High-Energy-Density Cathode Material Achieved by Upgrading Low-Voltage Li₃V₂O₅ via Ni Doping

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• High-energy-density lithium-ion batteries require advanced cathode materials with superior specific discharge capacity.
• Lithium vanadium oxide (Li₃V₂O₅) possesses high theoretical capacity but is limited by its low operating voltage, typically used as an anode material.
• There is a critical need to develop Li₃V₂O₅ for cathode applications to harness its potential in high-performance batteries.

Purpose of the Study:

• To develop Li₃V₂O₅ as a high-energy-density cathode material for lithium-ion batteries.
• To investigate the effects of nickel (Ni) doping on the structure and electrochemical properties of Li₃V₂O₅.
• To enhance the specific discharge capacity, operating voltage, and overall performance of Li₃V₂O₅-based cathodes.

Main Methods:

• Synthesis and structural characterization of Ni-doped Li₃V₂O₅ (LVON2).
• Electrochemical testing including galvanostatic cycling, rate capability tests, and electrochemical impedance spectroscopy.
• Density functional theory (DFT) calculations to understand doping mechanisms and structural effects.
• Thermal stability analysis using differential scanning calorimetry (DSC) and finite element analysis.

Main Results:

• Ni doping transforms Li₃V₂O₅ into a cation-disordered rock-salt phase (LVON2) with uniform Ni distribution.
• LVON2 exhibits a prolonged V-based plateau at ~2.5 V and a new Ni²⁺/Ni³⁺ redox plateau at ~3.5 V.
• Achieved high specific discharge capacities of 270.8 mA h g^-1 at 50 mA g^-1 and 339.4 mA h g^-1 at 20 mA g^-1, yielding an energy density of 837 W h kg^-1.
• Improved rate capability (143.3 mA h g^-1 at 1000 mA g^-1 for LVON2 vs. 94.1 mA h g^-1 for pristine Li₃V₂O₅) and reduced charge-transfer resistance.
• Enhanced thermal stability of Ni-doped Li₃V₂O₅ was confirmed.

Conclusions:

• Nickel doping effectively enables Li₃V₂O₅ to function as a high-energy-density cathode material.
• The structural modifications induced by Ni doping significantly improve electrochemical performance and thermal stability.
• This work establishes a promising pathway for developing advanced Li₃V₂O₅-based cathode materials for next-generation lithium-ion batteries.