Electrochemical intercalation of Li into Sample 1 (Sr2MnO2Cu0.35Li0.13S2) displayed a 2.0 V (vs. Li + /Li) plateau corresponding to insertion of ~0.5 equiv. of Li, followed by a long sloping process before reaching a capacity equivalent to about 1.75 mol of Li per formula unit at 0.5 V (Fig. ). This contrasts with the electrochemical behaviour of the parent phase Sr2MnO2Cu1.5S2, where the long sloping plateau corresponding to Li-Cu exchange was observed at much lower potential (~1.3 V) . This implies that a different The similar recovery of the original I4/mmm structure type was confirmed when the "collapsed" oxysulphides were treated with n-butyllithium (Fig. ). were present within parts of the "collapsed" phase samples. Fig. shows the stacking of Sr2MnO2 slabs, whose interlayer spacing (Fig. ) was comparable with the C2/m model of the "collapsed" phase (Fig. ). The image directly showed relative sliding of the Sr2MnO2 slabs along a diagonal direction (i.e. the 0.32 shift along ab resulting in monoclinic symmetry). Besides the "collapsed" phase, we also observed domains containing the original I4/mmm structure with Cu or Li in its antifluorite-type metal sulphide layers and its intergrowth with the "collapsed"-type slabs (Fig. ). Fig. highlights the intergrowth domain; it features periodic dark strips separating pairs of Sr2MnO2 slabs with a spacing between pairs comparable to that in the "collapsed"