Hexavalent Ions Insertion in Garnet Li7 La3 Zr2 O12 Toward a Low Temperature Densification Reaction.

Nowadays, solid electrolytes are considered the main alternative to conventional liquid electrolytes in lithium batteries. The fabrication of these materials is however limited by the strict synthesis conditions, requiring high temperatures which can negatively impact the final performances. Here, it is shown that a modification of garnet-based Li7 La3 Zr2 O12 (LLZO) and the incorporation of tellurium can accelerate the synthesis process by lowering the formation temperature of cubic LLZO at temperatures below 700 °C. Optimized synthesis at 750 °C showed a decrease in particle size and cell parameter for samples with higher amounts of Te and the evaluation of electrochemical performances reported for LLZO Te0.25 a value of ionic conductivity of 5,15×10-5  S cm-1 after hot-pressing at 700 °C, two orders of magnitude higher than commercial Al-LLZO undergoing the same working conditions, and the highest value at this densification temperature. Partial segregation of Te-rich phases occurs for high-temperature densification. Our study shows the advantages of Te insertion on the sintering process of LLZO garnet and demonstrates the achievement of highly conductive LLZO with a low-temperature treatment.

Unveiling the Cation Exchange Reaction between the NASICON Li1.5Al0.5Ge1.5(PO4)3 Solid Electrolyte and the pyr13TFSI Ionic Liquid.

Recently, the formation of the ceramic-ionic liquid composite has attracted huge interest in the scientific community. In this work, we investigated the chemical reactions occurring between NASICON LAGP ceramic electrolyte and ionic liquid pyr13TFSI. This study allowed us to identify the cation exchange reaction pyr13-Li occurring on the LAGP surface, forming a LiTFSI salt that was detected by the nuclear magnetic resonance analysis. In addition, using 6Li foils, we succeeded in demonstrating that both LAGP and LiTFSI:pyr13TFSI participate in the diffusion of Li ions by the formation of an ionic bridge between two species.

A New CuO-Fe2 O3 -Mesocarbon Microbeads Conversion Anode in a High-Performance Lithium-Ion Battery with a Li1.35 Ni0.48 Fe0.1 Mn1.72 O4 Spinel Cathode.

A ternary CuO-Fe2 O3 -mesocarbon microbeads (MCMB) conversion anode was characterized and combined with a high-voltage Li1.35 Ni0.48 Fe0.1 Mn1.72 O4 spinel cathode in a lithium-ion battery of relevant performance in terms of cycling stability and rate capability. The CuO-Fe2 O3 -MCMB composite was prepared by using high-energy milling, a low-cost pathway that leads to a crystalline structure and homogeneous submicrometrical morphology as revealed by XRD and electron microscopy. The anode reversibly exchanges lithium ions through the conversion reactions of CuO and Fe2 O3 and by insertion into the MCMB carbon. Electrochemical tests, including impedance spectroscopy, revealed a conductive electrode/electrolyte interface that enabled the anode to achieve a reversible capacity value higher than 500 mAh g-1 when cycled at a current of 120 mA g-1 . The remarkable stability of the CuO-Fe2 O3 -MCMB electrode and the suitable characteristics in terms of delivered capacity and voltage-profile retention allowed its use in an efficient full lithium-ion cell with a high-voltage Li1.35 Ni0.48 Fe0.1 Mn1.72 O4 cathode. The cell had a working voltage of 3.6 V and delivered a capacity of 110 mAh gcathode-1 with a Coulombic efficiency above 99 % after 100 cycles at 148 mA gcathode-1 . This relevant performances, rarely achieved by lithium-ion systems that use the conversion reaction, are the result of an excellent cell balance in terms of negative-to-positive ratio, favored by the anode composition and electrochemical features.