Perovskite solar cells power rechargeable aqueous zinc battery in new design

Scientists from Nankai University in China have developed an integrated solar rechargeable zinc battery (SRZB), powered by perovskite solar cells, that could be used for wearable smart electronics, Internet of Things (IoT) devices, and other electrically powered equipment.

The device consists of a perovskite solar cell part and a rechargeable aqueous zinc metal cell, which are combined via a sandwich joint electrode. Image from study

The system has a 4-layer configuration including a perovskite light absorber, a sandwich joint electrode, an aqueous alkaline electrolyte, and zinc metal. 'Benefiting from the integrated device structure, specially designed components and narrow-range voltage-matching mechanism, our inexpensive SRZB shows remarkably high specific energy, high specific power, high safety and high overall efficiency,' the researchers said.

The sandwich joint electrode was embedded in the device to integrate the aqueous zinc battery with the water-sensitive perovskite solar cells. 'Intrinsically, the sandwich joint electrode possesses a hydrophilic-hydrophobic-hydrophilic structure feature, which 'hides' the impermeable protective layer internally and exposes two external hydrophilic interfaces to simultaneously achieve protection and electrical performance,' the team explained.

One of the two hydrophilic sides of the electrode was doped with nickel cobaltite (NiCo₂O₄) to improve its compatibility with the other layers, while the other side acts as the counter electrode of perovskite solar cells to obtain better interfacial contact.

The electricity generated by the perovskite solar cells is fed into the fluorine-doped tin oxide (TiO₂/FTO) substrate and is transferred to the Zn electrode to reduce zinc ions. Holes can then spread through the sandwich joint carbon layer to achieve an oxidation reaction on the positive electrode. 'In this way, the SRZB can harness the infinite power of solar irradiation and store this solar energy in terms of electrochemical energy,' the group stated. 'The as-stored electrochemical energy can be subsequently released with controllable and steady output according to the demand.'

After measuring the system performance, the scientists found it can achieve high specific energy of 366'Wh/kg, high specific power of 54.01'kW/kg, an overall efficiency of 6.4%, and a steady operation for more than 200 cycles with little performance degradation. 'High safety and low-cost demands are also satisfied owing to the use of cost-effective materials, a safe aqueous electrolyte and a special photocharge mode,' they concluded.