Silicon-based energy storage devices with electrolyte containing a benzoyl peroxide based compound

1. An energy storage device comprising:

a negative electrode comprising Si particles;

a positive electrode;

a separator between the negative electrode and the positive electrode; and

an electrolyte system comprising:

a benzoyl peroxide based compound at a concentration of about 0.1% to about 10%;

a linear carbonate;

a cyclic carbonate; and

a Li-containing salt; and wherein the electrolyte system further comprises 2,2-Bis(trifluoromethyl)oxirane (BFMO) at a concentration of about 0.1% to about 10%; and,

wherein the benzoyl peroxide based compound is of the formula (I):

wherein A is selected from the group consisting of

wherein D is phenyl optionally substituted by a C1-C4 alkyl, a C1-C3 alkenyl, —F, a C1 fluoroalkyl,

and

wherein E is selected from the group consisting of a bond, phenyl, a C1-C3 alkyl, and a C6 cycloalkyl and is optionally substituted by a C1-C4 alkyl, a C1-C3 alkenyl, —F, a C1 fluoroalkyl,

wherein if E is phenyl, then D and E may be connected by a bond; and

wherein if E is a bond, then E is a bond to D.

2. The energy storage device of claim 1 , wherein the benzoyl peroxide based compound is selected from the group consisting of benzoyl peroxide (BPO), benzoyl 4-propan-2-ylbenzenecarboperoxoate; benzoyl 4-methylbenzenecarboperoxoate; benzoyl 4-tert-butylbenzenecarboperoxoate; (2-(ethoxycarbonyloxy)benzoyl)benzoyl peroxide; (3-methylbenzoyl) 3-methylbenzenecarboperoxoate; 3-methylbenzoyl) 2-methylbenzenecarboperoxoate; (2-methylbenzoyl) 2-methylbenzenecarboperoxoate; Bis(4-methylbenzoyl)peroxide; (4-propan-2-ylbenzoyl) 4-propan-2-ylbenzenecarboperoxoate; (4-tert-butylbenzoyl) 4-tert-butylbenzenecarboperoxoate; bis-(2-methoxycarbonyl-benzoyl)-peroxide; (2,4-dimethylbenzoyl) 2,4-dimethylbenzenecarboperoxoate; (3,5-dimethylbenzoyl) 3,5-dimethylbenzenecarboperoxoate; (2,3,4-trimethylbenzoyl) 2,3,4-trimethylbenzenecarboperoxoate; benzoyl 2-ethenylbenzenecarboperoxoate; (4-ethenylbenzoyl) 4-ethenylbenzenecarboperoxoate; (3-prop-1-en-2-ylbenzoyl) 3-prop-1-en-2-ylbenzenecarboperoxoate; (2-ethenylbenzoyl)oxy 2-ethenylbenzenecarboperoxoate; [4-(trifluoromethyl)benzoyl] 4-(trifluoromethyl)benzenecarboperoxoate; (2,3,4,5,6-pentafluorobenzoyl) 2,3,4,5,6-pentafluorobenzenecarboperoxoate; benzoyloxy benzenecarboperoxoate; benzoylperoxy benzenecarboperoxoate; benzoylperoxycarbonyl benzenecarboperoxoate; Acetyl benzoyl peroxide; Acetyl 4-methylbenzenecarboperoxoate; 2-methylpropanoyl 4-methylbenzenecarboperoxoate; 1-O-acetyl 2-O-tert-butylbenzene-1,2-dicarboperoxoate; cyclohexanecarbonyl benzenecarboperoxoate; acetyloxy benzenecarboperoxoate; bibenzoyl peroxide; and 3,4,5-trioxabicyclo[5.2.2]undeca-1 (9),7,10-triene-2,6-dione.

3. The energy storage device of claim 2 , wherein the benzoyl peroxide based compound comprises BPO.

4. The energy storage device of claim 1 , wherein the cyclic carbonate is selected from the group consisting of fluoroethylene carbonate (FEC), di-fluoroethylene carbonate (DiFEC), Trifluoropropylene carbonate (TFPC), ethylene carbonate (EC), vinyl carbonate (VC), propylene carbonate (PC), -fluoromethyl-5-methyl-1,3-dioxolan-2-one (F-t-BC), 3,3-difluoropropylene carbonate (DFPC), and 3,3,4,4,5,5,6,6,6-Nonafluorohexyl-1-ene carbonate.

5. The energy storage device of claim 1 , wherein the cyclic carbonate is a fluorine containing cyclic carbonate.

6. The energy storage device of claim 5 , wherein the fluorine containing cyclic carbonate is FEC at a concentration from about 20% to about 40%.

7. The energy storage device of claim 1 , wherein the electrolyte is free of non-fluorine containing cyclic carbonate.

8. The energy storage device of claim 1 , wherein the linear carbonate is selected from the group consisting of ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), and diethyl carbonate (DEC).

9. The energy storage device of claim 1 , wherein the Li-containing salt is a fluorinated Li salt.

10. The energy storage device of claim 1 , wherein the electrolyte system further comprises a co-solvent selected from the group consisting of methyl acetate (MA), ethyl acetate (EA), methyl propanoate, and gamma butyrolactone (GBL).

11. The energy storage device of claim 1 , wherein the negative electrode is a Si-dominant anode.

12. The energy storage device of claim 1 , wherein the negative electrode comprises:

greater than 0% and less than about 99% by weight of the Si particles, and

greater than 0% and less than about 90% by weight of one or more types of carbon phases, wherein at least one of the one or more types of carbon phases is a substantially continuous phase that holds the composite material film together such that the silicon particles are distributed throughout the composite material film.

13. The energy storage device of claim 12 , wherein the negative electrode comprises greater than 50% and less than about 97% by weight of the Si particles.