Membranes suitable for use as separators and electrochemical cells including such separators
Disclosed are membranes suitable for use as separators in electrochemical cells as well as electrochemical cells, where the membranes are configured to substantially reduce the passage of multivalent ions therethrough without substantially reducing the permeability of the membranes to lithium ions.
1. An electrochemical cell, comprising:
a. an electrode assembly including:
i. at least one positive electrode having a height, a breadth and a thickness bearing a positive active material on at least one face thereof;
ii. at least one negative electrode having a height, a breadth and a thickness bearing a negative active material on at least one face thereof, facing said positive electrode; and
iii. a separator disposed between said positive electrode and said negative electrode and electrically insulating said positive electrode from said negative electrode; and
b. an electrolyte contacting said positive electrode, said negative electrode and said separator;
said separator a membrane permeable to lithium ions and including:
a support sheet; and on said support sheet, binding functions configured to bind multivalent cations preferentially to lithium ions
wherein said support sheet comprises a sheet of polymer to which at least one type of said binding function is grafted, and
wherein said support sheet comprises an aminoethylphosphonic acid PPO polymer derivative, including aminoethylphosphonic acid residues as a said binding function.
2. The electrochemical cell of claim 1 , being a lithium-ion secondary electrochemical cell, wherein:
said positive-active material is a lithium-ion containing positive active material;
said negative-active material is a lithium-ion intercalating negative active material; and
wherein said electrolyte includes lithium ions.
3. The electrochemical cell of claim 1 , further comprising on said support sheet, lithium-permeation functions configured to enhance the permeability of the membrane to lithium ions.
4. The electrochemical cell of claim 3 , wherein said support sheet comprises a sulfonated polysulfone polymer derivative and an iminodiacetic acid PPO polymer, includes sulfonic groups as said lithium-permeation function and iminodiacetic groups as said binding function.
5. The electrochemical cell of claim 3 , wherein said support sheet comprises a fluorinated sulfonated polysulfone polymer derivative and an iminodiacetic acid PPO polymer, includes sulfonic groups as said lithium-permeation function and iminodiacetic groups as said binding function.
6. The electrochemical cell claim 1 , wherein said support sheet comprises a sheet of polymer to which at least one type of said binding function is grafted, and
wherein said support sheet comprises an iminodiacetic acid PPO polymer derivative, including iminodiacetic acid residues as a said binding function.
7. The electrochemical cell of claim 1 , said support sheet further comprising a HFP copolymer of PVDF.
8. The electrochemical cell of claim 1 ,
wherein said support sheet comprises a sheet of polymer to which a layer of adhering substrate adheres,
wherein at least one type of said binding function is borne by particles, said particles adhered to said support sheet with said adhering substrate,
wherein said particles are selected from the group consisting of organic particles, inorganic particles, hybrid particles and mixtures thereof,
wherein said inorganic particles are selected from the group consisting of bentonite and zeolite.
9. The electrochemical cell of claim 1 ,
wherein said support sheet comprises a sheet of polymer to which a layer of adhering substrate adheres,
wherein at least one type of said binding function is borne by particles, said particles adhered to said support sheet with said adhering substrate,
wherein said particles are selected from the group consisting of organic particles, inorganic particles, hybrid particles and mixtures thereof,
wherein said organic particles are selected from the group consisting of ion-exchange resins.
10. The electrochemical cell of claim 9 , wherein:
said support sheet includes a sheet of microporous PVDF;
said adhering substrate includes Hexafluoropropylene (HFP) copolymer of PVDF; and
said binding function includes particulate ion-exchange resin.
11. An electrochemical cell, comprising:
a. an electrode assembly including:
i. at least one positive electrode having a height, a breadth and a thickness bearing a positive active material on at least one face thereof;
ii. at least one negative electrode having a height, a breadth and a thickness bearing a negative active material on at least one face thereof, facing said positive electrode; and
iii. a separator disposed between said positive electrode and said negative electrode and electrically insulating said positive electrode from said negative electrode; and
b. an electrolyte contacting said positive electrode, said negative electrode and said separator;
said separator a membrane permeable to lithium ions and including:
a support sheet; and on said support sheet, binding functions configured to bind multivalent cations preferentially to lithium ions
further comprising on said support sheet, lithium-permeation functions configured to enhance the permeability of the membrane to lithium ions,
wherein said support sheet comprises a fluorinated sulfonated polysulfone polymer derivative and an iminodiacetic acid PPO polymer, includes sulfonic groups as said lithium-permeation function and iminodiacetic groups as said binding function.
12. The electrochemical cell of claim 11 , being a lithium-ion secondary electrochemical cell, wherein:
said positive-active material is a lithium-ion containing positive active material;
said negative-active material is a lithium-ion intercalating negative active material; and
wherein said electrolyte includes lithium ions.
13. The electrochemical cell claim 11 , wherein said support sheet comprises a sheet of polymer to which at least one type of said binding function is grafted, and
wherein said support sheet comprises an iminodiacetic acid PPO polymer derivative, including iminodiacetic acid residues as a said binding function.
14. The electrochemical cell of claim 11 ,
wherein said support sheet comprises a sheet of polymer to which at least one type of said binding function is grafted, and
wherein said support sheet comprises an aminoethylphosphonic acid PPO polymer derivative, including aminoethylphosphonic acid residues as a said binding function.
15. The electrochemical cell of claim 11 , said support sheet further comprising a HFP copolymer of PVDF.
16. The electrochemical cell of claim 11 ,
wherein said support sheet comprises a sheet of polymer to which a layer of adhering substrate adheres,
wherein at least one type of said binding function is borne by particles, said particles adhered to said support sheet with said adhering substrate,
wherein said particles are selected from the group consisting of organic particles, inorganic particles, hybrid particles and mixtures thereof,
wherein said inorganic particles are selected from the group consisting of bentonite and zeolite.
17. The electrochemical cell of claim 11 ,
wherein said support sheet comprises a sheet of polymer to which a layer of adhering substrate adheres,
wherein at least one type of said binding function is borne by particles, said particles adhered to said support sheet with said adhering substrate,
wherein said particles are selected from the group consisting of organic particles, inorganic particles, hybrid particles and mixtures thereof,
wherein said organic particles are selected from the group consisting of ion-exchange resins.
18. The electrochemical cell of claim 17 , wherein:
said support sheet includes a sheet of microporous PVDF;
said adhering substrate includes Hexafluoropropylene (HFP) copolymer of PVDF; and
said binding function includes particulate ion-exchange resin.