Boosting Low-Temperature Resistance of Energy Storage Devices by Photothermal Conversion Effects

Abstract

While flexible supercapacitors with high capacitance and energy density is highly desired for outdoor wearable electronics, their application under low-temperature environments, like other energy storage devices, remains an urgent challenge. Solar thermal energy converts solar light into heat and has been extensively applied for solar desalination and power generation. In the present work, to address the failure problem of energy storage devices in a cold environment, solar thermal energy was used to improve flexible supercapacitor performance at low temperature. As a proof of concept presented here, a typical all-solid-state supercapacitor composed of activated carbon electrodes and gel polymer electrolyte was coated by a carbonized melamine sponge. Due to the ability of photothermal conversion of carbonized melamine sponge, the capacitance of the supercapacitor was greatly enhanced, which could be further improved by adding surface plasmonic nanomaterials, for example, Ag nanowires. Compared with the device without photothermal conversion layers, the specific capacitance increased 3.48 times at −20 °C and retained 87% capacitance at room temperature and the specific capacitance increased 6.69 times at −50 °C and retained 73% capacitance at room temperature. The present work may provide new insights on the application of solar energy and the design of energy storage devices with excellent low-temperature resistance.

Photothermal Supercapacitors with Gel Polymer Electrolytes for Wide Temperature Range Operation

“…To the best of our ability, in our literature search on state-of-the-art photothermal supercapacitors, the lowest environmental temperature where the device stayed operational was −50 °C at 1 kW/m 2 illumination. 14 Here with our improved GPE with sPS, our photothermal superpcapacitor was demonstrated to work at an even lower temperature of −60 °C with the same intensity of 1 kW/m 2 illumination as previous work while achieving an areal energy density of 94 μWh/cm 2 at the output power density of 0.4 mW/cm 2 (inverted open triangle symbols in Figure 5b). At −20 °C, the photothermal conversion effect increased the device energy density to 183 μWh/cm 2 at the power output of 0.6 mW/cm 2 .…”

“…The photothermal conversion layer absorbs light and converts the energy into heat due to phonon vibrations, effectively raising the cell temperature above the environmental temperature. As such, prior photothermal supercapacitors − were demonstrated to function down to −50 °C but suffer from severe self-discharge and very low energy density. In this work with the improved GPE and photothermal conversion effect, the supercapacitors are shown to operate at −60 °C, which notably is below the freezing point of the electrolyte solvent propylene carbonate (−48 °C).…”

“…The photothermal conversion efficiency, calculated according to eq S1 with the parameter values listed in the Experimental Methods section (Table S2), was determined to be η PT ≈ 54%. This efficiency was in the middle level among the photothermal supercapacitors being compared in Table , since our photothermal layer was made with only carbon black, unlike other references which use plasmonic materials , that increased light absorption and phonon coupling for higher heat generation. In other works, the photothermal conversion materials were incorporated in the electrodes, but this design would require the encapsulation to be transparent while there are limited choices with clear encapsulation materials.…”

Black TiO2 Nanoparticle/Carbonized Melamine Sponge Photothermal Conversion Layers for Improved Low-Temperature Performance of Supercapacitors

“…As a typical energy storage device, supercapacitors (SCs) have attracted great attention due to fast charging/discharging capability, high power density, and long cycle life. However, their poor performance under a low-temperature extreme environment limits their application. , This is due to the gradual increase in the internal resistance of the electrolyte, which leads to the inactivation of the electrolyte and the decrease of the anion and cation mobility in the electrolyte. − At present, the main strategy to address this issue is to develop a low-temperature-resistant electrolyte. Numerous electrolytes such as PVA-LiCl-glycerol, PAM-PVP GPE, and cross-linked PVA hydrogel have been prepared and applied in SCs, which did improve SC performance at low temperature.…”

Photothermal-Conversion-Enhanced LiMn2O4 Pouch Cell Performance for Low-Temperature Resistance: A Theoretical Study

“…This generated an opencircuit voltage of 1.5 mV under infrared light illumination (83.12 mW/cm 2 ). Yu et al [16] added silver nanowires to carboxytrimamine sponges (AgNWs @CMF), as a photothermal conversion material. The materials covered the surface of the flexible supercapacitors, and increased the specific capacity by factors of 3.48 and 6.69, at −20 • C and −50 • C, respectively.…”