|SCIENTIFIC DISCIPLINARY SECTOR
The course introduces the student to electrochemical devices for energy conversion and storage: fuel cells, electrolysers, batteries, supercapacitors and photoelectrochemical cells. The student will understand the crucial role of these devices in the context of the energy landscape that is being defined, based mainly on the use of renewable sources. Principles of electrochemistry, heterogeneous catalysis and materials science, which are necessary to understand their functioning, design and development in order to critically optimise performance, will be discussed.
AIMS AND CONTENT
"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).
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.
Basics of thermodynamics and electrochemical kinetics.
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.
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.
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.
TEACHERS AND EXAM BOARD
MARIA PAOLA CARPANESE (President)
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The exam consists of a final written test, which will weigh on the overall grade for 60%.
The take home assignments will weigh 40% on the final grade overall.
If the student wishes to improve the final grade, he/she can ask to take an oral test.
The take home assignment is mainly structured through open questions. It is used to evaluate (i) the learning of basic concepts and information transmitted during lectures and/or through the didactic material made available by the teacher; (ii) the ability to critically use these basic concepts and information to set up simple applications. It is a test to be carried out at home, open book, due within a given day of delivery. Any book, handout or material suggested by the teacher, or other material that needs to be specified, can be consulted, but the student must work independently, without consulting other people.
The final written test is structured through open and closed questions, and possible reports of the lessons. This last type of assessment serves to evaluate the ability to correctly interpret the issues addressed and to place them correctly in the logical and conceptual schemes learned during the course. It is allowed to have a certain number of pages of personal notes during the exam, but it is not possible to consult notes, books, other people or Internet resources during the exam.
The optional oral test, which the student can choose to take in order of improving the written test mark, is a reflection that takes its cue from concepts and information dealt with throughout the course.