Solid Solution Engineering of Co–Ni-Based Ternary Molybdate Nanorods toward Hybrid Supercapacitors and Lithium-Ion Batteries as High-Performance Electrodes

Recently, molybdates have received enormous attention in the electrochemical energy storage field as attractive electrodes. However, they always suffer from modest high-rate behaviors and cycling stability. Rational design/construction in components renders infinite possibilities to address the concerns. Herein, we purposefully design and fabricate one-dimensional (1D) ternary Ni0.5Co0.5MoO4·xH2O solid solution nanorods (NCMO-SSNRs) via a scalable two-step method and further utilize them as electrodes for supercapacitors and Li-ion batteries (LIBs). The unique solid solution nature of 1D mesoporous NCMO-NRs enhances ionic/electronic transport, electroactive sites, electrochemical stability, and high-rate charge storage capability, which are especially superior to those of NiMoO4/CoMoO4 NRs or their simple mixture. The NCMO-SSNR electrode exhibits a large specific capacitance of ∼665.0 F g–1 at 5.0 A g–1, which guarantees a high energy density (∼45.5 Wh kg–1 at 815 W kg–1) and superb capacitance retention (∼93% after 9950 cycles at 2.0 A g–1) of the NCMO-SSNR-based hybrid supercapacitors. Besides, the NCMO-SSNR anode obtains a high initial Coulombic efficiency of ∼87.0% and a high rate capacity of ∼998.2 mAh g–1 at 2.0 A g–1 for LIBs, benefiting from its remarkable pseudocapacitive contribution. More significantly, the solid solution engineering strategy here can be flexibly extended to other advanced multicomponent electrodes toward energy storage applications and beyond.