g-C 3 N 4 nanosheets were coupled with oxygen-defective ZnO nanorods (OD-ZnO) to form a heterojunction photocatalyst with a core-shell structure. Multiple optical and electrochemical analysis including electrochemical impedance spectroscopy, photocurrent response and steady/transient photoluminescence spectroscopy revealed that the g-C 3 N 4 /OD-ZnO heterojunction exhibited increased visible-light absorption, improved charge generation/separation efficiency as well as prolonged lifetime, leading to the enhanced photocatalytic activities for the degradation of 4-chlorophenol under visible-light illumination (>420 nm). An oxygen defects-mediated Z-scheme mechanism was proposed for the charge separation in the heterojunction, which involved the recombining of photoinduced electrons that were trapped # These two authors contributed equally.

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Currently, there is an urgent demand for Ni-rich cathode materials with excellent electrochemical properties under harsh conditions; however, obtaining such materials is very challenging. Here, we propose an innovative modification strategy that combines gradient phosphate polyanion doping and dual-conductive layer (Li3PO4-PANI) coating. The phosphate polyanion gradient doping can be described as acting in a “support role” to optimize the crystal structure. Moreover, the dual-conductive (Li3PO4-PANI) layers can be described as acting in a “palisade role” to inhibit side reactions and enhance the ionic/electronic conductivity of the NCM cathode. For the NCM cathode, this strategy synergistically achieves three main objectives: enhancement of structure stability, improvement of the ionic/electronic conductivity of the interface, and reduction of residual lithium salts. The modified NCM cathode delivers superior cycling stability, with 81.4% capacity retention after 100 cycles (4.5 V/55 °C), whereas the original NCM shows only a quite low capacity retention (57.7%). Moreover, this strategy also significantly improves the rate performance of the NCM cathode. These results indicate that this innovative modification strategy can be utilized to enhance the electrochemical performance of the NCM cathode at 4.5 V and 55 °C.

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Ni-rich LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) cathode is considered to be among the most promising candidates for high-energy-density lithium-ion batteries (LIBs). However, both capacity fading and structural degradation occur during long-term cycling, which extremely limit the commercial applications of NCM811, especially at a high cutoff voltage (>4.3 V). Here, we design a doubleshell hybrid nanostructure consisting of a Li 2 SiO 3 coating layer and a cation-mixed layer (Fm3̅ m phase) to improve its electrochemical performance. Consequently, the Si-modified NCM811 electrode shows outstanding cycling stability with a 95.2% capacity retention at 4.3 V after 100 cycles and 87.3% at a 4.5 V high cutoff voltage after 100 cycles. This designed double-shell hybrid nanostructure alleviates side reactions, structural degradation, and internal cracking, effectively enhancing the surface structural stability. This efficient strategy provides a valuable step toward further commercial applications of the LiNi 0.8 Co 0.1 Mn 0.1 O 2 cathode and enriches the fundamental understanding of layered cathode materials. KEYWORDS: LiNi 0.8 Co 0.1 Mn 0.1 O 2 , double-shell modification, hybrid nanostructure, structural degradation, cycling stability