The authors regret to inform that the XRD pattern of the LiMn2O4 sample was mixed up with those of LiNixMn2−xO4 (x = 0.05 and 0.1) samples. Last week, the authors noticed this error when they prepared a progress report on aqueous batteries. Then the authors checked the raw data. Probably because the XRD patterns of these three samples are very similar to each other, the authors made an error when processing the XRD patterns. Thus, the authors would like to make a correction for Fig. 1 in this corrigendum. This correction does not affect the discussions and conclusions of the article as the XRD patterns of LiNixMn2−xO4 (x = 0.05 and 0.1) still show the spinel phase. The authors apologize for this oversight. The correct data for Fig. 1 is shown here:Image 1 Fig. 1. XRD patterns of LiNixMn2−xO4 (x = 0, 0.05, 0.10) samples.