Ge-Regulated Ordered Phase in Pseudosphere-Structured LiNi_0.5Mn_1.5O₄ Spinel Effectively Inhibits Mn Dissolution

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-ion batteries (LIBs) rely on cathode materials like LiNi0.5Mn1.5O4 (LNMO) for high energy density and stability.
• LNMO faces challenges from interfacial reactions and bulk degradation, leading to capacity fade.
• Suppressing transition-metal dissolution is crucial for improving LNMO cathode longevity.

Purpose of the Study:

• To investigate the effect of germanium (Ge) doping on the ordered/disordered phase ratio in LNMO.
• To enhance the structural stability and electrochemical performance of LNMO cathodes.
• To explore Ge-doping as a strategy for suppressing transition-metal dissolution in LIBs.

Main Methods:

• Ge-doping was employed to modify the LNMO spinel structure.
• Electrochemical cycling tests were performed to evaluate capacity retention and voltage stability.
• Structural analysis focused on the ordered/disordered phase ratio and its impact on stability.

Main Results:

• Ge-doping effectively adjusted the ordered/disordered phase ratio in LNMO, enhancing structural stability.
• The Ge-doped LNMO cathode exhibited exceptional cycling performance with 92.2% capacity retention over 1000 cycles at 1C.
• Minimal voltage drop and suppressed transition-metal dissolution were observed in the modified cathode.

Conclusions:

• Ge-doping provides a robust strategy to improve the stability and performance of LNMO cathodes.
• This approach effectively increases Mn4+ content and blocks transition-metal ion diffusion.
• The ordered/disordered phase regulation via doping offers a pathway for designing advanced high-stability cathode materials.