Upcycled Co ₃ O ₄ Nanorods From Spent LiCoO ₂ Batteries as Robust Catalysts for Enhanced Kinetics in Li–CO ₂ Battery Cathodes

ABSTRACT Rational recycling of spent lithium‐ion batteries (LIBs) into high‐value functional materials represents a sustainable strategy for resource conservation and environmental protection. Herein, a facile and scalable approach for the upcycling of discarded LiCoO 2 cathodes from 3C electronic waste into catalytically active Co 3 O 4 nanorods is demonstrated by direct hydrothermal transformation of Co 2+ ions. When employed as a cathode catalyst in Li─CO 2 batteries, the upcycled Co 3 O 4 nanorods exhibited superior electrocatalytic activity toward both CO 2 reduction and evolution reactions. The batteries delivered enhanced electrochemical performance, including high specific capacity (7785 mA h g −1 ), improved discharge voltage plateau (2.58 V), reduced overpotential (1.27 V), and significantly extended cycle life (>147 cycles) at a current of 100 mA g −1 . Density functional theory calculations were integrated with experimental analyses to elucidate the origin of the enhanced performance, revealing the unique electronic structure and surface properties of the Co 3 O 4 nanorods facilitate favorable adsorption/desorption of key reaction intermediates, lowering the reaction energy barriers and promoting efficient bifunctional catalysis. This work not only presents a practical pathway for the functional upcycling of spent LIBs into advanced energy materials but also provides valuable insights into the rational design of efficient catalysts for metal‐CO 2 batteries.