Copolymer Helps Make Flexible Li-Ion Battery Electrodes

In a step toward making thin, flexible batteries, researchers have hybridized a candidate for lithium-ion battery electrodes, V₂O₅, with a conductive polymer. Not only does that process convert the electrode material from a paperlike form that easily cracks to one that’s flexible and robust, it also improves its electrochemical properties (Sci. Rep. 2015, DOI: 10.1038/srep14166). Such an electrode material could speed development of bendable, stretchable electronics incorporated into clothing and other unconventional products. A research team led by Texas A&M University chemical engineers Hyosung An, Jared Mike, and Jodie L. Lutkenhaus used a simple water-based process to blend V₂O₅ with poly(3-hexylthiophene)-block-poly(ethyleneoxide), or P3HT-b-PEO, a block copolymer composed of electron- and ion-conducting units. The researchers found that adding just 5 wt % polymer led to a hybrid that’s three times as flexible and twice as tough as pure V₂O₅. Hybridizing also roughly doubled the lithium-ion diffusion, eliminated cracking during battery charging and discharging, and slowed the battery’s loss of capacity over time. The team attributes the enhancements to the hybrid material’s unique self-assembled structure, which consists of interlocking V₂O₅ layers held together by micellar aggregates of P3HT-b-PEO.