A research team led by scientists from Purdue University in the United States has developed a testing platform for solar-plus-storage systems operating under extreme temperatures, within a range of -180 C to 300 C.
As a first experiment with the platform, the scientists tested a PV system equipped with a lithium-ion battery (LIB) in a temperature range of -105 C and 80 C. “The research introduces an Integrated Photovoltaic and Battery (IntPB) system that resolves extreme-temperature incompatibility between energy harvesting and storage by pairing polycrystalline silicon PV, leveraging over 0.5% efficiency gain per C below 25 C, with a novel lithium metal battery made with a niobium tungsten oxide cathode and 1M LiFSI electrolyte,” the research’s corresponding author, Vilas G. Pol, told pv magazine.
The researchers also explained that the IntPB system was conceived to allow for individual testing of energy generation sources like PV and nuclear batteries, along with energy storage technologies such as LIBs and capacitors.
The test chamber consists of an aluminum clamshell with a glass window, allowing illumination from the light source. There are two sets of feedthrough ports: one for liquid nitrogen (LN2), which cools the internal components, and the other for argon gas, which keeps the chamber free from water vapor and any ice crystals. Heating is achieved via heating coils, while eight electrical throughputs are provided for data acquisition.
The research group said that the temperature of the test chamber is controlled by an Instec controller in line with the LN2 cooling tubing before entering the test chamber. “Inside the Instec chamber, there is a stainless steel block on which the PV and LIB sit, with channels bored into it that allow LN2 to be pumped through, directly cooling through conductive heat transfer,” it said.
“A proportional-integral-derivative controller regulates the temperature using feedback from a thermocouple that measures the stainless steel block’s surface temperature by adjusting the LN2 scroll pump’s speed.”
The researchers specified that the system was developed as a commercially available test system that is capable of testing PV cells or batteries separately at a range of temperatures. Furthermore, they stated that relevant commercial temperature chambers can reach up to 100 C, but none can drop below -100 C.
For their first test in the new platform, the team used a commercially available polycrystalline silicon 5 V, 30 mA PV cell, coupled with it a niobium tungsten oxide LIB (NbWO||Li) coin cell of 3 V. A a 5 V PV was selected, the group explained, to account for roughly 2 V of additional drop across the diodes and resistors. A 9 W and 32 W LED grow light were used to irradiate the device.
When discharged with the battery cycler, the battery provided similar capacities at a constant current discharge. At 80 C, the charge capacity was 195 mAh g⁻¹ and the discharge capacity was 205 mAh g⁻¹; at 50 C the charge capacity was 156 mAh g⁻¹ and the discharge capacity was 162 mAh g⁻¹; at -60 C the charge capacity was 71 mAh g⁻¹ and the discharge capacity was 76 mAh g⁻¹; at -80 C the charge capacity was 53 mAh g⁻¹ and the discharge capacity was 58 mAh g⁻¹; and at -105 C the charge capacity was 33 mAh g⁻¹ and the discharge capacity was 36 mAh g⁻¹. “This setup allows for reliable testing, as the charge and discharge capacities of the battery are within 5% of each other,” the group highlighted.
“We achieved functional charging/discharging at -120 C of 6 mAh g⁻¹—surpassing conventional Li-ion batteries (over 20% capacity below -60 C),” Pol added.
“Follow-up research will focus on testing pouch cells below -125 C and integrating them with advanced perovskite solar cells, which offer higher efficiency and improved performance under extreme temperature fluctuations compared to conventional silicon solar cells.”
The system was presented in “Efficient photovoltaics integrated with innovative Li-ion batteries for extreme (+ 80 C to −105 C) temperature operations,” published in Scientific Reports. Researchers from Indiana’s Naval Surface Warfare Center also participated in the study.
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