Design of ultrafine silicon structure for lithium battery and research progress of silicon-carbon composite negative electrode materials

As demand for high-performance electric vehicles, portable electronic equipment, and energy storage devices increases rapidly, the development of lithium-ion batteries with higher specific capacity and rate performance has become more and more urgent. As the main body of lithium storage, negative electrode materials have become the key to improving the performance of lithium batteries. The high specific capacity and low lithium insertion potential of silicon materials make them the best choice to replace traditional graphite negative electrodes. Pure silicon negative electrodes have huge volume expansion effects and SEI membranes (solid electrolyte interface) are easily damaged. Therefore, researchers have improved the performance of negative electrode materials through silicon-carbon composites. This article introduces the current design ideas of ultra-fine silicon structure for lithium batteries and the method of compounding with carbon materials, and reviews the research progress of the performance of silicon-carbon composite negative electrode materials. Ultra-fine silicon materials include disorderly dispersed ultra-fine silicon particles such as porous structures, hollow structures, and core-shell structures; and ordered ultra-fine silicon, such as silicon nanowire arrays, silicon nanotube arrays, and interconnected silicon nano-films. The article analyzes and compares the composite method of ultrafine silicon and carbon materials with different structural designs, and the effect of composite negative electrode materials on the specific capacity and cycle performance of the battery. Finally, the research direction of silicon-carbon composite negative electrode materials is prospected.

The basics of radiation damage in crystalline silicon networks by NIEL

Basically, radiation can cause two effects on materials: ionization and non-ionization. This work presented the theory involved in defects caused by non-ionization, known as NIEL, with a focus on silicon materials. When energy is transferred directly to the atoms in the crystalline lattice, it can either be dissipated in the form of vibrations or be large enough to pull atoms out of that lattice. This weakens the lattice, causing measurement errors that can lead to permanent damage. This study is extremely important because silicon materials are used in radiation detectors. These detectors cannot return false measurements, especially in dangerous situations, such as in nuclear reactor monitoring. After presenting the theory involved, examples are shown. Failures of up to 30% were found by the researchers.

CLINICAL STUDY TO EVALUATE THE RETENTION OF LOWER COMPLETE DENTURES WITH DIFFERENT TECHNIQUES

The retention of the lower denture, was one of the most important factors for success the complete dentures (CD) for edentulous patients with resorbed mandibular ridge. Therefore, this study was conducted to compare the retention of the lower complete denture for patients with full resuscitation treated by traditional complete denture and denture manufactured by silicon materials. The studied sample consisted of (12) patients (5 males and 7 females) between the ages of (55-71) years, with an average age of (63) years. Two lower dentures were made in two different ways: the conventional method and the silicon material method opposite to one upper whole denture. The retention of the lower denture was measured on the digital forces meter when the dentures was delivered to the patient. Three readings were recorded for each technique. The results showed a difference in the retention of the lower denture. The retention value by Newton (N) In set of lower manufactured using silicon materials of the lower denture were (7.03) higher in the set of lower denture manufactured in the traditional way.

Carrier Mobility in Semiconductors at Very Low Temperatures

Carrier mobilities and concentrations were measured for different p- and n-type silicon materials in the temperature range 0.3–300 K. Simulations show that experimentally determined carrier mobilities are best described in this temperature range by Klaassen’s model. Freeze-out reduces the carrier concentration with decreasing temperature. Freeze-out, however, depends on the dopant type and initial concentration. Semi-classical calculations are useful only for temperatures above 100 K. Otherwise quantum mechanical calculations are required.

Density and Mechanical Properties of Selective Silicon Materials to Produce 3D Printed Paediatric Brain Model

This study presents a step towards exploring the possibility of using silicon materials as a surrogate to produce a multi-material 3D printed soft silicone brain model to be used in the investigation of Traumatic Brain Injury (TBI) in paediatric populations. Silicone represents a popular choice of material due to its viscoelastic properties, 3D printability, and capability to be tuned to possess different properties. Dynamic oscillatory shear tests were carried out for seven types of silicon materials at three different speeds against a different range of frequencies. The mechanical parameters response has been ranked on, which is the most appropriate to try. It also agrees with the range of reported paediatric brain tissue imitating grey and white matter as a surrogate brain material. Utilising of silicone for 3D printing represents a new approach to fabricate surrogate models that closely mimic biofidelic features and advance the medical engineering discipline.