Cheap, Large-Scale, and High-Performance Graphite-Based Flexible Thermoelectric Materials and Devices with Supernormal Industry Feasibility

Abstract

Flexible thermoelectric materials and devices show great potential to solve the energy crisis but still face great challenges of high cost, complex fabrication, and tedious postprocessing. Searching for abnormal thermoelectric materials with rapid and scale-up production can significantly accelerate their applications. Here, we develop superlarge 25 × 20 cm2 commercial graphite-produced composite films in batches, achieved by a standard 10 min industrial process. The high cost effectiveness (S 2σ/cost) of 7250 μW g m–1 K–2 $–1 is absolutely ahead of that of the existing thermoelectric materials. The optimized composite film shows a high power factor of 94 μW m–1 K–2 at 150 °C, representing the optimal value of normal carbon materials so far. Furthermore, we design two types of flexible thermoelectric devices fabricated based on such a novel composite, which achieve an output open-circuit voltage of 3.70 mV using the human wrist as the heat source and 1.33 mV soaking in river water as the cold source. Our study provides distinguished inspiration to enrich flexible and cost-effective thermoelectric materials with industrial production.

Dual Post‐Treatments Boost Thermoelectric Performance of PEDOT:PSS Films and Their Devices

“…With increasing the Δ T up to 74 K, a V oc was increased to 14 mV. Figure 6f shows the V oc as a function of load resistance at a Δ T of 25 K. [ 9 ] When the load resistance was close to the internal resistance of the device, the maximum output power was 2.8 nW at a Δ T of 25 K. After calculation, the corresponding power density is 2.56 µW cm –2 . Our work indicates great application potential for sustainably charging low‐grade wearable electronics.…”

“…[ 5–8 ] Their thermoelectric potential can be evaluated by the dimensionless figure‐of‐merit ZT = S 2 σT / κ , where S , σ , T , and κ are the Seebeck coefficient, electrical conductivity, absolute temperature, and thermal conductivity, respectively. [ 9,10 ] The S 2 σ is described as the power factor for thermoelectric materials. Generally, traditional thermoelectric materials are mostly solid‐state inorganics, [ 11 ] such as GeTe, [ 12–14 ] Cu 2 Se, [ 15 ] and SnSe [ 16 ] that which reported excellent thermoelectric properties with ZT s > 2.…”

Ultrafast and Cost-Effective Fabrication of High-Performance Carbon-Based Flexible Thermoelectric Hybrid Films and Their Devices

“…Further details can be consulted from our previous work. 27 4.3. Fabrication of the Thermoelectric Device.…”

“…Historically, some newly developed carbon materials such as graphene and carbon nanotubes (CNTs) have been studied to explore their thermoelectric potential. − However, these materials are relatively expensive; therefore, conventional carbon materials that can realize an industrial scale are valuable for practical thermoelectric applications and future commercialization. In this regard, developing efficient fabrication techniques, rising cost-effectiveness, and improving the thermoelectric performance become the three main goals for conventional carbon-based thermoelectrics that target industrial feasibility. − …”

“…Historically, conventional carbon-based materials developed for thermoelectric applications include natural graphite, expanded graphite, and carbon black . Among the conventional carbon-based materials, expanded graphite (EG) with a three-dimensional (3D) worm-like morphology is commercially massively available because of its cheap price. − Nowadays, the preparation of EG is relatively mature.…”