analysis of metal electrodeposition that captures chemical effects in the transport coefficients and their spatial variations at the electrolyte-electrode interphase. The aim is then to probe physical factors responsible for the nucleation and growth of morphologically unstable electrodeposits. During dendrite growth, it is revealed that the growing deposit front experiences a significant amount of compressive stress exerted by the bulk electrolyte, which if large enough can potentially slow down the growth rate. Development of structured electrolytes capable of increasing this compressive stress, while not yielding under compressive strain is proposed and demonstrated as an effective strategy to suppress dendrite growth. To address dendrite nucleation, artificial interphases and similar electrode engineering techniques are proposed as a potential drop-in solution. Careful design of the solid electrolyte interphase and tuning of its chemistry and physical properties are found to be crucial for driving stable nucleation of lithium electrodeposits. In particular, strategies to synthesize and fabricate electrochemically stable artificial interphases with precise thickness control are shown to be essential for achieving uniform ion transport, for enhancing surface tension forces, and for reducing the equilibrium reduction rate at the metal surface. Importantly, these methods enable planar lithium electrodeposition in both nucleation and growth stages.

Description

238 pages

Date Issued

2021-05

Keywords

Electrochemistry; Energy Storage; Polymers

Committee Chair

Archer, Lynden

Committee Member

Ober, Christopher
Coates, Geoffrey

Degree Discipline

Chemical Engineering

Degree Name

Ph. D., Chemical Engineering

Degree Level

Doctor of Philosophy

Types

dissertation or thesis