Lignocellulosics as a Green Material Opportunity for Energy Storage Systems

Lignocellulose, due to its natural abundance, environmental friendliness, recyclability, and dimensional stability, has been widely used as a reliable/sustainable basic constituent for a vast variety of materials/devices in our daily lives. Recently, driven by its exceptional physical/chemical properties, lignocellulose has vigorously extended its potential application towards rapidly growing industrial fields including mobile/intelligent electronics, displays, sensors and energy storage/conversion systems, in addition to traditional use in paper and packaging substances. More notably, one-dimensional (1D) lignocellulose fibers at different length scales serve as a building block for enabling three-dimensional (3D) hierarchical structure with design versatility and also offer effective reaction sites that can readily form chemical bonds with many functional groups. Lignocellulose featuring the aforementioned unique attributes has been extensively investigated as a promising building element for next-generation energy storage systems (ESSs). Notably, cellulose nanofibrils, which are a core constituent of cellulose and characterized with a high aspect ratio (typically, a few nanometers in diameter and several micrometers in length), stimulated by their 1D-based structure and functional groups, have brought significant benefits to design/fabrication of ESSs which lie far beyond those achievable with traditional battery technologies. In this chapter, we describe recent advances in lignocellulose as a building block for advanced batteries materials, with a particular focus on application to flexible Li-ion batteries/supercapacitors, electroconductive carbonaceous materials, solid composite electrolytes, and separator membranes.