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

SiOx 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 SiOx 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 SiOx anodes. The introduction of TA into PGA helps to buffer the volume changes of the SiOx anodes, facilitate diffusion of Li+, and construct stable SEI layers. Benefiting from this proposed binder, the SiOx anode maintains a reversible capacity of 973.0 mAh g-1 after 500 cycles at 500 mA g-1 and the full cell, pairing with LiNi0.5Co0.2Mn0.3O2 cathode, delivers a reversible capacity of 133 mA h g-1 (73.2% retention) after 100 cycles. This study offers valuable insights into advanced binders that are used in high-performance Li-ion batteries.SiOx 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 SiOx 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 SiOx anodes. The introduction of TA into PGA helps to buffer the volume changes of the SiOx anodes, facilitate diffusion of Li+, and construct stable SEI layers. Benefiting from this proposed binder, the SiOx anode maintains a reversible capacity of 973.0 mAh g-1 after 500 cycles at 500 mA g-1 and the full cell, pairing with LiNi0.5Co0.2Mn0.3O2 cathode, delivers a reversible capacity of 133 mA h g-1 (73.2% retention) after 100 cycles. This study offers valuable insights into advanced binders that are used in high-performance Li-ion batteries.