Stabilizing Zn 2 SiO 4 Anode by a Lithium Polyacrylate Binder for Highly Reversible Lithium-Ion Storage.

Binders are crucial for maintaining the mechanical stability of the electrodes. However, traditional binders fail to adequately buffer the volume expansion of Zn 2 SiO 4 anode, causing electrode contact failure and considerable capacity loss during cycling. In this study, we propose a simple and effective solution to address these challenges through a combined strategy of hollow structure design and the introduction of an aqueous lithium poly(acrylic acid) (LiPAA) binder. Hollow structures can shorten ion-transfer distance and accommodate volume change outside. The excellent adhesion of the LiPAA binder created a secure connection between the active Zn 2 SiO 4 particles, conductive additives, and the current collector, which enhanced the mechanical stability and integrity of the electrode. As a result of these positive factors, a Zn 2 SiO 4 electrode using LiPAA as a binder can deliver an excellent capacity of 499 mAh g -1 at a high current density of 5 A g -1 and a long life span of 1000 cycles at 1 A g -1 with a capacity retention of 98%, which significantly outperforms other binders. As demonstrated by ex situ X-ray diffraction and ex situ X-ray absorption spectroscopy, the storage of lithium ions in Zn 2 SiO 4 follows a dual conversion-alloying mechanism, using Zn as the redox center. In this process, Zn is first reduced to metallic Zn and then forms a LiZn alloy upon lithium-ion insertion. This work shows that LiPAA offers a promising approach to improve the cycling longevity of conversion and alloying anodes in Li-ion batteries.