SURFACE STRUCTURED INTERPHASE BASED ON PHASE SEPARATION POROUS FILM FOR STABLE LITHIUM METAL ANODE

1 . A rechargeable lithium metal battery, comprising:

a lithium metal negative electrode;

a cycling performance-enhancing porous polymer film disposed on the lithium metal negative electrode, the cycling performance-enhancing porous polymer film comprising polar functional groups and having:

pores having an average diameter ranging from 100 nm to 40 microns;

a porosity between 50% and 90%,

a thickness between 10 μm and 100 μm,

a Gurley value lower than 30 s/100 cc, and

a tensile strength between 0.5 MPa and 5 MPa;

a separator;

an electrolyte; and

a positive electrode;

wherein the cycling performance-enhancing porous polymer film is configured to trap detached or dislodged components of the solid electrolyte interphase (SEI) that form during battery cycling, and to retain these components within its porous structure for potential reincorporation into the SEI during subsequent charge-discharge cycles, thereby enhancing SEI stability and improving cycling performance;

wherein the battery retains at least 90% of discharge capacity after at least 500 charge-discharge cycles at a rate of 1C.

2 . The rechargeable lithium metal battery of claim 1 , wherein the porous polymer film comprises one or more of polyvinylidene difluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), copolymers of polyacrylonitrile (PAN), polyacrylate copolymers, polystyrene copolymers, polymethyl methacrylate (PMMA) copolymers, polyvinylpyrrolidone (PVP) and its copolymers, polyetherimide (PEI) and its copolymers, polysulfone and its copolymers, polyimide (PI) and its copolymers, polyphenylene sulfide (PPS), polyether sulfone (PES) and its copolymers, polydimethylsiloxane (PDMS) and its copolymers, cellulose acetate (CA), or cellulose.

3 . The rechargeable lithium metal battery of claim 2 , wherein the cycling performance-enhancing porous polymer film further comprises an additive selected from one or more of carbon nanotubes, vapor-grown carbon fibers, graphene, metal-organic frameworks (MOFs), and conducting polymers.

4 . The rechargeable lithium metal battery of claim 3 , wherein the MOF is selected from MOF-808, MOP-17, UiO-66, ZIF-8, ZIF-67, or HKUST-1.

5 . The rechargeable lithium metal battery of claim 3 , wherein the conducting polymer is selected from polyaniline (PANI), polypyrrole (PPY), polythiophene, or poly(3,4-ethylenedioxythiophene) (PEDOT).

6 . The rechargeable lithium metal battery of claim 1 , wherein the lithium metal negative electrode comprises a lithium metal foil laminated on a copper current collector.

7 . The rechargeable lithium metal battery of claim 6 , wherein the lithium metal foil has a thickness of 50 μm or less.

8 . The rechargeable lithium metal battery of claim 1 , wherein the positive electrode includes one or more of lithium iron phosphate, lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, spinel type lithium manganese oxide, or spinel type lithium nickel manganese oxide.

9 . The rechargeable lithium metal battery of claim 1 , further comprising a separator disposed between the negative electrode and the positive electrode.

10 . The rechargeable lithium metal battery of claim 1 , wherein the cycling performance-enhancing porous polymer film promotes uniform lithium-ion flux across the electrode surface and mitigates dendritic lithium growth during repeated cycling.

11 . The rechargeable lithium metal battery of claim 1 , wherein the trapped detached or dislodged components of the SEI are re-integrated into the SEI layer during subsequent lithiation/delithiation cycles.

12 . A method of fabricating the rechargeable lithium metal battery of claim 1 , comprising:

forming the cycling performance-enhancing porous film by a phase separation technique followed by subsequent drying;

laminating the cycling performance-enhancing porous polymer film onto the lithium metal negative electrode; and

assembling the negative electrode, positive electrode, separator, and electrolyte to form the rechargeable lithium metal battery.

13 . The method of claim 12 , wherein the phase separation technique includes depositing a polymer film by depositing a polymer solution onto a substrate followed by immersion into a bath that includes a polymer solvent and a polymer non-solvent.

14 . The method of claim 13 , wherein the polymer solution has a concentration ranging from 5% to 30%.

15 . The method of claim 13 , wherein the solvent is selected from one or more of acetone, chloroform, tetrahydrofuran (THF), dimethylformamide (DMF), dimethylacetamide (DMAc), N-Methyl pyrrolidone (NMP), dimethyl sulfoxide (DMSO); and the non-solvent is selected from one or more of deionized water, ethanol, methanol, glycerin, glycerol, butanol, hexanol, or octanol.

16 . The method of claim 13 , wherein the wet thickness of the deposited polymer solution on the substrate is 50 to 300 μm.

17 . The method of claim 13 , wherein the casting temperature of forming the cycling performance-enhancing porous film ranges from 25° C. to 80° C.

18 . The method of claim 13 , wherein the substrate deposited with the polymer film is exposed at room temperature for 5 minutes to 60 minutes before the immersion.

19 . The method of claim 12 , wherein the immersion time ranges from 1 hour to 24 hours.

20 . The method of claim 12 , wherein the substrate is a glass plate, polyethylene terephthalate (PET) film, polyethylene (PE) film, polypropylene (PP) film, or polytetrafluoroethylene (PTFE) film.