Shear-aligned nanocellulose enabling the development of stable all-solid-state lithium batteries

Abstract

Composite polymer electrolytes (CPEs) combining a polymer matrix and functional fillers have gained significant attention due to their potential to overcome the limitations of single-component electrolytes. However, the disordered ion transport networks in conventional CPEs limit their ionic conductivity and interfacial stability. Here, we propose a shear-induced alignment strategy to construct anisotropic architectures through precisely orienting lithiated cellulose nanocrystals (CNCs-Li) within poly(ethylene oxide) matrices. This ordered microstructure establishes planar Li⁺ transport pathways with optimized coordination environments, achieving a room temperature (RT) ionic conductivity of 0.107 mS cm⁻¹, representing a 1.7-fold enhancement over randomly structured counterparts. Facilitated ion migration enables homogeneous lithium deposition, demonstrating a long-term cycling of 3200 h at 0.1 mA cm⁻² at 60 °C in Li symmetric cells. The assembled LiFePO₄/Li ASSLBs can retain steady operation for 500 cycles with 85% capacity retention at 1C and 60 °C and deliver a RT capacity of 140 mAh g⁻¹ at 0.5C. This work provides a scalable strategy for designing high-performance CPEs through structural anisotropy control.