Recent progress in batteries and future problems

Abstract

In 1990 Sony succeeded in the development of a new kind of electrochemical cells with non-aqueous electrolytes, lithiated carbon anodes and LiCoO 2 cathodes. They were named lithium ion secondary batteries (LIBs) and were introduced into the market for the first time in 1991 by Sony [1]. LIBs have outstanding properties in comparison with conventional secondary batteries such as nickel / cadmium, nickel / metal hydride and lead-acid batteries. Several among them are: 1) High operating voltage, 2) High energy density (both gravimetric and volumetric), 3) No memory effect, 4) Low self-discharge rate (less than 10% per month), 5) Operation over a wide temperature range. Much effort has been done incessantly to improve further the performances of LIBs, which boost LIBs into the most suitable power sources for portable equipment like cellular phones and notebook computers. The latest status of Sony's LIBs will be described in the pages that follow. 2.1.2 Lithium ion secondary battery Electrolyte solutions based on organic solvents have been used in LIBs. Due to the lower ionic conductivity of non-aqueous electrolytes than aqueous ones, it was misunderstood at the start of LIBs manufacturing (in the first half of 1990's) that LIBs could not have excellent performances, especially regarding to low temperature characteristics and drain capability.