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The demand for sustainable and stretchable thin‐film printed batteries for bioelectronics, wearables, and e‐textiles is rapidly increasing. Recently, we developed a fully 3D‐printed soft‐matter thin‐film Ga‐Ag 2 O battery with 3R characteristics: resilient to mechanical strain, repairable after damage, and recyclable. This battery achieved a record‐breaking areal capacity of 26.37 mAh cm −2 , increasing to 30.32 mAh cm −2 after 10 cycles under 100% strain. This performance stems from the synergistic effects of gallium's liquid metal properties and the styrene‐isoprene‐styrene polymer in the anode. Gallium's high specific capacity (1153.2 mAh g −1 ), deformability, and self‐healing abilities, supported by its supercooled liquid phase, significantly enhance the battery's resilience and efficiency. However, the cathode's lower theoretical capacity, due to Ag 2 O (231.31 mAh g −1 ), remains a limitation. Traditional Ag 2 O‐carbon black‐styrene‐isoprene‐styrene cathodes experience rapid capacity decay as only the surface area of the active materials interacts with the electrolyte. To overcome this, we designed a carbon‐filled Ag 2 O foam electrode using a sacrificial sugar template, increasing the effective surface area. This optimization enhanced ion‐exchange efficiency, specific capacity, and cyclability, achieving a specific capacity of 221.16 mAh g −1 . Consequently, the Ga‐Ag 2 O stretchable battery attained a record areal capacity of 40.91 mAh cm −2 —double that of nonfoam electrodes—and exhibited fivefold improved charge–discharge cycles. Using ultrastretchable Ag‐EGaIn‐styrene‐isoprene‐styrene and carbon black‐styrene‐isoprene‐styrene current collectors, the battery's specific capacity increased by 33% under 50% strain. Integrated into a soft‐matter smart wristband for temperature monitoring, the battery demonstrated its promise for wearable electronics.
Parvini et al. (Sun,) studied this question.