EP4244916A1 - Cathodes de batterie pour une stabilité améliorée - Google Patents

Cathodes de batterie pour une stabilité améliorée

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Publication number
EP4244916A1
EP4244916A1 EP21901629.2A EP21901629A EP4244916A1 EP 4244916 A1 EP4244916 A1 EP 4244916A1 EP 21901629 A EP21901629 A EP 21901629A EP 4244916 A1 EP4244916 A1 EP 4244916A1
Authority
EP
European Patent Office
Prior art keywords
sulfur battery
battery according
cnts
cathode
lithium
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP21901629.2A
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German (de)
English (en)
Inventor
Bilal M. El-Zahab
Amir Chamaani
Neha Chawla
Meer Safa
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Florida International University FIU
Original Assignee
Florida International University FIU
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Filing date
Publication date
Priority claimed from US17/097,674 external-priority patent/US11038160B2/en
Application filed by Florida International University FIU filed Critical Florida International University FIU
Publication of EP4244916A1 publication Critical patent/EP4244916A1/fr
Pending legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/581—Chalcogenides or intercalation compounds thereof
    • H01M4/5815—Sulfides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/417—Polyolefins
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • Li-O2 batteries have nearly 10 times the theoretical specific energy of common lithium-ion batteries and in that respect have been regarded as the batteries of the future.
  • a typical Li-O 2 battery comprises a Li anode, a porous cathode open to oxygen, and a Li + ion conducting electrolyte separating the electrodes.
  • a Li-O 2 battery stores energy via a simple electrochemical reaction (2Li + O 2 «-> Li 2 O 2 ) in which Li 2 O 2 is deposited on the surface of the cathode via a forward reaction (oxygen reduction reaction, ORR) during discharge and a backward reaction (oxygen evolution reaction, OER) takes place during charging to decompose Li 2 O 2 on the surface of cathode.
  • ORR oxygen reduction reaction
  • OER oxygen evolution reaction
  • Carbonaceous materials such as carbon nanoparticles, carbon nanofibers, carbon nanotubes, graphene platelets, and other forms of carbons have been commonly used as cathode materials in Li-O 2 batteries.
  • carbon nanotubes CNTs
  • CNTs carbon nanotubes
  • Single-walled have been used as cathode materials in Li-O2 batteries and shown discharge specific capacities as high as 2540 mAh g -1 , which were obtained at a 0.1 mA- cm -2 discharge current density.
  • Redox mediators minimize charge polarization by acting as charge carriers between the cathode and Li 2 O2 surface.
  • different noble metals and metal oxide catalysts have also been integrated in the cathodes of Li-O2 batteries.
  • the catalyst may influence the performance of Li-O 2 batteries by destabilizing the oxidizing species which decreases the charging overpotential. They may also increase the surface active sites and facilitate charge transport from oxidized reactants to the electrode which can also lead to formation of nanocrystalline Li 2 O2.
  • the catalyst on the oxygen cathode in Li-O 2 batteries is easily deactivated due to continuous accumulation of discharge and charge products upon cycling.
  • Embodiments of the subject invention provide Li-oxygen (Li-O 2 ) cathodes using palladium -filled carbon nanotubes (CNTs) that increase the stability of the electrolyte during both discharging and charging of a battery.
  • Li-O2 cathodes and Pd-filled CNTs can be applied to lithium-ion batteries, lithium-silicon, lithium-sulfur, lithium oxygen, as well as other non-lithium based batteries.
  • a lithium battery can comprise: an anode including a lithium metal; a cathode disposed on the anode; and an electrolyte disposed between the anode and the cathode, the cathode comprising a carbon cloth gas diffusion layer and a carbon structure with a metal catalyst or a metal oxide catalyst, the metal catalyst or the metal oxide catalyst including a platinum group metal.
  • a battery can comprise: an anode; a cathode disposed on the anode; and a separator including an electrolyte and disposed between the anode and the cathode, the cathode comprising a carbon cloth gas diffusion layer, a carbon structure, and a nanoparticle catalyst, and the nanoparticle catalyst including a platinum group metal.
  • a battery can comprise: an anode including a lithium metal; a cathode disposed on the anode; and a separator including an electrolyte and disposed between the anode and the cathode; a stainless steel tube disposed on the cathode; and a stainless steel rod disposed on the anode, the cathode comprising a carbon cloth gas diffusion layer, a multi-walled carbon nanotube coated on the carbon cloth gas diffusion layer, and a palladium nanoparticle catalyst coated on a surface of the multi-walled carbon nanotube or filled in the multi-walled carbon nanotube, the separator being a polypropylene, and the electrolyte including a lithium salt.
  • Figure 1 shows a Li-O2 battery according to an embodiment of the subject invention.
  • Figure 2 shows a plurality of carbon structures of a Li-O 2 battery according to an embodiment of the subject invention.
  • Figure 3(a) is a transmission electron micrograph of Pd-coated CNTs.
  • Figure 3(b) is a transmission electron micrograph of Pd-filled CNTs.
  • Figure 3(c) is a plot of a Raman spectrum of Pd-filled and Pd-coated CNTs.
  • Figure 4 is a plot of the first discharge/charge capacity of pristine CNT, Pd-coated CNTs and Pd-filled CNTs at a constant current density of 250 mAh.
  • Figure 5 is a plot of cyclic voltammetry of pristine, Pd-filled, and Pd-coated CNTs in range of 2-4.5 V vs Li/Li + , wherein all scans rates are 1 mV- s' 1 .
  • Figure 6(a) is a plot of Raman spectrum after discharging and charging the batteries for pristine, Pd-coated, and Pd-filled CNTs.
  • Figure 6(b) is a plot of an x-ray diffraction patterns confirming the presence of Li 2 O 2 and Li 2 CO 3 in Pd-coated and Pd-filled discharged cathodes.
  • Figure 7(a) is an image of a scanning electron micrograph of cathodes after discharge for pristine CNTs.
  • Figure 7(b) is an image of a scanning electron micrograph of cathodes after discharge for Pd-coated CNTs.
  • Figure 7(c) is an image of a scanning electron micrograph of cathodes after discharge for Pd-filled CNTs.
  • Figure 8(a) is a plot of a chronopoteniometric test at 250 mA g' 1 from OCV to 4.5 V for pristine, Pd-coated, and Pd-filled CNTs.
  • Figure 8(b) is a plot of a linear sweep voltammetry of pre-discharged Pd-coated and Pd- filled CNTs under oxygen between OCV and 4.5 V vs Li/Li + at a scan rate of 1 mV- s' 1 , wherein the scale bars are 1 pm.
  • Figure 9 is a plot of the cyclability of the Li-O 2 batteries for fixed cycle capacities of 500 mAh g -1 at a current density of 250 mA g -1 and with voltage cutoffs of 2.0-4.5 V for pristine, Pd-coated, and Pd-filled CNTs.
  • the marker o denotes discharge capacity and the marker • denotes charge capacity.
  • Figure 10 is a plot of current (in milliamps (mA) versus potential (in Volts (V)), showing the cyclic voltammetry of lithium-sulfur (Li-S) batteries at a scan rate of 0.5 millVolts per second (mV/s).
  • the (blue) curve with the lowest peak value at 2.45 V is for a Li-S battery containing pristine CNT cathodes; the (green) curve with the highest peak value at 2.45 V is for a Li-S battery containing Pd-filled CNT cathodes; and the (red) curve with the second-highest peak value at 2.45 V is for a Li-S battery containing platinum (Pt)-filled CNT cathodes.
  • Figure 11 is a plot of specific capacity (in mAh/(g-s)) versus cycle number, showing the capacity retention due to cycling for the first 100 cycles of Li-S batteries, cycled at 837.5 mA/(g- s) (C/2).
  • the (blue) dots with the lowest value at 50 cycles are for a Li-S battery containing pristine CNT cathodes; the (green) dots with the second-highest value at 50 cycles are for a Li-S battery containing Pd-filled CNT cathodes; and the (red) dots with the highest value at 50 cycles are for a Li-S battery containing Pt-filled CNT cathodes.
  • Embodiments of the subject invention provide Li-oxygen (Li-O 2 ) cathodes using palladium-coated and palladium-filled carbon nanotubes (CNTs).
  • CNTs can be replaced with various catalysts (for example, ruthenium, or platinum-based catalysts) filled carbon structures, (for example fullerenes, buckminsterfullerenes, or graphenes).
  • catalysts for example, ruthenium, or platinum-based catalysts
  • Empirical data shows that the full discharge of batteries in a 2-4.5 V range shows 6-fold increase in the first discharge cycle of the Pd-filled over the pristine CNTs and 35% increase over their Pd-coated counterparts.
  • the Pd-filled also exhibits improved cyclability with 58 full cycles of 500 mAh g -1 at current density of 250 mA g -1 versus 35 and 43 cycles for pristine and Pd-coated CNTs, respectively.
  • the effect of encapsulating the Pd catalysts inside the CNTs leads to increased stability of the electrolyte during both discharging and charging of the battery. Voltammetry, Raman spectroscopy, FTIR, XRD, UV/Vis spectroscopy and visual inspection of the discharge products using scanning electron microscopy can be used to confirm the improved stability of the electrolyte due to this encapsulation and that this approach could lead increasing the Li-O2 battery capacity and cyclability performance.
  • Multi -walled carbon nanotubes can be decapped by nitric acid solution treatment and then 1 mM aqueous solution of PdCb can be used to swell 100 mg of decapped MWCNTs until a slurry is formed.
  • Pd-coated CNTs can also be prepared following the same procedure on untreated capped MWCNTs. Both slurries of Pd-coated and Pd-filled MWCNTs can be dried overnight at room temperature and calcinated in air at 350 °C for 2 hours. Corresponding particles can then be hydrogenated in an oven under hydrogen gas to yield ⁇ 5 wt% Pd nanoparticles.
  • Cathodes can be prepared by coating a slurry of MWCNT (Pristine, Pd- filled and Pd-coated)/PVDF (90/10 wt% in NMP) on a 0.5” diameter carbon cloth gas diffusion layer (CCGDL) followed by drying at 120 °C for 12 hours. The cathodes can then be stored in an Ar-filled glove box to be used later.
  • the typical loading of MWCNT can be 0.5 ⁇ 0.01 mg. All reported capacities in this application are reported per total mass of active cathode (CNTs and catalyst).
  • FIG. 1 shows a Li-O2 battery according to an embodiment of the subject invention.
  • the Li-O2 battery 100 comprises a cathode 200, an anode 400, and an electrolyte 300 disposed between the cathode 200 and the anode 400.
  • the Li-O 2 battery 100 further comprises a conductive current collector 250 (e.g., a porous conductive current collector) disposed on the cathode 200 and a conductive current collector 450 disposed on the anode 400;
  • the conductive current collector 250 disposed on the cathode 200 can be a tube, and the conductive current collector 450 disposed on the anode 400 can be a rod.
  • the Li-O 2 battery 100 can be assembled by using a Swagelok type cell, in which the tube 250 is a stainless steel tube and the rod 450 is a stainless steel rod.
  • the electrolyte 300 can be formed as a separator soaked with an electrolyte, and the separator can be a polyolefin (e.g., polypropylene).
  • the anode 400 is formed by a lithium metal disk including a lithium metal.
  • the cathode 200 comprises a carbon structure with a metal catalyst or metal oxide catalyst, wherein the metal catalyst or metal oxide catalyst includes a platinum group metal.
  • the platinum group metal includes at least one of ruthenium, rhodium, palladium, osmium, iridium, and platinum.
  • a palladium nanoparticle catalyst is coated on a surface of the carbon structure or filled in the carbon structure.
  • the cathode 200 further comprises the CCGDL, and the carbon structure having a platinum group metal catalyst is coated on the CCGDL.
  • the cathode 200 includes a porous structure open to an oxygen and the CCGDL has a woven structure.
  • Figure 2 shows a plurality of carbon structures of a Li-O2 battery according to an embodiment of the subject invention.
  • the carbon structure of Li-O2 battery includes at least one of graphene, fullerenes, amorphous carbons, and carbon nanotubes.
  • the carbon nanotubes can be a single-walled carbon nanotube or a multi-walled carbon nanotube.
  • the electrolyte 300 can be prepared by adding 1 mol kg -1 of LiTFSI salt (/. ⁇ ., Lithium salt) into tetraethyl glycol di-methyl ether (TEGDME) solvent.
  • TEGDME tetraethyl glycol di-methyl ether
  • the lithium metal disc of the anode 400 is covered by an electrolyte soaked separator, MWCNT- CCGDL and a stainless steel mesh can be used as a current collector.
  • Li-O 2 batteries can be rested inside an Ar-filled glove box overnight before electrochemical tests. All electrolyte preparation and cell assembly can be performed inside an Ar-filled glove box ( ⁇ 1 ppm O2 and ⁇ 0.1 ppm H 2 O).
  • the Li-O 2 batteries can be removed from the argon glove box and placed in the gastight desiccator filled with ultra-high purity oxygen gas (Airgas, purity > 99.994%). The batteries can be rested under oxygen for 5 hours before testing.
  • ultra-high purity oxygen gas Airgas, purity > 99.994%
  • the CNTs can be prepared such that the Pd nanoparticles fill the carbon nanotubes without a Pd surface coating.
  • CNTs can be decapped by introducing the nanotubes to an acid treatment. The decapped CNTs can then be rinsed with water in order to remove any remaining acid treatment. The decapped CNTs can be dried and then immersed into a palladium salt solution and swelled until a slurry is formed. The CNTs can remain in the palladium salt solution until such time that the nanotubes are filled. The CNTs can then be dried, in a drying device, under oxygen to convert the pallidum salt to palladium oxide particles.
  • the CNTs can then be rinsed to remove any debris remaining on the surface of the nanotubes.
  • the CNTs can then be hydrogenated in a furnace to convert the palladium oxide into palladium.
  • the Pd-filled CNTs can then be stored, for example in Argon, until future use.
  • Palladium (II) chloride PdCh, 59% Pd
  • Bis (trifluoromethane) sulfonamide LiTFSI, purity > 99.95%)
  • TEGDME tetraethylene glycol dimethyl ether
  • NMP N-Methylpyrrolidine
  • MWCNT multi-walled carbon nanotubes
  • D 5-20 nm
  • L 5 pm, purity > 95.00% carbon basis
  • TiOSO ⁇ >29% Ti (as TiO2) basis
  • Lithium Peroxide Li 2 O2 O2
  • CCGDL carbon cloth gas diffusion layer
  • Lithium foil chips purity>99.90%)
  • a polypropylene separator thinness ⁇ 25 pm
  • PVDF Polyvinylidene fluoride
  • a Solartron 1470 battery tester can be used for galvanostatic discharge/charge tests within a voltage range of 2.0-4.5 V at a current density of 250 mA g -1 .
  • Voltammetry measurements are performed by an electrochemical workstation (Gamry reference 600) at the rate of 1 mV s" 1 in the range of 2.0-4.5 V to investigate the catalytic behavior of oxygen electrodes. All charge/discharge and electrochemical tests are measured in a temperature controlled environment at 25 °C. After charge/discharge cycling, the oxygen cathodes are recovered from the batteries in the Ar-filled glove box, rinsed with acetonitrile and dried under vacuum.
  • Cathodes can be investigated by Raman spectroscopy (Bay Spec’s Nomadic, excitation wavelength of 532 nm), Fourier transform infrared (FTIR) spectroscopy (JASCO FT-IR 4100), and Scanning electron microscopy (SEM) (JEOL 6330F).
  • Raman spectroscopy Boy Spec’s Nomadic, excitation wavelength of 532 nm
  • FTIR Fourier transform infrared
  • JASCO FT-IR 4100 JASCO FT-IR 4100
  • SEM Scanning electron microscopy
  • JEOL 6330F Scanning electron microscopy
  • a parallel X-ray beam in size of 100 pm diameter is
  • Li 2 O2 is quantified in the cathodes after discharge using a colorimetric method. Briefly, discharged cathodes are first immersed in water then aliquots are taken and added to 2% aqueous solution of TiOSCL. Instantaneously a color change occurred and the absorbance spectra of the solutions are collected using a UV-Vis spectrophotometer (Gamry UV/Vis Spectro-115E). The peak intensity at 408 nm is calibrated against solutions with known concentrations of Li 2 O 2 , in the range of 0.1 to 10 mg/ml and linear calibration curve is obtained. Transmission Electron Microscopy (Phillips CM-200 200 kV) is also used to inspect the carbon nanotubes.
  • a colorimetric method Briefly, discharged cathodes are first immersed in water then aliquots are taken and added to 2% aqueous solution of TiOSCL. Instantaneously a color change occurred and the absorbance spectra of the solutions are collected using a UV
  • the cathodes of the Li-O2 battery can comprise MWCNTs (pristine, Pd-coated and Pd- filled) coated on the woven carbon cloth gas diffusion layer (CCGDL). Homogenous three- dimensional networks of carbon nanotubes over CCGDL yield high surface area with an open structure which improves the electronic contact during charging and discharging processes.
  • Figures 3(a) and 3(b) show TEM images of Pd-coated and Pd-filled CNTs, respectively. Referring Figure 3(b), in Pd-filled cathodes, Pd nanocatalysts are formed in the inner tubular region of decapped CNTs.
  • Figure 3(c) shows the Raman spectra of the Pd-coated and Pd-filled CNTs.
  • D and G bands of Pd-filled and Pd-coated CNTs are identical in location and intensity ratios [I(G)/I(D) ⁇ 1.2] indicating that the decapped CNTs do not have high density of defects on their surface.
  • the left peak corresponds to the D band and the right peak corresponds to the G band.
  • Figure 4 shows a plot of the first discharge/charge capacity pf pristine CNT, PD-coated CNTs and Pd-filled CNTs at a constant current density of 250 mAh.
  • the first discharge and charge behaviors of the Pd-coated, Pd-filled and pristine CNTs batteries using 1 M LiTFSI in TEGDME electrolyte in the voltage window of 2.0-4.5 vs Li/Li+ at the constant current density of 250 mA g" 1 are shown in Figure 4.
  • the pristine CNTs show a first discharge capacity of 1980 mAh g -1 compared to 8197 mAh g -1 and 11,152 mAh g -1 for the Pd- coated and Pd-filled CNTs, respectively.
  • the ⁇ 6-fold discharge capacity improvement of Pd- coated CNTs over pristine CNTs resulted from improved ORR and increased surface sites for lithium discharge product deposition due to the presence of Pd nanocatalysts.
  • Figure 5 shows a plot of cyclic voltammetry of pristine, Pd-filled, and Pd-coated CNTs in range of 2-4.5 V vs Li/Li + , wherein all scans rates are 1 mV- s' 1 .
  • Cyclic voltammetry (CV) measurements confirm higher ORR and OER currents for Pd containing CNTs over pristine CNTs. This also confirms retained catalytic activity of Pd when encapsulated inside the CNTs, consistent with previously observations.
  • Figure 6(a) shows a plot of Raman spectrum after discharging and charging the batteries for pristine, Pd-coated, and Pd-filled CNTs.
  • Raman spectroscopic characterization on the discharged cathodes shows Li 2 O 2 formation at ⁇ 790 cm -1 Raman shift for all discharged cathodes.
  • the Pd-coated CNTs cathode shows a pronounced Raman shift peak at 1080 cm -1 , which corresponds to the electrolyte decomposition product Li 2 CO 3 . This peak is absent from the pristine CNT cathodes.
  • the amounts of Li 2 O 2 in the cathode are determined to be 11.6, 21.4, and 35.4 pmols for pristine, Pd-coated, and Pd-filled CNT cathodes, respectively. These amounts correspond to capacity yields of approximately 88%, 23%, and 37% of the experimental capacities recorded by the pristine, Pd- coated, and Pd-filled CNT cathodes, respectively.
  • the cathodes are analyzed using FTIR. Using peak intensities ratio at 600 cm -1 (Li 2 O 2 ) and 862 cm -1 (Li 2 CO 3 ), Pd-coated and Pd-filled cathodes have 19.3% and 33.2% Li 2 O 2 by mole, respectively.
  • Li 2 O 2 and Li 2 CO 3 discharge species this observation is in agreement with the UV-Vis quantification and further confirms the stabilizing effect of the encapsulation of Pd inside the CNTs compared to coating the CNTs.
  • the CV and Raman data also back up these claims, indicating that the electrolyte undergoes more decomposition in cells with Pd-coated CNTs cathodes.
  • Figure 6(b) show a plot of an x-ray diffraction patterns confirming the presence of Li 2 O 2 and Li 2 CO 3 in Pd-coated and Pd-filled discharged cathodes. Referring to Figure 6(b), the presence of Li 2 O 2 and Li 2 CO 3 is additionally confirmed by XRD.
  • Figures 7(a), 7(b), and 7(c) show images of a scanning electron micrograph of cathodes after discharge for pristine CNTs, Pd-coated CNTs, and Pd-filled CNTs, respectively.
  • the formation of discharge products is visually confirmed using scanning electron microscopy on discharged cathodes.
  • the discharge products (Li 2 O 2 ) of the pristine CNTs are conformal around the cathode in rod-like structures with low porosity. The growth of layers in this morphology often yields to passivation and blockage of oxygen to the cathode and eventually limits the discharge capacity and cycle life of the battery.
  • the Pd-coated CNTs cathode as shown Figure 7(b) shows some platelet-shaped Li 2 O2 buried by thick conformal layer, suspected to be Li 2 CO3 as shown in Raman and FTIR measurements.
  • the Pd-filled CNTs show nano-thin platelets of Li 2 O 2 covering the cathode as shown Figure 7(c). These platelets of Li 2 O 2 yield high surface porosity which in turn do not block the access to the CNTs and enhance the performance.
  • the oxidation stability limit of the electrolyte is determined using a chronopotentiometric stability test and linear sweep voltammetry under oxygen atmosphere. Batteries using Pd-coated, Pd-filled and pristine CNTs are assembled and charged without prior discharging at constant current density of 250 mA s" 1 up to cutoff voltage of 4.5 V.
  • Figure 8 shows higher capacity for Pd-coated compared to Pd-filled and pristine.
  • Figure 8(a) shows a plot of a chronopoteniometric test at 250 mA g' 1 from OCV to 4.5 V for pristine, Pd-coated, and Pd-filled CNTs
  • Figure 8(b) shows a plot of a linear sweep voltammetry of pre-discharged Pd-coated and Pd-filled CNTs under oxygen between OCV and 4.5 V vs Li/Li + at a scan rate of 1 mV- s' 1 , wherein the scale bars are 1 pm. Since no discharge products existed, the capacities obtained are attributed to electrolyte and cathode undesirable reactions.
  • Figure 9 shows the cycling stability of Li-O 2 batteries based on Pd-filled, Pd-coated, and pristine CNTs.
  • Galvanostatic discharge/charge cycling of Li-O 2 batteries at a current density of 250 mA g -1 at a limited capacity of 500 mAh g -1 in a voltage window of 2.0-4.5 V vs Li/Li + are conducted.
  • Li-O 2 cells using Pd-filled CNTs show the highest discharge cycling performance of 58 cycles compared to 43 cycles for Pd-coated, and 35 for pristine CNTs.
  • the cycling stability improvement in the case of Pd-coated and Pd-filled CNTs is a result of previously confirmed OER/ORR improvement due to the Pd nanocatalysts.
  • the encapsulation of nanocatalyst inside the CNTs improves the stability of the electrolyte by decreasing the formation of Li 2 CO3 compared to nanocatalyst- coated CNTs.
  • the cathodes for a lithium sulfur battery can comprise, for example, Pd-filled, Pt-filled, or pristine CNTs coated on a conductive layer (e.g., an aluminum, copper, silver, or gold layer such as an aluminum, copper, silver, or gold foil).
  • a conductive layer e.g., an aluminum, copper, silver, or gold layer such as an aluminum, copper, silver, or gold foil.
  • the CNTs can be the same as described above for use in, e.g., an Li-O 2 battery cathode and can contain nanocatalysts at a weight percentage of 0.1% to 20% by weight (preferably 0.5% - 5% by weight).
  • Sulfur can be added to the cathodes as, for example, elemental sulfur (Ss), lithium sulfide (Li 2 S), and/or lithium polysulfide (Li 2 Sg, Li 2 Se, Li 2 S4, Li 2 S 2 , etc.).
  • the sulfur to carbon weight ratio in the cathode can be, for example, 0.2 - 2.0 (preferably 0.5 - 1.0).
  • a polymeric binder such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), or carboxymethyl cellulose (CMC) can be used.
  • the film thickness can typically be in a range of 20 micrometers (pm) - 400 pm (preferably 100 pm - 200 pm).
  • the electrolyte can include, for example, a mixture of 1,3-dioxolane (DOL) and dimethyl ether (DME) with 1 : 1 by volume containing a lithium salt (e.g., lithium bis(trifluoromethane)sulfonamide) at a predetermined concentration (e.g., a 1 M concentration).
  • the electrolyte can also include a solid-electrolyte interface forming additive such as lithium nitrate (e.g., at 2% - 10% by weight, preferably 5% or about 5% by weight).
  • the anode can be, for example, a lithium metal or a lithium metal film on a metallic current collector (e.g., copper).
  • CNT: sulfur: PVDF (25:70:5 by weight) are mixed in a dispersing solvent (e.g., n-methyl-2-pyrrolidone (NMP)) to form a slurry or suspension, and the slurry is then coated on an aluminum foil (e.g., using a standard film coating technique such as a Mayer rod or a doctor blade).
  • NMP n-methyl-2-pyrrolidone
  • the film is then dried (e.g., at room temperature for 2 hours) followed by drying (e.g., at 60 °C) under vacuum (e.g., for 12 hours). After drying the film is stored in an inert environment (e.g., an argon-filled glovebox) until cell assembly.
  • lithium foil purity>99.90%)
  • a polyolefin separator e.g., a propylene separator
  • the cells are typically rested (e.g., for 6 hours) prior to testing.
  • a Solartron 1470 battery tester can be used for galvanostatic discharge/charge tests within a voltage range of l.7 - 3.0 V at a current density of 167.5 mA (C/10) to 3350 mA (2C) per gram of sulfur. Voltammetry measurements were performed by an electrochemical workstation (Gamry reference 600) at the rate of 1 mV/s in the range of 1.7 - 3.0 V to investigate the catalytic behavior of the sulfur electrode. All charge/discharge and electrochemical tests were measured in a temperature controlled environment at 25 °C. After charge/discharge cycling, the sulfur cathodes were recovered from the batteries in the Ar-filled glove box, rinsed with dimethyl ether and dried under vacuum.
  • Cathodes can be investigated by Raman spectroscopy (BaySpec's Nomadic, excitation wavelength of 532 nm), Fourier transform infrared (FTIR) spectroscopy (JASCO FT-IR 4100), and/or Scanning electron microscopy (SEM) (JEOL 6330F).
  • Raman spectroscopy BoySpec's Nomadic, excitation wavelength of 532 nm
  • FTIR Fourier transform infrared
  • JASCO FT-IR 4100 JASCO FT-IR 4100
  • SEM Scanning electron microscopy
  • JEOL 6330F Scanning electron microscopy
  • Bruker GADDS/D8 X-ray powder diffraction (XRD) with MacSci rotating Molybdenum anode (k 0.71073) operated at 50 kV generator and 20 mA current was also used to collect the diffraction patterns.
  • Transmission Electron Microscopy Phillips CM-200 200 kV was
  • Figure 10 shows a plot of cyclic voltammetry of pristine CNTs, Pd-filled CNTs, and Pt-filled CNTs in range of 1.6 - 2.9 V versus Li/Li+, wherein all scans rates were 0.5 mV/s.
  • cyclic voltammetry (CV) measurements confirm higher cathode and anodic currents for Pd- and Pt-containing CNTs over pristine CNTs and lower charge to discharge over-potential.
  • Prisitne CNTs cathodes also had broader peaks.
  • Figure 11 shows the capacity retention due to cycling of the pristine CNT, Pd-filled CNT, and Pt- filled CNT lithium sulfur batteries for the first 100 cycles.
  • Lithium sulfur batteries containing Pd-filled CNT cathodes or Pt-filled CNT cathodes retained almost double the capacity of batteries containing pristine CNT cathodes after 100 cycles of full charge and discharge.
  • a lithium sulfur battery can comprise an anode, a cathode, and an electrolyte disposed between the anode and the cathode, where the cathode comprises: a conductive layer (e.g., an aluminum, copper, silver, or gold layer such as an aluminum, copper, silver, or gold foil) coated with a sulfur source; and a carbon structure having a catalyst filled therein without a surface coating of the catalyst on the carbon structure.
  • the catalyst can include, for example, nanoparticles of a platinum group metal (e.g., at least one of ruthenium, rhodium, palladium, osmium, iridium, and platinum).
  • the catalyst can be a palladium nanoparticle catalyst.
  • the carbon structure can include at least one of graphene, fullerenes, amorphous carbons, and carbon nanotubes (e.g., multi-walled carbon nanotubes).
  • the carbon structure can be coated on the conductive layer.
  • the sulfur source can comprise, for example, elemental sulfur, lithium sulfide, lithium polysulfide, or a combination thereof.
  • the lithium sulfur battery can further comprise a separator (e.g., a polyolefin separator such as a polypropylene separator) disposed between the anode and the cathode, the electrolyte being soaked in the separator.
  • a lithium sulfur battery can comprise an anode, a cathode, and a separator including an electrolyte and disposed between the anode and the cathode, where the cathode comprises: a conductive layer (e.g., an aluminum, copper, silver, or gold layer such as an aluminum, copper, silver, or gold foil) coated with a sulfur source; a multi-walled carbon nanotube coated on the conductive layer; and a catalyst filled in an annular cavity of the multiwalled carbon nanotube without a surface coating of the catalyst on the multi-walled carbon nanotube.
  • the catalyst can be, for example, a palladium nanoparticle catalyst.
  • the electrolyte can include a lithium salt.
  • the lithium sulfur battery can further comprise a conductive current collector (e.g., a stainless steel rod) disposed on the cathode and/or a conductive current collector (e.g., a stainless steel rod) disposed on the anode.
  • the separator can be a polyolefin separator (e.g., a polypropylene separator), and/or the electrolyte can be soaked in the separator.

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Abstract

L'invention concerne une batterie au lithium et un procédé de fabrication de celle-ci. La cathode de batterie comprend une structure de carbone remplie d'un catalyseur, par exemple des nanotubes de carbone (CNT) remplis de catalyseur au palladium. La structure de carbone fournit une barrière entre le catalyseur et l'électrolyte assurant une stabilité accrue de l'électrolyte pendant la décharge et la charge d'une batterie.
EP21901629.2A 2020-11-13 2021-11-10 Cathodes de batterie pour une stabilité améliorée Pending EP4244916A1 (fr)

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US17/097,674 US11038160B2 (en) 2017-12-29 2020-11-13 Battery cathodes for improved stability
PCT/US2021/072330 WO2022120315A1 (fr) 2020-11-13 2021-11-10 Cathodes de batterie pour une stabilité améliorée

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EP2494634A1 (fr) * 2009-10-29 2012-09-05 Uchicago Argonne, LLC, Operator Of Argonne National Laboratory Réactions de pression autogène pour fabrication de matériaux pour accumulateur
WO2012177104A2 (fr) * 2011-06-24 2012-12-27 한양대학교 산학협력단 Batterie lithium-air

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