Materials Aspects: An Overview

The exponential growth in portable electronic devices such as cellular phones and laptop computers during the past decade has created enormous interest in compact, light-weight batteries offering high energy densities. Also, growing environmental concerns around the globe are driving the development of advanced batteries for electric vehicles. Lithium-ion batteries are appealing for these applications as they provide higher energy density compared to the other rechargeable battery systems such as lead-acid, nickel-cadmium, and nickel-metal hydride batteries as shown in Figure l.l.1 The higher volumetric and gravimetric energy densities of the lithium-ion cells in Figure 1.1 are due to the higher cell voltages (~ 4 V) achievable by the use of non-aqueous electrolytes, which also allow a wider temperature of operation. Lithium-ion cells have become a commercial reality after the initial announcement by Sony in the early 1990s because of an intense world-wide activity on lithium insertion compounds (electrode materials) during the past three decades. This chapter provides an overview of the electrode materials aspects of rechargeable lithium batteries. A more detailed discussion of the specific cathode and anode materials systems as well as the electrolytes is presented by various authors in the subsequent chapters.