We present an investigation of the compact structure of the active galactic nucleus 2021+317 based on multiepoch very long baseline interferometry (VLBI) observations at 15, 22, and 43 GHz in the period from 2013 through 2024. The VLBI images show a core-jet structure extended to the south, with two stationary components in the northern region, one of which is likely to be the core of the source. We also detected two new moving jet components (S4 and S5) in the observations of 2021. Based on these observational findings, we analyzed two distinctive jet models involving one or another stationary component mentioned above as the jet core. One model assumes a moderate bulk motion velocity, a wider viewing angle, and a lower Doppler factor, with the magnetic field energy density significantly dominating over the nonthermal particle energy density. The other model involves a higher bulk motion velocity, a narrower viewing angle, and a higher Doppler factor, with an even greater dominance of magnetic field energy in the core. The position angle of the jet ridgeline rotates counterclockwise over the observed period. The apparent kinematics of the jet components is more consistent with a model of the precessing jet, which has recently completed the first half of the precession cycle. Our results provide constraints on the dynamic evolution of the jet and its interaction with the surrounding medium.

For practical application of lithium-oxygen batteries, one of the challenges is the development of efficient bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in cathode. In this work, perovskite Sr _0.9 Y _0.1 CoO _3-δ nanorods are synthesized by an electrospinning method. The performance of the Li-O ₂ cell with Sr _0.9 Y _0.1 CoO _3-δ catalysts is better than that of the cell only with Super-P. Furthermore, modification of CoO nanoparticles on the cathode can provide an obviously improved electrochemical performance with a reduced voltage gap (∼80-140 mV), which is ascribed to the superior catalytic activity of CoO nanoparticles toward OER. All of these results demonstrate that the perovskite Sr _0.9 Y _0.1 CoO _3-δ is an efficient bifunctional electrocatalyst for lithium-oxygen batteries, and the incorporation of CoO nanoparticles is an effective approach for improving the cathode performance as well.