Long life lithium batteries with stabilized electrodes
The present invention relates to non-aqueous electrolytes having stabilization additives and electrochemical devices containing the same. Thus the present invention provides electrolytes containing an alkali metal salt, a polar aprotic solvent, a first additive that is a substituted or unsubstituted organoamine, substituted or unsubstituted alkane, substituted or unsubstituted alkene, or substituted or unsubstituted aryl compound, and/or a second additive that is a metal(chelato)borate. When used in electrochemical devices with, e.g., lithium manganese oxide spinel electrodes, the new electrolytes provide batteries with improved calendar and cycle life.
1. A non-aqueous electrolyte comprising:
lithium salt;
a polar aprotic solvent comprising ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dimethyl ether, or gamma butyrolactone;
a first additive comprises a vinyl pyridine; and
a second additive that is Li(C 2 O 4 )BF 2 .
2. The non-aqueous electrolyte of claim 1 wherein the vinyl pyridine is 2-vinyl pyridine or 4-vinyl pyridine.
3. The non-aqueous electrolyte of claim 1 wherein the lithium salt is LiClO 4 , LiBF 4 , LiAsF 6 , LiPF 6 , LiCF 3 SO 3 , Li(CF 3 SO 2 ) 2 N, Li(CF 3 SO 2 ) 3 C, LiN(SO 2 C 2 F 5 ) 2 , lithium alkyl fluorophosphates, or a mixture of any two or more thereof.
4. An electrochemical device comprising:
a cathode;
an anode; and
the non-aqueous electrolyte of claim 1 .
5. The electrochemical device of claim 4 wherein the device is a lithium secondary battery; the cathode is a lithium metal oxide cathode; the anode is a carbon or lithium metal anode; and the anode and cathode are separated from each other by a porous separator.
6. The electrochemical device of claim 5 wherein the cathode comprises LiCoO 2 , LiNiO 2 , LiNi 1−x ,Co y Met z O 2 , LiMn 0.5 Ni 0.5 O 2 , LiMn 0.3 Co 0.3 Ni 0.3 O 2 , LiFePO 4 , LiMn 2 O 4 , LiFeO 2 , LiMet 0.5 Mn 1.5 O 4 , vanadium oxide, or mixtures of any two or more thereof, wherein Met is Al, Mg, Ti, B, Ga, Si, Ni, or Co, and wherein 0<x<0.3 , 0<y <0.5, and 0<z<0.5.
7. The electrochemical device of claim 5 wherein the cathode comprises a spinel manganese oxide with a formula of Li 1+x Mn 2−z Met y O 4−m X n , wherein Met is Al, Mg, Ti, B, Ga, Si, Ni, or Co, and X is S or F, and wherein 0<x<0.3, 0<y<0.5, 0<z<0.5, 0<m<0.5 and 0<n<0.5.
8. The electrochemical device of claim 5 wherein the anode comprises graphite, carbon, Li 4 Ti 5 O 12 , tin alloys, silica alloys, intermetallic compounds, lithium metal, or mixtures of any two or more thereof.
9. The electrochemical device according to claim 5 wherein the first additive and the second additive are independently present in an amount from about 0.0005 to about 30 wt %.
10. The electrochemical device according to claim 5 wherein the first additive is present in an amount from about 0.001 to about 10 wt %.
11. The electrochemical device of claim 5 wherein the first additive is present in an amount of about 0.01 to 2 wt %.
12. The electrochemical device of claim 5 wherein the second additive is present in an amount of about 0.001 to about 2 wt %.
13. A method of making the non-aqueous electrolyte of claim 1 , the method comprising combining
the lithium salt;
the polar aprotic solvent;
the first additive; and
the second additive.