Mitsubishi Chemical Corporation

Mitsubishi Plastics, Inc.

Mu Ionic Solutions Corporation

Ryoichi Kato

Hitoshi Suzuki

Minoru Kotato

Shinichi Kinoshita

Takashi Fujii

Masamichi Onuki

Hiroyuki Tokuda

Youichi Ohashi

Masahiro Takehara

Hidekazu Miyagi

Hirofumi Suzuki

Takayuki Nakajima

Jun Sasahara

Hiroyuki Oshima

Yasushi Usami

Hitoshi Matsumoto

Manabu Hayashi

Masakazu Yokomizo

Hiroyuki Uono

Satoshi Nakashima

Akihiko Sakai

Tomohiro Satou

A lithium secondary battery comprising: a positive electrode and a negative electrode which each has a specific composition and specific properties; and a nonaqueous electrolyte which contains a cyclic siloxane compound represented by general formula (1), fluorosilane compound represented by general formula (2), compound represented by general formula (3), compound having an S&#x2014;F bond in the molecule, nitric acid salt, nitrous acid salt, monofluorophosphoric acid salt, difluorophosphoric acid salt, acetic acid salt, or propionic acid salt in an amount of 10 ppm or more of the whole nonaqueous electrolyte. This lithium secondary battery has a high capacity, long life, and high output. [In general formula (1), Rand Rare an organic group having 1-12 carbon atoms and n is an integer of 3-10. In general formula (2), Rto Rare an organic group having 1-12 carbon atoms; x is an integer of 1-3; and p, q, and r each are an integer of 0-3, provided that 1&#x2264;p+q+r&#x2264;3. In general formula (3), Rto Rare an organic group having 1-12 carbon atoms and symbol A is a group constituted of H, C, N, O, F, S, Si, and/or P.]

Lithium secondary batteries and nonaqueous electrolyte for use in the same

A nonaqueous electrolyte containing a monofluorophosphate and/or a difluorophosphate and a compound having a specific chemical structure or specific properties. The nonaqueous electrolyte can contain at least one of a saturated chain hydrocarbon, a saturated cyclic hydrocarbon, an aromatic compound having a halogen atom and an ether having a fluorine atom.

Nonaqueous electrolytes and nonaqueous-electrolyte secondary batteries employing the same

A difluorophosphate effective as an additive for a nonaqueous electrolyte for secondary battery is produced by a simple method from inexpensive common materials. The difluorophosphate is produced by reacting lithium hexafluorophosphate with a carbonate in a nonaqueous solvent. The liquid reaction mixture resulting from this reaction is supplied for providing the difluorophosphate in a nonaqueous electrolyte comprising a nonaqueous solvent which contains at least a hexafluorophosphate as an electrolyte lithium salt and further contains a difluorophosphate. Also provided is a nonaqueous-electrolyte secondary battery employing this nonaqueous electrolyte.

Method for producing difluorophosphate, non-aqueous electrolyte for secondary cell and non-aqueous electrolyte secondary cell

A lithium secondary battery comprising: a positive electrode and a negative electrode which each has a specific composition and specific properties; and a nonaqueous electrolyte which contains a cyclic siloxane compound represented by general formula (1), fluorosilane compound represented by general formula (2), compound represented by general formula (3), compound having an S&#x2014;F bond in the molecule, nitric acid salt, nitrous acid salt, monofluorophosphoric acid salt, difluorophosphoric acid salt, acetic acid salt, or propionic acid salt in an amount of 10 ppm or more of the whole nonaqueous electrolyte. This lithium secondary battery has a high capacity, long life, and high output. [In general formula (1), Rand Rare an organic group having 1-12 carbon atoms and n is an integer of 3-10. In general formula (2), Rto Rare an organic group having 1-12 carbon atoms; x is an integer of 1-3; and p, q, and r each are an integer of 0-3, provided that 1&#x2266;p+q+r&#x2266;3. In general formula (3), Rto Rare an organic group having 1-12 carbon atoms and symbol A is a group constituted of H, C, N, O, F, S, Si, and/or P.]

A subject is to provide a nonaqueous electrolyte excellent in cycle performances such as capacity retention after cycling, output after cycling, discharge capacity after cycling, and cycle discharge capacity ratio, output characteristics, high-temperature storability, low-temperature discharge characteristics, heavy-current discharge characteristics, high-temperature storability, safety, high capacity, high output, high-current-density cycle performances, compatibility of these performances, etc. Another subject is to provide a nonaqueous-electrolyte secondary battery employing the nonaqueous electrolyte. The subjects have been accomplished with a nonaqueous electrolyte which contains a monofluorophosphate and/or a difluorophosphate and further contains a compound having a specific chemical structure or specific properties.

A lithium secondary battery is provided. The battery comprises: a positive electrode and a negative electrode which each has a specific composition and specific properties; and a nonaqueous electrolyte which contains a cyclic siloxane compound of formula (1), a fluorosilane compound of formula (2), a compound of formula (3), compound having an S&#x2014;F bond in the molecule, nitric acid salt, nitrous acid salt, monofluorophosphoric acid salt, difluorophosphoric acid salt, acetic acid salt, or propionic acid salt in an amount of 10 ppm or more of the whole nonaqueous electrolyte. 

The present invention provides a simple method for producing a difluorophosphate from a source material, the difluorophosphate being useful as additives for nonaqueous electrolyte solutions for secondary batteries. In the method, a source material containing a carbonate and/or a borate is allowed to react with a source gas which contains P and F and which may further contain O as required. The source material may contain lithium carbonate. The source gas may be produced by decomposing LiPF. The source gas may be produced in such a manner that LiPFand lithium carbonate are mixed and then subjected to reaction. The nonaqueous electrolyte solution contains the product obtained from the reaction.

Method for producing difluorophosphate, nonaqueous electrolyte solution for secondary batteries, and nonaqueous electrolyte secondary battery

A subject for the invention is to improve the cycle characteristics of a high-capacity secondary battery containing an active material packed at a high density, by using a particulate active material having a low aspect ratio. The invention relates to a nonaqueous-electrolyte secondary battery comprising a negative electrode and a positive electrode each capable of occluding/releasing lithium, a separator, and a nonaqueous electrolyte solution comprising a nonaqueous solvent and a lithium salt, characterized in that the separator comprises a porous film made of a thermoplastic resin containing an inorganic filler, and at least either of the following is satisfied: the active material contained in the negative electrode is a particulate active material having an aspect ratio of from 1.02 to 3; and the active material contained in the positive electrode is a particulate active material having an aspect ratio of from 1.02 to 2.2.

Growing community of inventors

Inashiki-gun, Japan

Ryoichi Kato