Enhanced stability of vanadium-doped Li_1.2Ni_0.16Co_0.08Mn_0.56O₂ cathode materials for superior Li-ion batteries

Abstract

The high-valence V5+ can improve the discharge capacity and coulomb efficiency and inhibit the voltage attenuation of cathode materials.

Redox Mediator V5+ Doping for Effective Charge Compensation in the Li-Rich Mn-Based Layered Oxide Cathode of Li1.2Ni0.13Co0.13Mn0.54O2

“…The previously mentioned studies above have primarily discussed the formation of the strengthened dopant−oxygen bond to explain the enhanced electrochemical stability of highvalent cation-doped LRMOs. [44][45][46][47][48][49]52 In this work, we observed the enhancement of oxygen redox reversibility and the mitigation of TM migration in pentavalent cation-doped Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 such as V 5+ -doped (V- LRMO), Sb 5+ -doped (S-LRMO), Ta 5+ -doped (T-LRMO), and Nb 5+ -doped ones (N-LRMO). Thermal analyses were performed to verify the effects of strong cation-O bonds for suppressing oxygen sublattice distortion: dihydrogen temperature-programmed reduction (H 2 -TPR), thermogravimetric analysis (TGA), and differential thermogravimetry (DTG) were introduced to compare the reducibility of TM ions and the quantity of oxygen loss to analyze the difference in chemical stabilities between the pentavalent cation-doped Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 (P-LRMO) and undoped one.…”

“…This preference for the C2/m phase might arise from Mn 4+ abundancy of the Li 2 MnO 3 phase because the pentavalent dopant cations prefer to replace the Mn 4+ site due to its similar charge valence to the substituted The white values inside the different colored bars denote the ionic radii of pentavalent dopants. The ionic radius value of undoped LRMO is expressed with the radius of Mn 4+ (low spin), which is the preferentially replaced ions when pentavalent dopant cations is substituted into lattice; high-valent dopant cations such as Ti 4+ , 66 Sn 4+ , 67 V 5+ , 43,44 Ta 5+ , 50 Nb 5+ , 45,48,49 Mo 6+ , 51 W 6+ , 52 and Re 7+53 are reported to prefer to replace Mn 4+ site among TM ions (Ni 2+ , Co 3+ , and Mn 4+ ) due to its similar charge valence to the substituted elements. elements.…”

“…42−53 Introduction of high-valent ions into the LRMO lattice can ensure the structural integrity, especially at a deep charged state, due to the formation of the strengthened dopant−oxygen bond. [44][45][46][47][48][49]52 The strengthened bond between the more highly oxidized dopant and the oxide ion could solidly hold the TM-O slabs and mitigate vigorous oxygen redox in the LRMOs. In other words, the local distortion of oxygen sublattice and the destruction of Li 2 MnO 3 -like ordering caused by the formation of O−O pairs could be hindered by rigid TM−O−TM angle or TM−O bond, which can be obtained with high-valent cations.…”

“…Recently, doping methods with high-valent elements have been demonstrated as an effective way to mediate oxygen redox and deliver reversible electrochemical performance of LRMOs. − Introduction of high-valent ions into the LRMO lattice can ensure the structural integrity, especially at a deep charged state, due to the formation of the strengthened dopant–oxygen bond. − , The strengthened bond between the more highly oxidized dopant and the oxide ion could solidly hold the TM-O slabs and mitigate vigorous oxygen redox in the LRMOs. In other words, the local distortion of oxygen sublattice and the destruction of Li 2 MnO 3 -like ordering caused by the formation of O–O pairs could be hindered by rigid TM–O–TM angle or TM–O bond, which can be obtained with high-valent cations. , The rigid local structure can lead to the well-preserved global layered structure, suppressing the evolution of O 2 gas and phase transformation from a layered to cubic structure. − Meanwhile, studies on the effect of high-valent dopants have rarely focused on whether the doping elements serve as electron donors in LRMOs and participate in a charge compensation during the cycle, ultimately relieving the deep oxidation of the oxide ion.…”

Research Progress and Commercialization of Biologically Derived Hard Carbon Anode Materials for Sodium-Ion Batteries

“…From the analysis and summary of previous studies, we also find that when woody plants with higher lignin content are selected as precursors of hard carbon materials, the initial Coulombic efficiency of hard carbon derived from woody plants is generally higher than that derived from herbaceous plants. In the equilibrium range of cellulose, hemicellulose, and lignin, the higher the lignin content, the higher the initial Coulombic efficiency of the material. − The complex and varied microstructure of plants can provide additional space for sodium storage but also introduce some drawbacks to the final material, such as a large initial irreversible capacity due to the large specific surface area and a low initial Coulombic efficiency. The natural microstructure of plant-derived hard carbon material inherits the precursors, which affects the electrochemical properties of the material.…”