{"title":"Active Cell Balancing of Li-Ion Batteries for Electric Vehicles","authors":"Debadyuti Banerjee, A. Giri, S. Saha","doi":"10.2139/ssrn.3495810","DOIUrl":"https://doi.org/10.2139/ssrn.3495810","url":null,"abstract":"Electric vehicles (EV) use battery banks containing series-parallel combinations of several small units to meet the high power demand of the drive system. In recent years, lithium-ion (Li-ion) batteries are being popularly used in EVs for energy storage instead of conventional lead acid batteries due to the advantages of higher cell voltage, no memory effect, low self-discharge, longer battery life and reduced size and weight. However, Li-ion battery packs require external power balancing circuits for its protection from getting damaged by overcharge and deep discharge. This work proposes an active circuit for charge balancing of Li-ion battery packs. The proposed charge balancing circuit uses a multi-winding flyback converter with n+1 number of active switches to protect a stack of n number of series connected cells. Performance of the proposed system has been verified through computer simulation in MATLAB with a 4 cell battery pack. Simulated results were found in close agreement with the predicted behaviour of the system.","PeriodicalId":391497,"journal":{"name":"ChemRN: Fuel Cells (Topic)","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130097917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Microstructure, Formation, and Diffusion Kinetics of Multilayered Oxides Formed on a Co-W Electroplated Ferritic Stainless Steel Followed by Oxidation Treatment","authors":"L. Gan, Tomoyuki Yamamoto, H. Murakami","doi":"10.2139/ssrn.3491242","DOIUrl":"https://doi.org/10.2139/ssrn.3491242","url":null,"abstract":"Numerous attempts have been made to improve the oxidation resistance and electrical conductivity of the interconnectors in solid oxide fuel cells. A Co-W alloy coating on ferritic stainless steel has attracted attention because the Co-W oxide layer formed by the oxidation treatment of the Co-W alloy coating has proven effective in reducing the outward diffusion of Cr and improving oxidation resistance. This study was designed to elucidate the formation kinetics and diffusion barrier mechanism of the Co-W coating. After oxidation in air at 750 °C, a dense, multilayered oxide formed, comprising (from the stainless steel substrate to the outer layer) Cr oxide, Cr-Fe-Co oxide, Co-W oxide, Co-Fe oxide, and Co oxide layers. The CoWO<sub>4</sub> layer and neighboring oxide layers were carefully analyzed by scanning electron microscopy and transmission electron microscopy, which revealed that the innermost Cr<sub>2</sub>O<sub>3</sub> layer grows via the reaction between Cr in the substrate and inward-diffusing oxygen, whereas outward diffusion of Fe and Co is involved in the formation and growth of (Co,Fe)<sub>3</sub>O<sub>4</sub> and Co<sub>3</sub>O<sub>4</sub>. Analysis by electron energy-loss spectroscopy confirmed the absence of trivalent cations (Co<sup>3+</sup>, Fe<sup>3+</sup>, and Cr<sup>3+</sup>) and the presence of Fe<sup>2+</sup> ions in the CoWO<sub>4</sub> layer; thus, CoWO<sub>4</sub> functions as a selective diffusion barrier to trivalent cations as hypothesized.","PeriodicalId":391497,"journal":{"name":"ChemRN: Fuel Cells (Topic)","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121679559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}