Wednesday, December 6, 2023

Stabilizing nickel-rich cathodes for use in long-life lithium-ion batteries

Nickel-rich layered cathodes have been considered promising candidates for the next generation of high-energy lithium-ion batteries due to their high energy density and competitive cost. However, with the long-term operation, these cathodes suffer from rapid capacity fading due to structural and interfacial instability.

Now, researchers at the East China University of Science and Technology (ECUST) have developed a simple, one-step dual-modification strategy to restrain these side reactions that occur and enhance the stability of nickel-rich cathode in Li-ion batteries.

Scientists first used tactics such as surface coating and element doping with the cathode materials. But single modification processes cannot solve the structural and interfacial instability at the same time. The single-element doping strategy fails to prevent the cathode-electrolyte reaction, while the coating materials typically exhibit poor lithium-ion conductivity.

In order to achieve advanced nickel-rich oxides with high specific capacity and long cycling life, a high-efficiency dual-modification was needed. The new work provides a simple, one-step dual-modification strategy that limits the interfacial parasitic side reactions and enhances the structural stability to meet the commercial requirements of nickel-rich cathodes.

The team synthesized the titanium-doped and lithium yttrium dioxide-coated (LiYO2) nickel-rich layered cathode via a facile one-step sintering strategy. The sintering process uses heat and pressure to form a solid mass of material. According to researchers, this strategy significantly restrains the interfacial parasitic side reactions and enhances structural stability.

Researchers tested their cathodes using X-ray diffraction and scanning electron microscopy. Their results showed that their dual-modified cathode material had an improved capacity retention of 96.3% after 100 cycles and 86.8% after 500 cycles, much higher than the unmodified cathode materials.

The LiYO2 nickel-rich coating successfully prevents the interfacial parasitic side reactions and the dissolution of transition metal ions. This enhances the cathode-electrolyte interface stability. The team’s dual-modification strategy results in a cathode material with a faster lithium-ion diffusion rate and outstanding electrochemical stability.

The team is now planning to develop its strategy for large-scale production. “In the next step, we would like to apply this dual modification strategy to large-scale industrial production, taking both cathode materials with stable interface/crystal structure and excellent electrochemical performance,” said Hao Jiang, a professor at East China University of Science and Technology.

Additionally, the team will explore the consistency after amplification to ensure uniform doping and coating effect. “Moreover, the stability under extremely harsh conditions will be studied to ensure the safety of the material and facilitate its commercial application,” said Jiang.

Journal reference:

  1. Hanwen Zheng, Zhihong Wang, Ling Chen, Hao Jiang, Chunzhong Li. Integrating trace Ti-doping and LiYO2-coating to stabilize Ni-rich cathodes for lithium-ion batteries. Particuology, 2023. DOI: 10.1016/j.partic.2022.12.003