Ion conducting membrane, making method thereof, secondary battery comprising the same
An ion conducting membrane includes: a membrane substrate including a membrane-forming particle and an ion conductive particle disposed on the membrane substrate, wherein the membrane-forming particle include an expandable material, and the ion conductive particle is exposed on both an upper surface and an opposing lower surface of the membrane substrate.
1. An ion conducting membrane, comprising:
a membrane substrate comprising a membrane-forming particle, and
an ion conductive particle disposed on the membrane substrate,
wherein the membrane-forming particle comprise an expandable material, and
the ion conductive particle is exposed on both an upper surface and an opposing lower surface of the membrane substrate.
2. The ion conducting membrane of claim 1 , wherein the membrane substrate has an electrical conductivity of less than 10 −7 Siemens per centimeter.
3. The ion conducting membrane of claim 1 , wherein the expandable material comprises a thermoplastic resin, a thermal fusion resin, or a combination thereof.
4. The ion conducting membrane of claim 1 , wherein the membrane substrate comprises a fused product of at least two expanded membrane-forming particles.
5. The ion conducting membrane of claim 1 , wherein
the membrane-forming particle comprises a hollow core, and
a shell surrounding the core, wherein the shell comprises the expandable material.
6. The ion conducting membrane of claim 5 , wherein the membrane-forming particle consists of the expandable material and comprises at least two pores thereinside.
7. The ion conducting membrane of claim 1 , wherein a diameter of the membrane-forming particles before expansion satisfies Equation 1:
Equation 1
Dos ≤Di/(2*N 1/3 )
wherein
Di is a diameter of the ion conductive particles,
Dos is a diameter of the membrane-forming particles before expansion, and
N is a ratio of a volume after expansion relative to a volume before expansion of the membrane-forming particles.
8. The ion conducting membrane of claim 7 , wherein Di, Dos, and N satisfy Equation 2:
Equation 2
Dos ≤Di/(0.155*N 1/3 ).
9. The ion conducting membrane of claim 7 , wherein N is from about 10 to about 500.
10. The ion conducting membrane of claim 1 , wherein the ion conductive particle conducts a lithium ion, a sodium ion, a proton, a potassium ion, an iron ion, a zinc ion, a magnesium ion, a potassium ion, or a combination comprising at least one of the foregoing.
11. The ion conducting membrane of claim 1 , wherein the ion conductive particle has an ion conductivity of about 1×10 −5 Siemens per centimeter to about 1×10 −3 Siemens per centimeter.
12. The ion conducting membrane of claim 1 , wherein the ion conductive particle comprises a sulfide, an oxide, a nitride, or a combination comprising at least one of the foregoing.
13. The ion conducting membrane of claim 1 , wherein
the ion conductive particle comprises ZrO 2 , AlO 3 , a compound represented by Chemical Formula 1 to Chemical Formula 4
Chemical Formula 1
Li 3 La (2/3-x) TiO 3 ,
Chemical Formula 2
Li y La 3 M 1 2 O 12 ,
Chemical Formula 3
Li( 2-2z )Zn( 1-z )GeO 4 ,
Chemical Formula 4
LiM 2 2 (PO 4 ) 3 ,
or a combination comprising at least one of the foregoing,
wherein, in Chemical Formula 1 to Chemical Formula 4,
M 1 is zirconium, niobium, tantalum, antimony, bismuth, or a combination comprising at least one of the foregoing,
M 2 is germanium, titanium, hafnium, zirconium, or a combination comprising at least one of the foregoing, and
0 ≤x ≤2/3, 5 ≤y≤7, and 0 ≤z≤1.
14. The ion conducting membrane of claim 1 , wherein the ion conductive particle has a specific gravity which is greater than a specific gravity of the membrane-forming particle.
15. The ion conducting membrane of claim 1 , wherein a thickness of the ion conducting membrane is from about 15 micrometers to about 100 micrometers.
16. A method of making the ion conducting membrane of claim 1 , the method comprising:
distributing the membrane-forming particle on a first substrate;
distributing the ion conductive particle on the first substrate; and
compressing the membrane-forming particle and the ion conductive particle to make the ion conducting membrane.
17. The method of claim 16 , wherein the distributing of the ion conductive particle is after the distributing of the membrane-forming particle.
18. The method of claim 17 , wherein further comprising vibrating the first substrate after distribution of the ion conductive particles to settle the ion conductive particle.
19. The method of claim 16 , wherein the compressing the membrane-forming particles and the ion conductive particles further comprises disposing a second substrate on the distributed membrane-forming particle, the ion conductive particle, and the first substrate, and pressing the first substrate, the membrane-forming particle, the ion conductive particle, and the second substrate.
20. The method of claim 19 , wherein the pressing is performed at a pressure of about 1 megaPascal to about 50 megaPascals.
21. The method of claim 19 , wherein the compressing the membrane-forming particle and the ion conductive particle further comprises heating the distributed membrane-forming particle and ion conductive particle.
22. The method of claim 21 , wherein the heating is performed at a temperature of about 120° C. to about 300° C. for about 15 seconds to about 5 minutes.
23. A secondary battery, comprising:
a positive electrode;
a negative electrode; and
the ion conducting membrane according to claim 1 between the negative electrode and the positive electrode.