Mixed Electronic and Ionic Conductor-Coated Cathode Material for High-Voltage Lithium Ion Battery

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• High-voltage lithium ion batteries require stable electrode materials to achieve high energy density.
• Magnesium-doped lithium cobalt oxide (Mg-doped LiCoO2) is a promising cathode material for high-voltage applications.
• Surface degradation and side reactions limit the electrochemical performance of high-voltage cathodes.

Purpose of the Study:

• To improve the electrochemical performance of Mg-doped LiCoO2 for high-voltage lithium ion batteries.
• To investigate the effect of a Li1.3Al0.3Ti1.7(PO4)3 (LATP) coating on Mg-doped LiCoO2.
• To evaluate the long-term cycling stability and rate capability of the coated material.

Main Methods:

• Coating Mg-doped LiCoO2 with LATP.
• Characterization using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Electron Energy Loss Spectroscopy (EELS), Energy-Dispersive X-ray Spectroscopy (EDS), and Conductive Atomic Force Microscopy (C-AFM).
• Electrochemical testing of half-cells (vs. Li anode) and full cells (vs. graphite anode) at high voltage (4.5 V).

Main Results:

• The LATP coating forms a stable, electrically conductive layer on the Mg-doped LiCoO2 surface.
• The coated material exhibits enhanced initial capacity, superior cycling stability, and improved rate capability.
• Full cells demonstrate 85% capacity retention after 500 cycles and over 60% after 700 cycles at 4.4 V.

Conclusions:

• LATP is an effective coating material for enhancing the electrochemical performance of high-voltage Mg-doped LiCoO2 cathodes.
• The conductive LATP layer mitigates surface degradation and facilitates ion transport, leading to improved battery longevity.
• This LATP coating strategy shows significant potential for developing next-generation high-energy-density lithium ion batteries.