Josh Thomas tells Journal of Materials Chemistry about his hot paper.

1. Could you explain the significance of your article to the non-specialist? 
We are still hunting for a self-standing polymer film with high enough Li-ion conductivity for use in the Li-ion battery industry. This would make Li-ion batteries both intrinsically safer and cheaper to fabricate; something which is critical for their full-scale incorporation into upscaled batteries for, typically, hybrid electric-vehicle (HEV) applications.  It was earlier believed that "disorder" was the basic requirement for high ionic conductivity in "solid" polymer electrolytes, but all efforts failed to find a disordered polymer electrolyte with sufficiently high conductivity.  Only when Peter Bruce's group at St. Andrews, Scotland found (in 2001) that higher ionic conductivity could, in fact, be obtained in the crystalline form of a polymer-salt system did research strategy shift.  It was subsequently found that even higher conductivities were found for ordered short-chain polymer systems. In this work, we seek to understand the detailed anion and cation conductivity mechanisms in such materials, especially the possible role of the many chain-ends. This should give us insights into how the net Li-ion conductivity can be further improved.

2. What has motivated you to conduct this work? 
To discover the structural and mechanistic elements needed to attain higher ionic conductivities in solid polymer electrolyte materials.  (also see above)

3. Where do you see this work developing in the future? 
It should help generate new ideas in the design of polymer electrolytes for Li-ion polymer battery applications. The ultimate goal of achieving ambient temperature conductivities in excess of 1mS/cm will likely be reached through a sequence of incremental synthesis breakthroughs of the type discussed above; hopefully inspired by ideas emanating from our simulation results.

4. Are there any particular challenges facing future research in this area? 
As stated - despite considerable successes, we are still at least 2 orders of magnitude away from reaching our goal. New insights, possible provoked by our simulation work, are sorely needed to reach the ultimate goal.

Josh Thomas (left) is Professor of Solid State Electrochemistry at the Department of Materials Science, Uppsala University.  He has long specialised in the experimental  (single-crystal and powder XRD/ND) and theoretical (espescially MD simulation) study of ion insertion/extraction mechanisms in transition-metal oxides, and ion-transport mechanisms in polymer electrolytes and in the region of the electrode/electrolyte interface.  More recently, he has developed a special interest in the detailed processes involving nano-materials in an electrochemical context - and in the related development of in situ structural/ electrochemical techniques for their closer study. In forming the Ångström Advanced Battery Centre five years ago, his overriding goal was to secure a quality research base in Uppsala for the study of electrochemical storage materials.

Daniel Brandell (centre) received his PhD from Uppsala University, Sweden in 2005; his thesis work was on MD simulation of solid-state polymer electrolytes. He is currently a postdoc at Virginia Polytechnic and State University, USA.

Anti Liivat (right) received his PhD from Uppsala University, Sweden in May 2007. His thesis work was on MD simulation of short-chain polymer electrolytes.  He is currently continuing as a postdoc at Uppsala University.