Electrodeposition‐Potential Tuning Rejuvenates the Concurrent Preparation from α‐Co(OH)2 with Larger Interlayer‐Spacings to β‐Co(OH)2

Electrodeposition is a popular method for preparing α‐Co(OH)2 as an electrode material for electrochemical energy storage. However, the preparation of technically important β‐Co(OH)2 through electrodeposition remains lacking thus far. Herein, we successfully prepared Co(OH)2 in two phases, α‐ and β‐Co(OH)2, by simply adjusting the electrodeposition potentials, as evidenced by a package of microcopy and spectroscopy analysis. Benefited from a delicate embedding and sectioning technique that may inhibit the loss of interlayer water in microscopy analysis, we find the presence of Co tetrahedron in the interlayer of α‐Co(OH)2 results in a large interlayer spacing of 7.2 Å for the crystal plane (003) compared to β‐Co(OH)2, as well as a higher chemical valence of cobalt in electrodeposited β‐Co(OH)2. The large interlayer spacing creates wider ion channels and more active storage sites for effective energy storage. Consequently, the α‐Co(OH)2 electrode exhibits more competitive electrochemical performance compared to its β counterpart.