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Liquid and gel electrolytes based on common commercial and recently commercialized salts for application in lithium-ion (Li-ion) batteries are presented herein. Various solvent mixtures and electrolytes based on them are presented. Selected organic carbonates' mixtures are chosen as the base for these electrolytes. LiTDI (lithium 4,5-dicyano-2-(trifluoromethyl)-imidazolide) and LiPF6 (lithium hexafluorophosphate) are chosen to compare the behavior and the electrochemical properties of the investigated systems. The limited optimizations of electrolytes are presented for LiTDI salt. Results for LiPF6 electrolytes are presented as a benchmark. The detailed comparison of lithium transference numbers is presented. All liquid electrolytes present quite high values of conductivity at room temperature and in some cases reach above 6 mS cm−1 for LiTDI solutions. The base for gel electrolytes is PVdF-HFP co-polymer (poly(vinylidene difluoride-co-hexafluoropropylene)). The conductivity of gel electrolytes exceeds 1 mS cm−1 in case of the LiTDI system. All presented electrolytes show relatively high stability vs. Li/Li+, up to 4.7 V in both liquid and gel systems. [ABSTRACT FROM AUTHOR]

Energy harvesting devices are self-powered systems which are associated with input ambient energy and convert such energy to electrical one. In this study, we focus on input ambient energy deriving from compressed air. Using arbitrary pneumatic machine, the compressed air after work - with its typical parameters as overpressure 6 bar or higher and variable volume flow - is exhausted to atmosphere. This generates energy losses. We have constructed some device which transforms the loss of compressed air energy to electricity. It illustrates the principle of action very well and does not perturb operation of pneumatic machines being source of energy losses.

Herein, NaxFe1–yMnyO2 (y = 0.4, 0.5, 0.6, 0.7, and 0.8) oxides, which are a potential cathode materials group for Na‐ion batteries, are presented. Samples are prepared by solid‐state synthesis and crystallized in P2‐type structure (P63/mmc). Mössbauer spectroscopy studies revealed that in pristine and deintercalated samples the whole iron occurs at a high‐spin Fe3+ state. Electrochemical impedance spectroscopy measurements exhibited the thermally activated electrical conductivity of Na0.67Fe1–yMnyO2 with relatively high activation energies (≈0.4 eV). Obtained results are supported by the electronic structure calculations (KKR‐CPA method), which indicates that total density of states at the Fermi level increases with manganese content in the sample. Electrochemical properties of Na|Na+|NaxFe1–yMnyO2 test cells and the specific charge/discharge capacities analysis confirmed that only the manganese ions in NaxFe1–yMnyO2 are active in electrochemical processes and higher content of manganese results in obtaining higher specific capacities (≈150 mAh g−1 for y = 0.8 under C/10 current load). [ABSTRACT FROM AUTHOR]

Generation of large strains upon Na+ intercalation is one of the prime concerns of the mechanical degradation of Prussian blue (PB) and its analogs. Structural construction from the atomic level is imperative to maintain structural stability and ameliorate the long-term stability of PB. Herein, an inter nickel hexacyanoferrate (NNiFCN) is successfully introduced at the out layer of iron hexacyanoferrate (NFFCN) through ion exchange to improve structural stability through compressive stress locking by forming NNiFCN shell. Furthermore, the kinetics of sodium ion diffusion is enhanced through the built-in electric pathway. The electrochemical performance is therefore significantly improved with a remarkable long-term cycling stability over 3,000 cycles at 500 mA·g−1 in the full sodium-ion batteries (SIBs) with a maximum energy density of 91.94 Wh·g−1, indicating that the core-shell structured NNiFCN/NFFCN could be the low-cost and high-performance cathode for full SIBs in large-scale EES applications. [ABSTRACT FROM AUTHOR]

New generation cathode materials from the Li-rich NMC group are under constant investigation due to their extremely high energy densities. However, the exact mechanism of lithium (de)insertion in those materials, especially the reactions involving the redox of lattice oxygen, is still elusive. In this paper the structural and electrochemical properties of a high performance cathode material (Li[Li0.2Mn0.6Ni0.1Co0.1]O2) are investigated with special attention focused on the TM and oxygen ion contributions in electrochemical processes. The detailed description of the structural, electronic and electrochemical properties of nano-Li[Li0.2Mn0.6Ni0.1Co0.1]O2 during lithium (de)insertion are determined by means of electrochemical investigation as well as ex situ XAFS and operando XRD measurements. The obtained results show the correlation of the changes in the electronic structure of the materials with specific structural rearrangements and C2/m → R3¯m ↔ Fd3¯m phase transitions. This paper shows the detailed analysis of the origins of the high capacity and low capacity fade of Li-rich layered oxides conditioned by the reversibility of the Li ion removal thanks to oxygen redox reactions as well as the migration of transition metal ions in the Li sublattice. [ABSTRACT FROM AUTHOR]

In hunting for safe and cost‐effective materials for post‐Li‐ion energy storage, the design and synthesis of high‐performance solid electrolytes (SEs) for all‐solid‐state batteries are bottlenecks. Many issues associated with chemical stability during processing and storage and use of the SEs in ambient conditions need to be addressed. Now, the effect of water as well as oxyhdryl group (.OH) on NaBi3O4Cl2 are investigated by evaluating ionic conductivity. The presence of water and.OH results in an increase in ionic conductivity of NaBi3O4Cl2 owing to diffusion of H2O into NaBi3O4Cl2, partially forming binding.OH through oxygen vacancy repairing. Ab initio calculations reveal that the electrons significantly accumulate around.OH and induce a more negative charge center, which can promote Na+ hopping. This finding is fundamental for understanding the essential role of H2O in halide‐based SEs and provides possible roles in designing water‐insensitive SEs through control of defects. [ABSTRACT FROM AUTHOR]

A new method of synthesis of stoichiometric Na2FeM(SO4)3 (M = Fe, Mn, Ni) materials is developed. The proposed unique methodology is based on a facile processing of dissolution of Na2SO4 and transition metal (Fe, Mn, and Ni) sulfates in an aqueous solution, solvent evaporation, and annealing. This novel method is characterized by a very low degree of complexity but still ensures the highest purity, resulting in the high purity of Mn and Ni substituted alluaudite compounds. Synthesized materials possess nanometric size grains with uniform composition distribution. Na2FeM(SO4)3 exhibits great transport properties with low charge transport activation energy related to sodium ion diffusion. Electrochemical characterization of the processed Na2Fe2(SO4)3 compound in both half-cell and full cell formats demonstrates the highest power density among all polyanion Na cathodes. [ABSTRACT FROM AUTHOR]

NASICON-type of solid-state electrolyte, Na 3 Zr 2 Si 2 PO 12 (NZSP), is one of the potential solid-state electrolytes for all-solid-state Na battery and Na-air battery. However, in solid-state synthesis, high sintering temperature above 1200 °C and long duration are required, which led to loss of volatile materials and formation of impurities at the grain boundaries. This hampers the total ionic conductivity of NZSP to be in the range of 10 -4 S cm -1 . Herein, we have reduced both the sintering temperature and time of the NZSP electrolyte by sintering the NZSP powders with different amounts of Na 2 SiO 3 additive, which provides the liquid phase for the sintering process. The addition of 5 wt % Na 2 SiO 3 has shown the highest total ionic conductivity of 1.45 mS cm -1 at room temperature. A systematic study of the effect of Na 2 SiO 3 on the microstructure and electrical properties of the NZSP electrolyte is conducted by the structural study with the help of morphological and chemical observations using X-ray diffraction (XRD), scanning electron microscopy, and using focused ion-beam-time of flight-secondary ion mass spectroscopy. The XRD results revealed that cations from Na 2 SiO 3 diffused into the bulk change the stoichiometry of NZSP, leading to an enlarged bottleneck area and hence lowering activation energy in the bulk, which contributes to the increment of the bulk ion conductivity, as indicated by the electrochemical impedance spectroscopy result. In addition, higher density and better microstructure contribute to improved grain boundary conductivity. More importantly, this study has achieved a highly ionic conductive NZSP only by facile addition of Na 2 SiO 3 into the NZSP powder prior to the sintering stage.