A multifunctional network binder enables stable and high performance of silicon-based anode in lithium-ion battery

Abstract

Rechargeable lithium-ion batteries with high energy density have attracted attention as a means of solving environmental problems. Silicon (Si) has been considered as one of the most promising anode materials due to its high theoretical capacity of 3579 mAh g-1 (Li15Si4). However, the enormous volume change of Si occurs during lithiation/delithiation process, which seriously deteriorates the mechanical/electrochemical stability of Si anodes. To address these inherent problems, it is of importance to develop a functional binder capable of reducing the volume variation of Si anodes. In this work, we first design a new binder system by employing a Multifunctional Network Binder (MNB) to synergistically improve the electrochemical stability and performances of Si-based electrodes. The introduction of MNB into the Li-PAA-based electrode system constructs a strong binding matrix through abundant functional bridges. In addition, the MNB with high dispersion stability improves the ionic conductivity of Si-based electrodes. Owing to these synergistic effects of Li-PAA/MNB binder system, the volume expansion of Si-based electrodes was significantly suppressed, contributing to the excellent Coulombic efficiency (99.9%) and capacity retention (87% after 100 cycles).