Lithium-sulphur battery

Patent metadata

Field	Value
Publication number	US-10109860-B2
Application number	US-201515322714-A
Country	US
Kind code	B2
Filing date	Jul 16, 2015
Priority date	Jul 17, 2014
Publication date	Oct 23, 2018
Grant date	Oct 23, 2018

Abstract

The present invention relates to the field of lithium-sulphur batteries having high energy and power densities. In particular the present invention relates to a lithium-sulphur battery comprising a porous separator made of biaxially oriented polypropylene and to its process of manufacture.

First claim

The invention claimed is:

1. Lithium-sulphur battery comprising:
a negative electrode comprising lithium metal or an alloy of lithium metal,
a positive electrode comprising at least one sulphur-comprising agent chosen from elemental sulphur S 8 and an organic sulphur-comprising compound having at least one S—S bond, at least one polymer binder P 1 and at least one agent generating an electron conductivity,
an electrolyte comprising at least one liquid linear or cyclic polyether of low molar mass and at least one lithium salt L 1 , and
a porous separator,
wherein the porous separator is a biaxially oriented separator comprising at least polypropylene and said positive electrode comprises at least 40% by weight approximately of sulphur (S) with respect to the total weight of said positive electrode.

2. Battery according to claim 1 , wherein the separator exhibits a thickness ranging from 5 μm to 50 μm.

3. Battery according to claim 1 , wherein the separator exhibits a porosity of greater than or equal to 50% by volume.

4. Battery claim 1 , wherein the separator exhibits pores with a mean size ranging from 50 nm to 3 μm.

5. Battery claim 1 , wherein the separator exhibits a porosity of Gurley type ranging from 50 to 500 s/100 cm 3 .

6. Battery claim 1 , wherein the separator exhibits a heat shrinkage in the longitudinal direction and/or a heat shrinkage in the transverse direction strictly of less than 15%.

7. Battery claim 1 , wherein the polyether is chosen from:
polyethylene glycols of formula H—[O—CH 2 —CH 2 ] m —OH in which m is between 1 and 13, glycol ethers of formula R—[O—CH 2 —CH 2 ] p —O—R in which p is between 1 and 13 and R and R′, which are identical or different, are linear, branched or cyclic alkyl groups which can comprise from 1 to 20 carbon atoms,
ethers of formula R 1 -[CH 2 -O] q —R 1′ in which q is between 1 and 13 and R 1 and R 1′ , which are identical or different, are linear, branched or cyclic alkyls which can comprise from 1 to 20 carbon atoms and optionally heteroatoms,
cyclic ethers which can comprise from 2 to 20 carbon atoms or cyclic polyethers which can comprise from 3 to 40 carbon atoms, and
one of their mixtures.

8. Battery claim 1 , wherein the lithium salt L 1 is chosen from lithium fluorate (LiFO 3 ), lithium bis(trifluoromethanesulphonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF 6 ), lithium fluoroborate (LiBF 4 ), lithium metaborate (LiBO 2 ), lithium perchlorate (LiClO 4 ), lithium nitrate (LiNO 3 ), lithium bis(fluorosulphonyl)imide (LiFSI) and their mixtures.

9. Battery claim 1 , wherein the electrolyte is a liquid electrolyte and the concentration of the lithium salt Li in the liquid electrolyte ranges from 0.8 to 8 mol/1.

10. Battery claim 1 , wherein the electrolyte is a gelled polymer electrolyte and it additionally comprises at least one polymer binder P 2 .

11. Battery according to claim 10 , wherein the electrolyte comprises from 20 to 70% by weight of polymer binder P 2 .

12. Battery according to claim 10 , wherein the electrolyte comprises from 15 to 45% by weight of lithium salt L 1 .

13. Battery according to claim 10 , wherein the electrolyte comprises from 5 to 40% by weight of polyether.

14. Battery claim 1 , wherein the agent generating an electron conductivity is an essentially mesoporous carbon-comprising agent exhibiting the following characteristics:
an S BET specific surface of greater than or equal to 800 m 2 /g, said specific surface being calculated by the BET method,
a mean size of the mesopores of between 4 and 10 nm, said size being calculated by the BJH method, and
a total pore volume of greater than or equal to 1.5 cm 3 /g, said total pore volume being calculated by the BET method.

15. Battery according to claim 14 , wherein said essentially mesoporous carbon-comprising agent is subjected, in the presence of the sulphur-comprising agent, to a pretreatment in order to form a composite material comprising sulphur (S) and carbon (C), said pretreatment comprising the following stages:
i) a stage of mixing an essentially mesoporous carbon-comprising agent as defined in claim 14 and a sulphur-comprising agent as defined in claim 1 , the amount of sulphur (S) in said mixture ranging from 75% to 85% by weight,
ii) a stage of grinding the mixture obtained in the preceding stage i),
iii) a stage of heat treatment of the ground mixture obtained in the preceding stage ii) in a closed container, at a temperature sufficient to cause the sulphur to melt, and
iv) a stage of grinding the heat-treated mixture of the preceding stage iii) in order to obtain a composite material comprising sulphur (S) and carbon (C).

16. Battery according to claim 14 , wherein the carbon-comprising agent is carbon black.

17. Process for the manufacture of a battery as defined in claim 1 , wherein said process comprises the following stages:
A) a stage of preparation of a liquid or gelled polymer electrolyte,
B) a stage of assembling a positive electrode, a negative electrode and a separator,
said process initially comprising one or other of the following stages:
C-1) a stage of impregnation of the assembly as obtained in stage B) by the liquid electrolyte prepared in stage A), or
C-2) a stage of impregnation of the separator by the gelled polymer electrolyte prepared in stage A), said impregnation being prior to the assembling stage B).

Assignees

• Centre Nat Rech Scient
• Blue Solutions
• Univ Nantes

Inventors

• Lecuyer Margaud
• Deschamps Marc
• Gaubicher Joël
• Lestriez Bernard
• Guyomard Dominique
• Poizot Philippe

Classifications

• H01M2300/0025

  Organic electrolyte · CPC title

• H01M2300/0085

  Immobilising or gelification of electrolyte · CPC title

• H01M4/625

  Carbon or graphite · CPC title

• H01M4/622

  being polymers · CPC title

• H01M10/052

  Li-accumulators · CPC title