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9.5: Battery Types

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    18995
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    Battery Variety

    An ideal battery has many desirable qualities. It should:

    • have high specific energy and energy density
    • contain no toxic chemicals so that it is environmentally friendly and easy to dispose of safely
    • be safe to use
    • be inexpensive
    • be rechargeable
    • require no complicated procedure to recharge
    • be able to output large current
    • be able to withstand a wide range of temperatures
    • produce a constant voltage output throughout its life (have a flat discharge curve)
    • remain charged for a long time while in storage

    The list above is not complete, and it is in no particular order. Tradeoffs are needed because many of these qualities inherently contradict. For example, a device with a high specific energy necessarily requires more safety precautions and controlled use than a device with low specific energy.

    Batteries are used in a wide range of applications, so one type is not best in all situations. As an example, a car ignition battery must be rechargeable, have high capacity, output large current, and operate over a wide temperature range. However, car batteries do not require particularly high specific energies. As another example, tiny batteries are used to power microelectromechanical systems such as micropumps [142] [143]. These batteries must have high specific energy and be able to be produced in small packages. Some are even built into integrated circuits [144] [145].

    One way to classify batteries is as primary or secondary. A primary battery is used once, then disposed. A secondary battery is a rechargeable battery. Primary batteries have the advantage of simplicity [128, ch. 8]. They do not require maintenance, so they are simple to use. Also, their construction may be simpler than secondary batteries because they do not need additional circuitry built in to monitor or control the recharging process. They often have high specific energy too [128, ch. 8]. They come in a variety of sizes and shapes, and they are made with a variety of electrode and electrolyte materials. Many alkaline and lithium ion batteries are designed to be primary batteries. Secondary batteries have the obvious advantage of not producing as much waste that ends up in a landfill. Also, the user does not need to continually purchase replacements. While secondary batteries may cost more initially, they can be cheaper in long run. They are often designed to be recharged thousands of times [128, ch. 15]. Many secondary batteries have a very flat discharge curve, so they produce a constant voltage throughout use, even upon multiple charging cycles [128, ch. 15]. Two of the most common types of secondary batteries are lead acid batteries and lithium batteries.

    There are many battery types, distinguished by choice of electrolyte and electrodes. Four common battery types are discussed in this section: lead acid, alkaline, nickel metal hydride, and lithium. Not all batteries fit into one of these families. Some devices, like zinc air batteries, are even harder to categorize. Zinc air batteries are actually battery fuel cell hybrids because the zinc of the anode is consumed as in battery operation while oxygen from air is consumed as in fuel cell operation. However, by considering these four classes, we will see some of the variety available. For a more thorough and encyclopedic discussion of battery types, see reference [128].

    Table \(\PageIndex{1}\) summarizes example batteries of each of these four types. The first three rows list example materials used to make the anode, cathode, and electrolyte for batteries. Materials listed in the table are just examples, so batteries of each type can be made with a variety of other materials too. The next two rows give approximate values for the specific energy in units of \(\frac{W \cdot h}{kg}\). All values are approximate values for representative devices provided to give an approximate value for comparison, not necessarily values for a particular device. The fifth row lists example values for the theoretical specific energy of the chemical reaction involved while the sixth row lists example specific energy values for practical devices which are necessarily lower than the theoretical values. The specific energy values in the table can be compared to specific energy of various other materials or energy conversion devices listed in Appendix D.

    Lead acid Alkaline Lithium Nickel Metal Hydride
    Example anode material Pb Zn Li LaNi\(_5\)
    Example cathode material PbO\(_2\) MnO\(_2\) CF or MnO\(_2\) NiOOH
    Example electrolyte H\(_2\)SOH\(_4\) KOH or NaOH Organic solvents and LiBF\(_4\) KOH
    Example applications Car ignitions Toys Cellphones, Medical devices Power tools
    Theoretical specific energy, \(\frac{W \cdot h}{kg}\) 252 358 448 240
    Practical specific energy, \(\frac{W \cdot h}{kg}\) 35 154 200 100
    References [128, p. 15.11] [140] [128, p. 8.10] [140] [128, p. 15.1, p. 31.5] [128, p. 15.1] [146]
    Table \(\PageIndex{1}\): Example material components and specific energy values for batteries based on different chemistries.

    Lead Acid

    Lead acid batteries are secondary batteries which typically have an anode of Pb and a cathode of PbO\(_2\) [128, ch. 15]. The electrolyte is a liquid solution of the acid H\(_2\)SO\(_4\) which ionizes into 2H\(^+\) and SO\(_4^{2-}\). The reaction at the anode is

    \[\mathrm{Pb}+\mathrm{SO}_{4}^{2-} \rightarrow \mathrm{PbSO}_{4}+2 e^{-} \nonumber \]

    with a redox potential of \(V_{rp} = 0.37\) V [140]. The reaction at the cathode is

    \[\mathrm{PbO}_{2}+\mathrm{SO}_{4}^{2-}+4 \mathrm{H}^{+}+2 e^{-} \rightarrow \mathrm{PbSO}_{4}+2 \mathrm{H}_{2} \mathrm{O} \nonumber \]

    with a redox potential of \(V_{rp} = 1.685\) V [140]. The overall cell voltage is \(V_{cell} = 2.055\) V, so in a car battery, six cells are packaged in series.

    Lead acid batteries have a long history. The development of the battery dates to the work of Volta around 1795 [3, p. 2], and practical lead acid batteries were first developed around 1860 by Raymond Gaston Planté [128, p. 16.1.1]. Today, lead acid batteries are used to start the ignition system in cars and trucks, used as stationary backup power systems, and used in other applications requiring large capacity and large output current. Typically, lead acid batteries can handle relatively high current, and they operate well over a wide temperature range [128, p. 15.2]. Additionally, they have a flat discharge curve [128, p. 15.2]. Other types of batteries have a higher energy density and specific energy, so lead acid batteries are used in situations where specific energy is less of a concern than other factors.

    Alkaline

    Alkaline batteries typically have a zinc anode and a manganese dioxide MnO\(_2\) cathode [128, p. 8.10]. Figure \(\PageIndex{1}\) shows naturally occurring manganese dioxide (the dark mineral) on feldspar (the white mineral) from Ruggles mine near Grafton, New Hampshire. The batteries are called alkaline due to the use of an alkaline electrolyte, typically a liquid potassium hydroxide KOH solution [128, p. 8.10]. Most alkaline batteries are primary batteries, but some secondary alkaline batteries are available. Alkaline batteries have many nice properties. They can handle high current outputs, they are inexpensive, and they operate well over a wide temperature range [128, p. 8.10]. One limitation, though, is that they have a sloping discharge curve [128, p. 8.10]. Alkaline batteries were originally developed for military applications during WWII [128, ch. 8]. They became commercially available in 1959, and they became popular in the 1980s with improvements in their quality [128, p.11.1]. They are commonly used today in inexpensive electronics, toys, and gadgets.

    9.5.1.png
    Figure \(\PageIndex{1}\): Naturally occurring manganese dioxide (the dark mineral) on feldspar (the white mineral).

    Nickel Metal Hydride

    Nickel metal hydride batteries have an anode made from a nickel metal alloy saturated with hydrogen. One example alloy used is LaNi\(_5\) [146]. Another rare earth atom may replace the lanthanum [146], and other alloys like TiNi\(_2\) or ZrNi\(_2\) saturated with hydrogen are also used as anode materials [146]. The cathode is typically made from a nickel oxide, and the electrolyte is potassium hydroxide, KOH [128, p. 15.11]. The reaction at the anode is [146]

    \[\text { Alloy }(\mathrm{H})+\mathrm{OH}^{-} \rightarrow \text { Alloy }+\mathrm{H}_{2} \mathrm{O}+e^{-} \nonumber \]

    and the reaction at the cathode is [146]

    \[\mathrm{NiOOH}+\mathrm{H}_{2} \mathrm{O}+e^{-} \rightarrow \mathrm{Ni}(\mathrm{OH})_{2}+\mathrm{OH}^{-}. \nonumber \]

    This cathode reaction has a redox potential of \(V_{rp} = 0.52\) V [137].

    Nickel metal hydride batteries have many advantages. They have a flat discharge curve. They are secondary batteries which can be charged reliably many times [128, p. 15.1] [147]. Additionally, they are better for the environment than the related nickel cadmium batteries, so there are less constraints on how they can be safely disposed [147]. However, they do not have as high of energy density as lithium batteries [147]. Nickel metal hydride batteries were first developed in the 1960s for satellite applications, and research into them accelerated in the 1970s and 1980s. At the time, they were used in early laptops and cellphones, but lithium batteries are used in these applications today [128, p. 22.1]. They are found now in some portable tools, in some cameras, and in some electronics requiring repeated recharging cycles or requiring high current output. The International Space Station is powered by 48 orbital replacement units, and each orbital replacement unit contains 38 nickel-hydrogen battery cells. Figure \(\PageIndex{2}\) illustrates an orbital replacement unit [148].

    9.5.2.png
    Figure \(\PageIndex{2}\): The illustration shows a nickel-hydrogen battery and orbital replacement unit which powers the International Space Station. This figure is used with permission from [148].

    Lithium

    Lithium has a high specific energy, so it is very reactive and a good choice for battery research. For this reason, many different battery chemistries utilizing lithium have been developed. The anode may be made out of lithium or carbon [128, ch. 8,15]. Possible cathode materials include MnO\(_2\), LiCoO\(_2\), and FeS\(_2\) [128, ch. 8,15]. Electrolytes may be liquid or solid. A possible electrolyte is the mixture of an organic solvent such as propylene carbonate and dimethoxyethane mixed with lithium salts such as LiBF\(_4\) or LiClO\(_4\) [128, p. 31.5]. Figure \(\PageIndex{3}\) shows lepidolite, a lithium containing ore of composition K(Li,Al)\(_{2-3}\) (AlSi\(_3\)O\(_{10}\))(O,OH,F)\(_2\), from Ruggles mine near Grafton, New Hampshire.

    Lithium batteries have been in development since the 1960s, and they were used in the 1970s in military applications [128, p. 14.1]. Both primary and secondary lithium batteries are available today. They are popular due to their high specific energy and energy density. They are used in many consumer goods including cellphones, laptops, portable electronics, hearing aids, and other medical devices [149]. Many lithium batteries are designed to output relatively low current to prevent damage, and secondary lithium batteries require controlled recharging to prevent damage [128, ch. 15]. Even with these limitations, over 250 million cells are produced each month [128, ch. 15].

    9.5.3.png
    Figure \(\PageIndex{3}\): Naturally occurring lepidolite, an ore of lithium.

    This page titled 9.5: Battery Types is shared under a CC BY-NC 4.0 license and was authored, remixed, and/or curated by Andrea M. Mitofsky via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.