Anode for an electrochemical cell
An anode for an electrochemical cell comprises a lithium metal or lithium metal alloy, and a polymer coating deposited on the lithium metal or lithium metal alloy. The polymer coating is doped with lithium ions and comprises a polyisocyanurate material. The polyisocyanurate material contains ether- and/or silicone-containing further groups. The ether-containing group is a polyether, and/or wherein the silicone-containing group is a siloxane group.
1. An anode for an electrochemical cell, the anode comprising:
a lithium metal or lithium metal alloy, and
a polymer coating deposited on the lithium metal or lithium metal alloy,
wherein the polymer coating is doped with lithium ions and comprises a polyisocyanurate material,
wherein the polyisocyanurate material contains ether- and/or silicone-containing further groups, and
wherein the ether-containing group is a polyether and/or wherein the silicone-containing group is a siloxane group.
2. The anode as claimed in claim 1 , wherein the polymer coating further includes an inorganic filler.
3. The anode as claimed in claim 2 , wherein the filler comprises silica or clay nanoparticles.
4. The anode as claimed in claim 1 , wherein the polymer coating comprises at least 5 weight % lithium ions.
5. A lithium-sulphur cell comprising:
an anode as claimed in claim 1 ,
a cathode comprising an electroconductive material and an electroactive material comprising sulphur, and
an electrolyte.
6. The anode as claimed in claim 1 , wherein the polyether is a polyalkyleneoxide-monoalkylether.
7. The anode as claimed in claim 1 , wherein the siloxane group is a trialkoxysilane group.
8. A method of forming a coating on the anode of the electrochemical cell of claim 1 , said method comprising the steps of:
a) contacting an anode formed of lithium metal or lithium metal alloy with a coating composition, wherein the coating composition is in form of a dispersion or a solution and contains a polymer precursor comprising isocyanate groups, a lithium metal salt and a solvent, and
b) trimerising the polymer precursor as a coating on the anode, wherein at least 50 mol % of the isocyanate groups of the polymer precursor form structures selected from the group consisting of isocyanurate, uretdione-, allophanate-, and iminooxadiazinedione structures.
9. The method as claimed in claim 8 , wherein the polymer precursor comprises oligomeric polyisocyanate, and wherein the oligomeric polyisocyanate is trimerised as the coating on the anode, wherein at least 50 mol % of the isocyanate groups comprised by the oligomeric polyisocyanate form structures selected from the group consisting of isocyanurate, uretdione-, allophanate-, and iminooxadiazinedione structures.
10. The method as claimed in claim 8 , wherein the dispersion or solution further includes inorganic filler(s).
11. The method as claimed in claim 9 , wherein the oligomeric polyisocyanate is an oligomer of a monomeric diisocyanate.
12. The method as claimed in claim 11 , wherein the oligomeric polyisocyanate is an oligomer of hexamethylene diisocyanate.
13. The method as claimed in claim 12 , wherein the oligomeric polyisocyanate comprises monomer units formed from a trimer of hexamethylene diisocyanate.
14. The method as claimed in claim 9 , wherein at least some of the NCO groups in the oligomeric polyisocyanate are capped with ether- and/or silicon-containing groups.
15. The method as claimed in claim 14 , wherein the ether-containing group is a polyether, in particular a polyalkyleneoxide-monoalkylether, and/or wherein the silicone-containing group is a siloxane group, in particular a trialkoxysilane group.
16. The method as claimed in claim 8 , wherein the coating composition comprises a trimerisation catalyst, in particular an alkali metal acetate and a crown ether.
17. The method as claimed in claim 16 , wherein the trimerisation step is carried out at a temperature of 60-150° C.