Presented here, is an extensive 35 parameter experimental data set of a cylindrical 21700 commercial cell (LGM50), for an electrochemical pseudo-two-dimensional (P2D) model. The experimental methodologies for tear-down and subsequent chemical, physical, electrochemical kinetics and thermodynamic analysis, and their accuracy and validity are discussed. Chemical analysis of the LGM50 cell shows that it is comprised of a NMC 811 positive electrode and bi-component Graphite-SiOx negative electrode. The thermodynamic open circuit voltages (OCV) and lithium stoichiometry in the electrode are obtained using galvanostatic intermittent titration technique (GITT) in half cell and three-electrode full cell configurations. The activation energy and exchange current coefficient through electrochemical impedance spectroscopy (EIS) measurements. Apparent diffusion coefficients are estimated using the Sand equation on the voltage transient during the current pulse; an expansion factor was applied to the bi-component negative electrode data to reflect the average change in effective surface area during lithiation. The 35 parameters are applied within a P2D model to show the fit to experimental validation LGM50 cell discharge and relaxation voltage profiles at room temperature. The accuracy and validity of the processes and the techniques in the determination of these parameters are discussed, including opportunities for further modelling and data analysis improvements.

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This paper reports the electrochemical behaviour of supercapacitor carbon electrodes operating in different aqueous solutions modified by various redox-active species (hydroxybenzenes, bromine derivatives and iodide). Three dihydroxybenzenes with varying stereochemistry, i.e., -OH substitution, have been considered as electrolyte additives (0.38 mol L(-1)) in acidic, alkaline and neutral solutions. High capacitance values have been obtained, especially for the acidic and alkaline solutions containing 1,4-dihydroxybenzene (hydroquinone). Bromine derivatives of dihydroxybenzenes were also considered as the additive in alkaline solution for use as a supercapacitor electrolyte, and a significant increase in capacitance value was observed. The redox couple investigated next was an iodide/iodine system, where 2 mol L(-1) NaI aqueous electrolyte was utilized. In this case, the most promising faradaic contribution during capacitor operation was achieved. In particular, stable capacitance values from 300-400 F g(-1) have been confirmed by long-term galvanostatic cycling (over 100 000 cycles), cycling voltammetry and floating. The mechanism of pseudocapacitance phenomena was discussed and supported by electrochemical and physicochemical measurements, e.g., in situ Raman spectroscopy.

O3-type layered oxide materials are considered to be a highly suitable cathode for sodium-ion batteries (NIBs) due to their appreciable specific capacity and energy density. However, rapid capacity fading caused by serious structural changes and interfacial degradation hampers their use. A novel Sn-modified O3-type layered NaNi 1/3 Fe 1/3 Mn 1/3 O 2 cathode is presented, with improved high-voltage stability through simultaneous bulk Sn doping and surface coating in a scalable one-step process. The bulk substitution of Sn 4+ stabilizes the crystal structure by alleviating the irreversible phase transition and lattice structure degradation and increases the observed average voltage. In the meantime, the nanolayer Sn/Na/O composite on the surface effectively inhibits surface parasitic reactions and improves the interfacial stability during cycling. A series of Sn-modified materials are reported. An 8%-Sn-modified NaNi 1/3 Fe 1/3 Mn 1/3 O 2 cathode exhibits a doubling in capacity retention increase after 150 cycles in the wide voltage range of 2.0–4.1 V vs Na/Na + compared to none, and 81% capacity retention is observed after 200 cycles in a full cell vs hard carbon. This work offers a facile process to simultaneously stabilize the bulk structure and interface for the O3-type layered cathodes for sodium-ion batteries and raises the possibility of similar effective strategies to be employed for other energy storage materials.