My primary research interests are in the fields of solid state chemistry and electrochemistry; particularly solid state ionics, which embraces ionically conducting solids and intercalation compounds. I am interested in the fundamental science of ionically conducting solids (ceramic and polymeric materials) and intercalation compounds, in the synthesis of new materials with new properties or combinations of properties, in understanding these properties and in exploring their applications in new devices, especially energy storage devices such as rechargeable lithium batteries. Although ionically conducting solids represent the starting point for much of our research, we have extended our interests well beyond the confines of this subject alone.

INTERCALATION COMPOUNDS:

Lithium intercalation into solid hosts is the fundamental mechanism underpinning the operation of electrodes in rechargeable lithium batteries. We seek to synthesise new lithium intercalation compounds with unusual properties or combinations of properties. We are especially interested in nanomaterials since the nanoscale can enhance the intercalation properties.

CRYSTALLOGRAPHY:

In the absence of single crystals it is important to establish methods by which the entire crystal structure can be solved ab initio from powder X-ray or neutron diffraction. We are involved in the development of a powerful new method by which this can be achieved. The method uses a simulated annealing approach to minimise the difference between observed and calculated powder diffraction patterns. It is the direct descendant of the Rietveld technique, which is well established in powder diffraction for refining crystal structures. This area of research has far reaching benefits beyond crystallography itself and can be used to solve the structures of many important compounds, e.g. new drugs.

POLYMER ELECTROLYTES:

Since the discovery of crown ethers and cryptands by Pederson, Cram and Lahn (for which they received the Nobel Prize in 1987), the significance of molecules containing the repeat units -CH₂-CH₂-O- as coordinating ligands for metal cations has been recognised. By combining salts and polyethers such as polyethylene oxide (-CH₂-CH₂-O-)_n, it is possible to synthesise thousands of metal-polyether complexes, alternatively known as polymer electrolytes. Such materials are in effect co-ordination compounds in the solid state. Despite the synthesis of many such materials, little was known of their structures because such structures proved inaccessible to many conventional methods of structure determination. We developed a powerful crystallographic method by which complete crystal structures could be solved ab initio from powder diffraction data. Using these fundamental structural studies, we recognised that the 6:1 complexes (6 ether oxygen's per lithium), poly(ethylene oxide)₆:LiXF₆, where X=P,As,Sb, had a structure composed of polymer tunnels within which the Li⁺ ions reside. We predicted that this structure should support ionic conductivity and we went on to show that this is so. This work represented the discovery of ionic conductivity in crystalline polymer electrolytes when all such materials had been considered to be insulators for the last 30 years. It represents a new direction in the study of ion transport in the solid state that is quite different from the conventional picture of ion transport in amorphous polymers that has dominated the field since the late 1970's. We have gone on to show that it is possible to dope the 6:1 complexes thus raising the conductivity of these materials substantially to levels equalling and exceeding that of the best amorphous polymers and paving the way for the application of polymer electrolytes in devices such as all-solid-state rechargeable lithium batteries.

SELECTED RECENT PUBLICATIONS

1. Crystalline Small-Molecule Electrolytes, C Zhang, Y G Andreev, P G Bruce, Angewandte Chemie International Edition, 2007, 46(16), 2848-2850
2. Mesoporous crystalline ß-Mn0₂ a reversible positive electrode for rechargeable lithium batteries, F Jiao, P G Bruce, Advanced Materials, 2007, 19(5), 657-660
3. Structural evolution of layered LixMnyO₂: Combined neutron, NMR, and electrochemical study, A R Armstrong, A J Paterson, N Dupre, C P Gray, P G Bruce, Chemistry of Materials, 2007 19(5), 1016-1023
4. Rechargeable Li₂O₂ electrode for lithium batteries, T. Ogasawara, A. Debart, M. Holzapfel, P. Novak, P. G. Bruce, J. Am. Chem. Soc., 2006 128(4),1390-1393
5. Increasing the conductivity of crystalline polymer electrolytes, A.M. Christie, S. J. Lilley, E. Staunton, Y. G. Andreev, P G Bruce, Nature, 2005, 433(7021), 50-53