New lithium salts on the computer: fiction or fact?

The need for improved lithium salts for 'traditional' neat salt/polymer polymer electrolyte systems is still urgent. However, the development of new salts is time-consuming and costly and we raise the question if it is possible to find new lithium salts in an intelligent way and if their properties can be predicted a priori to some accuracy? We here present the use of ab initio quantum mechanical calculations as a primary selection and search tool in the quest for new lithium salts. To evaluate the validity of this approach we present results obtained for 'traditional' polymer electrolyte salts like LiBF4, LiClO4, LiTFSI, etc. These results are then used as a reference system and compared to experimental studies with a focus on vibrational spectroscopy to elucidate the anion dependence of the local coordination strength. Along the same lines the successes and failures of some more recently employed lithium salts are investigated and explained with our method. Finally, we also challenge the polymer electrolyte community to actually synthesize and lest some new computer constructed salts that, judging from the current approach and results, seem to be worthwhile alternatives for neat salt/polymer systems. The a priori calculated effects on different substitutions possible for a given basic system are exemplified. (C) 2001 Elsevier Science Ltd. All rights reserved.