Nanocellulose applications in sustainable electrochemical and piezoelectric systems: A review

•Promising opportunities for Nature-built polymers in electronic systems.•Green strategies are introduced to enhance permeability and conductivity in PEMs.•Nanocellulose serves as an electrolyte reservoir to boost ion diffusion.•Cellulosic hybrids can be used as substrate, separator and binder in batteries.•Cellulose nanocrystals exhibit piezoelectric behavior usable in sensors and actuators. Recent studies advocate the use of cellulose nanomaterials (CNs) as a sustainable carbohydrate polymer in numerous innovative electronics for their quintessential features such as flexibility, low thermal expansion and self-/directed assembly within multiphase matrices. Herein, we review the contemporary advances in CN-built electrochemical systems and highlight the constructive effects of these nanoscopic entities once engineered in conductive composites, proton exchange membranes (PEMs), electrochromics, energy storage devices and piezoelectric sensors. The adopted strategies and designs are discussed in view of CN roles as copolymer, electrolyte reservoir, binder and separator. Finally, physiochemical attributes and durability of resulting architectures are compared to conventional materials and the possible challenges/solutions are delineated to realize the promising capabilities. The volume of the up-to-present literature in the field indeed implies to nanocellulose overriding importance and the presented angles perhaps shed more lights on prospect of the biosphere’s most dominant biomaterial in the energy-related arena that deserve attention.