Entropy modulation strategy of P2-type layered transition metal oxide cathodes for sodium-ion batteries with a high performance

Abstract

P2–type Na0.67Ni0.33Mn0.67O2 is a promising cathode for sodium-ion batteries due to its high theoretical capacity, facile fabrication, low cost, and environmental friendliness, however, it suffers from an undesirable phase transformation...

Solid-Solution Reaction and Ultrasmall Volume Change in High-Entropy P2-type Layered Oxide Cathode for All-Climate Sodium-Ion Batteries

“…The weakening of the shoulder at 625 cm –1 in HEO implies the decrease of the orthorhombic symmetry and the increase of the local lattice disorder due to the interruption of cation ordering or sodium-vacancy ordering caused by multiple elemental substitutions. In addition, the configurational entropy of HEO is calculated (Supporting Information), which is close to the value reported previously about high-entropy oxide, , confirming that Na 0.85 Li 0.08 Mg 0.04 Ni 0.22 Al 0.04 Mn 0.62 O 2 studied in this work is a high-entropy system.…”

A High-Entropy Approach to Activate the Oxygen Redox Activity and Suppress the Phase Transition of P2-Type Layered Cathode for Sodium-Ion Batteries

“…30 However, few studies have dealt with the reduction of the first-cycle Coulombic efficiency, the voltage hysteresis and attenuation, and the slow reaction kinetics caused by the excitation of oxygen redox reactions in P2-type materials. 31 Meanwhile, the substitution of Li + and Ti 4+ can disrupt Na + / vacancy ordering and achieve solid solution reactions. 32−34 The substitution of Li + and Cu 2+ can reduce the irreversible migration of Li + in the TM layer under high voltage.…”

“…Guo et al alleviated the unfavorable P2–O2 phase transition through the synergistic effect of Li, Mg, and Ti cosubstitution, resulting in a “ Z ” symbiotic structure and improved cycling stability . However, few studies have dealt with the reduction of the first-cycle Coulombic efficiency, the voltage hysteresis and attenuation, and the slow reaction kinetics caused by the excitation of oxygen redox reactions in P2-type materials . Meanwhile, the substitution of Li + and Ti 4+ can disrupt Na + /vacancy ordering and achieve solid solution reactions. − The substitution of Li + and Cu 2+ can reduce the irreversible migration of Li + in the TM layer under high voltage. , However, the synergistic effect of high-entropy systems constructed with multiple elements of Li + , Cu 2+ , and Ti 4+ has not been studied yet, although it is generally recognized that the introduction of Li + can increase Na content, stimulate the oxygen redox reactions, and increase the theoretical capacity, the introduction of Cu 2+ can stabilize the oxygen environment and reduce oxygen loss, and the introduction of Ti 4+ can stabilize the TM layer framework. − …”

A two-step method to prepare P2-type layered oxide materials for stable sodium-ion batteries via a precursor and sintering temperature control

“…[11][12][13] P2-type oxides, characterized by lower sodium content and wider interlayer spacing, exhibit reduced phase transitions and enhanced rate capabilities during the electrochemical process, progressively positioning themselves as a promising option among positive electrode materials for sodium-ion batteries. 14,15 Nevertheless, when operating within a high voltage range, substantial capacity decay persists after prolonged cycling. 16 Layered metal oxides are regarded as promising candidates with potential advantages as high-capacity cathode materials.…”