Wiederaufladbare Batterien

As a matter of fact, most of our technical electrochemical energy storage systems operate outside the limitations of thermodynamics. As in the case of rechargeable batteries with aqueous electrolytes (part I of this article), kinetics control the operation and safety also in batteries with nonaqueous electrolytes (this second and final part).A striking example is the lithium ion battery which possesses an operating voltage of >3,5 V and a very high energy density. From a thermodynamic viewpoint such a cell is impossible because the used organic electrolyte is in contact with two lithium insertion electrodes that operate at extreme reducing and oxidizing potentials, respectively. However, a unique mechanism kinetically prevents the decomposition of the electrolyte due to the formation of electronically insulating interphases between electrode and electrolyte that are still permeable to the electrochemically active Li + cations. Lithium ion batteries have already made their breakthrough into the market as small format systems for portable electronics. The only „kinetically shielded” high energy density, however, might be a safety complication for large format batteries, which are assembled for electric vehicle (EV) propulsion. Safety concerns are also valid for high temperature (300°C) batteries such as the sodium‐sulfur and sodium‐nickel chloride systems. These systems are still in the stage of „experimental batteries”, which may find future application in large units for EV's or uninterruptible power systems. The paper is concluded by a performance comparison of various rechargeable battery systems with aqueous and nonaqueous electrolytes. (Possible) applications in consumer electronics and EV's are discussed in more detail.