Study on various battery systems for high-energy-density battery

Abstract

As the world undergoes rapid development, the excessive utilization of energy has led to the looming threats of global warming and environment issues. In response, numerous scientists are actively seeking fundamental solutions to address these challenges on a global scale. Among the viable approaches, one involves harnessing energy from natural sources. However, it’s important to note that environmentally friendly energy, if not immediately utilized, undergoes a transformation into thermal energy and dissipates. Consequently, the development of efficient energy storage system (ESS) becomes imperatively to effectively counteract this issue. An ideal energy storage system is characterized by its ability to efficiently capture generated energy, store substantial quantities, and sustainably power devices over extended periods. Lithium-ion batteries (LIBs) have garnered significant attention as a prominent ESS among various energy storage devices. The LIBs currently in commercial use exhibit high stability and find widespread applications. However, material limitations pose challenges in achieving elevated energy density. Especially, graphite, commonly employed as an anode material, faces limitations in achieving high-energy density batteries due to its low theoretical capacity. Consequently, the substitution of anode materials with enhanced capacity becomes imperative for realizing high-capacity electrodes. The lithium (Li) metal anode presents a promising alternative, characterized by its low reaction voltage and high theoretical capacity. However, the uncontrolled volume expansion resulting from its high reactivity with Li ions undermines cell lifespan stability, rendering the battery susceptible to critical risks such explosions. In this study, we employed diverse battery systems utilizing the anode with high capacity to maximize stability and energy density. We investigated the behavior of the Li metal anode within both liquid electrolyte and solid electrolyte systems, and introduced an anode-free system in conjunction with effective material synthesis to enhance energy density. Moreover, employing in situ microscopic techniques, we validated the actual behavioral characteristics arising from electrochemical reactions. Thorough X-ray analysis and simulations, we gained a comprehensive understanding of the material’s electrochemical properties. In Chapter II, we introduce a polymer protective film in the form of micelles bonded electrically with lithium nitrate (LiNO3) to effectively safeguard Li metal anode. The thin polymer protective film in the micellar form reduces anode resistance and promotes the even distribution of LiNO3 on the surface of the Li metal. The uniformly dispersed LiNO3 predominantly decomposes during electrochemical reactions, resulting in an outstanding solid electrolyte interface (SEI) constituent material and, simultaneously, the stable formation of initial Li electrodeposition. We confirmed this effect on the anode side through the evaluation of a tree-electrode cell and effectively observed the Li electrodeposition process through in-situ optical microscopy (OM). In Chapter III, we present a novel anode-free electrode model designed to optimize energy density. Anode-free batteries exhibit behavior similar to Li metal batteries but forego the use of any anode active material, including Li metal, thus maximizing energy density per unit volume and weight. Through the development of a unique ion-conductive layer, we have successfully minimized Li consumption within the cathode and mitigated the volume expansion of the anode. This groundbreaking advancement has led to a significant enhancement in the performance of anode-free batteries. Furthermore, we have extended this innovation to all-solid- state batteries to validate its compatibility with solid electrolytes. In Chapter IV, we focus on all-solid-state batteries and introduce a method to mitigate interfacial resistance. All-solid-state batteries represent an ideal battery paradigm capable of maximizing energy density and greatly enhancing battery stability. However, they require additional processing steps due to the substantial interfacial resistance that exists between the sulfide-based solid electrolyte and the electrode material. In this chapter, we present a hybrid all-solid-state battery model that significantly reduces interfacial resistance. This is achieved by introducing a small quantity of liquid electrolyte at the interface between the electrodes and the solid electrolyte. We also discuss the advantages and limitations of this novel model. In Chapter V, we conducted research on thin polymer layers were applied to prevent direct contact between the sulfide solid electrolyte and anode using the initiated chemical vapor deposition (iCVD) process. The vapor-phase deposition method allowed for conformal coverage of the polymer with uniform nanoscale thickness, even on highly irregular metal surfaces. This induced a uniform flow of ions and charge, as well as, minimizing contact resistance at the interface between the anode and sulfide solid electrolyte. Furthermore, despite the critical role of polymers in sulfide solid-state batteries, there is currently a dearth of research on their interaction with sulfide solid electrolytes. Our findings have the potential to address the lack of knowledge regarding the interactions between polymers and SSE, an aspect previously unexplored. Consequently, this approach enables us to make predictions regarding the suitability of specific polymers for enhanced performance in sulfide solid-state batteries. In Chapter VI, we offer a concise overview of different battery systems designed for high energy density applications. To address unresolved challenges in large-scale Li batteries, it is imperative to consider the broader context and tailor solutions to meet specific objectives.