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Deciphering the sophisticated interplay between thermodynamics and kinetics of high‐temperature lithiation reaction is fundamentally significant for designing and preparing cathode materials. Here, the formation pathway of Ni‐rich layered ordered LiNi0.6Co0.2Mn0.2O2 (O‐LNCM622O) is carefully characterized using in situ synchrotron radiation diffraction. A fast nonequilibrium phase transition from the reactants to a metastable disordered Li1−x(Ni0.6Co0.2Mn0.2)1+xO2 (D‐LNCM622O, 0 < x < 0.95) takes place while lithium/oxygen is incorporated during heating before the generation of the equilibrium phase (O‐LNCM622O). The time evolution of the lattice parameters for layered nonstoichiometric D‐LNCM622O is well‐fitted to a model of first‐order disorder‐to‐order transition. The long‐range cation disordering parameter, Li/TM (TM = Ni, Co, Mn) ion exchange, decreases exponentially and finally reaches a steady‐state as a function of heating time at selected temperatures. The dominant kinetic pathways revealed here will be instrumental in achieving high‐performance cathode materials. Importantly, the O‐LNCM622O tends to form the D‐LNCM622O with Li/O loss above 850 °C. In situ XRD results exhibit that the long‐range cationic (dis)ordering in the Ni‐rich cathodes could affect the structural evolution during cycling and thus their electrochemical properties. These insights may open a new avenue for the kinetic control of the synthesis of advanced electrode materials.

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Commercially available 18650 Li-ion batteries are considered for high energy density storage and usage in mobile applications as well as to store energy from intermittent energy sources. This has triggered intense research for suitable electrode and electrolyte materials, while their current stateof-the-art, temperature dependent performance is hardly described in detail. The fatigue process in two brands of rechargeable commercial high-energy Li-ion batteries (18650-type, 3500 mAh, LiNi 0.83 Mn 0.07 Co 0.11 O 2 (NMC-811) and LiNi 0.86 Co 0.11 Al 0.03 O 2 (NCA)) as a function of cycling temperature has been investigated using in-situ neutron powder diffraction (NPD) and electrochemical impedance spectroscopy (EIS). The batteries (~140) were cycled at conditions specified by the manufacturer and simulated realistic user conditions with good statistics. Cycling temperature (25, 35 and 45 °C) had a significant influence on the capacity fade with 35 °C showing the highest capacity retention. The NCA

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Normally, high temperatures are required for solid-state reactions to overcome energy barriers in the formation of lithium insertion materials. Consequently, conventional high-temperature lithiation reactions are very time- and energy-consuming and often accompanied by undesirable side reactions. Thus, how to synthesize Li-containing cathode materials with a desired structure under a short reaction time and low temperature is of paramount significance. Herein, layered sodium-deficient Na2/3□1/3(Ni0.25Mn0.75)­O2 (□ for vacancy) oxides with different oxygen stackings (P2 or P3 structure) were deployed in lithium ion batteries. An interesting Li+/Na+ ion-exchange reaction between the electrode material and LiPF6-based carbonate electrolyte was observed at room temperature for the first time. Such a reaction can produce the layered Li2/3□1/3(Ni0.25Mn0.75)­O2 compounds having the O2 or O3 structure, which show the ability to reversibly accommodate lithium ions over a relatively wide voltage range. Our experiments may open up a pathway toward the development of novel electrode materials.