Li electrodes in any relevant electrolyte solution (i.e., polar aprotic) are covered by surface films of a very complicated structure. It was found that even in cases where the surface films formed on lithium contain elastomers, or where the lithium metal reactivity is reduced by doping with elements such as N, As, Al, Mg, Ca, etc., it is impossible to achieve sufficient passivation with lithium electrodes and liquid solutions. Passivation is considerably worsened when Li electrodes are operated at high rates (especially at high charging, Li deposition rates). Thus, there is no way that rechargeable Li batteries can compete with Li-ion batteries in any application that requires high charging rates (e.g., in powering portable electronic devices). The electrochemical behavior of lithiated graphite electrodes also depends on passivation phenomena. The surface films formed on lithiated graphite are similar to those formed on Li metal in the same solutions. The volume changes of graphite electrodes during Li insertion-deinsertion are small enough to enable their reasonable passivation in a variety of electrolyte solutions. A critical factor that determines the stability of graphite electrodes is their morphology. It was found that the shape of graphite particles plays a key role in their application as active mass in anodes for Li-ion batteries.
Bibliographical noteFunding Information:
Partial support for the work described in this paper was obtained from the BMBF, the German Ministry of Science, in the framework of the DIP project, from the Israeli Ministry of Science and Technology, in the framework of the Infrastructure Research Program, and from the Israel National Foundation of the Israel Academy of Science.
- Li-ion batteries
- Liquid electrolyte solutions