Exploration of Perovskite and Phosphate Frameworks for Metal-ion and Metal-air Batteries

Abstract

The history of batteries began in 1800 when Alessandro Volta invented the Voltaic Pile, the first battery made from alternating zinc and copper discs separated by salt-soaked cloth. This discovery demonstrated that chemical reactions could generate electricity, laying the foundation for modern energy storage. In 1836, John Daniell introduced the Daniell Cell, which provided a more stable and longer-lasting current. This improvement enabled practical applications such as powering early telegraph systems. A key milestone came in 1859 with Gaston Planté’s invention of the lead-acid battery, the first rechargeable system, which is still widely used in vehicles and backup power supplies. Later, in the late 1800s, the development of the dry cell made batteries safer and portable by using a paste electrolyte instead of liquid. This advancement powered early flashlights and radios. The 20th century brought nickel-cadmium (Ni-Cd) and nickel-metal hydride (NiMH) batteries, both offering rechargeability and better performance for portable devices. The major turning point, however, arrived in 1991 when Sony commercialized the lithium-ion battery, based on pioneering work by John Goodenough and Akira Yoshino. Lithium-ion technology has since become the backbone of mobile devices, electric vehicles, and renewable energy storage. Today, the rising global demand for energy, largely driven by fossil fuel consumption, has led to an energy crisis and intensified climate change. Renewable sources such as solar and wind are essential alternatives, but their intermittent nature requires efficient and reliable energy storage systems. Rechargeable lithium-ion batteries dominate this field and are widely used in electronics, electric vehicles, and grid storage. However, current anode materials face limitations. Graphite, the most common anode, shows poor performance for sodium-ion storage and has safety risks under harsh conditions. Spinel Li4Ti5O12 is a safer alternative with good rate capability, but its low capacity and high working potential (1.55 V vs. Li) reduce overall energy density. To address these limitations, conversion-type reactions offer a pathway to much higher capacities compared to conventional intercalation mechanisms. In these reactions, electrode materials transform into metal nanoparticles embedded in a Li2O matrix during discharge, allowing higher storage capacity. Perovskite, double perovskite, and Ruddlesden-Popper structures have gained attention as potential anodes in alkali-ion batteries due to their ability to support multiple charge storage mechanisms, including conversion, alloying, and intercalation. Compared to cathodes, anodes provide a wider space for material exploration, as the lower lithium potential allows the use of less stable but higher-capacity structures. This thesis discusses the development of battery technologies with a focus on perovskite oxide anodes for lithium-ion and sodium-ion batteries. It also highlights the future potential of perovskite, phosphate and metaphosphate based electrocatalysis-driven systems, such as metal-air batteries, which could significantly transform energy storage. The main goal of this research is to contribute to the advancement of sustainable, high-performance energy storage solutions to address urgent global energy challenges. The thesis is organized into six chapters. Chapter 1 reinforces the need for alternative anodes. Within the context of the global terawatt energy challenge, the chapter discusses conventional primary energy resources such as fossil fuels, oil, and coal, emphasizing the critical transition toward renewable energy generation and its storage in batteries through (electro)chemical means. The historical development of batteries and their growing importance in electric vehicles and other modern applications are presented. Different anode operation mechanisms, along with their hybrid combination approaches, are systematically described. Key issues associated with anodes, including the use of graphite anode, safety concerns with graphite, its electrochemical inactivity in sodium-ion batteries, and the formation of SEI, are explained. Furthermore, the role of transition-metal-based and perovskite oxide-based anodes functioning through diverse charge storage mechanisms is elaborated. The chapter concludes with a discussion of significant contributions on perovskite oxides, phosphates, and metaphosphates as electrocatalysts in metal-air batteries (particularly Zn-air systems), thereby setting the stage for the present thesis work. Chapter 2 details the experimental methodologies employed throughout the thesis. The synthesis strategies covered include ball milling, solid-state (dry), solution combustion (wet), sol-gel (wet), and solvothermal (wet) methods. Comprehensive descriptions of physicochemical characterization techniques, along with spectroscopy, microscopy, and diffraction analyses, are provided. Procedures for electrode coating, coin-cell fabrication, and electrochemical evaluation methods such as galvanostatic cycling, potentiodynamic measurements, and electrochemical impedance spectroscopy are systematically outlined. Additionally, the preparation of electrocatalyst inks, fabrication of electrocatalyst-coated electrodes, and electrochemical testing protocols using a three-electrode configuration for the oxygen evolution reaction (OER), oxygen reduction reaction (ORR), and hydrogen evolution reaction (HER) are described. Finally, the computational approach for optimising the catalysts surface for OER and determining lithium-ion migration pathways and activation energy barriers using the Bond Valence Site Energy (BVSE) method is presented. Chapter 3 explored different perovskite oxides as anodes for Li/Na‑ion Batteries. I investigated three structural families of perovskites: simple ABO3, double A2BB′O6, and layered Ruddlesden-Popper (An-1A2’BnO3n+1) as anode materials. For each, I employed scalable syntheses, characterized crystal structures, and evaluated electrochemical performance in both Li/Na‑ion half‑cells. My work reveals how B‑site composition and layered architectures influence conversion‑alloying versus insertion mechanisms, capacity, rate capability, and cycling stability. Chapter 4 extended the application of perovskite oxides to electrocatalysis in Zn-air battery. Building on the anode studies, I turned to oxygen and hydrogen electrocatalysis. I synthesized single and double perovskite oxides, investigated their surface chemistry, benchmarking their activity for ORR, OER, and HER in alkaline electrolyte. Detailed mechanistic insights combining rotating‑ring disk voltammetry, impedance spectroscopy, and in-situ spectroscopies led to correlate perovskite composition and electronic structure with bifunctional and trifunctional performance. Chapter 5 explored phosphate and metaphosphate‑based bifunctional electrocatalysts for zinc-air and hybrid sodium-air batteries. I examined transition‑metal phosphates and metaphosphates rich in P-O bonds and redox‑active centres as low‑cost, earth‑abundant catalysts for both OER and ORR. Using solution and solid‑state routes, I prepared a series of (meta)phosphates (NaCo4(PO4)3, MNi(PO3)3, M = Li, Na, K and Cs) and integrated them with conductive supports. Electrochemical testing in alkaline media, coupled with post‑mortem X‑ray and electron microscopy, demonstrated how phosphate chemistry and nano‑morphology govern bifunctional activity and catalyst durability. Chapter 6 presents a comprehensive summary of the entire thesis, while also highlighting potential future research directions to further advance the field of perovskite, phosphate, and metaphosphate-based materials as promising anodes for alkali-ion batteries and as cathodes for metal-air batteries. Overall, this thesis focuses on the design and exploration of perovskite and polyanionic frameworks for metal-ion batteries and metal-air batteries.