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With the development of electronic devices towards miniaturization, light weight and integration, dielectric thin film-capacitors for recoverable energy storage applications have attracted ever-growing interests owing to their fast charging and discharging rate. In continuation to our investigations for achieving high energy density, we have grown lead free BaZr0.2Ti0.8O3 (BZT)/Ba0.7Ca0.3TiO3 (BCT) heterostructures and studied the structural, dielectric, ferroelectric and energy density characteristics. The BZT/BCT bilayer epitaxial heterostructures were grown on La0.67Sr0.33MnO3 (LSMO) buffered LaAlO3 (LAO) single crystal substrate by optimized pulsed laser deposition technique. The ferroelectric phase transition has been probed above room temperature with relaxor behavior. These nanostructures show high discharge and charge energy densities of 9.74 and 26.55 J/cm3, respectively. These heterostructures show high dielectric permittivity, large polarization and high energy density characteristics well above room temperature which may be useful for both high power and energy density device applications. [ABSTRACT FROM AUTHOR]

All-solid-state batteries (ASSBs) are gaining traction in the arena of energy storage due to their promising results in producing high energy density and long cycle life coupled with their capability of being safe. The key challenges facing ASSBs are low conductivity and slow charge transfer kinetics at the interface between the electrode and the solid electrolyte. Garnet solid-state electrolyte has shown promising results in improving the ion conductivity but still suffers from poor capacity retention and rate performance due to the interfacial resistance between the electrodes. To improve the interfacial resistance, we prepared a composite consisting of Li7La2.75Ca0.25Zr1.75Nb0.25O12 (LLCZN) garnet material as the ceramic, polyethylene oxide (PEO) as the polymer, and lithium hexafluorophosphate (LiPF6) as the salt. These compounds are mixed in a stoichiometric ratio and developed into a very thin disc-shaped solid electrolyte. The LLCZN provides a lithium-ion transport path to enhance the lithium-ion conduction during charging and discharging cycles, while the LiPF6 contributes more lithium ions via the transport path. The PEO matrix in the composite material aids in bonding the compounds together and creating a large contact area, thereby reducing the issue of large interfacial resistance. FESEM images show the porous nature of the electrolyte which promotes the movement of lithium ions through the electrolyte. The fabricated LLCZN/PEO/LiPF6 solid-state electrolyte shows outstanding electrochemical stability that remains at 130 mAh g−1 up to 150 charging and discharging cycles at 0.05 mA cm−2 current. All the specific capacities were calculated based on the mass of the cathode material (LiCoO2). In addition, the coin cell retains 85% discharge capacity up to 150 cycles with a Coulombic efficiency of approximately 98% and energy efficiency of 90% during the entire cycling process. [ABSTRACT FROM AUTHOR]

The electrochemical performances of cathode materials depend on crystallinity and structural stability. We report improved electrochemical performances of Li 2 FeMn 3 O 8 (LFMO) cathode materials synthesized using the chemical solution combustion method and the obtained powders are calcined at various temperatures such as 600 °C, 700 °C, and 900 °C. The LLCZN/PEO/LiPF 6 is used as a solid electrolyte during the assembly of the coin cells. The calcining temperatures improve the crystallinity and structural stability, thereby improving the electrochemical performances of the LFMO because of the mutual diffusion region at the electrode/solid electrolyte interface. Among these, the LFMO calcined at 900 °C shows the best electrochemical performance. At 0.1 mA cm−2, the discharge capacity at the 150th cycle is 133 mAh g−1 with a Coulombic efficiency of approximately 97% and a retention rate of 85% for the 900 °C calcined sample. While the 700 °C calcined sample is 126 mAh g−1 after 150th cycles of the galvanostatic charge-discharge test, the Coulombic efficiency is maintained at about 95% and the capacity retention rate is 83%. The 600 °C calcined temperature exhibited 101 mAh g−1 with a Coulombic efficiency of 92% and a retention rate of 73% after the 150th discharge cycle. The findings suggest that the chemical solution combustion approach might be a viable way of producing nanosized LFMO as an active cathode material for lithium-ion batteries (LIB). • The combustion solution synthesis for cathode preparation • Calcination temperatures improve crystallinity and structural stability • Significant enhancements in cycling performance • Improved Coulombic efficiency and retention rate • Effects of calcination temperature on materials synthesis [ABSTRACT FROM AUTHOR]