STEM images of Li4-x1Ti5O12-y1 under 2.2 V. (a, b) HAADF and ABF images under 2.2 V, respectively. (c, d) the enlarged HAADF and ABF images from the red dotted frame in (a, b). Blue arrows in ABF image (c) indicated the oxygen atomic shift. Schematics of oxygen atomic shift (e), brown and purple arrows are used to label the displacement direction in the Ti-a and Ti-b columns, respectively. Scale bar: 1 nm.