Search

The requirements for volume and weight performance are becoming more and more urgent for the application of lithium-ion batteries in consumer electronics and electric vehicles. Herein, we demonstrate a facial and cost-effective synthesis approach of lithium-ion conducting glass ceramic (LICGC)/reduced graphene oxide (rGO) composite, in which the LICGC particles anchor on the rGO sheets densely and homogenously, forming a sandwich-like structure. The unique feature offers ultrafast Li-ion and electron pathways through the LICGC network and rGO sheets, resulting in the enhancement of the rate and cycle performances for the electrodes. For example, the results show that for LiFePO4 cathode with the polymer electrolyte, the addition of 10 wt% of LICGC/rGO composite achieved the higher rate capability (~122 mAh g−1, discharge at 3 C) and cyclability (~98.2% after 180 cycles at 1 C), compared to add LICGC only (~115 mAh g−1 and ~93.4%, respectively).

In this study, three different surface-sensitive techniques, grazing incidence X-ray diffraction (GIXD), attenuated total reflectance Fourier transform infrared (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS), were employed to analyze the local structure and composition around the surface region of a lithium ion conducting solid electrolyte sheet. It was revealed that the local structure and composition changed depending on depth from the top surface of the sheet. At the very surface, there was a layer with expanded lattice and high Li composition. And with increasing the depth from the surface, lattice shrank sharply, and then expanded again gradually. The change in the lattice seemed to be accompanied by Li and Al composition. It was supposed that the change in the Li composition and structure is induced by combination of chemical reaction, segregation, and defect distribution.

Li metal battery with garnet-type Li7La3Zr2O12 (LLZ) as a solid electrolyte has attracted attentions as a promising candidate for high-energy batteries. However, the interfacial resistance between LLZ and Li is huge due to a point-point contact, leading to poor battery performances such as rate capability and cycleability. Here, we have studied the hybrid-electrolyte structure using the liquid electrolyte interlayer containing LiBH4 between LLZ and Li at high operating temperature of 120 °C. This hybrid-electrolyte structure offers high current density usage and a long-term cycleability. The Li|LLZ|Li symmetric cell shows high critical current density of 13 mA cm−2 and a long term cycle. The liquid electrolyte interlayer containing LiBH4 provides an improved coulombic efficiency of Li striping/plating due to an excellent reductive stability. Our findings suggest that the interfacial conditions on LLZ|Li could be effectively improved by using the modified liquid electrolyte interlayer.

Li metal battery with garnet-type Li7La3Zr2O12 (LLZ) as a solid electrolyte has attracted attentions as a promising candidate for high-energy batteries. However, the interfacial resistance between LLZ and Li is huge due to a point-point contact, leading to poor battery performances such as rate capability and cycleability. Here, we have studied the hybrid-electrolyte structure using the liquid electrolyte interlayer containing LiBH4 between LLZ and Li at high operating temperature of 120 °C. This hybrid-electrolyte structure offers high current density usage and a long-term cycleability. The Li|LLZ|Li symmetric cell shows high critical current density of 13 mA cm-2 and a long term cycle. The liquid electrolyte interlayer containing LiBH4 provides an improved coulombic efficiency of Li striping / plating due to an excellent reductive stability. Our findings suggest that the interfacial conditions on LLZ|Li could be effectively improved by using the modified liquid electrolyte interlayer.

Electrochemical performances of a prototype lithium–bromine battery (LBB) employing a solid electrolyte is investigated. The discharge capacity decreases with repeating charge/discharge cycles. Electrochemical impedance analysis reveals that the capacity fading is mainly due to increase in the interfacial resistance between an aqueous active material solution and a solid electrolyte. Based on the results of symmetric cells and structural analysis of the surface of the solid electrolyte immersed in Br 2 solutions, it is suggested that a Li + -depletion layer is formed on the surface of the solid electrolyte as a result of contact with bromine. Addition of tetraethylammonium bromide (TEABr) depresses the interfacial resistance, which results in improved cycleability. LBB with 1.0 M LiBr and 0.25 M TEABr shows discharge capacity of 139 mAh/g-LiBr and Coulombic efficiency of 99.6% at 5th cycle.

Nanocomposites of a lithium ion conductor Li1.3Al 0.3Ti1.7(PO4)3 and electrode materials (TiO2 and FePO4) were prepared to investigate interfacial structure and ionic conductivity at the interface between the solid electrolyte and electrode materials. It was revealed that lithium ions in the solid electrolyte were attracted to the cathode materials with increasing electrode potential, which increases lithium vacancies in the solid electrolyte. For the FePO4 containing composites, due to the high electrode potential, lithium transfer across the interface and ionic conduction through the cathode materials was remarkable. The results suggest that severe lithium depletion occurs and interfacial resistance is large at the interface of high ionic conductors and cathode materials. The space charge layer thickness is also discussed., Solid State Ionics, 262, pp.879-882; 2014