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de la Llave, Ezequiel,Borgel, Valentina,Park, Kang-Joon,Hwang, Jang-Yeon,Sun, Yang-Kook,Hartmann, Pascal,Chesneau, Frederick- Francois,Aurbach, Doron American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.3
<P>The electrochemical behavior of Na-ion and Li-ion full cells was investigated, using hard carbon as the anode material, and NaNi0.5Mn0.5O2 and LiNi0.5Mn0.5O2 as the cathodes. A detailed description of the structure, phase transition, electrochemical behavior and kinetics of the NaNi0.5Mn0.5O2 cathodes is presented, including interesting comparison with their lithium analogue. The critical effect of the hard carbon anodes pretreatment in the total capacity and stability of full cells is clearly demonstrated. Using impedance spectroscopy in three electrodes cells, we show that the full cell impedance is dominated by the contribution of the cathode side. We discuss possible reasons for capacity fading of these systems, its connection to the cathode structure and relevant surface phenomena.</P>
Feasibility of Full (Li-Ion)–O<sub>2</sub> Cells Comprised of Hard Carbon Anodes
Hirshberg, Daniel,Sharon, Daniel,De La Llave, Ezequiel,Afri, Michal,Frimer, Aryeh A.,Kwak, Won-Jin,Sun, Yang-Kook,Aurbach, Doron American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.5
<P>Aprotic Li-O-2 battery is an exciting concept. The enormous theoretical energy density and cell assembly simplicity make this technology very appealing. Nevertheless, the instability of the cell components, such as cathode, anode, and electrolyte solution during cycling, does not allow this technology to be fully commercialized. One of the intrinsic challenges facing researchers is the use of lithium metal as an anode in Li-O-2 cells. The high activity toward chemical moieties and lack of control of the dissolution/deposition processes of lithium metal makes this anode material unreliable. The safety issues accompanied by these processes intimidate battery manufacturers. The need for a reliable anode is crucial. In this work we have examined the replacement of metallic lithium anode in Li-O-2 cells with lithiated hard carbon (HC) electrodes. HC anodes have many benefits that are suitable for oxygen reduction in the presence of solvated lithium cations. In contrast to lithium metal, the insertion of lithium cations into the carbon host is much more systematic and safe. In addition, with HC anodes we can use aprotic solvents such as glymes that are suitable for oxygen reduction applications. By contrast, lithium cations fail to intercalate reversibly into ordered carbon such as graphite and soft carbons using ethereal electrolyte solutions, due to detrimental co-intercalation of solvent molecules with Li ions into ordered carbon structures. The hard carbon electrodes were prelithiated prior to being used as anodes in the Li-O-2 rechargeable battery systems. Full cells containing diglyme based solutions and a monolithic carbon cathode were measured by various electrochemical methods. To identify the products and surface films that were formed during cells operation, both the cathodes and anodes were examined ex situ by XRD, FTIR, and electron microscopy. The HC anodes were found to be a suitable material for (Li-ion) O-2 cell. Although there are still many challenges to tackle, this study offers a more practical direction for this promising battery technology and sets up a platform for further systematic optimization of its various components.</P>