Electrochemically Derived Interfacial Li-Ion Conductor Enables High-Rate and Long-Cycling in Ni-Rich Layered Cathodes

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Fast-charging capability is crucial for next-generation lithium-ion batteries (LIBs).
• Layered high-nickel transition metal oxides (LiNi_xCo_yMn_(1-x-y)O₂, x ≥ 0.8) offer high capacity but suffer from poor Li⁺ diffusion and interfacial instability.
• Conventional surface coatings on secondary particles are often non-uniform and provide incomplete protection.

Purpose of the Study:

• To develop a novel surface engineering strategy for Ni-rich cathode materials.
• To overcome limitations in Li⁺ diffusion kinetics and interfacial instability.
• To enhance fast-charging performance and cycling durability of LIBs.

Main Methods:

• Electrochemical construction of a conformal fast-ion-conducting layer on primary particles.
• Characterization using high-resolution transmission electron microscopy with energy-dispersive X-ray spectroscopy (HRTEM-EDS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS).
• Electrochemical evaluation using Galvanostatic Intermittent Titration technique (GITT) and theoretical analysis via Density Functional Theory (DFT) calculations.

Main Results:

• Verified conformal and homogeneous nanoscale Li₂SeO₄ coating on primary particles.
• Demonstrated fast Li⁺-ion transport with a low migration barrier (260 meV) via GITT and DFT.
• Achieved significant improvements in high-rate performance (180.6 mAh·g^-1 at 10C) and cycling durability (94.2% retention after 100 cycles).

Conclusions:

• The proposed electrochemical surface engineering strategy effectively addresses Li⁺ diffusion and interfacial stability issues in Ni-rich cathodes.
• This method provides a versatile and scalable approach for advancing fast-charging layered cathode materials.
• The study presents a promising solution for developing high-performance LIBs for demanding applications.