Nondestructive flash cathode recycling

Weiyin Chen^#¹, Yi Cheng^#¹, Jinhang Chen^#¹, Ksenia V Bets², Rodrigo V Salvatierra¹, Chang Ge³, John Tianci Li¹, Duy Xuan Luong^{1

3}, Carter Kittrell^{1

4

5}, Zicheng Wang¹, Emily A McHugh¹, Guanhui Gao², Bing Deng¹, Yimo Han², Boris I Yakobson^{6

7

8}, James M Tour^{9

10

11

12

13}

Affiliations

¹ Department of Chemistry, Rice University, 6100 Main Street, Houston, TX, 77005, USA.
² Department of Materials Science and NanoEngineering, Rice University, 6100 Main Street, Houston, TX, 77005, USA.
³ Applied Physics Program, Rice University, 6100 Main Street, Houston, TX, 77005, USA.
⁴ Smalley-Curl Institute, Rice University, 6100 Main Street, Houston, TX, 77005, USA.
⁵ NanoCarbon Center and the Rice Advanced Materials Institute, Rice University, 6100 Main Street, Houston, TX, 77005, USA.
⁶ Department of Chemistry, Rice University, 6100 Main Street, Houston, TX, 77005, USA. biy@rice.edu.
⁷ Department of Materials Science and NanoEngineering, Rice University, 6100 Main Street, Houston, TX, 77005, USA. biy@rice.edu.
⁸ Smalley-Curl Institute, Rice University, 6100 Main Street, Houston, TX, 77005, USA. biy@rice.edu.
⁹ Department of Chemistry, Rice University, 6100 Main Street, Houston, TX, 77005, USA. tour@rice.edu.
¹⁰ Department of Materials Science and NanoEngineering, Rice University, 6100 Main Street, Houston, TX, 77005, USA. tour@rice.edu.
¹¹ Applied Physics Program, Rice University, 6100 Main Street, Houston, TX, 77005, USA. tour@rice.edu.
¹² Smalley-Curl Institute, Rice University, 6100 Main Street, Houston, TX, 77005, USA. tour@rice.edu.
¹³ NanoCarbon Center and the Rice Advanced Materials Institute, Rice University, 6100 Main Street, Houston, TX, 77005, USA. tour@rice.edu.

^# Contributed equally.

PMID: 39048568
PMCID: PMC11269590
DOI: 10.1038/s41467-024-50324-x

Nondestructive flash cathode recycling

Weiyin Chen et al. Nat Commun. 2024.

. 2024 Jul 24;15(1):6250.

doi: 10.1038/s41467-024-50324-x.

Authors

Affiliations

¹ Department of Chemistry, Rice University, 6100 Main Street, Houston, TX, 77005, USA.
² Department of Materials Science and NanoEngineering, Rice University, 6100 Main Street, Houston, TX, 77005, USA.
³ Applied Physics Program, Rice University, 6100 Main Street, Houston, TX, 77005, USA.
⁴ Smalley-Curl Institute, Rice University, 6100 Main Street, Houston, TX, 77005, USA.
⁵ NanoCarbon Center and the Rice Advanced Materials Institute, Rice University, 6100 Main Street, Houston, TX, 77005, USA.
⁶ Department of Chemistry, Rice University, 6100 Main Street, Houston, TX, 77005, USA. biy@rice.edu.
⁷ Department of Materials Science and NanoEngineering, Rice University, 6100 Main Street, Houston, TX, 77005, USA. biy@rice.edu.
⁸ Smalley-Curl Institute, Rice University, 6100 Main Street, Houston, TX, 77005, USA. biy@rice.edu.
⁹ Department of Chemistry, Rice University, 6100 Main Street, Houston, TX, 77005, USA. tour@rice.edu.
¹⁰ Department of Materials Science and NanoEngineering, Rice University, 6100 Main Street, Houston, TX, 77005, USA. tour@rice.edu.
¹¹ Applied Physics Program, Rice University, 6100 Main Street, Houston, TX, 77005, USA. tour@rice.edu.
¹² Smalley-Curl Institute, Rice University, 6100 Main Street, Houston, TX, 77005, USA. tour@rice.edu.
¹³ NanoCarbon Center and the Rice Advanced Materials Institute, Rice University, 6100 Main Street, Houston, TX, 77005, USA. tour@rice.edu.

^# Contributed equally.

PMID: 39048568
PMCID: PMC11269590
DOI: 10.1038/s41467-024-50324-x

Abstract

Effective recycling of end-of-life Li-ion batteries (LIBs) is essential due to continuous accumulation of battery waste and gradual depletion of battery metal resources. The present closed-loop solutions include destructive conversion to metal compounds, by destroying the entire three-dimensional morphology of the cathode through continuous thermal treatment or harsh wet extraction methods, and direct regeneration by lithium replenishment. Here, we report a solvent- and water-free flash Joule heating (FJH) method combined with magnetic separation to restore fresh cathodes from waste cathodes, followed by solid-state relithiation. The entire process is called flash recycling. This FJH method exhibits the merits of milliseconds of duration and high battery metal recovery yields of ~98%. After FJH, the cathodes reveal intact core structures with hierarchical features, implying the feasibility of their reconstituting into new cathodes. Relithiated cathodes are further used in LIBs, and show good electrochemical performance, comparable to new commercial counterparts. Life-cycle-analysis highlights that flash recycling has higher environmental and economic benefits over traditional destructive recycling processes.

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Conflict of interest statement

Rice University owns intellectual property on the flash recycling process disclosed here. That intellectual property is licensed to a company in which JMT is a shareholder, but he is not an officer, director or employee. Conflicts of interest are mitigated through compliance with the Rice University Office of Research Integrity. The other authors claim no current conflicts of interest.

Figures

**Fig. 1. Spend cathode recycling by rapid electrothermal process.**
a Scheme about destructive and nondestructive recycling process, categorized by whether the integrity of the three-dimensional structure of the cathode is retained. The final resynthesis step is shown to highlight the individual precursors from each method. b The scheme about flash Joule heating process. c The radar plot related to comparison among different recycling strategies. d Current-time curve and e Real-time temperature measurement obtained from cathode waste. f Ellingham diagram of carbon monoxide and various metal oxides. g The magnetic response of cathode waste (CW, black), ferromagnetic portion of flash Joule heating cathode waste (FJH-CW, orange), and the non-ferromagnetic portion (nonmag, blue). CW: cathode waste. FJH-CW: flash Joule heating cathode waste. Hydro: hydrometallurgical method. Pyro: pyrometallurgical method. Flash: flash recycling method.

**Fig. 2. Recovery efficiencies of various battery metals.**
a Schematic showing the removal of common metal impurities by evaporation during rapid electrothermal process and the removal of other inert impurities by subsequent magnetic separation. b Recovery yields of Li and Co in the ferromagnetic portion of flash Joule heating LCO (FJH-LCO). The error bars reflect the standard deviations from at least three individual measurements. The same below. c Recovery yields of Li, Co, Ni, and Mn in the ferromagnetic portion of flash Joule heating NMC (FJH-NMC). d Comparison of recovery yields of Li and TM by different recycling methods, with references noted. e The concentration of impurity metals in waste LCO and FJH-LCO. f The concentration of impurity metals in waste NMC and FJH-NMC. TM: transition metals.

**Fig. 3. Morphology and structure of flash Joule heating products.**
SEM images of a spent CW comprised of waste LCO and waste NMC, and b FJH-CW. c The size distribution of primary particles from spent CW particles and FJH-CW. The number of particles N = 200. d The XRD spectra of spent CW (black), FJH-CW (red), and non-ferromagnetic flash product (blue). Square: Graphite. Hollow Circle: NMC. Solid circle: LCO. e HR-TEM images of the FJH-new LCO (nLCO) particles. f, g Fast Fourier transform results of FJH-nLCO particles from different areas in Fig. 3e. h The scheme showing the hierarchical structure of the FJH-LCO particles. i Computed energy preference towards phase segregation of spent LCO cathode. Adapted from previous work (ref. ). j Atomistic structure of partially de-lithiated Li_xCoO₂ before FJH treatment, and high-quality LiCoO₂, Co₃O₄, and CoO obtained after FJH treatment. The right panel shows the magnetization of Co₃O₄ by plotting the computed spin polarization density isosurface at 0.02 e⁻/Å³ total magnetic moment of ~70 emu g⁻¹. FJH-CW: flash Joule heating cathode waste. FM: ferromagnetic. AFM: antiferromagnetic.

**Fig. 4. Characterization and electrochemical performance of resynthesized cathode.**
a SEM image of resynthesized cathode from FJH-LCO (flash-recycled LCO). b TEM image of flash-recycled LCO. The intensity profile in the image shows the alternative TM slab and Li slab, reflecting the layered cathode particles. The inset shows the fast Fourier transform results, confirming the layered structure. c The XRD spectrum of flash-recycled LCO. Powder diffraction file: 00-062-0420, LiCoO₂. d Molar ratio between cobalt and lithium from waste LCO and flash-recycled LCO. The center line and box limits of the plot represent the median and upper and lower quartiles, representatively. e Comparison of diffusion coefficients of Li⁺ in waste LCO and flash-recycled LCO. f Electrochemical impedance spectroscopy of waste LCO and flash-recycled LCO. g Voltage profiles of commercial LCO and flash-recycled LCO at different numbers of cycles. h Cycling performance of commercial LCO, flash-recycled LCO, and waste LCO with a Li anode at 0.2 C. I_p: peak current.

**Fig. 5. Economic and environmental analysis of flash recycling method.**
a–c Process flow diagrams of various spent lithium-ion battery recycling routes, displaying the life cycle inventory including all considered inputs and outputs. Incidental inputs and outputs are shown with small arrows to differentiate them from explicit inputs and outputs. a Hydrometallurgical method. b Pyrometallurgical method. c Flash recycling method. The unit is kg for all material flow. d Concentrated 12 M HCl consumption in treating 1 kg of spent batteries. e–h Water consumption, energy consumption, greenhouse gas emission, and cost analysis in treating 1 kg of spent batteries followed by producing ~0.35 kg cathode materials from their individual precursors. Hydro: hydrometallurgical method. Pyro: pyrometallurgical method. Flash: flash recycling method. Direct: direct recycling method. GHG: greenhouse gas.

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References

1. Rey, I., Vallejo, C., Santiago, G., Iturrondobeitia, M. & Lizundia, E. Environmental impacts of graphite recycling from spent lithium-ion batteries based on life cycle assessment. ACS Sustain. Chem. Eng.9, 14488–14501 (2021). 10.1021/acssuschemeng.1c04938 - DOI
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Nondestructive flash cathode recycling

Affiliations

Nondestructive flash cathode recycling

Authors

Affiliations

Abstract

Conflict of interest statement

Figures

References

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