Fig. 2
Flexing process for a bio-compatible flexible lithium-ion battery. a SEM images of a bulk thin-film Si-supported battery (left panel; 130 μm total thickness) compared to thinned flexible battery with complete removal of Si support (middle panel; 30 μm total thickness). Cross section SEM image of the flexible thinned battery components made from all solid-state materials (right panel; lithium-free anode battery configuration). b Progressive Si back surface evolution of the battery undergoing selective dry etching as observed in a 15 × 10 μm2 AFM mapped region of the battery’s backside at zero etching cycles (left panel; roughness from wafer grinding), and with completed etching at 50 cycles (right side panel; flat surface and complete Si consumption). c Etching efficiency calculation through determination of the total etched volume using optical profiler measured across different etching cycles. d Confirmation of Si removal from the battery’s backside using elemental linear scan EDS analysis with the corresponding HAADF-STEM image (inset image)
