A research team lead by the Institut de Ciències de Materials de Barcelona (ICMAB-CSIC) has published a new study on polyimides, a promising material for cathodes in metal-organic batteries, a more sustainable alternative to lithium-ion batteries. Operando measurements were performed, for the first time, at the MIRAS beamline.
Organic positive electrodes, in addition to being the most sustainable and potentially low-cost candidates, compared with their inorganic counterparts, currently present the best electrochemical performances in calcium and magnesium batteries. Unfortunately, organic positive electrodes suffer from relatively low capacity retention upon cycling, the origin of which is not yet fully understood.
ICMAB-CSIC scientists tested a plastic material called polyimide (specifically1,4,5,8-naphthalenetetracarboxylic dianhydride-derived polyimide or PNTCDA) in lithium (Li), sodium (Na), magnesium (Mg) and calcium (Ca) cells. In particular, the electrochemical performance of PNTCDA was evaluated as positive electrode for Li+, Na+, Mg2+ and Ca2+-ion batteries in organic electrolytes; for the sake of comparison in terms of redox potential, gravimetric capacities, capacity retention, and rate capability.
The redox mechanisms were also investigated by means of operando infrared experiments at the MIRAS beamline of the ALBA Synchrotron, and a parameter affecting most figures of merit has been identified: the presence of contact ion-pairs in the electrolyte. Moreover, operando infrared assisted experiments on Li+ and Ca2+ ion cells allowed scientists to observe the reversible enolation/carbonylation processes of the carbonyl bonds in the imide functionalities in real time.
Read more on ALBA website
Image: Operando Cell (ECC-Opto-Std, EL CELL)