Impact of interparticle contact on discharge capacity in all-solid-state batteries: A 3D simulation approach

The performance of all-solid-state batteries (ASSBs) highly depends on the electronic and ionic transport properties of composite electrodes. In this study, we performed 3D simulations of (1) scanning spreading resistance microscopy (SSRM), (2) effective electronic conductivity (σeff), and (3) discharge profile with sphere-filled structures to quantitatively evaluate the impact of electrical contact between active material particles on the discharge capacity of ASSBs. Simulation 1 revealed that the local resistance of active material particles measured by SSRM is influenced by interparticle contact, in addition to the intrinsic resistivity of the particles. The result indicates that, under the condition of uniform intrinsic resistivity, the experimentally obtained distribution of local resistance reflects differences in interparticle contact. Simulation 2 showed that σeff is primarily influenced by the interparticle contact area rather than by tortuosity. Finally, simulation 3 demonstrated that insufficient interparticle contact results in a substantial reduction in discharge capacity. Poor contact leads to a heterogeneous lithiation distribution, which reduces the discharge capacity of the active material. Conversely, increasing the volume fraction of the active material or the overlap ratio enhances the electronic conduction network, thereby improving discharge capacity. This study highlights the critical importance of interparticle contact in optimizing ASSB performance and offers valuable insights for improving battery design.