Sulfide-Compatible Conductive and Adhesive Glue-Like Interphase Engineering for Sheet-Type All-Solid-State Battery.

An all-solid-state lithium battery based on a sulfide electrolyte is one of the most promising next-generation energy storage systems. However, the high interfacial impedance, particularly due to the internal pores in the electrode or electrolyte layers, is the major limiting factor to the development of sheet-type all-solid-state batteries. In this study, a low-resistance integrated all-solid composite electrode is developed using a hybrid of a pyrrolidinium-based ionic liquid and a polyethylene oxide polymer with lithium salt as a multifunctional interphase material, which is engineered to be compatible with the sulfide electrolyte as well as the fabrication process of sheet-type composite electrode. The interphase material fills the pore in the composite sheet while binding the components together, which effectively increases the interfacial contact area and strengthens the physical network between the components, thereby enabling enhanced ion transport throughout the electrode. The interphase-engineered sheet-type LiNi0.8 Co0.1 Mn0.1 O2 /Li10 GeP2 S12 electrode shows a high reversible capacity of 166 mAh g-1 at 25 °C, corresponding to 92% of the observed capacity in a current liquid-based cathode system, as well as enhanced cycle and rate performances. This study proposes a novel and practical method for the development of high-performance sheet-type all-solid-state lithium batteries.

Rational Design of a Composite Electrode to Realize a High-Performance All-Solid-State Battery.

A potential solid electrolyte for realizing all-solid-state battery (ASB) technology has been discovered in the form of Li10 GeP2 S12 (LGPS), a lithium superionic conductor with a high ionic conductivity (≈12 mS cm-1 ). Unfortunately, the achievable Li+ conductivity of LGPS is limited in a sheet-type composite electrode owing to the porosity of this electrode structure. For the practical implementation of LGPS, it is crucial to control the pore structures of the composite electrode, as well as the interfaces between the active materials and solid- electrolyte particles. Herein, the addition of an ionic liquid, N-methyl-N-butylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([Py14 ][TFSI]), is proposed as a pore filler for constructing a highly reliable electrode structure using LGPS. [Py14 ][TFSI] is coated onto the surface of LGPS powder through a wet process and a sheet-type composite electrode is prepared using a conventional casting procedure. The [Py14 ][TFSI]-embedded composite electrode exhibits significantly improved reversible capacity and power characteristics. It is suggested that pore-filling with [Py14 ][TFSI] is effective for increasing contact areas and building robust interfaces between the active materials and solid-electrolyte particles, leading to the generation of additional Li+ pathways in the composite electrode of ASBs.

Application of ionic liquids in hydrometallurgy.

Ionic liquids, low temperature molten salts, have various advantages manifesting themselves as durable and environmentally friendly solvents. Their application is expanding into various fields including hydrometallurgy due to their unique properties such as non-volatility, inflammability, low toxicity, good ionic conductivity, and wide electrochemical potential window. This paper reviews previous literatures and our recent results adopting ionic liquids in extraction, synthesis and processing of metals with an emphasis on the electrolysis of active/light, rare earth, and platinum group metals. Because the research and development of ionic liquids in this area are still emerging, various, more fundamental approaches are expected to popularize ionic liquids in the metal manufacturing industry.