LEARNING OUTCOMES

The purpose of the course is to indicate the principles and operational practices that characterize the devices for the conversion and storage of energy. Besides, the course aims to assess the student's ability to apply this knowledge for problem solving or for performing laboratory tasks.

AIMS AND LEARNING OUTCOMES

The purpose of the course is to provide the concepts of electrochemistry and the aspects of materials science constituting the basis of the most promising electrochemical systems for energy. At the end of the course the student will have acquired the theoretical knowledge on the structure and operating principle of each device, whether it be for conversion (spontaneous current flows - galvanic cells, photoelectrochemical cells - and forced - electrolysers) or for storage (secondary batteries, supercapacitors).

Specifically, the student at the end of the course will be able to:

• know the different classes of conductors and charge carriers used in electrochemical cell; deepen the electrochemical mechanisms governing the electrical conduction of species (in each of the components of the chain) subjected to a potential difference;
• appreciate the chemical and structural relevance of state-of-the-art materials, to have a view on the possible development of new materials;
• know the thermodynamic, kinetic and transport mechanisms that drive the electrocatalysis processes and be able to critically analyse them in order to optimise structures and performances;
• learn from a theoretical and practical point of view the most important electrochemical techniques for the characterization of such systems (impedance spectroscopy, voltammetry);

apply this knowledge to solve one-two take home assignments limited to the program carried out, which must be solved individually to demonstrate that the student has acquired operational knowledge.

These training objectives are particularly suitable for the "Materials Scientist: Technology Specialist" profile.

PREREQUISITES

Basics of thermodynamics and electrochemical kinetics.

Complex numbers.

TEACHING METHODS

The course is divided into lectures held by the teacher, during which the theory will be exposed, applied to different examples and through the resolution of exercises.

During the evolution of teaching, the student is subjected to one- two take home assignments, limited to the program carried out, which must be solved over a period of several days, using the course material and books/papers suggested by the teacher, but working individually. In this personal work the student must therefore process the knowledge learned during the lectures and be able to solve complex exercises (possibly discussing with the teacher in case of any difficulties), in order to evaluate his ability as a problem solver.

The course provides for the compulsory attendance of twelve hours of laboratory experiences, related to the topics covered. Students, who will work in groups of more components, are required to perform electrochemical tests on real samples, useful for determining the performance of single components or complete cells. In the practical laboratory activities, the safety rules illustrated for operating in an electrochemistry laboratory must be strictly followed.

To help the student in learning, the teacher makes available the presentation used as a support to the lesson.

SYLLABUS/CONTENT

The teaching program includes the presentation and discussion of the following topics:

• Introduction. Global energy state: demands, challenges and future prospects. Greenhouse gas emissions and associated climate change. The crucial role of electrochemical systems in the energy scenario based on the use of renewable sources.
• Different classes of conductors and charge carriers. Characteristics of an electrochemical chain; trend of the potential at equilibrium and out of equilibrium.
• Fuel cells. Types (in-depth study of SOFCs and PEMFCs), structure and possible configurations; mechanisms underlying the transformation processes in a fuel cell; state-of-the-art and emerging materials; anionic and proton conductivity; criteria for choosing the electrolyte; energy balances; efficiency. Technical challenges and perspectives.
• Batteries. Types of the main current batteries (Leclanché, lead-acid batteries, zinc-air, ZEBRA system, nickel-cadmium, nickel-metal hydrides, lithium batteries, etc.) and advanced (lithium-air and lithium-sulfur); energy conversion mechanism in batteries; focus on materials; critical operating parameters; main types of reactions to the electrodes; effects of the discharge current; self-discharge; coulometric titration; relationship between voltage and electrode reactions; binary and ternary phase diagrams to understand the trend of the cell voltage vs the state of charge. Liquid and solid electrolytes; polymer electrolytes; experimental methods to evaluate the critical properties of electrodes and electrolytes. Technical challenges.
• Supercapacitors. Classification; Ragone plot. The electrochemical double layer; electrode materials: carbon-based and pseudocapacitive; asymmetric supercapacitors. Electrolytes: aqueous, ionic liquids and solids. Simulation of the electrochemical behavior; energy and power density; current and future applications.
• Photoelectrochemical cells. The photovoltaic effect. Functional materials for solar cells: p-n junction and multijunction photovoltaic systems. Systems based on crystalline and amorphous silicon; thin film cells (CuInSe2, CdTe). Equivalent electrical circuit, open circuit voltage and short circuit current; voltage-current and voltage-power curves. Dye-sensitized solar cells: advantages, production problems, sensitization. Liquid, gel and solid electrolytes.
• Electrochemical Impedance Spectroscopy (EIS). Complex numbers and Fourier transform; definition of impedance; different ways of representing data. Impedance in the presence of mass transport; impedance dispersion at solid interfaces; dispersion of time constants; impedance of porous electrodes. Conditions for obtaining reliable data. Introduction to the interpretation of experimental data. Cyclic voltammetry. Use in the characterization of electrochemical cells.

RECOMMENDED READING/BIBLIOGRAPHY

All the slides used during the lectures.

The teaching material suggested or delivered during the course.

The books indicated are suggested as supporting texts, but students can also use other university-level texts.

• J. Newman and K. E. Thomas-Alyea, "Electrochemicl Systems", Wiley Interscience, John Wiley & Sons.
• "Solid State Electrochemistry I - Fundamentals, Materials and their Applications", Edited By Vladislav V. Kharton, Wiley-VHC.
• "Handbook of Battery Materials", Ed. by C. Daniel and J. O. Besenhard, Wiley-VHC.
• "Fuel cells and hydrogen production", T. Lipman and A. Z. Weber Eds., Springer, 2019.