Low resistance composite silicon-based electrode
A silicon-based electrode forms an interface with a layer pair being: 1. a thin, semi-dielectric layer made of a lithium (Li) compound, e.g. lithium fluoride, LiF, disposed on and adheres to the electrode surface of the silicon-based electrode and 2. an molten-ion conductive layer of a lithium containing salt (lithium salt layer) disposed on the semi-dielectric layer. One or more device layers can be disposed on the layer pair to make devices such as energy storage devices, like batteries. The interface has a low resistivity that reduces the energy losses and generated heat of the devices.
1. An energy storage device comprising:
a composite electrode comprising:
a silicon-based electrode;
a semi-dielectric layer directly disposed on the silicon-based electrode, the semi-dielectric layer having a semi-dielectric layer thickness between 15 nanometers (nm) and 30 nm;
a molten-ion conductive layer disposed on the semi-dielectric layer, the molten-ion conductive layer and semi-dielectric layer forming a layer pair, the molten-ion conductive layer being made of a lithium containing salt that is highly conductive to lithium ions, the layer pair being on a trench bottom of a trench in the silicon-based electrode;
an anode disposed on the composite electrode and within the trench;
an electrolyte layer disposed on the anode;
a cathode electrode disposed on the electrolyte layer; and
a separator layer preventing electrode flow between the anode and the cathode, wherein the composite electrode has a resistivity less than 40 ohm-cm 2 .
2. The composite electrode, as in claim 1 , with a charge-transfer time constant of less than 2.25E-6 seconds.
3. The composite electrode, as in claim 1 , where the semi-dielectric layer thickness is between 18 nm and 23 nm.
4. The composite electrode, as in claim 1 , where the semi-dielectric layer is made of a lithium compound.
5. The composite electrode, as in claim 4 , where the lithium compound is one or more of the following: lithium fluoride, LiF, lithium niobium oxide, lithium aluminate (LiAlO 2 ), lithium titanate (Li 2 TiO 3 ), and lithium niobite (LiNbO 3 ).
6. The composite electrode, as in claim 4 , where the lithium compound is a lithiated version of one or more of the following: titanium dioxide, niobium oxide, rubidium oxide, tungsten oxide, aluminum oxide, zinc oxide, and zirconium oxide.
7. The composite electrode, as in claim 1 , where the where the semi-dielectric layer is made of one or more of the following: titanium dioxide, niobium oxide, rubidium oxide, tungsten oxide, aluminum oxide, zinc oxide, and zirconium oxide.
8. The composite electrode, as in claim 1 , where the lithium containing salt is one or more of the following materials: lithium hexafluorophosphate, lithium perchlorate, lithium trifluoromethanesulfonate, lithium fluoride, LiBF 4 , LiBF 6 , lithium chloride, lithium phosphate compounds, lithium bromide compounds, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium difluoro(oxalato)borate (LiDFOB), and lithium bis(oxalato)borate(LiBOB).
9. The composite electrode, as in claim 1 , where the molten-ion conductive layer has a molten-ion conductive layer thickness between 1 nm to 50 nm.
10. The composite electrode, as in claim 1 , where the silicon-based electrode is made of one or more of the following materials: a bulk silicon, a crystalline silicon, a non-crystalline silicon, a doped silicon, a boron doped silicon, a porous silicon, a non-porous silicon, a silicon germanium alloy, and a carbon-doped silicon-based alloy.
11. The composite electrode, as in claim 1 , further comprising an electrode contact made of one or more of the following: a conductive material, a metal, a metal nitride, tungsten (W), copper (Cu), titanium (Ti), platinum (Pt), nickel (Ni), aluminum (Al), gold (Au), and titanium nitride (TiN).
12. The composite electrode, as in claim 1 , where the layer pair is directly disposed on a silicon-based electrode so that a pair bottom surface of the layer pair is in direct physical and electrical contact with an electrode pair surface of the silicon-based electrode, and where an electrode interface is where the pair bottom surface and the electrode pair surface are in contact.
13. The device, as in claim 1 , where the electrolyte layer is one of the following: a solid polymer electrolyte (SPE), a solid electrolyte, a hybrid polymer/solid electrolyte, and a liquid electrolyte.
14. The device, as in claim 10 , composed of the composite have a charge-transfer time constant of less than 2.25E-6 seconds.
15. The device, as in claim 10 , where the silicon-based electrode is made of a boron doped crystalline silicon, the semi-dielectric layer is made of LiF, the molten ion conductive layer is made of bis(trifluoromethanesulfonyl)imide (LiTFSI), and the electrolyte layer is made of a solid polymer electrolyte (SPE) which further is made from a mixture of polycaprolactone, succinonitrile (SN), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).