US2016344016A1PendingUtilityA1

Anode battery materials and methods of making the same

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Assignee: BISWAL SIBANI LISAPriority: Aug 19, 2011Filed: Apr 14, 2016Published: Nov 24, 2016
Est. expiryAug 19, 2031(~5.1 yrs left)· nominal 20-yr term from priority
Inventors:Sibani Lisa BiswalMadhuri ThakurMichael S. WongSteven L. SinsabaughMark J. Isaacson
C25F 3/12H01B 1/04H01M 4/622H01M 4/0442C25F 5/00H01M 4/134H01M 4/1395H01M 10/0525H01M 4/386H01M 4/044H01M 4/621H01M 4/0471Y02E60/10
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Claims

Abstract

In some embodiments, the present invention provides methods of preparing porous silicon films and particles by: (1) etching a silicon material by exposure of the silicon material to a constant current density in a solution (e.g., hydrofluoric acid solution) to produce a porous silicon film over a substrate; and (2) separating the porous silicon film from the substrate by gradually increasing the electric current density in sequential increments. The methods of the present invention may also include a step of associating the porous silicon film with a binding material, such as polyacrylonitrile (PAN). The methods of the present invention may also include a step of splitting the porous silicon film to form porous silicon particles. Additional embodiments of the present invention pertain to methods of preparing porous silicon particles and anode materials that may be derived from the porous silicon films and porous silicon particles of the present invention.

Claims

exact text as granted — not AI-modified
What is claimed is: 
     
         1 . A method of preparing a porous silicon film, wherein the method comprises:
 etching a silicon material,
 wherein the etching comprises exposure of the silicon material to an electric current density, and 
 wherein the etching produces a porous silicon film over a silicon substrate; and 
   separating the porous silicon film from the silicon substrate,
 wherein the separating comprises a gradual increase of the electric current density in sequential increments. 
   
     
     
         2 . The method of  claim 1 , wherein the silicon material comprises a silicon wafer. 
     
     
         3 . The method of  claim 1 , wherein the etching of the silicon material further comprises use of an acid. 
     
     
         4 . The method of  claim 3 , wherein the acid comprises hydrofluoric acid. 
     
     
         5 . The method of  claim 1 , wherein the gradual increase of the electric current density during the separating step comprises an increase of the electric current density by about 1-2 mA/cm 2  per sequential increment. 
     
     
         6 . The method of  claim 5 , wherein the gradual increase of the electric current density during the separating step comprises an increase of the electric current density by about 1-2 mA/cm 2  per sequential increment for at least 5 to 10 increments. 
     
     
         7 . The method of  claim 1 , wherein the formed porous silicon film comprises a plurality of pores, wherein the plurality of pores comprise diameters between about 1 nanometers to about 5 micrometers. 
     
     
         8 . The method of  claim 7 , wherein the plurality of pores comprise diameters between about 500 nanometers to about 3 micrometers. 
     
     
         9 . The method of  claim 1 , wherein the formed porous silicon film has a thickness ranging from about 10 micrometers to about 200 micrometers. 
     
     
         10 . The method of  claim 1 , wherein the formed porous silicon film comprises pores that span at least 50% of a thickness of the porous silicon film. 
     
     
         11 . The method of  claim 1 , wherein the formed porous silicon film comprises pores that span an entire thickness of the porous silicon film. 
     
     
         12 . The method of  claim 1 , further comprising a step of associating the porous silicon film with a binding material. 
     
     
         13 . The method of  claim 12 , wherein the binding material is selected from the group consisting of binders, carbon materials, polymers, metals, additives, and combinations thereof. 
     
     
         14 . The method of  claim 12 , wherein the binding material comprises a polymer. 
     
     
         15 . The method of  claim 14 , wherein the polymer is selected from the group consisting of polyacrylonitrile (PAN), polyvinylidene difluoride (PVDF), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), and combinations thereof. 
     
     
         16 . The method of  claim 12 , wherein the binding material is carbonized. 
     
     
         17 . The method of  claim 12 , wherein the binding material comprises a carbonized polyacrylonitrile. 
     
     
         18 . The method of  claim 1 , further comprising a step of splitting the porous silicon film into particles. 
     
     
         19 . The method of  claim 18 , wherein the splitting forms particles comprising diameters from about 1 μm to about 50 μm. 
     
     
         20 . The method of  claim 18 , wherein the splitting occurs by at least one of physical grinding, crushing, sonication, ultrasonic fracture, pulverization, ultrasonic pulverization, and combinations thereof. 
     
     
         21 . A method of preparing porous silicon particles, wherein the method comprises:
 etching a silicon material,
 wherein the etching comprises exposure of the silicon material to an electric current density, and 
 wherein the etching produces a porous silicon film over a silicon substrate; 
   separating the porous silicon film from the silicon substrate, wherein the separating comprises a gradual increase of the electric current density in sequential increments; and   splitting the porous silicon film into particles.   
     
     
         22 . The method of  claim 21 , wherein the silicon material comprises a silicon wafer. 
     
     
         23 . The method of  claim 21 , wherein the etching comprises use of hydrofluoric acid. 
     
     
         24 . The method of  claim 21 , wherein the gradual increase of the electric current density during the separating step comprises an increase of the electric current density by about 1-2 mA/cm 2  per sequential increment for at least 5 to 10 increments. 
     
     
         25 . The method of  claim 21 , further comprising a step of associating the porous silicon particle with a binding material. 
     
     
         26 . The method of  claim 25 , wherein the binding material is selected from the group consisting of binders, carbon materials, polymers, metals, additives, and combinations thereof. 
     
     
         27 . The method of  claim 25 , wherein the binding material comprises a polymer. 
     
     
         28 . The method of  claim 27 , wherein the polymer is selected from the group consisting of polyacrylonitrile (PAN), polyvinylidene difluoride (PVDF), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), and combinations thereof. 
     
     
         29 . The method of  claim 25 , wherein the binding material is carbonized. 
     
     
         30 . The method of  claim 25 , wherein the binding material comprises a carbonized polyacrylonitrile. 
     
     
         31 . The method of  claim 21 , wherein the splitting forms porous silicon particles comprising diameters from about 1 μm to about 50 μm. 
     
     
         32 . The method of  claim 21 , wherein the splitting occurs by at least one of physical grinding, crushing, sonication, ultrasonic fracture, pulverization, ultrasonic pulverization, and combinations thereof. 
     
     
         33 . The method of  claim 21 , wherein the formed porous silicon particle comprises a plurality of pores, wherein the plurality of pores comprise diameters between about 1 nanometer to about 5 micrometers. 
     
     
         34 . The method of  claim 33 , wherein the plurality of pores comprise diameters between about 500 nanometers to about 3 micrometers. 
     
     
         35 . An anode material for lithium ion batteries, wherein the anode material comprises
 a porous silicon film comprising a plurality of pores; and   a binding material associated with the porous silicon film, wherein the binding material is selected from the group consisting of binders, carbon materials, polymers, metals, additives, and combinations thereof.   
     
     
         36 . The anode material of  claim 35 , wherein the plurality of pores comprise diameters between about 1 nanometer to about 5 micrometers. 
     
     
         37 . The anode material of  claim 36 , wherein the plurality of pores comprise diameters between about 500 nanometers to about 3 micrometers. 
     
     
         38 . The anode material of  claim 35 , wherein the porous silicon film is coated with the binding material. 
     
     
         39 . The anode material of  claim 35 , wherein the binding material comprises carbonized polyacrylonitrile. 
     
     
         40 . The anode material of  claim 35 , wherein the formed porous silicon film has a thickness ranging from about 10 micrometers to about 200 micrometers. 
     
     
         41 . The anode material of  claim 35 , wherein the porous silicon film comprises pores that span at least 50% of a thickness of the porous silicon film. 
     
     
         42 . The anode material of  claim 35 , wherein the porous silicon film comprises pores that span an entire thickness of the porous silicon film. 
     
     
         43 . The anode material of  claim 35 , wherein the anode material has a capacity of at least about 600 mAh/g, and a coulombic efficiency of at least about 90%.

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