Poly(ethylene oxide)-Based Electrolytes for Solid-State Potassium Metal Batteries with a Prussian Blue Positive Electrode

Potassium-ion batteries are an emerging post-lithium technology that are considered ecologically and economically benign in terms of raw materials’ abundance and cost. Conventional cell configurations employ flammable liquid electrolytes that impose safety concerns, as well as considerable degrees of irreversible side reactions at the reactive electrode interfaces (especially against potassium metal), resulting in a rapid capacity fade. While being inherently safer, solid polymer electrolytes may present a solution to capacity losses owing to their broad electrochemical stability window. Herein, we present for the first time a stable solid-state potassium battery composed of a potassium metal negative electrode, a Prussian blue analogue K₂Fe[Fe(CN)₆] positive electrode, and a poly(ethylene oxide)-potassium bis(trifluoromethanesulfonyl)imide polymer electrolyte. At an elevated operating temperature of 55 °C, the solid-state battery achieved a superior capacity retention of 90% over 50 cycles in direct comparison to a conventional carbonate-based liquid electrolyte operated at ambient temperature with a capacity retention of only 66% over the same cycle number interval

Supporting Information: Unexpected chain of redox events in co-based Prussian blue analogues

Comprehensive characterizing information about the series of materials; crystal, composition, and hyperfine parameters of the 57Fe Mössbauer spectra of samples K2−δMn1–xCox[Fe(CN)6]; SAED and TGA patterns, HAADF-STEM images, ATR–FTIR, 57Fe Mössbauer spectra, and electrochemical galvanostatic profiles of the mentioned series of samples; calculated fit of XAS experiments; and plots of KCMF50 and KCF operando SXRD in a 10–54° 2Θ range (λ = 1.0332 Å).Peer reviewe

Toward Efficient Recycling of Vanadium Phosphate-Based Sodium-Ion Batteries: A Review

Sodium-ion batteries (SIBs) have demonstrated noticeable development since the 2010s, being complementary to the lithium-ion technology in predominantly large-scale application niches. The projected SIB market growth will inevitably lead to the generation of tons of spent cells, posing a notorious issue for proper battery lifecycle management, which requires both the establishment of a regulatory framework and development of technologies for recovery of valuable elements from battery waste. While lithium-ion batteries are mainly based on layered oxides and lithium iron phosphate chemistries, the variety of sodium-ion batteries is much more diverse, extended by a number of other polyanionic families (crystal types), such as NASICON (Na3V2(PO4)3), Na3V2(PO4)2F3−yOy, (0 ≤ y ≤ 2), KTiOPO4-type AVPO4X (A—alkali metal cation, X = O, F) and β-NaVP2O7, with all of them relying on vanadium and phosphorous—critical elements in a myriad of industrial processes and technologies. Overall, the greater chemical complexity of these vanadium-containing phosphate materials highlights the need for designing specific recycling approaches based on distinctive features of vanadium and phosphorus solution chemistry, fine-tuned for the particular electrodes used. In this paper, an overview of recycling methods is presented with a focus on emerging chemistries for SIBs

Synthesis and electrochemical performance of Li2Co1−xMxPO4F (M = Fe, Mn) cathode materials

In the search for high-energy materials, novel 3D-fluorophosphates, Li2Co1−xFexPO4F and Li2Co1−xMnxPO4F, have been synthesized. X-ray diffraction and scanning electron microscopy have been applied to analyze the structural and morphological features of the prepared materials. Both systems, Li2Co1−xFexPO4F and Li2Co1−xMnxPO4F, exhibited narrow ranges of solid solutions: x ≤ 0.3 and x ≤ 0.1, respectively. The Li2Co0.9Mn0.1PO4F material demonstrated a reversible electrochemical performance with an initial discharge capacity of 75 mA·h·g−1 (current rate of C/5) upon cycling between 2.5 and 5.5 V in 1 M LiBF4/TMS electrolyte. Galvanostatic measurements along with cyclic voltammetry supported a single-phase de/intercalation mechanism in the Li2Co0.9Mn0.1PO4F material

Crystal Structure and Li-Ion Transport in Li₂CoPO₄F High-Voltage Cathode Material for Li-Ion Batteries

In this work, we provide a structural and computational investigation of the Li₂CoPO₄F high-voltage cathode material by means of neutron powder diffraction (SG <i>Pnma</i>, <i>a</i> = 10.4528(2) Å, <i>b</i> = 6.38667(10) Å, <i>c</i> = 10.8764(2) Å, <i>R</i>_F = 0.0145), crystal chemistry approaches (Voronoi–Dirichlet partitioning and bond valence sums mapping), and density functional theory. The material reveals low energy barriers (0.12–0.43 eV) of Li hopping and a possible 3D channel system for Li-ion migration. It is found that only one Li per formula unit can be extracted within the potential stability window of the commercially available electrolytes. The interrelation between dimensionality, topology and energetics of Li-ion diffusion and peculiarities of the Li₂CoPO₄F crystal structure are discussed in detail

Crystal Structure and Li-Ion Transport in Li₂CoPO₄F High-Voltage Cathode Material for Li-Ion Batteries

In this work, we provide a structural and computational investigation of the Li₂CoPO₄F high-voltage cathode material by means of neutron powder diffraction (SG <i>Pnma</i>, <i>a</i> = 10.4528(2) Å, <i>b</i> = 6.38667(10) Å, <i>c</i> = 10.8764(2) Å, <i>R</i>_F = 0.0145), crystal chemistry approaches (Voronoi–Dirichlet partitioning and bond valence sums mapping), and density functional theory. The material reveals low energy barriers (0.12–0.43 eV) of Li hopping and a possible 3D channel system for Li-ion migration. It is found that only one Li per formula unit can be extracted within the potential stability window of the commercially available electrolytes. The interrelation between dimensionality, topology and energetics of Li-ion diffusion and peculiarities of the Li₂CoPO₄F crystal structure are discussed in detail