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Phosphorus‐rich 6‐MnP4 nanoparticles are synthesized via high energy mechanical milling (HEMM) and their electrochemical properties as an anode for lithium‐ion batteries (LIBs) and sodium‐ion batteries (SIBs) are investigated focusing on the electrochemical activity and reaction mechanism. The 6‐MnP4 nanoparticles with a triclinic structure (P‐1) are successfully synthesized by HEMM and they are composed of 5 to 20 nm‐sized crystallites. During the lithiation process, the MnP4 phase undertakes the sequential alloying (MnP4 + 7 Li+ + 7 e−→ Li7MnP4) and conversion (Li7MnP4 + 5 Li+ + 5 e− → Mn0 + 4 Li3P) reactions. On the other hand, the MnP4 nanoparticles are directly converted to Mn0 and Na3P without the formation of an intermediate Na–Mn–P alloy phase during sodiation process. The MnP4 electrode shows high initial discharge and charge capacity (1876 and 1615 mAh g−1 for LIBs, and 1234 and 1028 mAh g−1 for SIBs) and high initial Coulombic efficiency (86% for LIBs and 83% for SIBs), indicating a promising candidate for high capacity anodes. In addition, the long‐term cyclability and high rate capability of MnP4 can be further improved through the formation of MnP4/graphene nanocomposites and vanadium substituted Mn0.75V0.25P4 solid solutions. [ABSTRACT FROM AUTHOR]

A new P2-type Na0.7(Ni0.6Co0.2Mn0.2)O2 was prepared via co-precipitation and its electrochemical properties as a cathode for sodium ion batteries were compared with those of O3-type Na(Ni0.6Co0.2Mn0.2)O2, focusing on phase stability and cycling performance. The P2-type delivered a high capacity of 108 mA h g−1 after 300 cycles at 2C. [ABSTRACT FROM AUTHOR]

V4P7 nanoparticles were synthesized via high-energy mechanical milling and their electrochemical properties as an anode for sodium-ion batteries were studied and compared with those of VO2(B)/Na and V4P7/Li cells, focusing on the electrochemical reaction mechanism and cycle performance. The V4P7 showed excellent cycling behavior even without any conductive material. [ABSTRACT FROM AUTHOR]

• Electrochemical reaction mechanism of MnV 2 O 6 as an anode for SIBs is investigated. • Electrochemical performance of MnV 2 O 6 nanobelt and nanoparticle is compared. • MnV 2 O 6 nanobelt electrode shows better cycle retention and long-term cyclability. Manganese vanadate (MnV 2 O 6) nanobelts (MVO-NBs) and nanoparticles (MVO-NPs) with a brannerite structure are synthesized by hydrothermal and high energy mechanical milling methods, respectively, and their electrochemical properties as an anode for sodium-ion batteries (SIBs) are investigated. Ex-situ X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) studies indicate that MnV 2 O 6 is transformed to a low crystalline phase during the first sodiation without a further amorphization, which is different from MnV 2 O 6 /Li cell and results in a relatively low reversible capacity in MnV 2 O 6 /Na cell. The MVO-NB electrode exhibits the better electrochemical performance than MVO-NP electrode, possibly due to the fast diffusion kinetics resulting from the short diffusion length. The MVO-NB electrode shows a stable long-term cycle stability, delivering a reversible capacity of 110 mA h g−1 after 1000 cycles at a high current density of 500 mA g−1. The MnV 2 O 6 nanobelt electrode is electrochemically active with sodium ion showing an excellent cycle retention with a high Coulombic efficiency. Image, graphical abstract [ABSTRACT FROM AUTHOR]

As electric vehicles (EVs) grow in popularity, the demand for lithium-ion batteries (LIBs) simultaneously grows, and the fast-charging capability is becoming increasingly important. However, it is generally believed that graphite anode still suffers from a poor rate capability for fast-charging applications, and other insertion-type oxide anodes with a high rate capability exhibit too high Li+-ion insertion/extraction potential, which cannot meet a requirement for high energy density anodes. In this work, the hexagonal structure of V 1-x Ti x P (x = 0.0, 0.25, and 1.0) phases were introduced as insertion-type anode materials for LIBs with a low reaction potential of Li+-ion insertion/extraction. The crystal structure and the corresponding electrochemical reaction mechanism of insertion-type anodes of TiP, VP, and MoP were compared. A facile strategy forming a substitutional solid solution is suggested to improve the electrochemical properties of anode materials by combining the end members among insertion-type VP, TiP, and MoP as forming V 1-x Ti x P and V 1-x Mo x P compounds. V 1-x Ti x P (x = 0.25) electrode, substituting V atoms with Ti atoms in VP structure, shows excellent long-term cycle stability at 1 A/g with a cycle retention of 87.7 % during 2500 cycles, delivering a two times higher capacity of 211.1 mAh g−1 compared to that of the commercial graphite electrode. [ABSTRACT FROM AUTHOR]