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NASICON-type (Na super ionic conductor) Na4VMn(PO4)3 (NVMP) cathode material has attracted increasing attention due to its higher sodium de-/intercalation voltage, lower cost and greener resources compared with Na3V2(PO4)3. However, the poor electronic conductivity limits the exploitation of its electrochemical performance. In this work, we achieved an ultrahigh rate capable and long cycle life NVMP/C-rGO composite using the simple and scalable spray-drying technique, in which low-fraction rGO nanosheets (2.14 wt%) highly dispersed and bridged the carbon shelled NVMP nanoparticles to form an effective electron conductive network. Benefiting from this favorable nano-architecture, the elaborately designed NVMP/C-rGO composite exhibited excellent performance as cathode in sodium ion batteries, delivering reversible capacities of 105.5 mA h g−1 at 1 C (1 C = 110 mA h g−1) and 102.6 mA h g−1 at 50 C with capacity retention of 90.6% (1 C) and 80.4% (50 C) over 500 cycles, respectively. This is the highest rate performance for Na4VMn(PO4)3 materials reported so far. This work provides a practicable tactic for fabricating advanced polyanion-type cathode materials which can be commercially scale up for sodium energy storage.

Ni-rich layered oxides, such as LiNi0.8Co0.1Mn0.1O2 (NCM811), are considered as promising cathode materials for lithium-ion batteries due to their high energy density. However, Ni-rich layered oxides are prone to react with water and carbon dioxide in ambient air forming residual lithium compounds, resulting in deterioration of electrochemical performance and bringing a challenge to the cathode electrode preparation. In this work, we have, for the first time, demonstrated that the chemical stability of the NCM811 material in ambient air can be significantly enhanced by passivating the surface with a hydrophobic self-assembled monolayer (SAM) of octadecyl phosphate (OPA). As a result, the degradation reaction between the NCM811 material and ambient air and thus the electrochemical performance deterioration were significantly suppressed during ambient air exposure. Specifically, the 5C-rate capacity retention deterioration of the NCM811 sample during 14-day ambient air exposure has been decreased from 12 to 2% by OPA passivation. Furthermore, the 200-cycle capacity retention deterioration of the NCM811 sample after 7-day ambient air exposure has been improved from 23 to 0.7% by OPA passivation. These results are very important for the practical application of Ni-rich oxide since no need for controlling of humidity is required on the cathode manufacture; thus, the cost can be reduced. The concept of molecular self-assembly on the NCM811 material also open vast possibilities to design reagents for surface passivation of Ni-rich layered oxides.

In recent years solid Li+ conductors with competitive ionic conductivity to those of liquid electrolytes have been reported. However, the incorporation of highly conductive solid electrolytes into the lithium-ion batteries is still very challenging mainly due to the high resistance existing at the solid-solid interfaces throughout the battery structure. Here, we demonstrated a universal interfacial modification strategy through coating a curable polymer-based glue electrolyte between the electrolyte and electrodes, aiming to address the poor solid-solid contact and thus decrease high interfacial resistance. The liquid glue exhibits both great wettability as well as chemical/electrochemical stability to most of the electrodes, and it can be easily solidified into a polymer electrolyte layer through a "post-curing" treatment. As a result, symmetric Li batteries with the glue modification exhibit much smaller impedance and enhanced stability upon plating/stripping cycles compared to the batteries without glue modification. The all-solid-state Li-S batteries with glue modification show significantly enhanced performances. The strategy of developing glue electrolytes to improve the electrode-electrolyte interface contact provides an alternative option for improving many other solid-state batteries. Accepted version