Chen Pengyu, Jiang Cheng, Jiang Jie, Zou Jian, Ran Qiwen, Wang Xin, Niu Xiaobin, Wang Liping
School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 611731, China.
ACS Appl Mater Interfaces. 2021 Jul 7;13(26):30576-30582. doi: 10.1021/acsami.1c05332. Epub 2021 Jun 24.
Fluorinated carbon (CF) cathodes have the highest theoretical energy density among lithium primary batteries. However, it is still a huge challenge to be reversible. Here, CF is proposed as a high-performance cathode material for rechargeable lithium-ion batteries in the extended voltage window of 0.5-4.8 V. Specifically, the fluorinated graphite CF exhibits an initial specific discharge capacity of 1382 mAh g (2362 Wh kg) and a specific discharge capacity of 782 mAh g at the 2nd cycle and maintains a specific discharge capacity of 543 mAh g (508 Wh kg) after the 20th cycle. This rechargeable behavior is associated with the conversion of CF to LiF + C (>1.5 V) and then to LiFC (0.5-1.5 V) during the initial discharge process; LiFC is reversible to LiF + C in the following charge-discharge process (0.5-4.8 V). By extending the voltage window, CF cathodes can show new electrochemical behaviors. Our research has provided new Li-free cathode materials for rechargeable batteries and insights for improving the performance of a Li/CF secondary battery.
氟化碳（CF）阴极在锂原电池中具有最高的理论能量密度。然而，实现其可逆性仍然是一个巨大的挑战。在此，CF被提议作为一种高性能的阴极材料用于可充电锂离子电池，其电压窗口扩展至0.5 - 4.8V。具体而言，氟化石墨CF在首次放电时的比放电容量为1382 mAh g（2362 Wh kg），在第二次循环时为782 mAh g，在第20次循环后仍保持543 mAh g（508 Wh kg）的比放电容量。这种可充电行为与首次放电过程中CF转化为LiF + C（>1.5V），然后转化为LiFC（0.5 - 1.5V）有关；在随后的充放电过程（0.5 - 4.8V）中，LiFC可逆向转化为LiF + C。通过扩展电压窗口，CF阴极可展现出新的电化学行为。我们的研究为可充电电池提供了新型无锂阴极材料，并为提高Li/CF二次电池的性能提供了见解。
