Dataset Information

Structure, Shift in Redox Potential and Li-Ion Diffusion Behavior in Favorite LiFe_1?xV_xPO₄F Solid-Solution Cathodes.

ABSTRACT: Solid-solution Li-ion cathode materials transform through a single-phase reaction thus leading to a long-term structural stability and improved cyclability. In this work, a two- to single-phase Li⁺-extraction/insertion mechanism is studied through tuning the stoichiometry of transition-metal Fe/V cations to trigger a transition in the chemical reactivity path. Tavorite triclinic-structured LiFe_1-xV_xPO₄F (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1) solid-solution powders were prepared by a facile one-step solid-state method from hydrothermal-synthesized and commercial raw materials. The broad shape of cyclic voltammetry (CV) peaks, sloping charge/discharge profiles and sloping open-circuit voltage (OCV) profiles were observed in LiFe_1-xV_xPO₄F solid-solution cathodes while 0 < x < 1. These confirm strongly a single-phase behavior which is different from the two-phase behavior in the end-members (x = 0 or 1). The electronegativity of M (M = Fe_1-xV_x) for the redox potential of Fe^2+/3+ couple or the M-O₄F₂ bond length for the V^3+/4+ couple plays respectively a dominant role in LiFe_1-xV_xPO₄F solid-solution cathodes.

SUBMITTER: Yan JL

PROVIDER: S-EPMC6572713 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature

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Publications

Structure, Shift in Redox Potential and Li-Ion Diffusion Behavior in Favorite LiFe1⁻xVxPO4F Solid-Solution Cathodes.

Yan Jia-Li JL Shao Gang-Qin GQ Fan Shu-Hao SH Zhu Can C Zhang Yong Y Wang Jun J Liu Qi Q

Molecules (Basel, Switzerland) 20190516 10

Solid-solution Li-ion cathode materials transform through a single-phase reaction thus leading to a long-term structural stability and improved cyclability. In this work, a two- to single-phase Li+-extraction/insertion mechanism is studied through tuning the stoichiometry of transition-metal Fe/V cations to trigger a transition in the chemical reactivity path. Tavorite triclinic-structured LiFe1-xVxPO4F (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1) solid-solutio ...[more]

PMID: 31100980

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Project description:Metallic contaminants pose a significant challenge to the viability of directly recycling Li-ion batteries. To date, few strategies exist to selectively remove metallic impurities from mixtures of shredded end-of-life material (black mass; BM) without concurrently damaging the structure and electrochemical performance of the target active material. We herein present tailored methods to selectively ionize two major contaminants-Al and Cu-while retaining a representative cathode (LiNi0.33Mn0.33Co0.33O2; NMC-111) intact. This BM purification process is conducted at moderate temperatures in a KOH-based solution matrix. We rationally evaluate approaches to increase both the kinetic corrosion rate and the thermodynamic solubility of Al0 and Cu0, and evaluate the impact of these treatment conditions on the structure, chemistry, and electrochemical performance of NMC. Specifically, we explore the impacts of chloride-based salts, a strong chelating agent, elevated temperature, and sonication on the rate and extent of contaminant corrosion, while concurrently evaluating the effects on NMC. The reported BM purification process is then demonstrated on samples of "simulated BM" containing a practically relevant 1 wt% concentration of Al or Cu. Increasing the kinetic energy of the purifying solution matrix through elevated temperature and sonication accelerates the corrosion of metallic Al and Cu, such that ∼100% corrosion of 75 μm Al and Cu particles is achieved within 2.5 hr. Further, we determine that effective mass transport of ionized species critically impacts the efficacy of Cu corrosion, and that saturated Cl- hinders rather than accelerates Cu corrosion by increasing solution viscosity and introducing competitive pathways for Cu surface passivation. The purification conditions do not induce bulk structural damage to NMC, and electrochemical capacity is maintained in half-cell format. Testing in full cells suggests that a limited quantity of residual surface species are present after treatment, which initially disrupt electrochemical behavior at the graphite anode but are subsequently consumed. Process demonstration on simulated BM suggests that contaminated samples-which prior to treatment show catastrophic electrochemical performance-can be recovered to pristine electrochemical capacity. The reported BM purification method offers a compelling and commercially viable solution to address contamination, particularly in the "fine" fraction of BM where contaminant sizes are on the same order of magnitude as NMC and where traditional separation approaches are unfeasible. Thus, this optimized BM purification technique offers a pathway towards viable direct recycling of BM feedstocks that would otherwise be unusable.

Dataset Information

Structure, Shift in Redox Potential and Li-Ion Diffusion Behavior in Favorite LiFe_1?xV_xPO₄F Solid-Solution Cathodes.

Publications

Structure, Shift in Redox Potential and Li-Ion Diffusion Behavior in Favorite LiFe<sub>1⁻x</sub>V<sub>x</sub>PO<sub>4</sub>F Solid-Solution Cathodes.

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Dataset Information

Structure, Shift in Redox Potential and Li-Ion Diffusion Behavior in Favorite LiFe1?xVxPO4F Solid-Solution Cathodes.

Publications

Structure, Shift in Redox Potential and Li-Ion Diffusion Behavior in Favorite LiFe<sub>1⁻x</sub>V<sub>x</sub>PO<sub>4</sub>F Solid-Solution Cathodes.

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OmicsDI is part of the ELIXIR infrastructure

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Structure, Shift in Redox Potential and Li-Ion Diffusion Behavior in Favorite LiFe_1?xV_xPO₄F Solid-Solution Cathodes.