A Flexible Li–Air Battery Workable under Harsh Conditions Based on an Integrated Structure: A Composite Lithium Anode Encased in a Gel Electrolyte

Abstract

Flexible lithium-air batteries (FLABs) with ultrahigh theoretical energy density are considered as the most promising energy storage devices for next-generation flexible and wearable electronics. However, their practical application is seriously hindered by various obstacles, including bulky and rigid electrodes, instability/low conductivity of electrolytes, and especially, the inherent semi-open structure. When operated in ambient air, moisture penetrated from an air cathode inevitably corrodes a Li metal anode, and most of the reported FLABs can only work under a pure oxygen or specific air (relative humidity: <40%) atmosphere, which cannot be regarded as a real "lithium-air battery". Herein, the author designed an innovative battery configuration by the synergy of a 3D open-structured Co₃O₄@MnO₂ cathode and an integrated structure: a composite lithium anode encased in a gel electrolyte. A composite lithium anode fabricated through a simple, low-cost, and effective rolling method significantly relieves the fatigue fracture of the lithium electrode. Subsequently, an in situ-formed gel electrolyte encloses the composite lithium electrode, which not only reduces the electrode/electrolyte interfacial resistance but also acts as a protective layer, effectively preventing the lithium anode from corrosion. Consequentially, the battery can achieve more than 100 stable cycles in ambient air with a high relative humidity of 50%. To our surprise, the FLAB remains operational under extreme conditions, such as bending, twisting, clipping, and even soaking in water, demonstrating widespread applications in flexible electronics.