Currently, Li is mainly produced from Li‐rich brines through the lime–soda evaporation process, which requires a long time and several purification steps, and has a severe environmental impact. Herein, ion‐pumping technology based on λ‐MnO2 as lithium‐capturing electrode is presented. The method has high lithium selectivity and can increase the lithium purity from 4.1 to 96 % in a single step. In addition, the time required to achieve the target lithium concentration (5000 ppm) can be reduced from the 12–14 months needed for the lime–soda evaporation process to less than 7.4 h. The small volume of water required, the absence of any chemical reactant, the recyclability of the used electrodes, and the possibility to combine ion‐pumping technology with renewable energy sources makes this process a potential ecofriendly alternative to the current lithium‐recovery methods.

Reversible mixed-ion intercalation in nonselective host structures has promising applications in desalination, mixed-ion batteries, wastewater treatment, and lithium recovery through electrochemical ion pumping. One class of host compound that possesses many of the requirements needed for such applications (cost effectiveness, fast ion kinetics, and stability in an aqueous medium) includes the Prussian blue derivatives. Herein, the fundamental process of intercalation of multiple cations is studied at the thermodynamic level by means of galvanostatic cycling. Nickel hexacyanoferrate is focused upon because of its stability and low potential for electrochemical process relative to other hexacyanoferrates. Various cations can be intercalated; large cations (K and NH ) are intercalated at higher potentials than those of smaller cations (Na ). When mixtures of cations are present in solution, the potential profile is not qualitatively altered with respect to single-salt solutions, but the potential of (de-)intercalation is shifted; a simple thermodynamic model is introducted that is able to predict the potential and distribution at which intercalation takes place.

The kinetics of the reversible insertion of lithium ions assisted by aqueous environment into LiMn 2 O 4 thin film fabricated by multi-layer pulsed laser deposition is studied using dynamic multi-frequency analysis (DMFA). This method allowed us to acquire time resolved impedance spectra in the range of 210 kHz to 11.5 Hz during cyclic voltammetry. The impedance spectra obtained comprises of two RC time constants (semi-circles) indicating that the reversible insertion process of lithium ions in LiMn 2 O 4 thin films in aqueous media follows a two-stage intercalation process with the first stage as the (de)solvation step of the lithium ions and the second stage as a (de)insertion process with a concurrent change in the oxidation state of manganese. The temporal development of the kinetic parameters with the state of charge during the voltage sweep was investigated and reported in this work.

Dynamic multi‐frequency analysis (DMFA) is capable of acquiring high‐quality frequency response of electrochemical systems under non‐stationary conditions in a broad range of frequencies. In this work, we used DMFA to study the kinetics of (de‐)intercalation of univalent cations (Na+ and K+) in thin films of nickel hexacyanoferrate (NiHCF) during cyclic voltammetry. For this system, the classic stationary electrochemical impedance spectroscopy fails due to the instability of the oxidized form of NiHCF. We are showing that such spectra can be fitted with a physical model described by a simple two‐step intercalation mechanism: an adsorption step followed by an insertion step. The extracted kinetic parameters are depending on the state of charge as well on the nature of the inserted cation.

Dynamic impedance spectroscopy is one of the most powerful techniques in the qualitative and quantitative mechanistic studies of electrochemical systems, as it allows for time-resolved investigation and dissection of various physicochemical processes occurring at different time scales. However, due to high-frequency artefacts connected to the non-ideal behaviour of the instrumental setup, dynamic impedance spectra can lead to wrong interpretation and/or extraction of wrong kinetic parameters. These artefacts arise from the non-ideal behaviour of the voltage and current amplifier (I/E converters) and stray capacitance. In this paper, a method for the estimation and correction of high-frequency artefacts arising from non-ideal behaviour of instrumental setup will be discussed. Using resistors, $$[\hbox {Fe(CN)}_6]^{3-/4-}$$ [ Fe(CN) 6 ] 3 - / 4 - redox couple and nickel hexacyanoferrate nanoparticles, the effect of high-frequency artefacts will be investigated and the extraction of the impedance of the system from the measured dynamic impedance is proposed. It is shown that the correction allows acquiring proper dynamic impedance spectra at frequencies higher than the bandwidth of the potentiostat, and simultaneously acquire high precision cyclic voltammetry.

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The spinel LiMn 2 O 4 (LMO) is a promising cathode material for rechargeable Li-ion batteries due to its excellent properties, including cost effectiveness, eco-friendliness, high energy density, and rate capability. The commercial application of LiMn 2 O 4 is limited by its fast capacity fading during cycling, which lowers the electrochemical performance. In the present work, phase-pure and crystalline LiMn 2 O 4 spinel in the nanoscale were synthesized using single flame spray pyrolysis via screening 16 different precursor−solvent combinations. To overcome the drawback of capacity fading, LiMn 2 O 4 was homogeneously mixed with different percentages of AlPO 4 using versatile multiple flame sprays. The mixing was realized by producing AlPO 4 and LiMn 2 O 4 aerosol streams in two independent flames placed at 20°to the vertical axis. The structural and morphological analyses by X-ray diffraction indicated the formation of a pure LMO phase and/or AlPO 4 -mixed LiMn 2 O 4 . Electrochemical analysis indicated that LMO nanoparticles of 17.8 nm (d BET ) had the best electrochemical performance among the pure LMOs with an initial capacity and a capacity retention of 111.4 mA h g −1 and 88% after 100 cycles, respectively. A further increase in the capacity retention to 93% and an outstanding initial capacity of 116.1 mA h g −1 were acquired for 1% AlPO 4 .