All Solid State Thin-Film Lithium-Ion Batteries

Materials, Technology, and Diagnostics

Alexander Skundin, Tatiana Kulova, Alexander Rudy, Alexander Miromemko

• Publisher: CRC Press
• Year: 2021
• Print ISBN:
  9780367763435
• eBook ISBN:
  9780429657191
• Topic: Technology & Engineering
• Subtopic: Biology
• Index: Technology & Engineering

A comprehensive, accessible introduction to modern all-solid-state lithium-ion batteries.

All-solid-state thin-film lithium-ion batteries present a special and especially important version of lithium-ion ones. They are intended for battery-powered integrated circuit cards (smart-cards), radio-frequency identifier (RFID) tags, smart watches, implantable medical devices, remote microsensors and transmitters, Internet of Things systems, and various other wireless devices including smart building control and so on.

Comprising four chapters the monograph explores and provides:

• The fundamentals of rechargeable batteries, comparison of lithium-ion batteries with other kinds, features of thin-film batteries.
• A description of functional materials for all-solid-state thin-film batteries.
• Various methods for applying functional layers of an all-solid-state thin-film lithium-ion battery.
• Diagnostics of functional layers of all-solid-state thin-film lithium-ion batteries.

The monograph is intended for teachers, researchers, advanced undergraduate students, and post-graduate students of profile faculties of universities, as well as for developers and manufacturers of thin-film lithium-ion batteries.

CHAPTER
1

Modern Lithium and Lithium-Ion Rechargeable Batteries

The chapter describes general principles of chemical power sources, and especially, of rechargeable batteries. It also discusses current-producing processes as a mechanism of chemical energy conversion in an electric one. Some definitions, classification and main performances are presented. The concept of normalized performances is explained. The chapter describes in brief the traditional kinds of rechargeable batteries and gives an account of lithium-ion batteries in length. The main part of the chapter relates to the features of thin-film batteries, as well as all-solid-state thin-film lithium-ion batteries. The place of all-solid-state lithium-ion batteries among other batteries, their short history, main performances, and the manufacturers are pointed out. The chapter defines design of all-solid-state lithium-ion batteries with special attention on 3D design, as well as the technologies of their production.

1.1 Fundamentals of rechargeable batteries.

1.1.1 General principles

Definitions and working principles. Rechargeable batteries concern a wide class of devices with the common name ‘chemical power sources’ [1]. Any chemical power source represents a device for direct conversion of chemical energy into an electrical one. More strictly, ‘chemical energy’ is energy of a chemical reaction occurring in a power source. This reaction is called a ‘current-producing reaction’. For instance, interaction of lithium metal with manganese dioxide is a current-producing reaction in popular button cells responsible for watches, remote controllers, calculators and so on. This reaction can be expressed by the equation

$Li+Mn{O}_2\to LiMn{O}_2$ (1.1)

Every current-producing reaction is a redox-process, i.e., the interaction between the reducer and oxidizer. On oxidizing a reducer releases electrons whereas an oxidizer gains electrons at reduction. For the process (1.1) MnO₂ is the oxidizer, and manganese valency changes in this case from +4 to +3. Lithium metal is a reducer, and its valency changes from 0 to +1.

Chemical power source consists of one or several galvanic cells. It is a galvanic cell in which the conversion of chemical energy in to an electrical one occurs.

The salient feature of a current-producing reaction is that it consists of spatially divided processes of reduction and oxidation. Each of these processes take place at the interface between an electrode and an electrolyte. In any case, the electrodes are made from materials with electronic conductivity, so-called first-class conductors (metals, carbonaceous materials, for instance). The electrolyte is the material with ionic conductivity, the so-called second-class conductors (solutions, melts and so on). In the above example the reduction process is expressed by the equation

$Mn{O}_2+L{i}^{+}+e^{-}\to LiMn{O}_2$ (1.2)

The oxidation process is expressed by

$Li\to L{i}^{+}+e^{-}$ (1.3)

It is easy to make sure that summation of Equations (1.2) and (1.3) gives the equation (1.1).

Therefore, every galvanic cell (or simply, cell) consists of two electrodes divided by an electrolyte. When functioning (discharge) of the above-mentioned cell the lithium ions are extracted from lithium electrode into the electrolyte, then transferred by the electrolyte to another electrode, where they interact with manganese oxide. The electrons at that time are transferred from a lithium electrode to manganese-dioxide-electrode by an external electrical circuit, producing useful work. That is why, partial reactions in chemical power source are always coupled ones. In the other words, the rate of electrons’ release at one electrode is strictly equal to that of electrons’ gain at another electrode.

The schematic of galvanic cell and the main processes in it are depicted in Fig. 1.1.

Figure 1.1. Schematic of typical galvanic cell: (1) cover, negative terminal, (2) negative electrode, (3) separator impregnated with an electrolyte, (4) insulator, (5) case, positive terminal, (6) positive electrode

It is worth noting that spatial division of partial processes of reduction and oxidation is an indispensable condition for producing electrical energy. If the reaction (1.1) is carried out in a flask by providing intimate contact between manganese dioxide and lithium, no electrical energy will be produced even though the electrons will transfer from lithium to manganese dioxide. In such situation the electron transfers will be spatially random and the total energy of a chemical reaction will be released in the form of heat.

The electrode at which oxidation occurs is referred to as ‘anode’. Its counterpart at which reduction occurs is called ‘cathode’. In other words, the anode is an electrode through which the electric current flows from the external circuit into the electrolyte, whereas the cathode is an electrode with an opposite current direction. If two different electrodes are divided by an electrolyte, a potential difference develops between them. If no current flows in the cell, the potential of the electrode containing a reducer is more negative because it has a higher tendency to release electrons. In the above-mentioned cell Li is a negative electrode, and manganese dioxide is a positive one. In the course of discharge a negative electrode is the anode, and the positive electrode is the cathode.

The combination of reactants of the current-producing reaction, namely the reducer and oxidizer, as well the electrolyte forms the electrochemical system of a given chemical power source. Conventionally, an electrochemical system is written as

$(-)reducer\left|electrolyte\right|oxidizer(+)$

(Short vertical bars denote electrode-electrolyte interfaces, in which the electrochemical reactions like (1.2) and (1.3) occur). The electrochemical system of the above-mentioned cell can be expressed as

$(-)Li\left|LiCl{O}_4\right|Mn{O}_2(+)$

The electrolyte in this case is the solution of LiC1O₄ in propylene carbonate. (The solvent is usually omitted in the notation of an electrochemical system).

According to Faraday’s laws, the total charge passing through an electrochemical cell is unambiguously related to the quantity of the reactants consumed in the electrochemical reaction, and to the quantity of the products of the reaction. In the other words, the Faraday’s laws can be expressed by the equation

$Q=nFm/A$ (1.4)

Here Q is a charge passing through an electrochemical cell, m is weight (mass) of reactant, A is its molecular (atomic) weight (mass), n is the number of electrons participating in the electrochemical process and F is a fundamental constant, so-called ‘Faraday number’ (or simply ‘Faraday’) equal to 96.487C/mole or 26.8 Ah/mole. The charge nF, therefore, corresponds to conversion of 1 mole of reactant. In reaction (1.1), the oxidation of 1 mole of lithium (7 g), the reduction of 1 mole MnO₂ (87 g), and the formation of 1 mole of LiMnO₂ (94 g) are accompanied by the transference of 26.8 Ah. The Faraday’s laws are, in essence, the conservation law in electrochemistry.

The important consequence from Faraday’s laws is the fact that current I, passing for the time t through a galvanic cell, is directly proportional to the rate of electrode reactions, v, as well as to the rate of overall current-producing reaction. In other words, the cell current is a measure of reaction rates in electrical units:

$I=dQ/dt=nFv=nF\left(dm/dt\right)/A$ (1.5)

Faraday’s laws give a possibility to calculate the amount of the reactant, necessary for producing a unit charge. This quantity is called ‘theoretical specific consumption of a reactant...

Table of contents

• Cover
• Title Page
• Copyright Page
• Acknowledgments
• Preface
• Abbreviations and Acronyms
• Table of Contents
• Introduction
• 1. Modern Lithium and Lithium-Ion Rechargeable Batteries
• 2. Materials for All-Solid-State Thin-Film Batteries
• 3. PVD Methods for Manufacturing All-Solid-State Thin-Film Lithium-Ion Batteries
• 4. Diagnostics of Functional Layers of All-Solid-State Thin-Film Lithium-Ion Batteries
• Conclusion
• Subject Index
• About the Authors