The development of renewable and sustainable energy has been identified as an effective strategy in tackling environmental pollution and the climate change crisis. To solve these problems, it is important to develop energy storage devices with high performance, low cost, and environmental friendliness. There are various types of energy storage, one of which is supercapacitors. Supercapacitors are a type of energy storage that has many advantages, including higher energy density than conventional capacitors, higher power density compared to batteries, fast charging rates, and long charging cycle life (Zhu et al., 2018).
One type of supercapacitor that has good cycle stability is Electric Double Layer Capacitor (EDLC). This is because, energy storage in EDLC is electrostatic so that there is no transfer of charge between the electrode and electrolyte (Du et al., 2019). During the charge and discharge process, EDLC does not undergo a chemical reaction but instead undergoes electrostatic charge separation in the electrical double layer formed between the electrode and electrolyte. Therefore, it is theoretically capable of high and fast current charging/discharging and has a long cycle life. The EDLC structure is divided into three parts, namely electrodes, electrolytes, and separators (Muramatsu et al., 2022). Also, the study using machine learning was done for observing properties of biomass as supercapacitor(Jamaluddin et al., 2023). One of the effectiveness levels of supercapacitors is influenced using electrode materials. One type of material used as an electrode material is carbon such as carbon nanosheet, graphene, carbon fiber, and activated carbon (Said et al., 2023). Activated carbon is the most widely used material as a supercapacitor electrode because of its abundant availability, affordable price, relatively low production costs, large specific surface area, and high electrochemical cycle stability (Cheng et al., 2015). Carbonaceous materials, sourced from non-renewable and unsustainable graphite and fossil fuels, have been frequently used in the creation of Supercapacitor(Ashok Kumar et al., 2023).
Biomass-based activated carbon is commonly produced by utilizing agricultural waste such as black betel leaf(Suci et al., 2023), rice husks, bamboo, coconut shells, empty oil palm bunches, and others(Ashok Kumar et al., 2023). EFBP itself is a by-product of palm oil processing which is abundant in Indonesia, that a common use today is to make it mulch in the garden, fuel, or as compost (Rustamaji et al., 2022). EFBP's biomass composition includes 41.3–45% cellulose, 25.3–33.8% hemicellulose, and 27.6–32.5% lignin. TKSBP's high carbon element content makes it an excellent raw material for the production of active carbon (Hardi et al., 2020). The process of producing activated carbon typically consists of three stages: dehydration (to remove the water content), carbonization (to enrich the carbon content by liberating elements other than carbon such as hydrogen and oxides through thermal decomposition), and activation. Furthermore, there are three approaches for activation: chemical activation, physical activation, and chemical-physical activation (Tembusai et al., 2020).
According to the description above, activated carbon derived from EFBP has the potential to serve as a supercapacitor electrode material. Farma conducted research on supercapacitor electrodes made from EFBP activated carbon in 2013, activating them with KOH + CO2. The results demonstrated outstanding electrochemical performance, with a specific energy of 4.3 Wh / kg and a specific power of 173.3 W / kg (Farma et al., 2013). Furthermore, in 2021, Tobi and Dennis did research on supercapacitor electrodes using palm waste composites (oil palm empty fruit bunches, palm fiber, and palm shells) with KOH chemical activation and physical activation by 700°C heating (Tobi & Dennis, 2021). The results show that supercapacitors function effectively with a specific energy of 8.6 Wh/kg and a specific power of 50 W/kg for physical activation, as well as 5.8 Wh/kg and a specific power of 50 W/kg for chemical activation. The use of chemical activation using ZnCl2 was chosen because based on research conducted by Rachmani and Sudibrandriyo in 2014, ZnCl2 activator provides activated carbon results with a wider surface (Rachmani & Sudibandriyo, 2014). Then the use of microwaves as a physical activation was chosen because from research that had been conducted by Duan et.al in 2017 obtained the results of activated carbon with a large surface area and pore volume (Duan et al., 2017).
In this study purposed to understand of chemical activation (CA) with ZnCl2 and microwave heating radiation (MR) for activating EFBP. The CAMR method was improved an electrical conductivity of EFBP up to 3.676 x 10− 3 S / m compared with EFBP-CA of 1.082 x 10− 3 S /m. Also, the EFBP-CAMR was demonstrated as a supercapacitor that achieved capacity up to 32.042 F/g. The CAMR is promoted to enhance the surface characteristics, electrical conductivity and electrochemical performance of EFBP.