Renewable energy production is inherently intermittent, necessitating large-scale implementation to enhance energy storage capacity, which presently accounts for less than 1% of global electrical energy production. The pursuit of greener, more affordable, and safer rechargeable batteries is currently recognized as strategically important in advancing electrochemical energy storage technology, addressing environmental concerns and establishing a sustainable energy economy. Li-ion batteries (LIBs) and Na-ion batteries (NIBs) play a crucial role as energy storage devices for electric vehicles and smart grids. It is widely recognized that a detailed analysis of an electrode reveals that each component (active material, conductive carbon, current collector, and binder) contributes to the overall battery performance. It has been demonstrated that the binder, despite its relatively low content, typically a few percent of the total composition, plays a decisive role in determining the electrode performance, which is noteworthy considering its chemical and electrochemical inactivity. In addition, the transformation from liquid- to gel-/quasi-solid or fully solid-state architectures is expected to improve safety by using low-volatile, non-flammable materials and energy density of energy storage devices by enabling the use of lithium metal anodes, particularly if constraints of low ionic conductivity, low cation transport properties and stringent processing conditions are overcome [1].

In this context, here an overview is offered of the recent developments in our laboratories on the development of innovative solutions including recycled or biosourced polymer binders/electrolytes towards the development of sustainable, safe, high-performing post-lithium batteries. These include the possibility of repurposing in batteries the recycled polyvinyl butyral (PVB) from post-consume laminated glasses (from automotive and construction) that cannot be reused in glasses because of degraded optical properties. Three strategies were pursued: using recycled PVB as binder in the electrode composition, transforming it into a membrane to be used as electrolyte separator [2], and utilizing it in advanced solid-state batteries. In the case of PVB as binder, we investigated the electrochemical and structural properties of polymer blends of PVB with standard binders, as polyacrylic acid (PAA) and poly(vinylidene fluoride) (PVDF), demonstrating its effective use in the development of various electrodes, including hard carbon (HC) anodes, and high-energy cathodes (NMC and NVP) showing full capacities even at high C-rates and stable long-term operation at ambient temperature, which pave the way to the development of more sustainable binders/separators from waste products for next-generation, sustainable energy storage. Regarding solid-state batteries, the incorporation of recycled PVB into polyethylene oxide (PEO)-based solid polymer electrolytes was investigated to address both performance and sustainability challenges. This approach enables the design of composite polymer electrolytes with improved mechanical strength, thermal stability, and electrochemical performance while promoting the use of recycled materials to reduce environmental impact.

Overall, in all cases, preliminary results are highly encouraging and pave the way to the development of more sustainable separators and binders from waste products for safe, low-cost energy storage devices.