WET-CHEMICALLY PREPARED POLYMERIC LITHIUM PHOSPHORUS OXYNI-TRIDE (LIPON), METHOD FOR THE PREPARATION THEREOF, USES THEREOF, AND BATTERY

Abstract

A polymeric lithium phosphorus oxynitride (LiPON) battery can be prepared by reacting a polymetaphosphonic acid with an organolithium compound to provide a reaction product of LiPON and including the reaction product in the LiPON battery. The LiPON is soluble in solvents selected from the group consisting of dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), toluene and N-methylpyrrolidone (NMP).

Claims

1. (canceled)

2. (canceled)

3. (canceled)

4. A method for preparing a polymeric lithium phosphorus oxynitride (LiPON) battery, the method comprising: reacting a polymetaphosphonic acid of the general formula II ##STR00007## with an organolithium compound to provide a reaction product of the general formula I ##STR00008## and including the reaction product in the LiPON battery.

5. The method according to claim 4, wherein the organolithium compound is selected from the group consisting of n-butyllithium, sec-butyllithium, tert-butyllithium, methyllithium, isopropyllithium; phenyllithium and mixtures thereof.

6. The method according to claim 4, wherein the reaction is carried out in dimethyl sulfoxide (DMSO), a solvent that can be mixed with dimethyl sulfoxide (DMSO), or a mixture of dimethyl sulfoxide (DMSO) and a solvent that can be mixed with dimethyl sulfoxide (DMSO), the solvent being selected from the group consisting of a mixture of dimethyl sulfoxide (DMSO) and toluene.

7. The method according to claim 4, wherein the polymetaphosphinic acid of the general formula II has been prepared by reacting poly(dichlorophosphazene) with dimethyl sulfoxide before being reacted with the organolithium compound, the preparation of the polymetaphosphinic acid of the general formula II and the preparation of the LiPON being performed in one-pot synthesis.

8. The method according to claim 4, wherein, based on the lithium equivalents, 2.3 to 2.5 of the organolithium compound are used in relation to the nitrogen equivalents of the polymetaphosphinic acid of the general formula II.

9. The method according to claim 4, wherein the reaction is carried out over a time period from 12 hours to 5 days, at a temperature of 10 to 30° C., and/or at a concentration of the polymetaphosphinic acid of the general formula II of from 10 to 100 g/l.

10. The method according to claim 4, wherein after the reaction is complete, the polymeric lithium phosphorus oxynitride solidifies by precipitation, crystallization and/or removal of the solvent.

11. The method according to claim 10, wherein the precipitation is carried out by adding acetonitrile.

12. Use of a wet-chemically prepared polymeric lithium phosphorus oxynitride (LiPON), containing a repeating unit of the general formula I ##STR00009## wherein: the LiPON is soluble in solvents selected from the group consisting of dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), toluene and N-methylpyrrolidone (NMP), and the LiPON is used as a solid-state electrolyte.

13. A battery comprising a wet-chemically prepared polymeric lithium phosphorus oxynitride (LiPON), containing a repeating unit of the general formula I ##STR00010## wherein: the LiPON is soluble in solvents selected from the group consisting of dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), toluene and N-methylpyrrolidone (NMP); and the LiPON is used as a solid-state electrolyte.

14. The battery according to claim 13, comprising an anode consisting of lithium or containing lithium, a cathode, and a solid-state electrolyte separating the anode and the cathode, the solid-state electrolyte being made of the LiPON.

15. The battery according to claim 14, wherein the cathode is made of or contains a material selected from the group consisting of lithium nickel cobalt manganese (Li(NiCoMn)O2), lithium manganese oxide spinel (LiMn2O4), lithium cobalt oxide (LiCoO2), lithium iron phosphate (LiFePO4), lithium nickel cobalt aluminum oxide (LiNiCoAlO2), lithium manganese phosphate (LMnP), lithium cobalt phosphate (LCoP), lithium nickel phosphate (LNiP), lithium manganese iron phosphate (LMFP), lithium manganese nickel oxide (LMNO), iron fluoride, copper fluoride, iron copper fluoride; vanadium oxide, metal sulfides, metal silicates, and mixtures and blends thereof.

16. The battery according to claim 14, wherein the anode is made of or contains a material selected from the group consisting of metal lithium, lithium titanate oxide (Li4Ti5O12), lithium-containing silicon, lithium-containing silicon-carbon composites, lithium alloys, with aluminum, with magnesium, with silicon and/or and with tin, and mixtures and blends thereof.

17. (canceled)

18. (canceled)

19. The method according to claim 4, wherein the reaction product is amorphous.

20. The method according to claim 4, wherein the solid-state electrolyte is not produced by sputtering.

21. The method according to claim 20, wherein the solid-state electrolyte is prepared by doctoring, tape casting, and/or pressing.

22. The method according to claim 20, wherein the solid-state electrolyte is amorphous.

23. Use of LiPON according to claim 12, wherein the LiPON is prepared by reacting a polymetaphosphinic acid of the general formula II ##STR00011## with an organolithium compound.

24. The battery according to claim 13, wherein the LiPON is prepared by reacting a polymetaphosphinic acid of the general formula II ##STR00012## with an organolithium compound.

25. The battery according to claim 13, wherein the LIPON is amorphous.

Description

[0033] The present invention will be described in more detail with reference to the following configurations without restricting the invention to the embodiments set out.

[0034] For the synthesis of polymeric LiPON, the polymeric polyphosphazene precursor [NPCl.sub.2].sub.n is usually used as a starting point.

[0035] There are two options for preparing [NPCl.sub.2].sub.n. First, cyclic N.sub.3P.sub.3Cl.sub.6 can be reacted at temperatures of approx. 250° C. with ring opening to form elongate chains (Allcock, H. R., Crane, C. A., Morrissey, C. T., & Olshavsky, M. A. A New Route to the Phosphazene Polymerization Precursors, Cl.sub.3PNSiMe.sub.3 and (NPCl.sub.2), Inorganic Chemistry (1999), 38(2), 280-283), and second, the cationic polymerization of Cl.sub.3P═NSi(CH.sub.3).sub.2 (phosphoranimine), as set out in reaction equation 1, can be carried out with PCl.sub.5 as the initiator (Wang, B. Development of a one-pot in situ synthesis of poly(dichlorophosphazene) from PCl.sub.3, Macromolecules (2005), 38(2), 643-645). The latter provides the option of being able to set the molar mass of the polymer on the basis of the initiator/monomer ratio (reaction equation 1; see below).

[0036] The synthesis of polymeric LiPON took place in two-stage synthesis (product (2.1) was not isolated, but instead directly processed further). Step (2.1) was based on a concept known in the literature (Walsh, E. J., Kaluzene, S., & Jubach, T. The reactions of halocyclophosphazenes with dimethylsulfoxide. Journal of Inorganic and Nuclear Chemistry (1976) 38(3), 397-399) which did not, however, exist for polymers, and step (2.2) was not previously known.

##STR00005##

Synthesis of Polymeric LiPON

State 1: Synthesis of Poly(dichlorophosphazene)—Reaction Equation (1)

[0037] LiN(SiMe.sub.3).sub.2 (5.17 g, 30.9 mmol) was weighed out with a septum in a heated 250 ml Schlenk flask in the glovebox, was dissolved in 120 ml dried toluene in an argon atmosphere and the solution was cooled to 0° C. PCl.sub.3 (2.7 ml, 30.9 mmol) was then added thereto dropwise over a time period of 10 minutes. The reaction mixture was first stirred for 30 minutes at 0° C. and then for 1 hour at room temperature. The resulting white suspension was cooled to 0° C. again and SO.sub.2Cl.sub.2 (2.55 ml, 31.5 mmol) was then added thereto dropwise over a time period of 10 minutes. The resulting SO.sub.2 was bound in a gas wash bottle filled with sodium hydroxide. The reaction mixture was then stirred for 1 hour at 0° C., PCIs (316 mg, 1.52 mmol) was then added thereto, and was lastly stirred overnight at room temperature.

[0038] After approx. 18 hours, the yellow, cloudy solution was filtered over Celite through a fritted glass filter in a heated 250 ml flask and the LiCl was thus removed from the solution. The flask and fritted glass filter were then rinsed twice with a few milliliters of toluene. The solvent was first removed on the rotary evaporator and then in the oil-pump vacuum; this resulted in a viscous, yellow solid.

[0039] Yield: 2.9 g (25.2 mmol, 81%)

[0040] The .sup.31P-NMR spectrum of [NPCl.sub.2].sub.n exhibits a signal at −16.8 ppm in CDCl.sub.3, which corresponds to the literature. The same applies to the FTIR spectrum with bands at 1208 cm-1 (P═N vibration) and 741 cm-1 (P—Cl vibration) (see FIGS. 1a and 1b).

Stage 2: Synthesis of Polymeric LiPON—Reaction Equations (2.1) and (2.2)

[0041] Poly(dichlorophosphazene) from stage 1 (1 g, 8.63 mmol) was placed into a 100 ml flask and 15 ml anhydrous DMSO was added thereto while being slowly stirred in a water bath with a little ice. After 2 hours, the water bath was removed and the reaction solution was stirred for 48 hours at 40° C. in an argon atmosphere.

[0042] The oil bath was then removed and a resulting, colorless solid was scraped off in the flask above the liquid and was added back into the solution. The suspension was treated in the ultrasound bath for 10 minutes and was then slowly stirred for another 18 hours at room temperature. The by-product was then removed using an upstream cold trap over several hours in the oil-pump vacuum. Once the solution had been topped up again to approx. 15 ml DMSO with 3 ml anhydrous DMSO, it was stirred for another 18 hours. The next day, it was washed 4 times with 15 ml anhydrous diethylether and the residues thereof were removed in the oil-pump vacuum.

[0043] Thereafter, the solution was diluted with anhydrous DMSO to a total volume of 30 ml and 7.6 ml of a 2.5 M n-butyllithium/toluene solution (19 mmol, 2.2 eq.) was added thereto dropwise by means of a dropping funnel at the highest stirring speed in a water bath with a little ice. The reaction solution was then stirred for 96 hours at room temperature in an argon atmosphere.

[0044] Volatile components were then removed from the solution in the oil-pump vacuum and said solution was washed 3 times with 30 ml diethylether. The remaining diethylether was then removed in the oil-pump vacuum, 60 ml anhydrous acetonitrile was added to the solution and treated in the ultrasound bath for 10 minutes before the product was filtered out by means of a fritted glass filter. The colorless powder obtained was then washed in the fritted glass filter with approx. 6 ml anhydrous acetonitrile and was then dried in the oil-pump vacuum.

[0045] Yield: 454 mg (5 mmol, 58%)

[0046] After DMSO was added in the second stage, the starting-material signal in the .sup.31P-NMR spectrum disappeared (see FIG. 2) and instead a different signal appeared in DMSO-d6, at approx. +0.3 ppm (see below). Since 85% H.sub.3PO.sub.4 in DMSO-d6 had a shift of +1.0 ppm, the intermediate product had to have a similar to that of phosphoric acid (H.sub.3PO.sub.4).

[0047] Since oxygen and nitrogen generate a similar chemical environment due to their similar electronegativity values, the .sup.31P-NMR of the intermediate product was indicative of the reaction being correct. The intermediate product could be isolated by the DMSO solution having the [H.sub.2PO.sub.2N]˜ being washed three times with anhydrous diethylether before the butyllithium was added and then being precipitated with anhydrous acetonitrile. The colorless powder obtained had the IR spectrum as shown in FIG. 3.

[0048] Since, in this spectrum, the bands of the starting material disappeared and the bands of almost all the functional groups in the expected product appeared at the same time, said product has been produced (also taking into account the .sup.31P-NMR spectrum).

[0049] The addition of butyllithium did not result in any change to the .sup.31P-NMR spectrum; the signal at approx. 0.3 ppm was still present. Therefore, nothing had changed at the bonds directly to the phosphorus atom. This observation is compatible with reaction equation (2.2), since only the bonding states of the nitrogen and oxygen change here. The FTIR spectrum, however, exhibited significant changes (see FIG. 4).

[0050] First, the band for the P—OH bond almost completely disappeared, which was indicative of successful lithiation (O—Li formation, reaction equation 2.2). The band at 1015 cm.sup.−1 was assigned to a P—O bond, i.e. a PO—Li.sup.+ group in the product. The width of this band and the observation that the P—O and P═O bands for the intermediate product were no longer apparent indicated that the negative charge over both oxygen atoms was delocalized (see below on the left), as is known from organic chemistry, e.g. in carboxylates (see below on the right):

##STR00006##

(Right: assumed structure of polymeric LiPON; left: mesomerism in deprotonated carboxylic acids where K.sup.+=cation).

[0051] FIG. 5 shows an exemplary construction of a battery, which can be produced using the polymeric LiPON according to the invention as the solid-state electrolyte. Here, the battery has the construction shown in FIG. 5, with the polymeric LiPON separating the lithium-metal anode and the cathode from one another. The polymeric LiPON can be applied to the cathode material or the anode by means of pressing.

[0052] The use of bulk batteries comprising lithium-metal anodes and the solid-state electrolyte described herein is beneficial for any field in which electrical energy accumulators are relevant. This particularly includes vehicle construction, the electrical industry and the building industry.