Research Of The Application Of Scanning Electrochemical Microscopy In Analysis Of Lithium-Ion/Sodium-Ion Battery

In recent decades, the electrode materials, the electrolyte and others in lithium ion and sodium ion battery has made stage progress. In order to get a bigger development space, we also should research the interphase between the electrode and electrolyte and study the electrochemical reaction mechanism, which we can analysis and solve problems fundamentally. Therefore, finding a suitable in-situ analysis technology will be of great significance for research the reaction process and mechanism in battery. As a new type of insitu analysis technology, Scanning electrochemical microscopy?SECM? has important application in the electrochemical analysis, and will have a lot of research prospects in the study of reaction mechanism of electrode material in battery. This article focused on sodium ion battery cathode materials Na₃V₂?PO₄?₃ and Na_0.44 MnO₂, sodium ion battery anode materials Ti O2 and Sn O2, lithium-ion battery cathode materials Li Fe PO₄ and Li Co O2 and explored the application of SECM in battery analysis.Synthesised Na₃V₂?PO₄?₃/C materials by sol-gel and solid phase method, and the results showed that the materials by these two methods have reversible capacity over 90 m Ahg-1, and at 1C the capacity remain at over 95% after 100 cycles; SECM study showed that the interfacial electron transfer rate constant of sol-gel method and solid phase synthesised Na₃V₂?PO₄?₃/C is respectively: kf =3.3x10-2 cm/s and kf =1.76x10-2 cm/s, the electrochemical morphology changes in SECM image reflected that the surface electrochemical activity change of Na₃V₂?PO₄?₃/C material is small during the charging and discharging process, so that the structure stability of the material is good.Used the sol-gel method to synthesize the Na_0.44 MnO₂ and results showed that the material has rod structure, and has six phase changes in the charging and discharging process, at 50 m Ag-1 the discharge capacity kept at 100 m Ahg-1 after 100 cycles, and the coulomb efficiency remained at 92%. The results of SECM research showed that the interfacial electron transfer rate constant of Na_0.44 MnO₂ materials was kf = 2.43 x 10-2 cm/s, and the SECM images showed that material phase change in the charging and discharging process affected the surface electrochemical activity, and in the process of charging surface electrochemical activity decreased, and in the process of discharging surface chemical activity increased.Explored the SECM application in anode materials Ti O2 and Sn O2 of sodium ion battery, studies showed that the substrate without a charge and discharge process had a trend of positive feedback in the PAC curve, and after a charge and discharge process the electrode showed a trend of negative feedback, this suggested that Ti O2 and Sn O2 for the first time of charging and discharging process would form the SEI film, the membrane is not electronic conductor, which affected the electrochemical activity of the substrate seriously.Explored the research of SECM technology in Li Fe PO₄ and Li Co O2 of lithium-ion battery cathode materials, the results showed that the interface electron transfer rate constant of Li Fe PO₄ and Li Co O2 were kf = 2.43 x 10-2 cm/s and kf = 1.3 x 10-2 cm/s. The analysis of SECM image can draw that the active of Li Fe PO₄ was smaller when at 3.0 V, which is related to the formation of new phase; while increased the Li Co O2 substrate potential to 4 V, the current is increased, this also related with redox reaction and the formation of new phase at 3.4 V, which resulted in the increased of electrochemical activity.