Effect of CO_2 on Atmospheric Corrosion of UNS G10190 Steel under Thin Electrolyte Film

The atmospheric corrosion of UNS G10190 steel under a thin electrolyte film in the atmosphere polluted by CO_2, has been studied in the lab using an atmospheric corrosion monitor (ACM) in combination with XRD and SEM observations of the surface of steel. The ACM study indicated that the corrosion rate of the steel increased with increasing carbon dioxide concentration. The XRD and SEM observations showed that no carbonate was found in the corrosion product on the steel surface. The corrosion product consisted of two layers, i. e., inner and outer layer. From the experimental results, it was concluded that CO_2 played an enhancing role in the atmospheric corrosion of UNS G10190 steel. The film of the corrosion product showed slight protection.

Fabrication and Characterization of GCO Electrolyte Films

Gd-doped Ceria (GCO:Gd_(0.1)Ce_(0.9)O_(1.95)) sensing films have been fabricated successfully on glasses and porous Al_2O_3 ceramic substrates by RF magnetron sputtering.Sputtering conditions such as power and temperature have been investigated and the sample was characterized in detail by XRD,SEM and AC impedance spectroscopy.The results show that the films grow preferentially along the (111) compact plane with a pure fluorite structure and the crystal grain grows more sufficiently with increasing of the annealing temperature.In addition,a high oxygen ion conductivity of 2.24×10^(-2) S.cm^(-1) is achieved at 800℃.

Study on SGDC Electrolyte Film Prepared by RF Magnetron Sputtering

Sm and Gd co-doped Ceria (SGDC:Sm_(0.1)Gd_(0.1)Ce_(0.8)O_(1.90)) films as the electrolytes were investigated for the IT-SOFCs (intermediate-temperature solid oxide fuel cells).SGDC sensing films were successfully prepared on the Al_2O_3 substrates by RF-magnetron sputtering.The relationship between sputtering parameters and film microstructure was discussed, and the optimum parameters were gained.The crystal structure analysis and surface morphologic observation of the SGDC films were carried out through X-ray diffraction (XRD) and scanning electron microscopy (SEM).The oxygen ion conductivity of the SGDC film was evaluated by AC impedance spectroscopy at the different temperatures.The XRD analysis shows that the SGDC films grow preferentially along the (111) compact plane.The crystallinity of the SGDC films is enhanced with the increase of the RF sputtering power from 150 W to 250 W.The oxygen ion conductivity of the SGDC was measured at the temperature from 600℃to 800℃in air by AC impedance spectroscopy.The result shows that a high oxygen ion conductivity of 2.44×10^(-2) S.cm^(-1) was achieved at 800℃.

High ceramic content composite solid-state electrolyte films prepared via a scalable solvent-free process

The development of high-performance solid-state electrolyte(SSE)films is critical to the practical application of all-solid-state Li metal batteries(ASSLMBs).However,developing high-performance free-standing electrolyte films remains a challenging task.In this work,we demonstrate a novel scalable solvent-free process for fabricating high ceramic content composite solid-state electrolyte(HCCSE)films.Specifically speaking,a mixture of ceramic and polymer is dry mixed,fibered,and calendered into a free-standing porous ceramic film,on which polymer precursor is coated and polymerized to bridge the inorganic ceramic particles,resulting in a flexible HCCSE film with a ceramic content of up to 80 wt.%.High ceramic content not only leads to high ionic conductivity but also brings good mechanical properties;while the organic phase enables electrode|electrolyte interfacial stability.When Li_(10)GeP_(2)S_(12)(LGPS)and polymeric ionic liquid-based solid polymer electrolytes(PIL-SPEs)were used as the inorganic and organic phases,respectively,the room temperature ionic conductivity of the resulted HCCSE reaches 0.91 mS·cm−1.Based on this HCCSE,Li||Li symmetric battery cycled stably for more than 2,400 h with ultra-low overpotential,and ASSLMBs with different cathodes(LiFePO4 and sulfurized polyacrylonitrile(PAN-S))present small polarization and decent cyclability at room temperature.This work provides a novel scalable solvent-free strategy for preparing high-performance freestanding composite solid-state electrolyte(CSE)film for room temperature ASSLMBs.

Vinylene carbonate additive for EMITFSI-based electrolyte for Li/LiFePO_4 batteries

Ionic liquids have been paid much attention and are considered to replace the conventional organic electrolyte and solve the safety issues by virtue of nonvolatility,non-flammability,high ionic conductivity and extended electrochemical steady window.The paper introduces ionic liquids electrolyte on basis of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMITFSI),which shows a wide electrochemical window (0.5-4.5 V vs.Li+/Li),and is theoretically feasible as an electrolyte for Li/LiFePO4batteries to improve the safety.Linear sweep voltammetry (LSV) was performed to investigate the electrochemical stability window of the polymer electrolyte.Interfacial resistance for Li/electrolyte/Li symmetric cells and Li/electrolyte/LiFePO4 cells were studied by electrochemical impedance spectroscopy (EIS).The results showed that additive vinylene carbonate (VC) enhances the formation of solid electrolyte interphase film to protect lithium anodes from corrosion and improves the compatibility of ionic liquid electrolyte towards lithium anodes.Accordingly,Li/LiFePO4cells delivers the initial discharge capacity of 124 mAh g-1 at a current rate of 0.1C in the ionic liquid electrolyte (EMITFSI+0.8 mol L-1LiTFSI+5 wt%VC),and shows better cyclability than in the ionic liquid electrolyte without VC.

INFLUENCE OF MAGNETIC FIELD ON ACCURACY OF ECM BY CHANGING THE CONDUCTIVITY OF ANODE FILM

The change of conductivity, thickness and scanning electron microscopy （SEM） appearance of the anode film of CrWMn in 10% NaNO3 at different anode potential either with or without the magnetic field applied are investigated by testing film resistance, galvanostatic transient and using SEM to design magnetic circuit in magnetic assisted electrochemical machining （MAECM）. The experiments show that the anode film has semi-conducting property. Compared with the situation without magnetic field applied, the resistance of the film formed at 1 .SV （anode potential） increased and decreased at 4.0V while B=0.4T and the magnetic north pole points toward anode. The SEM photo demonstrates that the magnetic field will densify the film in the passivation area and quicken dissolution of the anode metal in over-passivation area. Based on the influence of magnetic field on electrochemical machining（ECM） due to the changes of the anode film conductivity behavior, the magnetic north pole should be designed to point towards the workpiece surface that has been machined. Process experiments agree with the results of test analysis.

Regulating solid electrolyte interphase film on fluorinedoped hard carbon anode for sodium-ion battery

For the performance optimization strategies of hard carbon,heteroatom doping is an effective way to enhance the intrinsic transfer properties of sodium ions and electrons for accelerating the reaction kinetics.However,the previous work focuses mainly on the intrinsic physicochemical property changes of the material,but little attention has been paid to the resulting interfacial regulation of the electrode surface,namely the formation of solid electrolyte interphase(SEI)film.In this work,element F,which has the highest electronegativity,was chosen as the doping source to,more effectively,tune the electronic structure of the hard carbon.The effect of F-doping on the physicochemical properties of hard carbon was not only systematically analyzed but also investigated with spectroscopy,optics,and in situ characterization techniques to further verify that appropriate F-doping plays a positive role in constructing a homogenous and inorganic-rich SEI film.The experimentally demonstrated link between the electronic structure of the electrode and the SEI film properties can reframe the doping optimization strategy as well as provide a new idea for the design of electrode materials with low reduction kinetics to the electrolyte.As a result,the optimized sample with the appropriate F-doping content exhibits the best electrochemical performance with high capacity(434.53 mA h g^(-1)at 20mA g^(-1))and excellent rate capability(141 mAh g^(-1)at 400 mA g^(-1)).

Adjusting the solvation structure with tris(trimethylsilyl)borate additive to improve the performance of LNCM half cells

Tris(trimethylsilyl)borate(TMSB) has been intensively studied to improve the performances of lithiumion batteries. However, it is still an interesting issue needed to be resolved for the research on the Li^(+) solvation structure affected by TMSB additive. Herein, the electrochemical tests, quantum chemistry calculations, potential-resolved in-situ electrochemical impedance spectroscopy measurements and surface analyses were used to explore the effects of Li^(+) solvation structure with TMSB additive on the formation of the cathode electrolyte interface(CEI) film in LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)/Li half cells. The results reveal that the TMSB additive is easy to complex with Li^(+) ion, thus weaken the intermolecular force between Li^(+) ions and ethylene carbonate solvent, which is benefit for the cycle performance. Besides, the changed Li^(+) solvation structure results in a thin and dense CEI film containing compounds with Si–O and B–O bonds which is favorable to the transfer of Li^(+) ions. As a result, the performances of the LNCM811/Li half cells are effectively improved. This research provides a new idea to construct a high-performance CEI film by adjusting the Li^(+) solvation structures.

Evolutionary mechanism and frequency response of graphite electrode at extreme temperatures

The battery management system is employed to monitor the external temperature of the lithium-ion battery in order to detect any potential overheating.However,this outside–in detection method often suffers from a lag and is therefore unable to accurately predict the battery’s real-time state.Herein,an inside–out frequency response approach is used to accurately monitor the battery’s state at various temperatures in real-time and correlate it with the solid electrolyte interphase(SEI)evolution of the graphite electrode.The SEI evolution at temperatures of−15,25,60,and 90℃exhibits certain regular characteristics with temperature change.At a temperature of−15℃,the Li^(+)-solvent interaction of lithium-ion slowed down,resulting in a significant reduction in performance.At 25℃,a LiF-rich inorganic SEI was identified as forming,which facilitated lithium-ion transportation.However,high temperatures would induce decomposition of lithium hexafluorophosphate(LiPF_(6))and lithium-ion electrolyte.At the extreme temperature of 90℃,the SEI would be organic-rich,and Li_(x)P_(y)F_(z),a decomposition product of lithium salts,was further oxidized to Li_(x)PO_(y)F_(z),which led to a surge in the charge-transfer resistance at SEI(R_(sei))and a reduction in Coulombic efficiency(CE).This changing relationship can be recorded in real time from the inside out by electrochemical impedance spectroscopy(EIS)testing.This provides a new theoretical basis for the structural evolution of lithium-ion batteries and the regular characterization of EIS.