Towards outstanding energy-efficiency in a recyclable triboelectric nanogenerator based on a soft-rough composite material

Energy efficiency vs. degradability of materials making up triboelectric nanogenerators (TENGs) is critical for recyclable energy sources. In this work, we first compared voltage output expectation (V_exp) of contact-separation TENG consisting of two tribo-layers: paper and common plastics used in packaging (both non-biodegradable and biodegradable). Detailed analysis based on atomic force microscopy and capacitance measurements demonstrated surface roughness of soft-rough biodegradable polymers (SRBPs) is expected to yield larger V_exp, predictably. A SRBP composite-based TENG was expected to show ∼7.2 times larger V_exp than a hard-flat nonbiodegradable plastic, demonstrating promising charge transfer efficiency; while the measured voltage (V_mea) was only 6.5% of V_exp. This was unlike the other plastics, including a non-composite SRBP, (V_mea/V_exp ∼0.36) and the low V_mea/V_exp in the SRBP composite-based TENG was attributed to intrinsic material properties. Also, energy conversion efficiency in TENG-based on SRBPs was more than double of hard-flat plastics. This shows the potential of the composite SRBP-based TENG as effective energy harvester.