ICMCTF2015 Session F6-1: Thin Films and Coatings for Fuel Cells & Batteries

Tuesday, April 21, 2015 8:00 AM in Room Royal Palm 1-3

Tuesday Morning

Time Period TuM Sessions | Abstract Timeline | Topic F Sessions | Time Periods | Topics | ICMCTF2015 Schedule

Start Invited? Item
8:00 AM F6-1-1 Electrochemical Performance of Multilayered Si thin Film Anodes for Li-ion Batteries
Gayatri Dadheech (General Motors R&D Center, USA); ChananateUthaisar Uthaisar (Fraunhofer USA, USA); Victor Miller (University of California Berkeley, USA); Thomas Schuelke, Michael Becker (Fraunhofer USA, USA)

We present an alternative approach to integrate ultrathin Al2O3 into stacked C/SiOx layers for the stabilization of anode materials in Li-ion batteries. The heterogeneous C/SiOx/Al2O3 thin films were constructed by utilizing plasma magnetron PVD techniques. The deposition of the anodes followed either C/SiOx/C or C/SiOx/C/SiOx/C assemblies, 200nm on C substrates and 100 nm on SiOx substrates with an additional 20 nm Al2O3 coating to immobilize the two established films. Raman spectra show the C/SiOx stacks consist of amorphous structures for both C and SiOx layers. The multilayer thin films with Al2O3 coating exhibit a maximum initial discharge capacity of about 1000 mAh/g and maintained a reversible capacity of about 500 mAh/g over 100 cycles at a current density of 300 mA/g (~C/2) with a half-cell anode. The Al2O3 layers slightly improved the electrochemical performance of the stacked C/SiOx anodes, and the capacity retention rate increased about 25% with good rate-capability in comparison to those not coated with Al2O3. The improved electrochemical performance of depositing C/SiOx layers with Al2O3 coating can be attributed to the formation of an artificial solid electrolyte interphase layer stabilizing the interaction of C/SiOx and the electrolyte. Furthermore, we examined a full-cell battery using a C/SiOx/Al2O3 layered anode and a LiNiOx cathode, and their electrochemical performance will be presented.

8:20 AM F6-1-2 On the Surface Evolution in Stressed Films: from Metal Films at High Temperature to Electrode Films in Li-ion Batteries
Rahul Panat (Washington State University, USA)

Several physical processes show surface roughening under moderate to high stress under diffusive processes either at high or at low temperatures. Although the length scales and the time scales observed in these phenomenon are vastly different; they are governed by the same set of equations. Starting from internal energy and entropy terms, governing equation is derived that gives the amplitude change of such surfaces as a function of time. A parametric study is then carried out using a diverse range of practically important cases such as thin films electrodes of Li-ion batteries and metal films in thermal barrier systems. It is shown that the characteristic surface roughening observed depends upon the stress as well as diffusivity. These results have an important bearing on the crack initiation at thin film surfaces and interfaces.

9:00 AM F6-1-4 Study on Enhancing Performance of Thin Film Amorphous SnOx on C60 as an Anode Material for all Solid State Battery
KangSoo Lee (Yonsei University, Republic of Korea); YoungSoo Yoon (Gachon University, Republic of Korea)

Tin oxide, a potential anode material for all-solid-state batteries has high capacity (~ 1490 mAh g-1). Although it has high capacity, tin oxide shows volume expansion during electrochemical reaction and poor electrical conductivity. The volume expansion induces delamination of the active material from current collectors and then isolation from the electrical networks. Thus, modification of the active material structure is necessary to enhance the resistance of the volume expansion. In order to reduce the volume expansion and low conductivity, we have introduced a buffer and conducting layer of C60 thin film below SnOx layer which microstructure can be confirmed by scanning electron microscope (SEM) image and electric conductivity was measured by 4 point prove. After 50th cycle of charge-discharge, it shows significant reduction of volume expansion. The SnOx thin film layer was deposited on C60 thin layer using radio-frequency (RF) sputtering system under Ar gas atmosphere at different input power. Their electrochemical properties were evaluated with charge/discharge test and differential capacity plot. In these results, capacity, cycle life, and electrical conductivity of the SnOx/C60 structure show higher stability than bare SnOx thin film material.

9:20 AM F6-1-5 CeO2-Doped (Co,Mn)3O4 Coatings for Protecting Solid Oxide Fuel Cell Interconnect Alloys
Jiahong Zhu, Joseph Simpson, Matthew Lewis (Tennessee Technological University, USA)

In the planar design of a solid oxide fuel cell (SOFC) stack, the interconnect acts not only as electrical connection between the various cells but also as the mechanical support for the thin electroactive ceramic parts and as gas-proof separation of air and fuel gas. With the reduction of the SOFC operating temperatures to 600-800°C, chromia-forming ferritic steels are widely used as interconnect materials in the planar-type SOFC stacks currently under development. Two of the most serious problems for these ferritic steels such as Crofer 22 APU is (1) the Cr volatility and associated “poisoning” of the cathode under the operating environments of SOFC; and (2) the continuous oxidation of the alloy and subsequent thickening of the chromia scale and increase in scale electrical resistance. Reactive element-doped (Co,Mn)3O4 spinel is considered as the most promising coating system to protect the interconnect alloy. In this presentation, different approaches to adding reactive element into the spinel coating are reviewed. Two methods that have been developed in our research lab, i.e. electrolytic codeposition and environment-assisted reactive sintering, are compared and their advantages are outlined. The effect of the CeO2-doped (Co,Mn)3O4 coating on the oxidation resistance and scale area-specific resistance of Crofer 22 APU are discussed .

Time Period TuM Sessions | Abstract Timeline | Topic F Sessions | Time Periods | Topics | ICMCTF2015 Schedule