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D.-H. Nam, M.A. Lumley and K.-S. Choi Energy Storage Materials 37 (2021) 556–566 Fig. 1. A schematic diagram illustrating the operation of (a) Charging Cell 1, potentials for (d) Charging Cell 1, (e) Charging Cell 2, and (f) Discharging Cell. in degradation of the electrode. However, Bi is the most practical can- didate for use as a large-scale Cl-storage electrode reported to date be- cause of its relatively low cost, high specific capacity of 384.75 mAh g−1 (Cl-storage capacity = 169.6 mgCl /gBi ), exceptional stability in a wide range of pH conditions, and high Faradaic efficiency for Cl− removal [17,24,33,34]. Previously, we demonstrated that an electrodeposited Bi foam electrode could be cycled 200 times [17], which is not sufficient to seriously consider the use of Bi electrodes for a practical ESS. Thus, we invested a significant amount of effort to develop a new fabrication method to enable long-term cyclability of Bi electrodes. Our new fabrication method involves the preparation of Bi elec- trodes as sheet-type electrodes. In this process, a high-energy ball mill is used to mix Bi powder with a conductive carbon agent. A polytetraflu- oroethylene (PTFE) binder is then added to the Bi/carbon mixture and a rolling-pressing procedure is used to fabricate sheet-type electrodes. Unlike commercial battery electrodes that are manufactured by casting a slurry onto a metallic current collector, sheet-type electrodes are flex- ible and mechanically robust (Fig. 2a); they can bend without cracking or delaminating from a current collector. In the sheet-type electrode, in- dividual Bi particles are encapsulated by carbon and binder coating lay- ers (Fig. 2b). In the nanocrystalline Bi foam electrode that we reported previously, pulverization results in the formation of disintegrated parti- cles, which are mechanically detached from the electrode, resulting in capacity fading [17]. However, in this new sheet-type electrode, individ- ual Bi particles are surrounded by a 3D network of carbon and binder, and so even if disintegrated sub-particles are formed by pulverization, they still remain within the encapsulated region. Therefore, as long as the Bi particles remain in contact with the conductive carbon, they can still participate in electrochemical reactions, which alleviates capacity fading. Another effective strategy that we employed to increase the cyclabil- ity of Bi was to use Bi2O3 particles instead of Bi particles to fabricate the aforementioned sheet-type electrodes. We hypothesized that the encap- sulation method would work best if the encapsulation layer is formed (b) Charging Cell 2, and (c) Discharging Cell with the expected cathode and anode when the electrochemically active species is at its greatest volume (i.e. BiOCl rather than Bi). This strategy ensures that sufficient volume is secured within the encapsulated area so that the encapsulating layer does not need to further expand during cycling, minimizing possible structural damage. However, when we used BiOCl particles instead of Bi particles in our fabrication process, we found that the quality of the adhesion between the carbon and BiOCl particles was not as good as that between the carbon and Bi particles. Therefore, the use of BiOCl parti- cles did not result in a notable enhancement in the cyclability. Thus, we used Bi2O3 particles instead of BiOCl particles to prepare our sheet-type electrodes; the volume of Bi2O3 is larger than that of Bi by 135%, and the use of Bi2O3 results in good adhesion with carbon (Fig. S1-2). Fur- thermore, commercial Bi2O3 is significantly cheaper than commercial BiOCl and will be more compatible with the large-scale fabrication of Bi electrodes. After electrode fabrication, the resulting sheet-type Bi2O3 electrodes were first electrochemically reduced to Bi. The Bi electrodes were then used for the conversion between Bi and BiOCl through chlo- rination and dechlorination (Fig. S3). Another important strategy that we used to achieve maximum cycla- bility of Bi was not to completely convert Bi to BiOCl during the cycling test. Instead, we chose to use only ~33% of the Bi for electrochemi- cal reactions, and the remaining Bi was used to maintain the structural integrity of the electrode. During chlorination, the formation of BiOCl begins at the Bi/electrolyte interface, and the Bi/BiOCl phase boundary moves from the Bi/electrolyte interface toward the Bi/carbon interface (Fig. 2c-d). Therefore, by limiting the capacity during the cycling tests, the Bi at the Bi/carbon interface can remain as Bi to maintain good elec- trical contact to carbon. If full conversion of Bi is used during the cycling tests, while the Bi directly bound to carbon is transformed to BiOCl, the Bi/carbon contact can become loose or get damaged, resulting in the for- mation of electrochemically isolated Bi/BiOCl particles that ultimately causes capacity fading. The cyclabilities of the sheet-type Bi electrodes tested using 100% and ~33% of the capacity of Bi are compared in Fig. 3a-d. The cyclabil- 558PDF Image | seawater battery with desalination capabilities
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Product and Development Focus for Salgenx
Redox Flow Battery Technology: With the advent of the new USA tax credits for producing and selling batteries ($35/kW) we are focussing on a simple flow battery using shipping containers as the modular electrolyte storage units with tax credits up to $140,000 per system. Our main focus is on the salt battery. This battery can be used for both thermal and electrical storage applications. We call it the Cogeneration Battery or Cogen Battery. One project is converting salt (brine) based water conditioners to simultaneously produce power. In addition, there are many opportunities to extract Lithium from brine (salt lakes, groundwater, and producer water).Salt water or brine are huge sources for lithium. Most of the worlds lithium is acquired from a brine source. It's even in seawater in a low concentration. Brine is also a byproduct of huge powerplants, which can now use that as an electrolyte and a huge flow battery (which allows storage at the source).We welcome any business and equipment inquiries, as well as licensing our flow battery manufacturing.CONTACT TEL: 608-238-6001 Email: greg@salgenx.com (Standard Web Page)