Ultralong‐Discharge‐Time Biobattery Based on Immobilized Enzymes in Bilayer Rolled‐Up Enzymatic Nanomembranes

Abstract Glucose biofuel cells (GBFCs) are highly promising power sources for implantable biomedical and consumer electronics because they provide a high energy density and safety. However, it remains a great challenge to combine their high power density with reliable long‐term stability. In this study, a novel GBFC design based on the enzyme biocatalysts glucose dehydrogenase, diaphorase, and bilirubin oxidase immobilized in rolled‐up titanium nanomembranes is reported. The setup delivers a maximum areal power density of ≈3.7 mW cm⁻² and a stable power output of ≈0.8 mW cm⁻². The power discharges over 452 h, which is considerably longer than reported previously. These results demonstrate that the GBFC design is in principle a feasible and effective approach to solve the long‐term discharge challenge for implantable biomedical device applications.