Three-dimensional (3D) electrodes with freestanding feature represent the state-of-art electrode design for advanced lithium-ion batteries. Construction of 3D architectures for cathode materials, however, is still a great challenge. In this work, freestanding 3D LiCoO2 nanosheets assembled nanorod arrays are grown on carbon fabric via confined dissolution-recrystallization on the Co(CO3)1-x(OH)2x·nH2O nanowire arrays during hydrothermal treatment. The formed intermediate CoOOH nanosheets can catalyze the decomposition of H2O2 and the generated continuous oxygen bubble layer enables self-limiting dissolution-recrystallization. After final heat treatment at a low temperature of 380 °C, the obtained 3D hierarchy LiCoO2 nanorod arrays exhibit large specific capacity, excellent rate performance, and outstanding cycling stability when tested as cathode for aqueous lithium-ion batteries. It is found that the hydrothermally synthesized LiCoO2 sample without heat treatment still has some structure distortion with proton intercalation and Li+ occupancy at abnormal sites, which deteriorate its electrochemical performance. By using the 3D hierarchy LiCoO2 nanorod arrays as cathode, a flexible aqueous LiCoO2//LiTi2(PO4)3 lithium-ion battery device is successfully constructed, demonstrating superior rate performance and cycle performance.