Electrolyte system for lithium metal secondary battery and lithium metal secondary battery including the same
Disclosed is an electrolyte for a lithium metal secondary battery and a lithium metal secondary battery including the same. An electrolyte system is intended to maintain the energy density of a secondary battery based on a lithium metal negative electrode and to extend the life of a battery. Particularly, an electrolyte for a lithium metal battery which forms a stable SEI film capable of inhibiting formation and extension of lithium dendrite so that the negative electrode of a lithium metal battery having a high possibility of battery ignition may be stabilized and an internal short-circuit may be prevented, and a lithium metal secondary battery including the same is provided.
1. An electrolyte for a lithium metal secondary battery, comprising:
(a) a first salt selected from the group consisting of LiFSI, LiTFSI, and a combination thereof;
(b) a second salt selected from the group consisting of LiBOB, LiDFOB, and a combination thereof;
(c) a third salt comprising LiPF 6 ;
(d) a solvent comprising a mixture of EC and DMC;
(e) a first additive that has solvent properties and that is selected from the group consisting of 0.4-1.5 wt % of FEC, 0.01-3.5 wt % of VC, and combinations thereof based on total weight of the electrolyte; and
(f) a second additive that has solvent properties and that is 2.5-4.5 wt % of TFEC based on the total weight of the electrolyte.
2. The electrolyte for a lithium metal secondary battery according to claim 1 , wherein:
the first salt comprises 0.2-0.4 M of LiFSI and 0.2-0.4 M of LiTFSI or 0.3-1 M of LiTFSI alone,
the third salt comprises 0.03-0.07 M of LiPF 6 , and
the mixture of EC and DMC has a mixing ratio by weight of EC to DMC that is 3-6:7-4.
3. The electrolyte for a lithium metal secondary battery according to claim 2 , wherein:
the first salt comprises 0.5-0.7 M of LiTFSI alone,
the second salt comprises 0.3-0.5 M of LiBOB alone,
the third salt comprises 0.04-0.06 M of LiPF 6 , and
the mixture of EC and DMC has a mixing ratio by weight of EC to DMC that is 3.75-5.25:6.25-4.75.
4. The electrolyte for a lithium metal secondary battery according to claim 1 , wherein:
the electrolyte further comprises 0.4-0.5 M of LiF salt, and
the first additive comprises 0.7-1.2 wt % of FEC based on the total weight of the electrolyte.
5. The electrolyte for a lithium metal secondary battery according to claim 1 , wherein:
the first salt comprises 0.5-0.7 M of LiTFSI alone,
the second salt comprises 0.35-0.45 M of LiBOB alone,
the third salt comprises 0.04-0.06 M of LiPF 6 ,
the mixture of EC and DMC has a mixing ratio by weight of EC to DMC that is 3.75-5.25:6.25-4.75,
the electrolyte further comprises 0.4-0.5 M of LiF salt, and
the first additive comprises 0.8-1.2 wt % of FEC based on total weight of the electrolyte and optionally comprises 0.01-3.5 wt % of VC.
6. A lithium metal secondary battery, comprising:
the electrolyte as defined in claim 1 , and
a positive electrode that comprises lithium nickel cobalt manganese oxide.
7. An electric device comprising the lithium metal secondary battery as defined in claim 6 .
8. The electric device according to claim 7 , which is selected from the group consisting of a communication device, a transport device, an energy storage device, and an acoustic device.
9. An electrolyte for a lithium metal secondary battery, comprising:
(a) a first salt selected from the group consisting of LiFSI, LiTFSI, and a combination thereof;
(b) a second salt selected from the group consisting of LiBOB, LiDFOB, and a combination thereof;
(c) a third salt comprising LiPF 6 ; and
(d) a solvent comprising a mixture of EC and DMC,
(e) a first additive that has solvent properties and that is selected from the group consisting of 0.4-1.5 wt % of FEC, 0.01-3.5 wt % of VC, and a combination thereof based on total weight of the electrolyte;
(f) a fourth salt comprising 0.02-0.06 M of LiBF 4 , and
(g) a second additive that has solvent properties and that is 0.8-1.2 wt % of TFEC based on total weight of the electrolyte.
10. The electrolyte for a lithium metal secondary battery according to claim 9 , wherein:
the first salt comprises 0.2-0.4 M of LiFSI and 0.2-0.4 M of LiTFSI or 0.3-1 M of LiTFSI alone,
the third salt comprises 0.03-0.07 M of LiPF 6 ,
the mixture of EC and DMC has a mixing ratio by weight of EC to DMC that is 3-6:7-4.
11. The electrolyte for a lithium metal secondary battery according to claim 10 , wherein:
the first salt comprises 0.5-0.7 M of LiTFSI alone,
the second salt comprises 0.3-0.5 M of LiBOB alone,
the third salt comprises 0.04-0.06 M of LiPF 6 , and
the mixture of EC and DMC has a mixing ratio by weight of EC to DMC that is 3.75-5.25:6.25-4.75.
12. The electrolyte for a lithium metal secondary battery according to claim 9 , wherein the first additive comprises 0.5-1.3 wt % of FEC based on the total weight of the electrolyte and optionally comprises 0.01-3.5 wt % of VC based on the total weight of the electrolyte.
13. The electrolyte for a lithium metal secondary battery according to claim 12 , further comprising from 0.3-0.5 M of LiF salt.
14. The electrolyte for a lithium metal secondary battery according to claim 13 , wherein the first additive comprises 0.7-1.2 wt % of FEC based on the total weight of the electrolyte, and optionally comprises 0.01-3.5 wt % of VC based on the total weight of the electrolyte.
15. The electrolyte for a lithium metal secondary battery according to claim 9 , wherein:
the first salt comprises 0.5-0.7 M of LiTFSI alone,
the second salt comprises 0.35-0.45 M of LiBOB alone,
the third salt comprises 0.04-0.06 M of LiPF 6 ,
the mixture of EC and DMC has a mixing ratio by weight of EC to DMC that is 3.75-5.25:6.25-4.75,
the electrolyte further comprises 0.3-0.5 M of LiF salt, and
the first additive comprises 0.8-1.2 wt % of FEC based on the total weight of the electrolyte and optionally comprises 0.01-3.5 wt % of VC.
16. The electrolyte for a lithium metal secondary battery according to claim 15 , wherein:
the electrolyte further comprises 0.05-0.1 M of LiNO 3 salt.