Ionic liquid-containing cathodes empowering ceramic solid electrolytes.

Although ceramic solid electrolytes, such as Li7La3Zr2O12 (LLZO), are promising candidates to replace conventional liquid electrolytes for developing safe and high-energy-density solid-state Li-metal batteries, the large interfacial resistance between cathodes and ceramic solid electrolytes severely limits their practical application. Here we developed an ionic liquid (IL)-containing while nonfluidic quasi-solid-state LiCoO2 (LCO) composite cathode, which can maintain good contact with an Al-doped LLZO (Al-LLZO) ceramic electrolyte. Accordingly the interfacial resistance between LCO and Al-LLZO was significantly decreased. Quasi-solid-state LCO/Al-LLZO/Li cells demonstrated relatively high capacity retention of about 80% after 100 cycles at 60°C. The capacity decay was mainly because of the instability of the IL. Nevertheless, the IL-containing LCO cathode enabled the use of Al-LLZO as a solid electrolyte in a simple and practical way. Identifying a suitable IL is critical for the development of quasi-solid-state Li-metal batteries with a ceramic solid electrolyte.

Ceramic-Based Flexible Sheet Electrolyte for Li Batteries.

The increasing demand for high-energy-density batteries stimulated the revival of research interest in Li-metal batteries. The garnet-type ceramic Li7La3Zr2O12 (LLZO) is one of the few solid-state fast-ion conductors that are stable against Li metal. However, the densification of LLZO powders usually requires high sintering temperatures (e.g., 1200 °C), which likely result in Li loss and various side reactions. From an engineering point of view, high-temperature sintering of thin LLZO electrolytes (brittle) at a large scale is difficult. Moreover, the high interfacial resistance between the solid LLZO electrolytes and electrodes is a notorious problem. Here, we report a practical synthesis of a flexible composite Al-doped LLZO (Al-LLZO) sheet electrolyte (75 µm in thickness), which can be mass-produced at room temperature. This ceramic-based flexible sheet electrolyte enables Li-metal batteries to operate at both 60 and 30 °C, demonstrating its potential application for developing practical Li-metal batteries.

Electrochemical determination of NADH based on MPECVD carbon nanosheets.

Characterization and application of carbon nanosheets (CNSs) grown by microwave plasma enhanced chemical vapor deposition (MPECVD) have been investigated for the electrochemical biosensor. The as-grown CNS films possess a porous structure with a large amount of graphene edges which most of them are less than 2 nm in thickness, as confirmed by scanning and transmission electron microscopes. "Surface-sensitive" probe, Fe(CN)(6)(3-/4-), exhibits that the original CNSs have faster electron transfer than glassy carbon electrode, owing to much more edge plane sites on the original CNS surface. "Oxygen-sensitive" probe, Fe(3+/2+) also confirmed that the oxygen species in the CNS film can improve its electrochemical activity. The modified electrode by MPECVD CNS films has been used to detect NADH for the first time. The CNSs with many graphene edges efficiently catalyse the oxidation of NADH at 0.336 V. The biosensor linearly responds to NADH in the range of 0-500 µM (R=0.99665), the sensitivity of the electrode is 85.8 mA M(-1) or 715 mA M(-1) cm(-2), and the detection limit of NADH is about 0.44 µM (S/N=3). The biosensor also displays excellent stability for NADH detection and good selectivity in the interference from ascorbic acid.

Facile low-temperature growth of carbon nanosheets toward simultaneous determination of dopamine, ascorbic acid and uric acid.

The bare Pt electrode modified directly and simply by carbon nanosheets, which were synthesized by microwave plasma enhanced chemical vapor deposition at relatively low temperature, can be used to simultaneously and effectively detect dopamine, ascorbic acid and uric acid.