Cross-linking γ-Polyglutamic Acid as a Multifunctional Binder for High-Performance SiO Anode in Lithium-Ion Batteries.

SiO is a highly promising anode material for realizing high-capacity lithium-ion batteries owing to its high theoretical capacity. However, the large volume change during cycling limits its practical application. The development of a binder has been demonstrated as one of the most economical and efficient strategies for enhancing the SiO anode's electrochemical performance. In this work, a multifunctional binder (T-PGA) is fabricated by cross-linking γ-polyglutamic acid (PGA) and tannic acid (TA) for SiO anodes. The introduction of TA into PGA helps to buffer the volume changes of the SiO anodes, facilitate diffusion of Li, and construct stable SEI layers. Benefiting from this proposed binder, the SiO anode maintains a reversible capacity of 973.0 mAh g after 500 cycles at 500 mA g and the full cell, pairing with LiNiCoMnO cathode, delivers a reversible capacity of 133 mA h g (73.2% retention) after 100 cycles. This study offers valuable insights into advanced binders that are used in high-performance Li-ion batteries.