New strategy for cathode materials in rechargeable Li-Cl2 batteries

Traditional lithium-thionyl chloride (Li-SOCl₂) batteries are widely used for their high energy density and other advantages. But unlike lithium ion or lithium polymer batteries, these cells cannot be recharged once they have been discharged.

A rechargeable lithium-chlorine (Li-Cl₂) battery was first invented in 2021, with a high specific capacity of 1200 mAh/g, which is no less than six times greater than the 200 mAh achieved by today’s lithium-ion batteries.

However, a few problems stand in the way of the practical application of Li-Cl₂ batteries. For example, the Cl₂ reaction is limited by the weak physical adsorption of porous carbon to Cl₂ molecules. Also, the excessive LiCl generation into the carbon pores blocks the channels for Li+ transportation and Cl₂ diffusion, hindering further electrochemical reactions.

Moreover, the shuttle effect of unbonded Cl₂ leads to battery capacity decay, especially at high output capacities. Therefore, cathode materials with highly porous structures are important for realizing high-performance Li-Cl₂ batteries.

To overcome the above difficulties, a research team at the University of Science and Technology of China (USTC) adopted NH2-functionalized metal-organic frameworks (MOFs) in Li-Cl₂ batteries to achieve high specific capacities, cycle stability, and superior low-temperature performance.

The schematic diagram of the reaction mechanism of Li-Cl2@MOF(UiO-66-NH2) batteries. Credit: Xu Yan et al

Predicted by theoretical calculations, highly porous MOFs with -NH₂ functional groups, namely UiO-66-NH₂, were screened out as a model and applied in Li-Cl₂ batteries. The Li-Cl₂ battery using NH₂-functionalized MOF (Li-Cl2@MOF) demonstrated a maximum discharge specific capacity of 2000 mAh/g and is stable for more than 500 cycles under a specific capacity of 1,000 mAh/g at room temperature.

The batteries also performed stable functions under the temperature of -40 °C. This work presented an innovative design of cathode materials in Li-Cl₂ batteries, paving the way for future applications of rechargeable Li-Cl₂ batteries.

Journal reference:

1. Yan Xu, Long Jiao, Jiale Ma, Pan Zhang, Yongfu Tang, Lingmei Liu, Ying Liu, Honghe Ding, Jifei Sun, Mingming Wang, Zhenyu Li, Hai-Long Jiang, Wei Chen. Metal-organic frameworks for nanoconfinement of chlorine in rechargeable lithium-chlorine batteries. Joule, 2023; DOI: 10.1016/j.joule.2023.02.010

New strategy for cathode materials in rechargeable Li-Cl2 batteries
Source: Tambay News