The formation of heterogeneous Li structures at the anode/solid polymer electrolyte (SPE) membrane interphase of solid-state Li-metal batteries (SSLMBs) is one of the key factors that impede SSLMB performance. The relationship between Li+-ion transport kinetics and Li0 structural evolution at the buried interphase is critical but challenging to characterize. Here, we report an operando correlative X-ray Compton scattering and computed tomography imaging technique that quantifies the changes of Li+-ion concentrations in the bulk cathode, SPE membrane, and anode of the SSLMB full cell using a commercially standard configuration. We then visualize Li+-ion concentration distributions as well as Li0 microstructures at the buried anode/SPE interphase. Mechanistic analyses show that the Li-stripping step forms more irregular interfacial Li morphologies at the expense of bulk anode volume shrinkage compared to the Li-plating step during the first cycle.