Material for negative electrodes, and negative electrodes and batteries comprising this material, and process for producing the material
A material for a battery or an accumulator, especially for a negative electrode of an accumulator, for example, a lithium ion secondary battery, the use of such a material, an electrode that includes such a material, a battery having such an electrode, and a process for producing such a material. The material includes carbon, an alloy and/or a mixture of silicon with at least one element of main group 1 of the Periodic Table of the Elements excluding lithium, and optionally at least one further metallic element and production-related impurities, the elements being distributed within a silicon phase in the case of a mixture, and a binder which binds carbon and the alloy and/or the mixture to give a solid material.
1. A material for a battery, the material comprising:
a) carbon present in a proportion of about 5% to 40% by weight;
b) an alloy and/or a mixture of silicon with at least one element of main group 1 of the Periodic Table of the Elements excluding lithium comprising sodium and/or potassium present in a proportion of 0.01% to 10% by weight, at least one metallic element and production-related impurities, the elements being distributed within a silicon phase in the case of a mixture; and
c) a binder which binds carbon and the alloy and/or the mixture to thereby form a solid material,
wherein the alloy and/or mixture is present in a proportion of more than 40% by weight, and the binder is present in a proportion of 3% to 19% by weight.
2. The material of claim 1 , wherein the at least one element from main group 1 of the Periodic Table of the Elements excluding lithium comprising sodium and/or potassium is present in the alloy and/or the mixture in a proportion of 0.01% to 1.0% by weight.
3. The material of claim 1 , wherein the alloy and/or the mixture is in a form of particles.
4. The material of claim 3 , wherein the particles have an average particle size of less than 500 nm.
5. The material of claim 3 , wherein the particles have an average particle size of less than 200 nm.
6. The material of claim 1 , wherein the carbon is present in a proportion of about 5% to 15% by weight.
7. The material of claim 1 , wherein the carbon is in a form of one of graphite, carbon black and hard carbon.
8. The material of claim 1 , wherein the binder comprises a polysaccharide and/or a styrene-butadiene rubber.
9. The material of claim 8 , wherein the binder comprises sodium carboxymethylcellulose.
10. An electrode for a battery, the electrode comprising:
a material including carbon present in a proportion of about 5% to 40% by weight, an alloy and/or a mixture of silicon with at least one element of main group 1 of the Periodic Table of the Elements excluding lithium comprising sodium and/or potassium present in a proportion of 0.01% to 10% by weight, at least one metallic element and production-related impurities, the elements being distributed within a silicon phase in the case of a mixture, and a binder which binds carbon and the alloy and/or the mixture to thereby form a solid material,
wherein the alloy and/or mixture is present in a proportion of more than 40% by weight, and the binder is present in a proportion of 3% to 19% by weight.
11. A battery comprising:
an electrode composed of a material including carbon present in a proportion of about 5% to 40% by weight, an alloy and/or a mixture of silicon with at least one element of main group 1 of the Periodic Table of the Elements excluding lithium comprising sodium and/or potassium present in a proportion of 0.01% to 10% by weight, at least one metallic element and production-related impurities, the elements being distributed within a silicon phase in the case of a mixture, and a binder which binds carbon and the alloy and/or the mixture to thereby form a solid material,
wherein the alloy and/or mixture is present in a proportion of more than 40% by weight, and the binder is present in a proportion of 3% to 19% by weight.
12. A process for producing a material for a battery, the method comprising:
a) providing carbon in a proportion of about 5% to 40% by weight;
b) providing an alloy and/or a mixture of silicon with at least one element of main group 1 of the Periodic Table of the Elements excluding lithium comprising sodium and/or potassium in a proportion of 0.01% to 10% by weight, and optionally at least one further metallic element and production-related impurities, the elements being distributed within a silicon phase in the case of a mixture;
c) providing a binder which binds carbon and the alloy and/or the mixture to give a solid material; and then
d) mixing the components provided in steps a) to c) and treating the mixture thermally and/or mechanically in order to form the material in solid form,
wherein the alloy and/or mixture is present in a proportion of more than 40% by weight, and the binder is present in a proportion of 3% to 19% by weight.
13. The process of claim 12 , wherein particles of silicon having an average particle size of less than 500 nm are treated with the at least one element of main group 1 of the Periodic Table of the Elements excluding lithium comprising sodium and/or potassium in order to provide the alloy and/or the mixture.
14. The process of claim 12 , wherein particles of silicon having an average particle size of less than 200 nm are treated with the at least one element of main group 1 of the Periodic Table of the Elements excluding lithium comprising sodium and/or potassium in order to provide the alloy and/or the mixture.
15. The process of claim 12 , wherein the alloy and/or the mixture is produced by one of:
reacting solid silicon with the at least one element, present in liquid form at reaction temperature, of main group 1 of the Periodic Table of the Elements excluding lithium comprising sodium and/or potassium; and
reacting solid silicon with the at least one element, present in gaseous form at reaction temperature, of main group 1 of the Periodic Table of the Elements excluding lithium comprising sodium and/or potassium.
16. The process of claim 15 , wherein the at least one element present in gaseous form comprises sodium vapour and/or potassium vapour.
17. The process of claim 12 , wherein the alloy and/or the mixture is produced with the at least one element from main group 1 of the Periodic Table of the Elements excluding lithium comprising sodium and/or potassium in a proportion of 0.01% to 1.0% by weight.
18. The process of claim 12 , wherein the material is produced with the carbon in a proportion of about 5% to 15% by weight.
19. The process of claim 12 , wherein the binder comprises a polysaccharide and/or a styrene-butadiene rubber.
20. The process of claim 19 , wherein the binder comprises sodium carboxymethylcellulose.
21. The process of claim 20 , wherein the material is produced with the binder in a proportion of about 3% to 13% by weight.
22. The process of claim 20 , wherein step d) is performed in the aqueous phase.
23. The process of claim 12 , further including adding a surfactant prior to mixing the components provided in step d).
24. The material of claim 1 , wherein the at least one element from main group 1 of the Periodic Table of the Elements excluding lithium comprising sodium and/or potassium is present in the alloy and/or the mixture in a proportion of 0.01% to 1% by weight.
25. The material of claim 1 , wherein carbon black is present in a proportion of about 10% to 14% by weight, the alloy and/or mixture is present in a proportion of 75% to 85% by weight and the at least one element of main group 1 of the Periodic Table of the Elements excluding lithium is sodium, carboxymethylcellulose is present in a proportion of 6% to 10% by weight, and the specific capacity of the material is approximately 1500 mAh/g to 2000 mAh/g.