Classification of Batteries

The two mainstream classes of batteries are disposable/non-rechargeable (primary) and rechargeable (secondary) batteries. A primary battery is designed to be used once and then discarded, and not recharged with electricity. In general, primary batteries are assembled in a charged condition and the electrochemical reaction occurring in the cell is mostly irreversible, rendering the cell non-rechargeable. Leclanche, alkaline manganese dioxide, silver oxide, and zinc/air batteries are examples of primary batteries [5].

The secondary battery is a type of electrochemical device, in which the chemical reactions can be reversed by application of an external electrical energy source. Therefore, such a cell can be recharged many times by passing an electric current through it after it reached its fully discharged state, allowing it to be used for long periods. Generally, secondary batteries have a lower capacity and initial voltage, a flat discharge curve, higher self-discharge rates, and varying recharge life ratings. Secondary batteries usually have more active (less stable) chemistries that

TABLE 2.1

Common Battery Types Based on the Type of Materials and Their Rechargeability

TABLE 2.2

The Characteristics and Performance of Commonly Used Rechargeable Batteries

need special handling, containment, and disposal. Aluminum-ion battery, lead- acid battery, lithium-ion battery, nickel-cadmium battery, and sodium-ion battery are examples of secondary batteries. According to the chemical reaction involved, rechargeable batteries can further be classified as lead-acid, nickel-metal hydride, zinc-air, sodium-sulfur, nickel-cadmium, lithium-ion, lithium-air batteries, etc.

Batteries may also be classified by the type of electrolyte employed, either aqueous or non-aqueous systems. Some common battery types are listed in Table 2.1 and the characteristics and performance of commonly used rechargeable batteries are shown in Table 2.2 in accordance with these classifications. Among the aforementioned rechargeable batteries, lithium-ion batteries (LIBs) have gained considerable interest in recent years in terms of the high specific energy and cell voltage, good capacity retention, and negligible self-discharge [6]. Figure 2.2 shows the projected

FIGURE 2.2 Predicted increase in demand for lithium-ion batteries from 2005 to 2019 (2019 value is approximated from [17]) for electric vehicle and consumer device applications.

increase in demand for LIBs in the present decade, and it is clear that the importance of LIBs in day-to-day life is increasing over time.

History of Lithium-Ion Batteries

Understanding the brief history of the development of LIBs is quite interesting. The first rechargeable LIBs were described by the British chemist M. Stanley Whittingham, a key figure in the history of the development of LIBs, while working at Exxon. He fabricated the first rechargeable LIB with layered titanium disulfide (TiS,) as the cathode and metallic lithium as the anode in 1976 [18]. Exxon subsequently tried to commercialize the LIBs, but they were unsuccessful due to the problems of lithium-ion (Li⁺-ion) dendrite formation and subsequent short circuiting, following extensive cycling and consequent safety concerns [19]. In addition, TiS₂ has to be synthesized under completely sealed conditions, and is quite expensive (~$ 1000 per kilogram for TiS, raw material in the 1970s). When exposed to air, TiS, reacts to form toxic hydrogen sulfide, which has an unpleasant odor, causing environmental issues. Lithium (Li) is the lightest metal and the lightest solid element, and is a highly reactive element; it burns under normal atmospheric conditions because of its spontaneous reactions with water and oxygen [20]. During the charging cycle, the tendency for Li to readily precipitate onto the negative electrode (anode) in the form of dendrites causes short circuiting. The high chemical reactivity of metallic Li and the tendency for dendrite formation results not only in poor battery characteristics, including inadequate cycling stability, because of side reactions with the electrolyte, but also poses an inherent risk of a thermal runaway reaction, which was an insoluble issue in terms of safety. As a result, the researchers focused on developing LIBs which employed only Li compounds which were capable of accepting and releasing Li⁺-ions, instead of using metallic Li electrodes. As a result, reversible intercalation of Li⁺-ions into graphite [21-23] and cathodic oxides [24-26] was reported in 1976 by J. O. Besenhard, who proposed its application as the anode and cathode in Li⁺-ion cells [23, 26].

In 1977, Samar Basu demonstrated electrochemical intercalation of Li⁺-ions into graphite, which led to the development of a workable Li⁺-ion-intercalated graphite electrode (LiC₆) at Bell Labs to provide an alternative to the Li metal battery [27,28]. In 1979, Ned A. Godshall et al. [29-31], and, in the following year, John Goodenough et al. [32-34] demonstrated a rechargeable Li⁺-ion cell with a nominal voltage of 4 V, using layered LiCoO, as the high-energy and high-voltage material for the positive electrode and Li metal as the negative electrode, although layered LiCoO, did not attract much attention initially. In 1979, Godshall et al. demonstrated other ternary compound Li-transition metal-oxides, such as the spinel LiMn₂0₄, Li,MnO„ LiMn0₂, LiFeO,, LiFe₅0₈, and LiFe₅0₄, as electrode materials other than LiCoO, for LIBs [29-31, 35], and Fluggins was awarded a US patent in 1982 on the use of LiCoO, as cathodes in LIBs [36]. In 1983, Goodenough and colleagues also identified manganese spinel as a low-cost cathode material [37] and, in 1985, Godshall et al. identified Li-copper-oxide and Li-nickel-oxide as cathode materials for LIBs [35]. The lack of safe anode materials, however, limited the application of a layered oxide cathode of LiMO, (M=Mn, Ni, Co) in LIBs [38].

In 1978, Besenhard [23] and Basu [28], and. in 1980, Rachid Yazami [39, 40] demonstrated that graphite, also with a layered structure, could be a good candidate to reversibly store Li⁺-ions by electrochemical intercalation/deintercalation of Li⁺-ions in graphite. The publications of Yazami and Touzain [39, 40] are accepted as describing the world’s first successful experimental demonstration of the electrochemical intercalation and the release of Li⁺-ions in graphite. The organic electrolytes available for LIBs at the time decomposed during cell charging, when using graphite as an anode, slowing the commercialization of a practical rechargeable Li/ graphite battery. In Yazami’s studies, a solid electrolyte was used to demonstrate that Li could be reversibly intercalated in graphite through an electrochemical mechanism, and this experiment provided the scientific basis for the use of graphite as negative-electrode material, as is the standard in LIBs today. As of 2011, the graphite electrode developed by Yazami was the most commonly used electrode in commercial LIBs.

In 1985, Akira Yoshino assembled a prototype Li⁺-ion cell, using a carbonaceous anode (polyacetylene, which is an electrically conductive polymer discovered by Prof. Hideki Shirakawa, who received the Nobel Prize in Chemistry in 2000) into which Li⁺-ions could be inserted and discharged, with LiCoO, as the cathode [41, 42]. Both the carbon anode and the LiCoO, cathode are stable in air, which is highly beneficial from both an engineering and a manufacturing perspective. In addition, Yoshino [43] found that carbonaceous material with a certain crystalline structure provided greater capacity without causing decomposition of the propylene carbonate electrolyte solvent, as happened with the graphite electrode. This battery design, using materials without metallic Li, enabled industrial-scale manufacture, and proved to be the cornerstone of the current LIB.

After the successful demonstration of this prototype design of the LIB in 1986, Yoshino carried out the world’s first safety tests on LIBs and proved that this LIB overcame the safety issues that had prevented commercialization of non-aqueous secondary batteries in the past. Because of the risk of ignition or even explosion during the safety test, Yoshino had to borrow a facility designed for testing explosives. In these tests, a lump of iron was dropped on to the batteries and the effect compared with that from a set of cells assembled using the Li metal electrode; test results showed that a violent ignition occurred with a metallic Li battery, whereas no ignition occurred with a LIB. According to Yoshino, this was a great relief, because, if ignition had occurred in this test, the LIB would not have been commercialized. This was the crucial turning point for the commercialization of the LIB. I consider the success of these tests to be “the moment when the lithium-ion battery was born” [43].

Eventually, Sony, the dominant manufacturer of personal electronic devices at the time, such as the Walkman and pocket cameras, commercialized LIBs in 1991, as did a joint venture between Asahi Kasei and Toshiba in 1992. Table 2.3 shows some milestones in the commercialization of LIBs. LIBs proved to be a tremendous success and facilitated a major reduction in the size and weight of the power supply for portable devices, thereby supporting the evolution of the portable electronics industry. Commercialization of the LIB made available an energy density, in terms of both weight and volume, of around twice what was possible with nickel-cadmium or nickel-metal hydride batteries, and providing an electromotive force of 4 V or more; in this way, the LIB made it possible to power a cell phone with a single cell. To acknowledge their pioneering contribution to the development of LIBs, John

TABLE 2.3

Historical Milestones of the Commercial Lithium-Ion Batteries

^System management bus

Bannister Goodenough, Rachid Yazami, Akira Yoshino, and Yoshio Nishi were awarded the 2012 IEEE Medal for Environmental and Safety Technologies and the Draper Prize in 2014. Later, in 2019, John Bannister Goodenough, Michael Stanley Wittingham, and Akira Yoshino received the Nobel Prize in Chemistry for the development of lithium-ion batteries, an important technology by which the world was able to move away from fossil fuels.