Regulating segmental dynamics for ion clusters in polymer binders to realize high-areal-capacity electrodes in lithium batteries

Abstract

The growing demand for high-energy-density lithium batteries necessitates high-areal-capacity electrodes, typically involving high-mass-loading cathodes. However, achieving high mass-loading cathodes often leads to challenges such as structural instability and inefficient ion transport. In this study, a series of ionic soft polymer (ISP) binders have been designed to overcome these limitations. By modulating the segmental dynamics in the side chains, the ISP binder forms a reversible ion cluster, significantly enhancing ionic conductivity. Furthermore, electrostatic interactions and hydrogen bonding within the binder foster a robust network, providing strong adhesion and stability, while minimizing transition metal dissolution and surface side reactions. The ISP binder also exhibits remarkable self-healing properties and stretchability, effectively accommodating solvent-drying-induced stress. The designed binder-incorporated NCM811 cathodes achieve an impressive areal capacity of 17.9 mA h cm⁻² at 86.1 mg cm⁻² mass loading. A pouch-type Li metal full cell with a thin Li metal anode (40 μm) delivers a high energy density of 381.1 W h kg_cell⁻¹/1067.5 W h L_cell⁻¹, including packaging materials. This study demonstrates the promising potential of ISP binder to enable scalable high-areal-capacity electrodes for high-energy-density lithium batteries with enhanced stability and performance.