ACS Nano: Functional Organic Zinc Chelates, Zinc Negative Electrodes without Dendrites

Aqueous zinc-metal batteries lead to rapid cyclic degradation due to severe water corrosion and dendrite growth.
To solve these problems, Yuejiao Chen and Libao Chen of Central South University designed a highly water-resistant Znx-diethylenetriamine penta(methylenephosphonic acid) interfacial layer with good zincophilic properties and a special nanoscale three-dimensional (3D) particle structure on the zinc (Zn) metal surface.
Key points of the article
(1) The experimental results combined with theoretical analysis and COMSOL simulations show that the hydrophobic groups in this zinc-based organic complex are the decisive factor in preventing H2O from damaging the Zn anode surface. At the same time, the interaction of the methylenephosphonic acid group with zinc forms a large number of attractive sites for zinc ions, which provides ion channels for the rapid adsorption and migration of zinc ions. And the well-developed nanoparticle structure on the surface leads to the redistribution of zinc ion fluxes and uniform and dense Zn deposition on the surface.

(2) Under the synergistic effect, this modified Zn anode has a cycle life of up to 1300 h with a low polarization voltage at 5 mA cm-2. In addition, the researchers demonstrated full battery cells (including Zn//V2O5 and Zn//MnO2 cells) assembled based on this anode.
This work provides a simple, low-cost, and efficient pathway to prepare high-performance Zn anodes through the combination of two concepts: structural design and the construction of a protective layer on the surface, thus providing a pathway for the burgeoning aqueous Zn-metal batteries.
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Advantages of Organic Trace
2.1 High bio-availability
Compared with inorganic trace elements, organic trace elements have higher bioavailability. Mainly because the general trace elements inorganic salts and organic salts are ingested by the moving object, you must first rely on the role of coenzymes, and amino acids or other substances to form chelates or complexes, before they can be absorbed by the body. After absorption, the metal elements are combined with proteins and transported to the parts of the body where they are needed in order to be effective. Zinc methionine, copper methionine and other amino acid chelates or complexes are the main form of metal ion absorption and transportation in the animal body, and also the main intermediate product of protein synthesis process in the animal body, which is not only absorbed quickly, but also reduces many biochemical processes and saves energy consumption, which makes it have a high biological efficiency. In addition, there is an essential amino acid pool in the animal body, and the organic trace elements whose ligands are essential amino acids are more likely to be stored in the form of amino acids or small peptides in the body, preventing rapid metabolism, thus increasing the animal trace element body reserves. Therefore, compared with inorganic trace elements, the dosage of organic trace elements is less, and the safety and benefits are higher.

2.2 Reduce the mutual antagonism of mineral elements
Inorganic trace elements are characterized by instability and easy binding, and the possibility of interaction is easier than other substances. These interactions occur between feeds, in the digestive tract tissue and cellular metabolic processes between trace elements and with macronutrients in the absorption and excretion, transit metabolism, function and other processes there are many antagonistic. This antagonism occurs in the digestive tract in the form of: ① simple chemical reactions between elements. Such as dietary magnesium is too much, in the digestive tract can form magnesium phosphate, thus impeding the absorption of phosphorus. ② Adsorption by colloidal particles. Such as iron and manganese have the same electronic orbitals, configuration and coordination number, can be fixed in the non-soluble magnesium salt or aluminum salt surface, so that iron and manganese absorption in the digestive tract to reduce. (iii) Ions compete for carriers in the intestinal wall. Copper and zinc are both absorbed in the small intestine, and they can compete with each other for binding sites in the metallothionein or intestinal mucosa, leading to mutual absorption inhibition. The absorption of organic trace elements in the animal organism is different from that of inorganic salts. Amino acid and protein chelates utilize the absorption mechanism of peptides and amino acids, and are absorbed in the form of amino acids or peptides. Therefore there is no mutual antagonism, thus the dosage is more controllable and reasonable.
2.3 Avoid antagonism with anti-nutritional factors in feeds
Inorganic trace elements can combine with fiber and phytic acid to form a stable structure in animal intestines, such as neutral detergent fiber (NDF) can combine with divalent iron to affect absorption; phytic acid can combine with divalent copper, iron and zinc to produce precipitation, thus reducing absorption; while metal ions in organic trace elements are located in the center of chelates, and after combining with ligands through ligands and covalent bonds, the intramolecular charge tends to be neutral, forming a stable structure, which will not be absorbed by dietary fiber. After combining with the ligand through ligand and covalent bonding, it forms a stable structure and will not be combined with anti-nutritional factors in the diet and affect absorption.
2.4 Stronger antioxidant and immunity-enhancing ability
In recent years, a large number of studies have shown that organic trace elements are better than inorganic salt trace elements in improving immune function, improving intestinal health and reducing stress. It can enhance the body’s ability to resist pain, maximize the body’s immune response, promote cellular immunity and humoral immunity, and play the role of anti-stress and anti-disease.

2.5 Stable chemical properties
Inorganic salt molecules, anions and cations through electrostatic formation is not stable enough to form ionic bonds, so it is very easy to have chemical reactions with other substances, the chemical structure is extremely unstable; while the organic trace to trace element ions as the center of the amino acid oxygen and nitrogen atoms wrapped in the outside of the trace element, the trace element closed, which makes it has a more stable chemical properties, but also makes the molecule within the charge tends to be neutral, in the The body can effectively protect the metal ions, so that the metal ions avoid adverse reactions with substances such as gastric acid in the gastrointestinal tract and other ingredients in the diet. In particular, amino acid chelates are bonded by ligand covalent bonds, and their stability is higher than that of complexes bonded by ionic bonds.
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Conclusion
Trace elements are indispensable nutrients for dairy cows, and both excesses and deficiencies can have adverse effects on the organism. Compared with inorganic trace elements, organic trace elements can increase the feed intake of dairy cows, improve the growth rate and fertility, improve the quality of products and body immunity, antioxidant function, and reduce the stress, etc. Its better safety and stability can effectively avoid the destruction of other nutrients by trace elements, reduce the antagonism of trace elements, and improve the efficiency of the utilization of trace elements and the safety of farming.