A CO ₂ ‐Mediated Li‐O ₂ Battery With 3.3 V Discharge Voltage

Abstract

ABSTRACT Lithium‐oxygen (Li‐O 2 ) batteries overcome the ion‐intercalation chemistry in lithium‐ion batteries by employing oxygen conversion reactions beyond the solid cathode framework. However, sluggish kinetic limit practical discharge voltages below 2.85 V, establishing a “high capacity, low power output” dilemma that severely compromises achievable energy and power densities. Herein, a CO 2 ‐mediated Li‐O 2 battery (CLOB) is constructed to redefine the oxygen redox chemistry by strategically optimizing gas composition and catalytic architecture, successfully elevating the discharge voltage to 3.30 V comparable to the LiFePO 4 ‐based lithium‐ion batteries. O 2 and CO 2 are gradually reduced to form the intermediates of Li 2 CO 4 and Li 2 C 2 O 6 , and finally Li 2 CO 3 as the discharge product. It leads to an equilibrium voltage of 3.30 V in a two‐electrode electrochemical cell. Furthermore, iron phthalocyanine (FePc) is introduced as a soluble molecular carrier to mitigate the kinetic constraint. The demonstrated FePc‐based CLOB delivers an exceptional discharge voltage of 3.30 V and the assembled pouch cell exhibits a 1.38 Ah capacity with an ultrahigh energy density of 870.1 Wh kg −1 . This voltage enhancement substantially improves energy output and offers a new paradigm for the commercialization of metal‐gas batteries.