Sustainable Recovery of Silicon from End‐of‐Life Solar Panels for Next‐Generation Anodes in Lithium‐Ion Batteries and Capacitors with Robust Cycle Life

Lithium‐based energy storage devices such as lithium‐ion batteries (LIBs) and lithium‐ion capacitors (LICs) are efficient and widely used electrochemical energy storage technologies. However, these lack an anode with high practical capacity/energy density to store energy for a long period. Herein, a combined intercalation and alloying mechanism is introduced in the anode to enhance the specific capacity and energy density without compromising cycling performance. The work explores graphite with recovered silicon (from discarded solar panels) as an anode for both LIBs and LICs. The commercial graphite‐recovered silicon (CG‐Si) composite displays better electrochemical performance than the pristine graphite, as it is observed that even 5 wt.% of silicon can increase the specific capacity over 150 mAh g −1 . The LIB fabricated with CG(95):Si(5) composite as anode and lithium manganese oxide (LiMn 2 O 4 ) cathode exhibits a maximum energy density of 242 Wh kg −1 with stable cycling performance for more than 750 cycles. On the other hand, the LIC with the same anode and activated carbon cathode displays a maximum energy density of 196 Wh kg −1 with stable cycling performance over 10,000 cycles. Above all, both LIB and LIC are adaptable and display excellent electrochemical performance at various climatic conditions.