Biopolymer electrolytes for sodium-ion batteries: An informative concise and up-to-date review on the future of solid-state electrochemical devices

Solid polymer electrolytes (SPEs) have been widely studied since there is a need for effective, safer, and environmentally friendly devices. In this context, SPEs are promising materials for practical applications in electrochemical devices. Nevertheless, the need for the increasing use of biopolymers to make materials more environmentally friendly has become increasingly constant. In parallel, lithium-ion batteries (LIBs) play an important role as portable electronic devices, although lithium cost and availability are bottlenecks. Among the possibilities, sodium-ion batteries (SIBs) are interesting realistic alternatives, since SIBs are metal-ion rechargeable batteries employing the same principle as LIBs, relying on Na + ions for the charges' transfer. Furthermore, sodium (Na) is more abundant and has lower costs compared to lithium (Li). This review aims to present a concise summary of solid-state SIBs based on the most studied biopolymer electrolytes, showing accessible and viable alternatives to overcome some environmental issues associated with the use of conventional batteries, breaking new grounds for the future of energy storage devices.