Electrochemistry explores the charge transfer reaction across the interfaces,such as solid/liquid interface,liquid/liquid interface and solid/solid interface.Most reported charge transfer behaviours across the “solid/solid”interface are involved liquid electrolyte.For example,in the lithium-ion batteries,the redox of cobalt-based active material is coupled by the heterogeneous intercalation/deintercalation of Li+ ions,which is existed in the electrolyte solution.In another words,the electron transfer occurs at the interface between the solid current collector and the solid active material while the ion transfer occurs at the interface between the solid active material and the liquid electrolyte solution.We employ SECM to construct the pure solid-solid interface and to study the electron transfer phenomena therein.That means there is no liquid electrolyte environment.When the electron transfer occurs at the solid/solid interface,the counterion transfer will occur in the crystal due to the crystalline defects.For example,the NaCl microcrystals doped with hybrid iron hydroxide-oxide were cultured between a pair of electrodes on a microchip.The multi-step electron transfer processes of iron from Fe(0)to Fe(Ⅵ)through Fe(Ⅱ)and Fe(Ⅲ)were observed.In this presentation,we would like show the electrochemistry of solid/solid interface in the absence of liquid electrolytic environment.