Tandem Topotactic Reactions for Low-Temperature Synthesis of Ni-Rich Layered Oxide Cathodes without Anti-site Defect

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Ni-rich layered oxides (LiNi_xCo_yMn_zO₂, x > 0.6) are crucial for electric transportation due to high energy density (>700 Wh/kg).
• Conventional synthesis requires high temperatures (>700 °C) and long durations (∼10 h), leading to high energy consumption and synthesis control challenges.

Purpose of the Study:

• To develop a low-temperature synthesis route for Ni-rich cathodes.
• To reduce energy consumption and costs associated with cathode material production.
• To maintain structural integrity during synthesis for improved performance.

Main Methods:

• A two-step tandem topotactic phase-transition route was designed for low-temperature synthesis.
• Temperature-resolved X-ray scattering and ex situ spectroscopy were used to study the phase transitions.
• The process involves topotactic deprotonation of a layered hydroxide precursor followed by topotactic lithiation.

Main Results:

• Ni-rich cathodes were successfully synthesized at a low temperature of 150 °C.
• Energy consumption was reduced by 57% compared to conventional methods.
• The synthesized cathodes showed comparable electrochemical activity and improved cycling stability (∼80% after 500 cycles).

Conclusions:

• The topotactic route preserves the layered framework, unlike conventional methods that involve destruction-reconstruction.
• This methodology enables cost-effective and eco-friendly production of high-performance Ni-rich cathode materials.
• The study lays a foundation for industrial-scale manufacturing of advanced battery materials.