Hard-Soft Gradient-Engineered Oxychloride Coating on Ni-Rich Cathodes for All-Solid-State Lithium Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• All-solid-state lithium batteries (ASSLBs) offer high energy density and safety.
• Ni-rich layered oxide cathodes (NRLOs) and sulfide solid-state electrolytes (SSEs) are promising but face interfacial instability.
• This instability hinders the performance and lifespan of ASSLBs.

Purpose of the Study:

• To develop a stable interface for Ni-rich layered oxide cathodes (NRLOs) in ASSLBs.
• To improve the electrochemical performance and cycling stability of ASSLBs.
• To provide a scalable method for stabilizing the cathode/electrolyte interface.

Main Methods:

• Atomic layer deposition (ALD) was used to create a composite gradient coating on NRLOs.
• The coating consists of an oxygen-rich inner layer and a chlorine-rich outer layer.
• Characterization of the coating's structure and electrochemical performance of the modified cathode.

Main Results:

• The gradient coating effectively suppressed transition-metal dissolution and enhanced structural integrity.
• The outer layer improved compatibility with sulfide SSE, accommodating volume changes and reducing mechanical stress.
• Optimized NCM95 cathodes showed 96.9% capacity retention after 200 cycles and good rate capability (103 mAh g⁻¹ at 2 C).

Conclusions:

• Multifunctional coatings are crucial for stabilizing the cathode/electrolyte interface in ASSLBs.
• The developed gradient coating strategy enhances cycling stability and Li+ transport kinetics.
• This approach offers a scalable solution for high-energy ASSLBs.