In situ/Operando Synchrotron-Based X-Ray Diffraction Study on Energy Storage Materials

<i>In situ</i>/<i>operando</i> X-ray diffraction techniques have been used to monitor the real-time structural evolution of energy storage materials, including battery materials, hydrogen storage materials, and phase change materials. Benefits from synchrotron radiation X-ray with high brightness and photon flux, we have built an in situ multimodal platform at the diffraction beamlines of BL02U2 and BL14B1 in Shanghai Synchrotron Radiation Facility (SSRF), and developed a second time-resolved diffraction technique for studying various energy storage materials. For battery materials research, we developed operando coin and pouch cell for studying the energy storage mechanism of multivalent metal ion (Mg²⁺, Zn²⁺) batteries cathode materials. For hydrogen materials research, we reported the thermodynamic destabilization in Mg-In-D hydrogen storage system. For phase change materials research, we developed in situ grazing incidence X-ray diffraction technique to study the solid liquid interface of graphene oxide. We observed the dehydration behavior of graphene oxide (GO) in real time upon annealing at various temperatures, and found that three types of water (“bulk water”, “confined water”, “bound water”) trapped in GO interlayer. Subsequently, we investigated the interactions between metal ions and GO and found that metal cations (Mn²⁺, Co²⁺, Cu²⁺, Fe³⁺) and GO can self-assemble into a hydroxide/GO superlattice due to the electrostatic interactions. GO/cation ion systems experience four stages with increasing temperature including (1) hydrated cation intercalation into the GO interlayer, (2) GO/metal hydroxide superlattice formation at 250°C, (3) metal oxide nucleation within the rGO interlayers, and (4) complete graphene layer decomposition at 600°C. Moreover, we observed the crystallization behavior of water molecules confined by GO and found that the freezing temperature of water is as low as -35°C and the crystallization of water on the surface and interlayer of is not inconsistent.