Organic Electrode Materials, a New Opportunity for Low Cost and High Power Lithium Battery?

Nowadays electrodes of lithium batteries are mainly constituted by inorganic compounds based on transition metals such as cobalt, nickel or manganese. Although their performances are satisfying, these materials present several important drawbacks. Indeed these compounds are expensive because they are prepared due to energy-consuming techniques from rare mineral precursors. Moreover, some metals are toxic and often hard to recycle. Eventually their reactivity leads to safety issues in abusive conditions.

Organic compounds such as nitroxide based polymers offer a cost-effective and environmental friendly alternative to conventional active materials for high power batteries.^1,2Interestingly these polymers can be prepared from low cost precursors using classical organic and polymer chemistry techniques. Moreover these compounds are easy to recycle or reuse at their end of life. But until now, their use in electrodes is still challenging due to their solubility in common electrolytes and their very low electronic conductivity.

Our work is focused on the synthesis and the grafting of nitroxide radical on a polymer backbone to prepare poly(2,2,6,6-tetramethyl-1-piperidinyloxy-4-ylmethacrylate) [PTMA]. Various functional crosslinker have been introduced in order to decrease the solubility and improve the ionic conductivity of these organic materials. These polymers have been fully characterized by Gel Permeation Chromatography, UV spectroscopy and Electron Spin Resonance. Electrolytes compositions have also been optimized in order to prevent the active materials from leaching into the solvent of electrolytes during cycling. In addition, our development of specific formulation allows us to implement these types of materials in electrodes of lithium batteries and some impressive electrochemical performances, especially at high C-rate, have been obtained.

This work is part of the ROPAS project and has been sponsored by the 7^thframework of the EC.

1)     Nakahara, Chem. Phys. Lett., 2002, 359, 351-354

2)     Nishide, Electrochimica Acta, 2004, 50, 827-831