Ca-Doped Layered Oxide Cathode

84.2% after 500 cycles

Calcium doping enables continuous phase transition, greatly enhancing cycling stability of sodium-ion batteries.

Junjie, Ding · Guihong, Mao · Guo, Zhenyu · Yang, Hai · Tan, Peng · Jiang, Yu · Shen, Laifa · Bai, Ruilin · Jialong, Shen · Wang, Shuo · Yao, Yu · Wu, Yucheng · Yu, Yan

Advanced Materials 2026

Specifications

Specific capacity

{'zh': '140', 'en': '140'} mAh g⁻¹

Capacity retention after 500 cycles

{'zh': '84.2', 'en': '84.2'} %

Energy density

{'zh': '192', 'en': '192'} Wh kg⁻¹

Full cell capacity retention after 100 cycles

{'zh': '82.5', 'en': '82.5'} %

Advantages

Much higher capacity retention

Ca substitution lowers the phase transition potential, enabling smoother Na⁺ migration and slower slab sliding for a continuous phase transformation, resulting in 84.2% retention after 500 cycles at 1 C versus 26.4% for the undoped cathode.

Full-cell energy density of 192 Wh kg⁻¹

A 6.1 Ah full cell delivers an energy density of 192 Wh kg⁻¹ based on the entire cell mass, demonstrating practical scalability of the cathode.

Provides a rational design descriptor

The phase transition potential (Φphase) is introduced as a descriptor to predict and control phase evolution in layered oxide cathodes, guiding the design of other low-strain materials.

Applications

• Sodium-ion battery cathode：Directly used as cathode active material with Ca doping to improve cycling stability.
• High-energy-density batteries：Full-cell energy density of 192 Wh kg⁻¹ suits high-energy-density applications.
• Full-cell integration：Paired with Al@C anode to validate full-cell performance.
• Long-cycle batteries：84.2% retention after 500 cycles suits long-cycle demands.