Page 42 - Lindens Handbook of Batteries
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BASIC CONCEPTS       1.17

                            350
                                                                  Lithium
                            300

                            250
                          Specific energy (Wh/kg)  200     Alkaline-                        Lithium-ion




                            150
                                                            MnO
                                                               2
                                                     MnO
                                               High
                                                         2
                            100
                                            performance Alkaline-
                                             Leclanché                                 Ni-MH
                             50                                         Lead-acidNi-Cd
                                      Leclanché
                             0
                                        1946   1955  1965   1985   2010   1940  1955   1985   2010
                                                 Primary batteries            Secondary batteries
                         FIGURE 1.6  Advances in battery performance for portable applications.

                                is not included in the calculation, the values for the theoretical energy density do not exceed 1500 Wh/kg.
                                Even the values for hydrogen/air and liquid fuel cells have to be lowered to include, at least, the
                                weight and volume of suitable containers for these fuels.
                                   The data in Table 1.2 also show that the specific energy delivered by these batteries, based on the
                                actual performance when discharged under optimum conditions, does not exceed 600 Wh/kg, even
                                including the air-breathing systems. Similarly, the energy density values do not exceed 1300 Wh/L.
                                It is also noteworthy that the values for the rechargeable systems are lower than those of the primary
                                batteries, due in part to a more limited selection of materials that can be recharged practically and
                                the need for designs to facilitate recharging and cycle life.
                                   Recently, there has been much interest in the lithium/air system, which has a theoretical specific
                                energy of 11,000 Wh/kg, particularly as a rechargeable system for use in EVs. Primary cells have
                                produced 800 Wh/kg (see Chap. 33).
                                   Recognizing these limitations, while new battery systems will be explored, it will be more diffi-
                                cult to develop a new battery system that will have a significantly higher energy output and still meet
                                the requirements of a successful commercial product, including availability of materials, acceptable
                                cost, safety, and environmental acceptability.
                                   Battery research and development will focus on reducing the ratio of inactive to active compo-
                                nents to improve energy density, increasing conversion efficiency and rechargability, maximizing
                                performance under the more stringent operating conditions and enhancing safety. The fuel cell is
                                offering opportunities for powering electric vehicles, as a replacement for combustion engines, for
                                use in utility power and possibly for the larger portable applications (see Chap. 38). The develop-
                                ment of a fuel cell for small portable applications, such as cell phones, that will be competitive with
                                batteries presents a formidable challenge. (see Chap. 37).

                    REFERENCES


                                1.  D. Linden and T. B. Reddy, Battery Power and Products Technology, vol. 5, no. 2, pp. 10–12, March/April 2008.
                                2.  M. Winter and R. Brodd, Chemical Reviews, vol. 104, 4245–4270, 2004.
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