Coating and lithiation of inorganic oxidants by reaction with lithiated reductants

Abstract

A method for producing conductive carbon coated particles of an at least partially lithiated electroactive core material comprises the step of premixing an oxidant electroactive material with a metallated reductant followed by chemically reacting the oxidant electroactive material with the metallated reductant, said reductant being a coating precursor, said metal being at least one alkaline and/or at least one alkaline earth metal, and said chemically reacting being performed under conditions allowing reduction and metallation of the electroactive material via insertion/intercalation of the alkaline metal cation(s) and/or the alkaline earth metal cation(s) and coating formation via a polymerisation reaction like polyanionic or radicalic polymerisation of the reductant.

Claims

1. A coated at least partially metallated particulate electroactive material that is crystalline or amorphous, obtained by a process comprising: premixing an oxidant electroactive material with a metallated reductant, followed by chemically reacting the oxidant electroactive material with the metallated reductant, wherein: the metallated reductant is a coating precursor comprising an alkali metal or both an alkali metal and an alkaline earth metal, the chemically reacting is performed under a condition allowing reduction and metallation of the oxidant electroactive material via insertion or intercalation of the alkali metal and/or the alkaline earth metal and coating of the metallated electroactive material with a coating formed from the metallated reductant, and wherein the coating formed from the metallated reductant comprises at least one selected from the group consisting of: carbon nitride formed from Li.sub.2CN.sub.2; carbon boride formed from Li.sub.4BCB; carbon boron nitride formed from a lithium pyrazine precursor; polymeric sulfur nitride formed from Li.sub.9NS.sub.3; and polyacetylene formed from LiHC.sub.2.

2. An electrode comprising: the coated at least partially metallated particulate electroactive material of claim 1, a binder, which is optionally electronically conducting and is optionally in particulate form, and optionally a conductive additive.

3. A method for producing an electrode comprising the coated at least partially lithiated particulate electroactive material of claim 1, the method comprising mixing the coated particulate material with an optionally electronically conducting binder, optionally in particulate form and optionally in the presence of a conductive additive in an aprotic solvent followed by drying.

4. A battery comprising: an electrode of claim 2 as cathode, an anode, and an electrolyte.

5. The coated at least partially metallated particulate electroactive material of claim 1, wherein the condition comprises applying energy in at least one form selected from the group consisting of heat energy, tribological energy, ultrasonic energy, and microwave energy.

6. The coated at least partially metallated particulate electroactive material of claim 1, wherein the metallated reductant comprises an alkali metal comprising lithium and optionally sodium and/or potassium.

7. The coated at least partially metallated particulate electroactive material of claim 1, wherein the reductant of the metallated reductant is oxygen free.

8. The coated at least partially metallated particulate electroactive material of claim 1, wherein the oxidant of the oxidant electroactive material is selected from the group consisting of a transition metal oxide, a hydrated transition metal oxide, a transition metal oxynitride, a transition metal phosphate, a transition metal oxide glass, S, Se, and Si.

9. The coated at least partially metallated particulate electroactive material of claim 8, wherein the oxidant of the oxidant electroactive material is in the form of particles having an average particle size below 10 μm, and wherein the metallated reductant is in the form of particles with an average particle size of less than 10 μm.

10. The coated at least partially metallated particulate electroactive material of claim 1, wherein the coating has an average thickness of 0.5 nm to 30 nm.

11. The coated at least partially metallated particulate electroactive material of claim 1, wherein the condition allowing reduction and metallation of the oxidant electroactive material and coating deposition comprises applying tribological energy by ball milling at a rotation speed of 200 to 1500 rpm for 15 to 45 minutes, wherein a ratio between the weight of the balls and the weight of the sample is in the range from 6:1 to 4:1.

12. The coated at least partially metallated particulate electroactive material of claim 1, wherein the condition allowing reduction and metallation of the oxidant electroactive material and coating deposition comprises a heat treatment with a heating profile providing a slow heating rate of between 50 to 70 K/h for about at least the last hour before reaching the reaction temperature.

13. The coated at least partially metallated particulate electroactive material of claim 12, wherein the heating profile comprises a fast heating rate of 180 K/h-until about 60 K below the reaction temperature, followed by a slow heating rate of about 60 Kh.

14. The coated at least partially metallated particulate electroactive material of claim 1, wherein the coating formed from the metallated reductant comprises carbon nitride formed from Li.sub.2CN.sub.2.

15. The coated at least partially metallated particulate electroactive material of claim 1, wherein the coating formed from the metallated reductant comprises carbon boride formed from Li.sub.4BCB.

16. The coated at least partially metallated particulate electroactive material of claim 1, wherein the coating formed from the metallated reductant comprises carbon boron nitride formed from a lithium pyrazine precursor.

17. The coated at least partially metallated particulate electroactive material of claim 1, wherein the coating formed from the metallated reductant comprises polymeric sulfur nitride formed from Li.sub.9NS.sub.3.

18. The coated at least partially metallated particulate electroactive material of claim 1, wherein the coating formed from the metallated reductant comprises polyacetylene formed from LiHC.sub.2.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings, that show:

(2) FIG. 1: X-Ray Powder Diffraction of the synthesized Li.sub.0.3V.sub.2O.sub.5 compared to the theoretical pattern.

(3) FIG. 2: TEM-picture of Li.sub.0.3V.sub.2O.sub.5 with carbon coating. The inter plane distance corresponds to the a-lattice parameter of Li.sub.0.3V.sub.2O.sub.5.

(4) FIG. 3: EDX-analysis of Li.sub.0.3V.sub.2O.sub.5 with carbon coating (EDX=Energy Dispersive X-ray Analysis).

(5) FIG. 4: Potential vs. specific charge for the Li.sub.0.3V.sub.2O.sub.5 electrode.

(6) FIG. 5: X-Ray Powder Diffraction of the synthesized LiV.sub.2O.sub.5 compared to the theoretical pattern.

(7) FIG. 6: Thermogravimetry of the reaction of Li.sub.2C.sub.2 with V.sub.2O.sub.5.

(8) FIG. 7: Potential vs. specific charge for the LiV.sub.2O.sub.5 electrode.

(9) FIG. 8: X-Ray Powder Diffraction of LiFePO.sub.4 synthesized via heat treatment (450° C.) compared to the theoretical pattern.

(10) FIG. 9: Potential vs. specific charge for the via heat treatment synthesized LiFePO.sub.4 electrode.

(11) FIG. 10: TEM-bright field picture of LiFePO.sub.4 with carbon coating.

(12) FIG. 11: Indexed Fourier Transformation of FIG. 9.

(13) FIG. 12: X-Ray Powder Diffraction of LiV.sub.2O.sub.5 synthesized via ball milling compared to the theoretical pattern.

(14) FIG. 13: Potential vs. specific charge for the via ball milling synthesized LiV.sub.2O.sub.5 electrode.

(15) FIG. 14: TEM-bright field picture of Li.sub.0.3MoO.sub.3 with carbon coating

(16) FIG. 15: Thermogravimetry of the reaction of Li.sub.2C.sub.2 with MoO.sub.3 via ball milling.

(17) FIG. 16: Potential vs. specific charge for the via ball milling synthesized Li.sub.0.3MoO.sub.3 electrode.

(18) FIG. 17: X-Ray Powder Diffraction of LiH.sub.2V.sub.3O.sub.8 synthesized via ball milling.

(19) FIG. 18: Potential vs. specific charge for the via ball milling synthesized LiH.sub.2V.sub.3O.sub.8 electrode.

MODES FOR CARRYING OUT THE INVENTION

(20) Analytical and Investigation Methods:

(21) Electrochemical Measurements:

(22) Galvanostatic measurements were monitored by Astrol, a program from Astrol Electronic AG. A potentiostat (BAT-SMAL, battery cycler) was connected using a serial cable to a personal computer (running Windows XP) via a serial/analog converter. The composition of all electrodes was 73% active material, 15% Super P® Carbon (obtainable from TIMCAL) and 2% polyvinylidene fluoride (PVDF). The materials were mixed in a THF/Toluene 4:1 mixture. Finally the electrodes were dried at 180° C. under air. The only exception was the LiFePO.sub.4 electrode that was dried at 80° C. under vacuum. The measurements were done with fixed currents of 50 A/kg.

(23) The electrolyte was LP30 (obtainable from Merck Chemicals), 1.4 mol/L LiPF.sub.6 in ethylene carbonate/dimethyl carbonate 1/1 by weight. and the counter electrode was a disk of metallic lithium with a diameter of 13 mm and 0.5 mm thickness.

(24) Differential— and Thermogravimetry:

(25) The measurements were performed with a Netzsch STA 409 using corundum crucibles using a heating rate of 10 K/min. The reference powder was corundum, too. The measurements show (see FIGS. 6 and 15) that there is no significant mass loss below the reaction temperature of 600° C. for V.sub.2O.sub.5 and 400° C. for MoO.sub.3. Thus the reactions are completely proceeding to the lithiated oxidants.sub.reduced and carbon.

(26) Powder Diffractometry:

(27) The measurements were performed with a STOE STADI P2 diffractometer in transmission mode with germanium monochromator, CU.sub.ka1=1.54056 Å

(28) Electron Microscopy:

(29) Electron microscopy was performed in a Tecnai F30 microscope (manufactured by FEI) with a field emission gun (FEG), V.sub.acc=300 kV, and C.sub.s=1.2 mm

(30) Experimental Part:

(31) Commercial Reactants and Electrolytes:

(32) Lithium granule 99.9%, Aldrich Graphite powder natural microcrystal grade, APS 2-15 micron, 99.9995%, Alfa Aesar V.sub.2O.sub.5, 99.2%, Alfa Aesar FeCl.sub.3 anhydrous purum, Fluka H.sub.3PO.sub.4 ortho-phosphric acid 85%, Merck MoO.sub.3 99.5%, Sigma Aldrich LiMn.sub.2O.sub.4, Merck PVDF averabe Mw˜534,000 by GPC, Sigma Aldrich LP30; 1M LiPF6 in ethylene carbonate:dimethyl carbonate 1:1 (w/w), Merck LF30; 1M Li(C2F5)3PF3 in ethylene carbonate:dimethyl carbonate 1:1 (w/w), Merck, highly stable
Synthesized Materials [Source or Description of Method]:
Oxidants: FePO4 [C. Delacourt, Solid State Ionics, 173, 113-118, 2004] MnO2 [Asulab] NbNO [Nesper, R., Wang X.-J., EP 2 378 596 A1] Glasses of V2O5 and MoO3 [Sakurei et al. U.S. Pat. No. 4,675,260]
Metallated Reductants: Li.sub.2C.sub.2 [Armbruster, Dissertation (thesis), ETH Zurich No. 17553, 2008] LiNaC.sub.2 [R. Nesper, Habilitationsschrift, Stuttgart, 1998] LiKC.sub.2 [R. Nesper, Habilitationsschrift, Stuttgart, 1998] Li.sub.2NCN [Sokolov, Trudy po Khimi/Khimicheskoi Tekhnologii (2), 18-19, 1973] Li.sub.3BN.sub.2 [Yamane, Journal of Solid State Chemistry 71(1), 1-11, 1987]
Heat Treatment:

EXAMPLE 1

(33) FIGS. 1 to 4:
1.5Li.sub.2C.sub.2+10V.sub.2O.sub.5.fwdarw.10Li.sub.0.3V.sub.2O.sub.5+3C.sub.surface

(34) 1.8 g (10 mmol) V.sub.2O.sub.5 and 0.0569 g (1.5 mmol) Li.sub.2C.sub.2 were mixed in a mortar. Then the mixture was heated to 600° C. using a heating ramp of 180° C./h and kept at 600° C. for 0.5 hours.

EXAMPLE 2

(35) FIGS. 5 to 7:
5Li.sub.2C.sub.2+10V.sub.2O.sub.5.fwdarw.10LiV.sub.2O.sub.5+10C.sub.surface

(36) 1.8 g (10 mmol) V.sub.2O.sub.5 and 0.1895 g (5 mmol) Li.sub.2C.sub.2 were mixed in a mortar. Then the mixture was heated to 600° C. using a heating ramp of 180° C./h and kept at 600° C. for 0.5 hours.

EXAMPLE 3

(37) FIGS. 8 to 11:
3Li.sub.2C.sub.2+6FePO.sub.4.fwdarw.6LiFePO.sub.4+6C.sub.surface

(38) 0.905 g (6 mmol) FePO.sub.4 and 0.114 g (3 mmol) Li.sub.2C.sub.2 were mixed in a mortar. Then the mixture was heated to 450° C. using a heating ramp of 180° C./h and kept at 450° C. for 2 hours.

(39) Ball Milling:

(40) The starting materials indicated below were premixed in a mortar before reacted in a Fritsch Pulverisette 6 with 400 rpm for 0.5 hours and at a ratio between the weight of the balls and the weight of the sample of 1:5.

EXAMPLE 4

(41) FIGS. 12 and 13:
5Li.sub.2C.sub.2+10V.sub.2O.sub.5.fwdarw.10LiV.sub.2O.sub.5+10C.sub.surface

(42) 1.8 g (10 mmol) V.sub.2O.sub.5 and 0.1895 g (5 mmol) Li.sub.2C.sub.2 were premixed in a mortar. Then the mixture was reacted in a Fritsch Pulverisette 6 with 400 rpm for 0.5 hours.

EXAMPLE 5

(43) FIGS. 14 to 16:
1.5Li.sub.2C.sub.2+10MoO.sub.3.fwdarw.10Li.sub.0.3MoO.sub.3+3C.sub.surface

(44) 1.4394 g (10 mmol) MoO.sub.3 and 0.0569 g (1.5 mmol) Li.sub.2C.sub.2 were premixed in a mortar. Then the mixture was reacted in a Fritsch Pulverisette 6 with 400 rpm for 0.5 hours.

EXAMPLE 6

(45) FIGS. 17 and 18:
5Li.sub.2C.sub.2+10H.sub.2V.sub.3O.sub.8.fwdarw.10LiH.sub.2V.sub.3O.sub.8+10C.sub.surface

(46) 2.8284 g (10 mmol) H.sub.2V.sub.3O.sub.8 and 0.1895 g (5 mmol) Li.sub.2C.sub.2 were premixed in a mortar. Then the mixture was reacted in a Fritsch Pulverisette 6 with 400 rpm for 0.5 hours.

EXAMPLE 7

(47) Electrode Preparation

(48) From the coated particulate materials described above electrodes were prepared by mixing 73% coated LiEAM 15% Super P® Carbon (obtainable from TIMCAL) and 2% polyvinylidene fluoride (PVDF) in a THF/Toluene 4:1 mixture and then drying at 180° C. under air, except for the LiFePO.sub.4 electrode that was dried at 80° C. under vacuum.

(49) Analytical data and electrochemical behaviour is shown in the Figures as indicated to each example.

(50) While there are shown and described presently preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.