The disclosure relates to the use of fluorinated ethers such as 1,1,1,3,3,3-hexafluoro-2-methoxypropane (HFMOP) as a reaction solvent to prepare fluorinated dialkyl carbonate and sulfite compounds useful in batteries, and to electrolytes containing fluorinated compounds for use in batteries containing high Ni cathodes and silicon containing anodes.

A lithium ion secondary battery includes: a positive electrode, a negative electrode, a separator located between the positive electrode and the negative electrode, and an electrolytic solution. The negative electrode includes a negative electrode active material which contains silicon or a silicon alloy and a compound containing a first element, the electrolytic solution contains an imide salt which contains the first element and an imide anion, and the first element is any one or more elements selected from the group consisting of K, Na, Mg, Ca, Cs, Al, and Zn.

A lithium ion secondary battery includes: a positive electrode, a negative electrode, a separator located between the positive electrode and the negative electrode, and an electrolytic solution. The negative electrode includes a negative electrode active material which contains silicon oxide and a compound containing a first element. The electrolytic solution contains an imide salt which contains the first element and an imide anion. The first element is any one or more elements selected from the group consisting of K, Na, Mg, Ca, Cs, Al, and Zn.

A secondary battery according to the present invention comprises a positive electrode, a negative electrode and an electrolyte solution; the electrolyte solution contains a lithium salt and a solvent containing water; the negative electrode comprises a negative electrode active material that contains a carbon material; with respect to the carbon material, the peak intensity ratio (D/G value) of the D band to the G band in a Raman spectrum as obtained by Raman spectroscopy is from 0.05 to 0.7; a coating film is formed on the surface of the carbon material; and with respect to the coating film, if P1 is the peak intensity of the 1s electron orbital of an F atom at around the binding energy of 685 eV and P2 is the peak intensity of the 1s electron orbital of an O atom at around the binding energy of 532 eV in an XPS spectrum as determined by X-ray photoelectron spectroscopy, the ratio of the peak intensity P1 to the peak intensity P2, namely the value of P1/P2 is from 1.0 to 3.0.

An electrolyte solution containing at least one selected from a compound represented by the following formula (1-1) (wherein Rf.sup.111s are the same as or different from each other and are each a C2-C4 fluorinated alkenyl group), a compound represented by the following formula (1-2) (wherein R.sup.121 is a C1-C4 alkyl group; and Rf.sup.121 is a C2-C4 fluorinated alkenyl group), and a compound represented by the following formula (1-3) (wherein Rf.sup.131 is a C1-C3 fluorinated alkyl group; and R.sup.131 is a C6-C12 aryl group): ##STR00001##

The present invention relates to a lithium secondary battery which includes a non-aqueous electrolyte solution including lithium bis(fluorosulfonyl)imide (LiFSI) and a fluorobiphenyl compound, a positive electrode including a lithium-nickel-manganese-cobalt-based oxide as a positive electrode active material, a negative electrode, and a separator.

An electrolyte for a lithium metal secondary battery is provided. The electrolyte comprises a lithium salt and a non-aqueous solvent and provides improved lifespan characteristics and high rate charging performance when applied to a secondary battery including a lithium metal as a negative electrode active material due to fewer side reactions and excellent stability of the electrolyte.

A negative active material for a rechargeable lithium battery includes a core including a SiO.sub.2 matrix and a Si grain, and a coating layer continuously or discontinuously coated on the core. The coating layer includes SiC and C, and the peak area ratio of the SiC (111) plane to the Si (111) plane as measured by X-ray diffraction analysis (XRD) using a CuKα ray ranges from about 0.01 to about 0.5.

Provided are an electrolyte for a non-aqueous electrolyte battery using a positive electrode including nickel, where the battery generates a small amount of gas during a durability test even if the cell potential reaches 4.1 V or more, as well as a non-aqueous electrolyte battery using the electrolyte. In the electrolyte for a non-aqueous electrolyte battery including a positive electrode including at least one selected from the group consisting of oxides containing nickel and phosphates containing nickel as a positive electrode active material, the electrolyte comprises (I) a non-aqueous organic solvent, (II) a fluorine-containing solute being an ionic salt, (III) at least one additive selected from the group consisting of compounds represented by formulae (1) and (2), and (IV) hydrogen fluoride in an amount of 5 mass ppm or more and less than 200 mass ppm based on the total amount of the components (I), (II), and (III). ##STR00001##

Described herein are isosorbide-based electrolytes that are inexpensive, commercially available, green, and safe electrolytes. These electrolytes include a lithium salt, a solvent represented as a compound of Formula I, and optionally, a diluent. Such electrolytes have greatly enhanced cycle and calendar life when used with Si anodes, and exhibit very low leakage currents when compared to standard carbonate-based electrolytes.