Breakthrough high-entropy O3 layered oxide cathodes: Enhancing rate performance and cycling stability of solid-state sodium-ion batteries

As the global demand for sustainable and cost-effective energy solutions continues to rise, the development of advanced energy storage materials becomes increasingly important. Solid-state sodium-ion batteries (SSBs), due to the abundance and low cost of sodium, are emerging as a promising alternative to lithium-ion batteries. However, SSBs face challenges such as phase transitions, poor ion conductivity, and limited cycling stability, which hinder their widespread use. High-entropy oxides (HEOs), as a new class of materials, show great potential in addressing these challenges, making them ideal candidates for next-generation sodium-ion battery cathodes.

A team of researchers from the Shanghai Institute of Silicate Research, Chinese Academy of Sciences, led by Prof. Fuqiang Huang, has designed a high-entropy O₃-type layered oxide cathode material, Na_0.95Li_0.06Ni_0.25Cu_0.05Fe_0.15Mn_0.49O₂, for solid-state sodium-ion batteries. By incorporating multiple elements with similar ionic radii and different Fermi levels, this innovative cathode material successfully overcomes charge ordering issues, enhances ion conductivity, and ensures long-term cycling stability. This approach marks a significant advancement in the development of high-performance SSBs.

Key features of this high-entropy cathode include:

1. Excellent Rate Capability and Cycling Stability: The Na_0.95Li_0.06Ni_0.25Cu_0.05Fe_0.15Mn_0.49O₂ cathode exhibits a reversible capacity of 141 mAh g^-1 at 0.2C, and maintains high performance at 8C (111 mAh g^-1) and 20C (85 mAh g^-1). After 1,000 cycles, the capacity retention remains over 85%.

2. Superior Air and Thermal Stability: The material demonstrates remarkable stability in both air and high-temperature conditions, ensuring reliable long-term performance in real-world applications.

3. Optimized Electrochemical Performance: Detailed studies of the energy storage mechanism show that the high-entropy design effectively reduces stress and improves sodium ion diffusion, leading to excellent rate capability and cycling stability.

The success of this cathode lies in its high-entropy structure, which effectively suppresses phase transitions, and the synergistic effects of multiple elements. By enhancing ion conductivity and improving the material’s stability, this design allows solid-state sodium-ion batteries to achieve higher energy density and longer lifespans.

Despite these significant achievements, the platform faces challenges such as fabrication complexity and scalability. Future research will focus on optimizing the interface between the high-entropy cathode and solid-state electrolytes to improve integration and efficiency. Additionally, scaling up production will pave the way for the commercial application of high-performance solid-state sodium-ion batteries.

This study presents an innovative high-entropy O₃-type layered oxide cathode material for solid-state sodium-ion batteries, representing a breakthrough in energy storage technology. As the technology continues to develop, these innovations could drive the emergence of the next generation of sodium-ion batteries, offering transformative solutions for future energy storage needs.