Remarkable high-temperature ionic thermoelectric performance induced by graphene in gel thermocells

Abstract

Gels thermocells employing redox couple ions as carriers can convert heat into electricity, playing an important role in low-grade heat harvesting. However, a major challenge is maintaining the high ionic...

Ultra-high performance of ionic thermoelectric-electrochemical gel cells for harvesting low grade heat

“…29 The voltage of the gel-device reached 1.55 V, comparable to the reported values, e.g. , 0.025 V (Jiang), 37 0.12 V (Han), 33 2.2 V (Han), 16 and 2.8 V (Li). 28 In addition, the assembled gel-device could power a red LED at 313 K and Δ T = 5 K without a voltage booster (Fig.…”

“…3(c)). The normalized energy density of 3.4 J m −2 K −2 (2 h) was higher than the reported values of 0.37 and 0.99 J m −2 K −2 (2 h, Li), 28,29 0.19 J m −2 K −2 (1 h, Han), 33 and 1.43 J m −2 K −2 (1 h, Jiang), 37 as shown in Table S3 (ESI†). The decreased resistance from 7.5 to 5.0 kΩ indicated that the internal resistance of the i-TE-EC cell decreased after adding additives, corresponding to an increased σ i (Fig.…”

“…16,19,21,30,31,33–37 The fabricated i-TE-EC cell in this work delivered high P max /(Δ T ) 2 values of 10 and 20.5 mW m −2 K −2 and voltages of 176 and 224 mV, higher than the most reported results, e.g. , 0.61 mW m −2 K −2 and 8.3 mV (Lei et al ), 19 1.03 mW m −2 K −2 and 65 mV (Han et al ), 33 1.97 mW m −2 K −2 and 32.5 mV (Liu et al ), 35 11.31 mW m −2 K −2 and 75 mV (Jiang et al ), 37 etc. , and comparable to 20.26 mW m −2 K −2 and 133.5 mV (Zhang et al ) 30 (Table S1, ESI†).…”

“…Fig. 5(c) shows the comparison of P max /(Δ T ) 2 and voltage obtained in this work and the reported results 16,28,29,33,34,37,38 for i-TE gel-devices. A P max /(Δ T ) 2 of 5.2 mW m −2 K −2 was obtained for the gel-device in this work, which was higher than the reported results (Table S4, ESI†), e.g.…”

“…The operating temperature of the i-TE-EC cell was limited to 313 K due to the gel–sol transition of gelatin-based gels. 33 Ionic thermopower ( S i ) for the i-TE-EC cell was measured at different temperatures (Fig. 2(c)).…”