Abstract:

This study proposes a pre-strain optimization strategy for carbon fiber structural lithium-ion battery (SLIB) composites to inhibit the interfacial debonding between carbon fibers and solid-state electrolytes due to fiber lithiation. Through an analytical shear-lag model and finite element simulations, it is demonstrated that applying tensile pre-strain to carbon fibers before electrode assembly effectively reduces the interfacial shear stress, thereby suppressing debonding. However, the excessive pre-strain can induce the interfacial damage in the unlithiated state, necessitating careful control of the pre-strain within a feasible range. This range is influenced by electrode material properties and geometric parameters. Specifically, the electrodes with the higher solid-state electrolyte elastic modulus and larger electrolyte volume fraction exhibit more significant interfacial damage, making pre-strain application increasingly critical. However, these conditions also impose stricter constraints on the feasible pre-strain range. By elucidating the interplay between pre-strain, material properties, and geometric factors, this study provides valuable insights for optimizing the design of carbon fiber SLIBs.

Key words: pre-strain, carbon fiber, interfacial debonding, structural battery composite, mechanically-based design