Stabilized lithium metal impressions coated with alloy-forming elements and method for production thereof
The invention relates to particulate lithium metal composite materials, stabilized by alloy-forming elements of the third and fourth primary group of the PSE and method for production thereof by reaction of lithium metal with film-forming element precursors of the general formulas (I) or (II): [AR 1 R 2 R 3 R 4 ]Li x (I), or R 1 R 2 R 3 A-O-AR 4 R 5 R 6 (II), wherein R 1 R 2 R 3 R 4 R 5 R 6 =alkyl (C 1 -C 12 ), aryl, alkoxy, aryloxy-, or halogen (F, Cl, Br, I), independently of each other; or two groups R represent together a 1,2-diolate (1,2-ethandiolate, for example), a 1,2- or 1,3-dicarboxylate (oxalate or malonate, for example) or a 2-hydroxycarboxylate dianion (lactate or salicylate, for example); the groups R 1 to R 6 can comprise additional functional groups, such as alkoxy groups; A=boron, aluminum, gallium, indium, thallium, silicon, germanium, tin, lead; x=0 or 1 for B, Al, Ga, In, Tl; x=0 for Si, Ge, Sn, Pb; in the case that x=0 and A=B, Al, Ga, In, Tl, R 4 is omitted, or with polymers comprising one or more of the elements B, Al, Ga, In, Tl, Si, Ge, Sn, Pb, at temperatures between 50 and 300° C., preferably above the melting temperature of lithium of 180.5° C., in an organic, inert solvent.
1. A method for producing a stabilized particulate lithium metal, the method comprising:
bringing lithium metal into contact with one or more passivating agents in a range of 180.5° C. to 300° C. in an inert organic solvent; wherein the one or more passivating agents is/are of formula I or formula II, where:
[AR 1 R 2 R 3 R 4 ]Li x (I)
R 1 R 2 R 3 A-O-AR 4 R 5 R 6 (II)
wherein
each of R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 is independently of one another alkyl (C 1 -C 12 ), aryl, alkoxy, aryloxy or halogen or two radicals R together denote a 1,2-diolate, a 1,2- or 1,3-dicarboxylate or a 2-hydroxycarboxylate dianion;
radicals R 1 to R 6 may contain additional functional groups,
A is selected from the group consisting of boron, aluminum, gallium, indium, thallium, silicon, germanium, tin and lead;
x is 0 or 1 when A is boron, aluminum, gallium, indium, thallium; and
x is 0 when A is silicon, germanium, tin or lead;
wherein when x is 0 and A is boron, aluminum, gallium, indium or thallium, then R 4 is omitted, and
wherein the lithium metal has a content of sodium of less than 200 ppm.
2. The method according to claim 1 , wherein two radicals R together denote 1,2-ethanediolate, oxalate, malonate, salicylate, glycolate or lactate.
3. The method according to claim 1 , wherein the molar ratio between the lithium metal and the one or more passivating agents is 100:0.01 to 100:5.
4. The method according to claim 1 , wherein the molar ratio between the lithium metal and the one or more passivating agents is 100:0.05 to 100:1.
5. The method according to claim 1 , wherein inert organic solvent is selected from the group consisting of hexane, heptane, octane, decane, undecane, dodecane, toluene, ethylbenzene and cumene.
6. The method according to claim 1 , wherein an additional coating step is performed by bringing the stabilized particulate lithium metal into contact with the one or more passivating agents at temperature of less than 180.5° C.
7. The method according to claim 1 , wherein the stabilized particulate lithium metal has a core of metallic lithium which is surrounded with an outer passivating layer containing one or more elements of main groups 3 and/or 4 of the periodic table of elements that can be alloyed with lithium and wherein one or more elements of main groups 3 and/or 4 is/are present in the outer passivating layer in elemental form or as an alloy with lithium and the stabilized particulate lithium metal has an average particle size of max. 5000 μm.
8. The method according to claim 7 , wherein the stabilized particulate lithium metal has an average particle size of max. 1000 μm.
9. The method according to claim 7 , wherein the stabilized particulate lithium metal has an average particle size of max. 300 μm.
10. The method according to claim 7 , wherein the lithium metal is spherical lithium metal selected from lithium powder or granules of ball shaped particles.
11. The method according to claim 1 , wherein the lithium metal has a content of sodium in an amount of less than 200 ppm.
12. The method according to claim 1 , wherein the lithium metal has a content of sodium in an amount of less than 100 ppm.
13. The method according to claim 1 , wherein the lithium metal has a content of sodium in an amount of less than 50 ppm.
14. The method according to claim 1 , wherein the one or more passivating agents are not gaseous, acidic, caustic, or toxic passivating agents.