π‐d Conjugated coordination polymers (CCPs) have attracted a lot of attention for various applications, although the chemical states and structures of many CCPs are still blurry. Here, we report a one‐dimensional (1D) π‐d conjugated coordination polymer for high performance sodium‐ion batteries. We clearly revealed the chemical states of the obtained coordination polymer. Our results show that the electrochemical process undergoes a three‐electron reaction and the structure transforms from C=N double bonds and Ni(II) to C‐N single bonds and Ni(I), respectively. Our unintentional experiments provided visual proof of Ni(I). The existence of Ni(I) was further corroborated by its X‐ray absorption near‐edge structure (XANES) and its catalytic activity in Negishi cross‐coupling.