Research News

2D Single-Crystalline LiCoO2 Nanosheets Developed for High-Performance Battery-Supercapacitor Hybrid Devices

Posted: 2024-01-23

Recently, a team led by Prof. WU Zhong-Shuai has developed novel 2D atomically thin (001)-oriented single-crystalline LiCoO2 nanosheets with longer Li+ intercalation distance and (001) planes dominated surface for high-performance battery-supercapacitor hybrid devices.

This study was published in ACS Energy Letters on Jan 5.

Shorter Li+ intercalation distance or lower intercalation energy barrier enables fast diffusion in Li+ intercalation process. However, it is found that nanosize effect in nanocrystalline LiCoO2 affects surface-redox and Li+ intercalation processes simultaneously.

As the crystallite size decreases, more Li+ intercalation processes are replaced by surface-redox processes, which brings about decreased platform capacity, low initial coulombic efficiency, and poor cycle performance. Therefore, the nanosize effect restricted the application of nanostructured LiCoO2 in "double high" battery-supercapacitor hybrid devices.

To solve the above problem, Prof. WU's team attempted to regulate the nanosize effect by precisely controlling the Li+ intercalation process and surface-redox process.

They synthesized micro-sized atomically thin single-crystalline LCO nanosheets (SC-LCO) and nanocrystalline LCO nanosheets (NC-LCO). Compared with NC-LCO, SC-LCO presented longer Li+ intercalation distance and decreased side reactions.

They have found that both coulombic efficiency and discharge capacity of SC-LCO at 1C (194 mAh g-1, 92%) were higher than NC-LCO (173 mAh g-1, 86%). The specific capacity of SC-LCO maintained 151 mAh g-1 (83%) after cycling for 500 cycles, which preceded NC-LCO (84 mAh g-1, 63%).

Moreover, the researchers fabricated a battery-supercapacitor hybrid device with SC-LCO and achieved high-energy and high-power, demonstrating the practical applicability of this nanosheets.

The above study was supported by the National Natural Sciences Foundation of China, the DICP Innovation Foundation.