ИСТИНА

Electrochemical energy conversion and storage systems often plays a crucial role in overall performance of a wide variety of devices that we face in our everyday life – ranging from portable phones, laptops and power tools, to rather big facilities including power/heat cogeneration fuel cell systems, railway locomotives, power grid leveling facilities. Such systems that store (supercapacitors, rechargeable batteries) or generate hydrogen fuel and then electric power (electrochemical water splitting systems and fuel cells) in the listed examples all deal with electrochemical interfaces, where charge separation and chemical reactions occur. The evolution of structure, composition and chemistry at the interfaces between electrodes and electrolytes affects all the functional parameters of the device including power and long-term stability of its performance. That’s why chemical processes at the interface itself and transport phenomena in bordering layers from both electrode and electrolyte side should be deeply understood. Although it is of a great importance the analytical techniques are still very limited, in most cases electrochemists act blinded as they do not have an ability to accomplish electrochemical data with direct experimental characterization of the interface. There are few surface sensitive tools that can potentially address the problem but unfortunately as real electrochemical interfaces are buried they are not directly accessible to common surface science tools. Thus development of new techniques that can assess chemistry and structures of electrochemical interfaces and neighboring layers from both electrode and electrolyte side is of a great importance for electrochemical systems design. Ex situ studies are almost irrelevant in this case, since the chemical reactions occurring under electrochemical charging and resulting structures rather unique and cannot be “quenched” for post-process studies in most cases. Attempts to apply traditional surface sensitive tools (XPS, electron yield NEXAFS and some others) for investigation of electrochemical interfaces in supercapacitors, lithium-ion and lithium-air batteries are discussed in the talk. Recent observation of double electric layers in ionic liquids, side reactions and nucleation of discharge products on positive Li-air electrodes will serve as an examples for illustration of the new possibilities delivered by synchrotron radiation induced photoemission and X-ray absorption spectroscopy.