File Name : additional peaks video.mp4 Caption : fig. s4: motion images from operando xrd spectroscopy showing the synchronised behaviour of multiple reflections belonging to mapbbr₃ and pb⁽⁰⁾. (a - d) additional peaks associated with mapbbr₃. (indexed phase: cubic pm-3m). (a) (020) and (101). (b) (040) (c) (103) (d) integrated peak area intensity for the three peaks with multiple insertion/removal li cycles. all peaks unanimously decrease rapidly with increased li insertion and cycling. (e - f) additional peaks of metallic pb⁽⁰⁾. (indexed phase: cubic fm-3m). (e) (111) (f) (200) (g) (311) (h) integrated peak area intensity for the three peaks with multiple insertion removal cycles. peaks unanimously increase with li insertion and decrease with li removal.