Water-Soluble Multifunctional Binder with Extraordinary Bonding Strength for High-Voltage Sodium-Ion Batteries

Abstract

With the ever-increasing demand for low-cost energy storage systems, sodium-ion (Na-ion) batteries have received great attention. However, the large volume change, sluggish reaction kinetics, and unstable electrode/electrolyte interphase during cycling inevitably deteriorate the performance of Na-ion batteries. Herein, a high-voltage water-soluble multifunctional binder with an extraordinary bonding strength is investigated. Such water-soluble binder not only exhibits an excellent adhesion strength to maintain the mechanical integrity and enhance the Na-ion diffusion across the interfac but also constructs a robust protective layer to prevent side reactions and improve the cycle durability at high voltages. As a result, a specific capacity of 91.3 mAh g−1 at 10.0C and high capacity retention of 92.3% for 1000 cycles are achieved. A good cycle stability and rate performance between 2.5 and 4.4 V can be observed after pairing with a high-voltage electrode, and the practical application of the high-voltage water-soluble multifunctional binder is further confirmed by a 0.95 Ah Na-ion pouch cell.