news-details

Optics-based battery diagnostics: Decoding of chemo-mechanical evolution

NCM811 materials have been considered as the main cathode materials for high energy density Li-ion batteries. However, cracks of poly-crystalline NCM materials caused by stress accelerate the loss of active materials, limiting the life cycle. Hence, monitoring and understanding the chemo-mechanical evolution of NCM materials is of importance.

To address this challenge, the research team led by Prof. Yunhui Huang and Prof. Zhen Li introduced an optical fiber to in operando detect the stress evolution of the NCM811 cathode. Through designing the integration of optical fiber and battery, the stress evolution at material level has been successfully monitored. Meanwhile, due to the small size and chemical stability, the implantation of fiber also has little impact on the performance of battery and transmission of sensing signals.

They found that the stress evolution of poly-crystalline NCM811 mainly consists of chemical stress and structural stress. Chemical stress is caused by (de)lithiation of materials, which is normal and unavoidable. Of importance is the fact that structural stress is found to induce cracks, which is harmful to performance. Hence, the elimination of cracks, which means the remission of structural damage, is the key to improving performance.

It has been proved that the structural stress of poly-crystalline with ordered arrangement structure is relieved. Meanwhile, this material delivers a high capacity retention of 82% after 500 cycles at 0.5C.

Related Posts
Advertisements
Market Overview
Top US Stocks
Cryptocurrency Market