KrF excimer laser-modified PVDF binder and its application in high-performance Li-ion battery

Abstract

Poly(vinylidene fluoride)(PVDF) plays a crucial role in Li-ion batteries. It could bond conductive agents and active substances firmly together, allowing each to play its role. However, PVDF does not conduct electricity, which is very detrimental to the transfer of charge. By using a KrF excimer laser to irradiate the PVDF powder, the conductivity is upgraded from 3.6 × 10−14 to 6.3 × 10−4 S cm−1 without reducing the bonding and stability performance, which greatly improves the electrochemical performance and physical stability of Li-ion battery. After using the laser-modified PVDF as a binder, the LiFePO4 cathode displays outstanding rate performance (160.2 mAh g−1 at 0.2 C and 119.4 mAh g−1 at 10 C), the considerable cycling stability (94.2% of capacity retention after 1000 cycles at 2 C), and the excellent low-temperature discharge ability(75.1% of capacity retention at –20 ℃). Using conductive PVDF as a binder is an important means to improve the electrochemical performance of Li-ion batteries.