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Applied Chemistry and Physics
Published in Robert A. Burke, Applied Chemistry and Physics, 2020
Families that are important to building compounds include the alkali metals in column 1, the alkaline earth metals in column 2, the halogensin column 7 and transitional metals between the “towers” and the noble or inert gasesin column 8. These elements are examples of the family effects of these elements. Alkali metals in column 1 begin with lithium and continue through sodium, potassium, rubidium, cesium and francium. These elements are all solids except for cesium and francium, which are liquids at normal temperatures. Alkali metals are water reactive. The reaction with water is violent producing flammable hydrogen gas and enough heat to ignite the gas. These elements are so reactive that they do not exist in nature as the pure element. Instead, they are found as compounds of the metal such as potassium oxide and sodium chloride. Isotopes of Cesium can be and all isotopes of francium are radioactive. Since these elements are somewhat rare, you are not likely to see them on the street.
Fundamental Principles of Lithium Ion Batteries
Published in Thandavarayan Maiyalagan, Perumal Elumalai, Rechargeable Lithium-ion Batteries: Trends and Progress in Electric Vehicles, 2020
A. Selva Sharma, A. Prasath, E. Duraisamy, T. Maiyalagan, P. Elumalai
An ideal electrode material for a high performance secondary battery should possess low electrode potential and high electrochemical equivalence. It is apparent from Table 1 that lithium possess the lowest redox potential (−3.05 V) and highest electrochemical equivalence (3.86 Ahg−1) among metals. Lithium, being an alkali metal is the lightest among all the metallic elements with superior theoretical gravimetric charge density with a fairly large potential window. LIBs basically function on the basis of electrochemical intercalation and de-intercalation (Fig. 1) in which both the anode and cathode essentially undergo insertion and de-insertion of lithium ions reversibly over several cycles. A typical LIB consists of a graphite anode (negative electrode, having a theoretical capacity of 372 mAh/g), a layered LiCoO2 as the cathode (positive electrode, having a theoretical capacity of 274 mAh/g) and the electrolyte is usually LiPF6 dissolved in non-aqueous organic solvent. During the charging processes, the Li ions from the host anode material LiCoO2 de-intercalate and move forth through the electrolyte and intercalate within the graphite layers (Fig. 1). On the other hand during the discharge step, the reverse will happen and will result in the continuous movement of Li ions during the charging and discharging processes. LIBs are also referred to as rocking chair batteries. In a LIB, it is usually observed that during the cycling process, the electrolyte undergoes a limited reaction with lithium to form a multi-layered film at the interface of both the electrodes which is referred to as the solid electrolyte interphase (SEI). This SEI play a vital role in preventing the electrolyte from undergoing side reactions with the electrode surface. Thus, in the subsequent cycling process the movement of Li ions will occur through the surface films, in a reversible electrochemical reaction as given in the following electrode reactions [10–15]:
A retrospect on recent research works in the preparation of zeolites catalyst from kaolin for biodiesel production
Published in Biofuels, 2023
Jane Mngohol Gadin, Eyitayo Amos Afolabi, Abdulsalami Sanni Kovo, Ambali Saka Abdulkareem, Moritiwon Oloruntoba James
Base catalysts are the most popular for accelerating biodiesel conversion processes. The major privilege associated with using them is that they induce much yield of esters quickly under clement conditions of reaction [46]. Nevertheless, base catalysts display acute sensitivity in the presence of free fatty acids. To this end, only virgin oils with minimal acid values can generate higher yields with base catalyst assistance. Therefore, vegetable oils are always de-acidified before reaction to eliminate this sensitivity. Common catalysts that are alkaline in nature include alkali metals, alkali metal carbonates, potassium hydroxide and sodium hydroxide.