Breaking the Electronic Conductivity Bottleneck of Manganese Oxide Family for High-Power Fluorinated Graphite Composite Cathode by Ligand-Field High-Dimensional Constraining Strategy.
basic_science · Level V
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- Record sourced from PubMed, PMID 36482825.
- Also identified by DOI 10.1002/adma.202209210.
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Abstract
Primary lithium fluorinated graphite (Li/CF<sub>x</sub> ) batteries with superior energy density are an indispensable energy supply for multiple fields but suffer from sluggish reaction kinetics of the CF<sub>x</sub> cathode. Designing composite cathodes emerges as a solution to this problem. Despite the optimal composite component for CF<sub>x</sub> , the manganese oxide family represented by MnO<sub>2</sub> is still faced with an intrinsic electronic conductivity bottleneck, which severely limits the power density of the composite cathode. Here, a cation-induced high-dimensional constraining strategy from the perspective of ligand-field stacking structure topological design, which breaks the molecular orbital hybridization of pristine semiconductive oxides to transform them into the high-conductivity metallic state while competitively maintaining structural stability, is proposed. Through first-principles phase diagram calculations, mixed-valent Mn<sub>5</sub> O<sub>8</sub> ( <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics> <mrow><msubsup><mtext>Mn</mtext> <mn>2</mn> <mrow><mn>2</mn> <mo>+</mo></mrow> </msubsup> <msubsup><mtext>Mn</mtext> <mn>3</mn> <mrow><mn>4</mn> <mo>+</mo></mrow> </msubsup> <msub><mi>O</mi> <mn>8</mn></msub> </mrow> <annotation>${\rm{Mn}}_2^{2 + }{\rm{Mn}}_3^{4 + }{{\rm{O}}_8}$</annotation></semantics> </math> ) is explored as an ideal high-dimensional constraining material with satisfied conductivity and large-scale production feasibility. Experiments demonstrate that the as-proposed CF<sub>x</sub> @ Mn<sub>5</sub> O<sub>8</sub> composite cathode achieves 2.36 times the power density (11399 W kg<sup>-1</sup> ) of pristine CF<sub>x</sub> and a higher CF<sub>x</sub> conversion ratio (86%). Such a high-dimensional field-constraining strategy is rooted in the established four-quadrant electronic structure tuning framework, which fundamentally changes the orbital symmetry under the ligand field to overcome the common conductivity challenge of wide transition metal oxide materials.