Importance\nof High Valence Element Nb in Ni-Rich Layered\nCathodes for High-Voltage Lithium-Metal Batteries

Ni-rich layered cathode materials have attracted extensive\nattention\ndue to their higher energy density and technological maturity in commercialization.\nAs the nickel content is raised, especially surpassing 80%, the increased\nenergy density comes with the tradeoff of diminished thermal stability\nand increased electrochemical structural instability of the cathode.\nCompared with Co, Al, B, and Ta, the introduction of high valence\nelement Nb significantly improved the electrochemical cycling, delivering\na capacity of 202 mAh/g, corresponding to a capacity retention of\n92% after 200 cycles tested at 45 °C. The ex situ differential\nscanning calorimetry and in situ isothermal microcalorimetry demonstrate\nthat the Nb-modified cathode has the potential to enhance the safety\nof ultrahigh nickel (Ni) NMCs and displays remarkable resilience to\nextensive cycling by inhibiting high-temperature decomposition reactions\nand exhibiting a lower heat flow during electrochemical cycling.