A Sustainable Li-Ion Capacitor Using Sawdust-Derived Activated Carbon Cathode Paired with Prelithiated Al Foil Anode

Abstract

Activated carbon (AC) has long been recognized as a promising electrode material for energy storage/harvesting devices. The extraordinarily high specific area (e.g., ~2000 m2/g) makes AC almost irreplaceable in some applications, such as electrical double-layer capacitors (EDLCs) and capacitive deionization (CDI). [1] Yet the production of AC is often a concern due to the release of unwanted contaminants, such as waste acids and gaseous CO/CO2, resulting from a series of processes involving heating, burning, and the use of strong acids.In this work, we present an activated carbon cathode that is fabricated following a more sustainable approach, namely by using sawdust waste as the carbon precursor via a physical activation process to modify its surface area and porosity. With the electrochemical performances being characterized by designated cyclic voltammetry (CV), galvanostatic charge-discharge cycling (GCD), and electrochemical impedance spectroscopy (EIS), the activation parameters, such as temperature, activation time and activation gas composition, are expected to be optimized for various application purposes.To quickly demonstrate the technical feasibility, a high-performance Li-ion capacitor (LIC) is assembled using the sawdust-derived AC cathode to pair with a piece of prelithiated Al foil anode (β-LiAl). [2] Such an LIC is considered a hybrid energy storage device that can potentially combine the high energy density of a Li-ion battery with the high power density of a supercapacitor. Despite decent electrochemical performances, the proposed LIC device using a waste-derived cathode and a simple metallic foil anode can indeed help to better realize sustainability. [3] It is believed that such a unique LIC architecture can be a promising alternative to conventional energy storage devices for various applications, such as renewable energy storage, electric vehicles, and portable electronic devices.