A consideration of total energetics for close-packed polytypes from viewpoint of atomistic interaction distance

AbstractUncontrollable dendrite growth resulting from the non-uniform lithium ion (Li+) flux and volume expansion in lithium metal (Li) negative electrode leads to rapid performance degradation and serious safety problems of lithium metal batteries. Although N-containing functional groups in carbon materials are reported to be effective to homogenize the Li+ flux, the effective interaction distance between lithium ions and N-containing groups should be relatively small (down to nanometer scale) according to the Debye length law. Thus, it is necessary to carefully design the microstructure of N-containing carbon materials to make the most of their roles in regulating the Li+ flux. In this work, porous carbon nitride microspheres (PCNMs) with abundant nanopores have been synthesized and utilized to fabricate a uniform lithiophilic coating layer having hybrid pores of both the nano- and micrometer scales on the Cu/Li foil. Physically, the three-dimensional (3D) porous framework is favorable for absorbing volume changes and guiding Li growth. Chemically, this coating layer can render a suitable interaction distance to effectively homogenize the Li+ flux and contribute to establishing a robust and stable solid electrolyte interphase (SEI) layer with Li-F, Li-N, and Li-O-rich contents based on the Debye length law. Such a physical-chemical synergic regulation strategy using PCNMs can lead to dendrite-free Li plating, resulting in a low nucleation overpotential and stable Li plating/stripping cycling performance in both the Li‖Cu and the Li‖Li symmetric cells. Meanwhile, a full cell using the PCNM coated Li foil negative electrode and a LiFePO4 positive electrode has delivered a high capacity retention of ∼ 80% after more than 200 cycles at 1 C and achieved a remarkable rate capability. The pouch cell fabricated by pairing the PCNM coated Li foil negative electrode with a NCM 811 positive electrode has retained ∼ 73% of the initial capacity after 150 cycles at 0.2 C.

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PHYSICAL DISTANCING ALARM SYSTEM BASED ON PROXIMITY SENSOR AND MICROCONTROLLER

Indonesian Physical Review ◽

10.29303/ipr.v4i2.85 ◽

2021 ◽

Vol 4 (2) ◽

pp. 79

Author(s):

Elfi Yuliza ◽

Riska Ekawita ◽

Vionita Vionita ◽

Muhammad Khafid Fauzi ◽

Vera Fuspita Sari ◽

...

Keyword(s):

System Performance ◽

The Other ◽

Alarm System ◽

Best Effort ◽

Interaction Distance ◽

Measurement Results ◽

Identity Card ◽

Left And Right ◽

Distance Sensor ◽

User Friendly

Keeping an interaction distance between 1 to 2 m is one of the health protocols during the COVID-19 pandemic. This attempt was made to reduce the spread of the Coronavirus. On the other hand, this health protocol activity is often overlooked, whether intentionally or not. According to the mechanism of the Coronavirus spreading in the form of droplets that comes out during communication, sneezing, or coughing, maintaining distance can be the best effort to minimize the transmission of this virus. Therefore, the availability of a simple, accurate and user-friendly physical distancing alarm system could be a solution in the implementation of this health protocol. In this study, a prototype of a physical distancing alarm based on a distance sensor and a microcontroller in the form of an identity card was developed. Several steps are conducted in developing of this system, namely designing the instrumentation system and testing the performance of the system. System performance is tested through variations in the distance and angle of the objects. The measurement results show that the system can detect objects in front of the sensor up to a distance of 2.8m and an angle of for a distance of 1m. The measurement using different angles of objects was performed for objects on the left and right sides of the sensor. In addition, a warning alarm will be on when the distance of the object exceeds the allowed distance.

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