Cross-linking γ‑Polyglutamic\nAcid as\na Multifunctional Binder for High-Performance SiO_<i>x</i> Anode in Lithium-Ion Batteries

Abstract

SiO_<i>x</i> is a highly promising\nanode material\nfor realizing high-capacity lithium-ion batteries owing to its high\ntheoretical capacity. However, the large volume change during cycling\nlimits its practical application. The development of a binder has\nbeen demonstrated as one of the most economical and efficient strategies\nfor enhancing the SiO_<i>x</i> anode’s\nelectrochemical performance. In this work, a multifunctional binder\n(T-PGA) is fabricated by cross-linking γ-polyglutamic acid (PGA)\nand tannic acid (TA) for SiO_<i>x</i> anodes.\nThe introduction of TA into PGA helps to buffer the volume changes\nof the SiO_<i>x</i> anodes, facilitate diffusion\nof Li⁺, and construct stable SEI layers. Benefiting from\nthis proposed binder, the SiO_<i>x</i> anode maintains\na reversible capacity of 973.0 mAh g^–1 after 500\ncycles at 500 mA g^–1 and the full cell, pairing\nwith LiNi_0.5Co_0.2Mn_0.3O₂ cathode, delivers a reversible capacity of 133 mA h g^–1 (73.2% retention) after 100 cycles. This study offers valuable insights\ninto advanced binders that are used in high-performance Li-ion batteries.