Supercapacitors are attractive as a major energy storage device due to their high coulombic efficiency and semi-permanent life cycle. Transition metal oxides are used as electrode material in supercapacitors due to their high conductivity, capacitance, and multiple oxidation states. Nanopowder transition metal oxides exhibit low specific surface area, ion diffusion, electrical conductivity, and structural stability compared with the three-dimensional (3D) structure. Furthermore, unstable performance during long-term testing can occur via structural transition. Therefore, it is necessary to synthesize a transition metal oxide with a high specific surface area and a stable structure for supercapacitor application. Transition metal oxides with a perovskite structure control structural transition and improve conductivity. In this study, a NiMnO₃ perovskite oxide with a high specific surface area and electrochemical properties was obtained via hydrothermal synthesis at low temperature. Hydrothermal synthesis was used to fabricate materials with an aqueous solution under high temperature and pressure. The shape and composition were regulated by controlling the hydrothermal synthesis reaction temperature and time. The synthesis of NiMnO₃ was controlled by the reaction time to alter the specific surface area and morphology. The prepared perovskite NiMnO₃ oxide with a three-dimensional structure can be used as an active electrode material for supercapacitors and electrochemical catalysts. The prepared NiMnO₃ perovskite oxide showed a high specific capacitance of 99.03 F·g⁻¹ and excellent cycle stability with a coulombic efficiency of 77% even after 7000 cycles.

This paper reports a modeling methodology to predict the effect of the loss of cyclable lithium of a lithium-ion battery (LIB) cell comprised of a LiNi_0.6Co_0.2Mn_0.2O₂ cathode, natural graphite anode, and an organic electrolyte on the discharge behavior. A one-dimensional model based on a finite element method is presented to calculate the discharge behaviors of an LIB cell during galvanostatic discharge for various levels of the loss of cyclable lithium. Modeling results for the variation of the cell voltage of the LIB cell are compared with experimental measurements during galvanostatic discharge at various discharge rates for three different levels of the loss of cyclable lithium to validate the model. The calculation results obtained from the model are in good agreement with the experimental measurements. On the basis of the validated modeling approach, the effects of the loss of cyclable lithium on the discharge capacity and available discharge power of the LIB cell are estimated. The modeling results exhibit strong dependencies of the discharge behavior of an LIB cell on the discharge C-rate and the loss of cyclable lithium.

This study aims to imitate the artificial structural degradation of a LiNi _0.6 Co _0.2 Mn _0.2 O ₂ (NCM622) cathode and the electrochemical data for the analysis of spent batteries. Degraded NCM622 was obtained by controlling the charging cut off voltage, and the structural degradation was investigated using X-ray diffraction and inductively coupled plasma optical emission spectrometry. X-ray photoelectron spectroscopy results confirmed the cathode electrolyte interface on the surface of the electrode. Galvanostatic charge/discharge tests were performed using a cell with an overcharged NCM622 cathode, fresh anode, and fresh electrolyte to investigate the structural degradation effect on the cathode. The capacity of the higher overcharged electrode decreased with the higher IR drop and concentration polarization. This study demonstrates that structural degradation results in different discharge behaviors in lithium-ion batteries.

In this study, we present a modeling approach to estimate the combined effects of cyclable lithium loss and electrolyte depletion on the capacity and discharge power fades of lithium-ion batteries (LIBs). The LIB cell based on LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) was used to model the discharge behavior in the multiple degradation modes. The discharge voltages for nine different levels of cyclable lithium loss and electrolyte depletion were measured experimentally. When there was no cyclable lithium loss, the 50% of electrolyte depletion brought about 5% reduction in discharge capacity at 0.05 C discharge rate, while it resulted in 46% reduction when it was coupled with 30% of cyclable lithium loss. The 50% of electrolyte depletion with no cyclable lithium loss caused 1% reduction in discharge power during 0.5 C discharge at the state of charge (SOC) level of 0.8, while it resulted in 13% reduction when it was coupled with 30% of cyclable lithium loss. The modeling results obtained by using the one-dimensional finite element method were compared with the experimental data. The justification of the modeling methods is demonstrated by the high degree of concordance between the predicted and experimental values. Using the validated modeling methodology, the discharge capacity and usable discharge power can be estimated effectively under various combined degradation modes of cyclable lithium loss and electrolyte depletion in the LIB cell.

Lithium–sulfur (Li-S) batteries are attractive next-generation energy storage systems owing to their high theoretical energy density of 2600 Wh/kg and earth-abundant, eco-friendly sulfur. However, their practical application is hindered by the insulating nature of sulfur, large volume changes during cycling, and the polysulfide shuttle effect. Herein, we designed a dual-confinement cathode architecture combining mesoporous carbon with earth-abundant titanium dioxide (TiO₂). Sulfur composites with 70 wt% sulfur loading were prepared. Structural characterization via X-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET) analysis showed a well-developed mesoporous network in KB but not in TiO₂. XRD confirmed that sulfur and anatase TiO₂ coexist in the composites, with weaker sulfur peaks in the mixed host. UV-vis absorption spectra showed that nano-TiO₂ removes more Li₂S₆ from solution than KB. Electrochemical evaluations revealed that the dual-confinement composite architecture balances the fast redox kinetics of carbon against the polysulfide affinity of TiO₂. Consequently, the composite achieved a high initial discharge capacity of 1300.89 mAh/g at 0.1 C and stable cycling over 100 cycles at 0.5 C. Furthermore, ex situ XRD analysis revealed nearly complete sulfur conversion while maintaining TiO₂ structural integrity. These results demonstrate an optimal balance between electronic conductivity and polysulfide mitigation via a sustainable material strategy.