A multifunctional tannic acid binder for 5.0 V LiNi0.5Mn1.5O4 electrodes and its interfacial characterization

Abstract

Due to the higher working voltage of spinel LiNi0.5Mn1.5O4 (LNMO), the electrolyte degrades at high potentials, leading to the generation of numerous alkyl radicals.The transition metals will dissolve under high-voltage reactions, resulting in an unstable LNMO/electrolyte interface, ultimately deteriorating the battery’s cycling performance. In this study, a PAALi-TAc composite binder was obtained through the crosslinking of polyphenolic hydroxides Tannic acid (TAc) with PAALi. The electrode fabricated using this binder achieved a maximum capacity of 132.6 mAh g−1 at a 1 C rate. After 100 cycles, the capacity remained at 130.3 mAh g−1, with a retention rate of 98.2%. Even after 400 cycles, the capacity was maintained at 113.2 mAh g−1, with a retention rate of 85.3%. During the 400 cycles of high-current fast charge and discharge at 5 and 10 C, the capacity retention rates were 89.3% and 88.0%, respectively. The PAALi-TAc binder played a crucial role in establishing a compatible electrolyte interface by terminating the free radical chain reactions and chelating the excess dissolved metals in high-voltage LNMO//Li batteries, and this led to improved cycling and rate performance.