Compositing effects for high thermoelectric performance of Cu₂Se-based materials

Thermoelectric materials can realize direct conversion between heat and electricity, showing excellent potential for waste heat recovery. Cu₂Se is a typical superionic conductor thermoelectric material having extraordinary ZT values, but its superionic feature causes poor service stability and low mobility. Here, we reported a fast preparation method of self-propagating high-temperature synthesis to realize in situ compositing of BiCuSeO and Cu₂Se to optimize the service stability. Additionally, using the interface design by introducing graphene in these composites, the carrier mobility could be obviously enhanced, and the strong phonon scatterings could lead to lower lattice thermal conductivity. Ultimately, the Cu₂Se-BiCuSeO-graphene composites presented excellent thermoelectric properties with a ZT_max value of ~2.82 at 1000 K and a ZT_ave value of ~1.73 from 473 K to 1000 K. This work provides a facile and effective strategy to largely improve the performance of Cu₂Se-based thermoelectric materials, which could be further adopted in other thermoelectric systems.