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High‐energy Ni‐rich lithium transition metal oxides such as Li[Ni0.8Co0.1Mn0.1]O2 (NCM811) are appealing positive electrode materials for next‐generation lithium batteries. However, the high sensitivity toward moist air during storage and the high reactivity with common organic electrolytes, especially at elevated temperatures, are hindering their commercial use. Herein, an effective strategy is reported to overcome these issues by coating the NCM811 particles with a lithium phosphonate functionalized poly(aryl ether sulfone). The application of this coating allows for a substantial reduction of lithium‐based surface impurities (e.g., LiOH, Li2CO3) and, generally, the suppression of detrimental side reactions upon both storage and cycling. As a result, the coated NCM811‐based cathodes reveal superior Coulombic efficiency and cycling stability at ambient and, particularly, at elevated temperatures up to 60 °C (a temperature at which the non‐coated NCM811 electrodes rapidly fail) owing to the formation of a stable cathode electrolyte interphase with enhanced Li+ transport kinetics and the well‐retained layered crystal structure. These results render the herein presented coating strategy generally applicable for high‐performance lithium battery cathodes. [ABSTRACT FROM AUTHOR]

This work reports the facile synthesis of a Sn–P composite combined with nitrogen doped hard carbon (NHC) obtained by ball‐milling and its use as electrode material for sodium ion batteries (SIBs). The "Sn4P3"/NHC electrode (with nominal composition "Sn4P3":NHC = 75:25 wt%) when coupled with a diglyme‐based electrolyte rather than the most commonly employed carbonate‐based systems, exhibits a reversible capacity of 550 mAh gelectrode−1 at 50 mA g−1 and 440 mAh gelectrode−1 over 500 cycles (83% capacity retention). Morphology and solid electrolyte interphase formation of cycled "Sn4P3"/NHC electrodes is studied via electron microscopy and X‐ray photoelectron spectroscopy. The expansion of the electrode upon sodiation (300 mAh gelectrode−1) is only about 12–14% as determined by in situ electrochemical dilatometry, giving a reasonable explanation for the excellent cycle life despite the conversion‐type storage mechanism. In situ X‐ray diffraction shows that the discharge product is Na15Sn4. The formation of mostly amorphous Na3P is derived from the overall (electro)chemical reactions. Upon charge the formation of Sn is observed while amorphous P is derived, which are reversibly alloying with Na in the subsequent cycles. However, the formation of Sn4P3 can be certainly excluded. [ABSTRACT FROM AUTHOR]