Since the successful first plasma generation in the middle of 2008, three experimental campaigns were successfully made for the KSTAR device, accompanied with a necessary upgrade in the power supply, heating, wall-conditioning and diagnostic systems. KSTAR was operated with the toroidal magnetic field up to 3.6 T and the circular and shaped plasmas with current up to 700 kA and pulse length of 7 s, have been achieved with limited capacity of PF magnet power supplies. The mission of the KSTAR experimental program is to achieve steady-state operations with high performance plasmas relevant to ITER and future reactors. The first phase (2008–2012) of operation of KSTAR is dedicated to the development of operational capabilities for a super-conducting device with relatively short pulse. Development of start-up scenario for a super-conducting tokamak and the understanding of magnetic field errors on start-up are one of the important issues to be resolved. Some specific operation techniques for a super-conducting device are also developed and tested. The second harmonic pre-ionization with 84 and 110 GHz gyrotrons is an example. Various parameters have been scanned to optimize the pre-ionization. Another example is the ICRF wall conditioning (ICWC), which was routinely applied during the shot to shot interval. The plasma operation window has been extended in terms of plasma beta and stability boundary. The achievement of high confinement mode was made in the last campaign with the first neutral beam injector and good wall conditioning. Plasma control has been applied in shape and position control and now a preliminary kinetic control scheme is being applied including plasma current and density. Advanced control schemes will be developed and tested in future operations including active profiles, heating and current drives and control coil-driven magnetic perturbation.

Lithium-oxygen batteries have attracted great attention for advanced energy storage systems because of their high specific energy. The enhancement of the interfacial stability of lithium negative electrodes is one of the many technical challenges toward high safety and long life lithium-oxygen batteries due to their high reactivity toward organic electrolytes and the lithium dendrite growth during the repeated cycling. Herein, we demonstrate that the protective layer comprising conductive polymer and AlF particles on lithium metal stabilized the lithium electrode by effectively reducing the reductive decomposition of the liquid electrolyte and suppressing the growth of lithium dendrite. As a result, the cycling performance of a lithium-oxygen cell assembled with a surface-modified lithium electrode was remarkably improved as compared to a cell with a pristine lithium electrode.

No abstract

An ester-functionalized ionic liquid-based solution was successfully employed as a promising electrolyte for lithium–oxygen batteries.

A large number of applications such as mobile electronics and electric vehicles requires rechargeable batteries with high energy density and enhanced safety. To achieve these goals, lithium metal batteries employing solid-state electrolytes have become common despite the safety concerns associated with lithium metal. Polymer electrolytes have been studied as a solution for enhancing the safety of lithium metal batteries because they are non-volatile, non-flammable, and suppress the growth of lithium dendrites. In this study, highly elastic polyurethane (PU)-based polymer electrolytes were prepared in the form of thin flexible films, and their electrochemical characteristics were investigated. To improve the ionic conductivity, non-volatile and non-flammable 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide was added as a plasticizing additive to the polymer electrolyte. The cell assembled using a Li anode, PU-based elastomeric polymer electrolyte and composite LiNi0.6Co0.2Mn0.2O2 cathode exhibited stable cycling performance by suppressing the growth of lithium dendrites as well as maintaining good interfacial contacts between electrolyte and electrodes during repeated cycling.