Lithium Ion Rechargeable Batteries

Materials, Technology, and New Applications

Kazunori Ozawa

• Publisher: Wiley-VCH
• Year: 2012
• Print ISBN:
  9783527319831
• Edition: 1
• eBook ISBN:
  9783527644650
• Topic: Technology & Engineering
• Subtopic: Electrical Engineering & Telecommunications
• Index: Technology & Engineering

Starting out with an introduction to the fundamentals of lithium ion batteries, this book begins by describing in detail the new materials for all four major uses as cathodes, anodes, separators, and electrolytes. It then goes on to address such critical issues as self-discharge and passivation effects, highlighting lithium ion diffusion and its profound effect on a battery's power density, life cycle and safety issues. The monograph concludes with a detailed chapter on lithium ion battery use in hybrid electric vehicles.
Invaluable reading for materials scientists, electrochemists, physicists, and those working in the automobile and electrotechnical industries, as well as those working in computer hardware and the semiconductor industry.

1

General Concepts

Kenzo Matsuki and Kazunori Ozawa

1.1 Brief Outline of Batteries

The first practical battery is the generally known Volta cell (also called the Galvanic cell). Its invention, over two centuries ago, spawned the invention of a variety of batteries based principally on the Volta cell. However, interestingly, during the last century, only three batteries, namely, the MnO₂ primary battery and the secondary batteries of lead/acid or nickel have been in use. Knowing why such batteries continue to be used would give us some important pointers toward the development of new technology in this line. These old batteries are close to reaching their technical limit. Recently, however, new concepts have been used in the development of lithium-ion secondary batteries with higher ability.

A battery generally provides two functions – the ability to supply power over a duration of time and the ability to store power. These are defined by two operations, charge/discharge (progress of the reaction) and storage/stop (termination of the reaction), that is, a battery is a device that provides two functions, namely, energy storage and energy conversion (from chemical to electrical, and vice versa). As shown in Figure 1.1, the field of energy conversion is a multiphase system that is composed of positive/negative terminals and positive/negative active materials and electrolyte; the ions and electrons transfer through their interfaces. The interfaces reflect the nature of each phase. In addition, the state of these interfaces changes over time with the operation of the battery. The cell voltage is supported by an electric double layer with a remarkably high electric field between the electrodes and the electrolytic solution in which the electrode reactions take place. It should be emphasized that battery technology is essentially the same as the technology that controls these interfaces.

Fig. 1.1 Multilayer system composed of five phases and four interfaces.

1.1.1 Galvanic Cell System – Aqueous Electrolyte System

To understand the cell structure and its reaction, the well-known Daniel cell is schematically shown in Figure 1.2.

Fig. 1.2 Daniel cell.

The two half cells of Zn|Zn²⁺ and Cu|Cu²⁺ are combined and a separator is placed between them so that they are not miscible with each other. The formula that shows the principle and the structure of the Daniel cell is as follows:

where the symbols | and || show the interface of different phases and the liquid–liquid junction (separator), respectively.

The cathode (positive electrode) active material of the Daniel cell is the Cu²⁺ ion in the electrolyte, while the Zn anode (negative electrode) dissolves to form the Zn²⁺ ion. The drop in voltage of the cell occurs because of self-discharge of the active materials. Generally, a self-discharge tends to occur when the dissolved chemical species such as Cu²⁺ ion are used as the cathode-active material. This is one of the reasons that the Daniel cell was not used for practical purposes.

Cathodeand anode-active materials in the Leclanche cell are MnO₂ (solid) and Zn metal, respectively. These electrode reactions are as follows:

When the discharge reaction takes place, the Zn anode dissolves to form a complex ion. Since MnO₂ has a depolarizing ability that reduces the potential drop produced, the Leclanche type battery has been improved progressively to produce several kinds of batteries for commercial use, such as the manganese dry cell, the ZnCl₂ cell, and the alkaline MnO₂ cell.

In 1859, Plante invented the lead acid storage battery. This battery has been improved over the years and is now industrially mass-produced. The electrode reactions in the lead storage battery are described as follows:

During discharge, a secondary solid phase of PbSO₄ is formed on both the anode and the cathode. Moreover, sulfuric acid in the aqueous solution – which is another active species – and water also participate in the charge/discharge reactions. These factors cause some polarizations that lower the cell performance.

Electrode reactions in Ni– Cd cell are as follows:

The cathode reaction involves the insertion of an H⁺ ion into the solid NiOOH, which is similar to the cathode reaction of MnO₂ in the manganese battery, while the anode reaction is the formation of a secondary solid phase Cd(OH)₂ on the Cd anode. This prevents a smooth reaction as the Cd anode is covered with Cd(OH)₂.

The cathode-active material of nickel – metal hydride (Ni – MH) battery is the H species, which is adsorbed by the hydrogen-adsorbing alloy (MH) instead of the Cd anode of the Ni– Cd battery; the cell reaction is very simple because only hydrogen participates in the charge/discharge reaction. The Ni– MH battery has almost same voltage and larger electric capacity when compared with that of the Ni– Cd battery; moreover, it is free from environmental contamination. Therefore, the industrial production of Ni – MH battery has increased rapidly in recent years.

1.1.2 Lithium-Cell System – Nonaqueous Electrolyte System

To realize a battery with high potential of 3 V, batteries using lithium metal as the anode-active material and a powerful oxidizing agent as the cathode-active material were considered to be ideal. One such promising cathode-active material was MnO₂ ; the development of lithium battery using this commenced in 1962. Fortunately, at that time, substantial amount of basic and application data with MnO₂ was available. About 10 years later, an Li– MnO₂ battery with a lithium metal anode was made available by SANYO Inc.; this became the first representative primary lithium battery.

Since then, considerable research and development has taken place in the design and manufacture of rechargeable lithium batteries. Many cathode-active materials such as TiSe, NbSe, MoS₂, and MnO₂ were studied. For example, rechargeable batteries based on a lithium metal anode and a molybdenum sulfide cathode (Li insertion electrode) were developed by MOLI Energy, Inc. in 1985. This battery system was abandoned owing to safety problems. Lithium batteries based on Li metal anodes and commonly used electrolyte systems revealed the thermal runaway of these systems, which can lead to their explosion; this was almost inevitable in abuse cases such as short circuit, overheating, and overcharging. Although the highest energy density available for Li batteries is achieved by a battery system that can use Li metal anode, a solution to safety issues needs to be found.

Active materials with good reversibility for the Li intercalation/deintercalation and low charge/discharge voltage were used as anode materials instead of Li metal. A carbon material was found to meet these requirements, and a rechargeable Li battery based on a carbon anode and LiCoO₂ (layered lithium cobalt oxide) cathode was developed, mass-produced, and commercialized by Sony Inc. in 1991; this lithium-ion battery was capable of high performance as well as a high voltage of 4 V. As shown schematically in Figure 1.3, lithium-ion rechargeable batteries are charged and discharged through the transport of Li⁺ ions between anode and cathode, with electron exchange as a result of insertion (doping) and extraction (undoping). Both anode and cathode materials are layered compounds, and, as a result, the battery reaction is very simple because only Li⁺ ions participate in the charge/discharge reactions.

Fig. 1.3 Schematic illustration of the reaction in a lithium-ion battery.

The features of the Li-ion batteries, compared with the other rechargeable batteries, can be summarized as follows: (i) Charge and discharge reactions transfer Li⁺ ions between cathode and anode with minimal side reactions; (ii) The electrolytes work only as a path for the Li⁺ ions; and (iii) The volume of the electrolyte between cathode and anode will not be required.

1.2 Early Development of Lithium-Ion Batteries

The UK Atomic Energy Authority showed in their patent [1] that the intercalation and deintercalation of A_x-ion of the compound A_xM_yO₂ reversibly occurs, where A_x is an alkaline metal and M_y is a transition metal. In 1990, Sony used this patent to first produce Li-ion batteries for a cellular phone HP-211. The cell sizes were 14500 and 20500, where 20 refers to the diameter and 50 the length in mm. The chemistry was LiCoO₂/soft carbon system, and the capacities of the 14500 and 20500 models were only 350 and 900 mAh, respectively. The production was on a pilot scale. However, the naming of the lithium-ion rechargeable battery [2] was a marketing success. It was a controversial issue whether Li existed as ion or metal in the carbon anode. By the measurement using NMR, it was revealed that some part of the Li could exist as ion [3].

The actual mass production of the lithium-ion cell was carried out for a camcorder TR-1 in 1991. The cell size was 18650, which has the same volume as the 20500 cell. The chemistry was LiCoO₂/hard-carbon system [4]. Figure 1.4 displays the inside structure of a 18650 cell.

Fig. 1.4 The inside structure of a 18650 lithium-ion cell.

The reasons for Sony’s success as the first producer of lithium-ion batteries is explained in the following section.

1.2.1 Ceramics Production Capability

Sony were already one of the biggest Mn – Zn ferrites producers in Japan. They also had considerable experience in the production of LiCoO₂.

1.2.2 Coating Technology

Sony had been producing magnetic tapes for audioand videotape recorders. The coating technology for magnetic tapes was very useful and very important in making cathode and anode electrodes, especially in making good slurry and performing intermittent coating.

1.2.3 LiPF₆ as a Salt for Electrolytes

LiPF₆ is unstable and easily decomposes with heat and moisture. Since the acid HF is produced in the presence of water, numerous arguments opposing the use of LiPF₆ were put forth in conferences and seminars. However, it was revealed that a small amount of HF increased the life cycle, because of the formation of a very strong passive layer such as AlF₃ on...

Table of contents

• Cover
• Related title
• Title
• Copyright page
• Preface
• List of Contributors
• 1: General Concepts
• 2: Lithium Insertion Materials Having Spinel-Framework Structure for Advanced Batteries
• 3: Overlithiated Li1+x (Niz Co1−2z Mnz)1−x O2 as Positive Electrode Materials for Lithium-Ion Batteries
• 4: Iron-Based Rare-Metal-Free Cathodes
• 5: Thermodynamics of Electrode Materials for Lithium-Ion Batteries
• 6: Raman Investigation of Cathode Materials for Lithium Batteries
• 7: Development of Lithium-Ion Batteries: From the Viewpoint of Importance of the Electrolytes
• 8: Inorganic Additives and Electrode Interface
• 9: Characterization of Solid Polymer Electrolytes and Fabrication of all Solid-State Lithium Polymer Secondary Batteries
• 10: Thin-Film Metal-Oxide Electrodes for Lithium Microbatteries
• 11: Research and Development Work on Advanced Lithium-Ion Batteries for High-Performance Environmental Vehicles
• Index