リチウムイオン電池 (US9190698)

US9190698 (Lithium-ion electrolytes with improved safety tolerance to high voltage systems)
"The invention discloses various embodiments of electrolytes for use in（ための、用）lithium-ion batteries, the electrolytes having improved safety and the ability to operate with high capacity anodes and high voltage cathodes. In one embodiment there is provided（倒置）an electrolyte for use in a lithium-ion battery comprising（から成る）an anode and a high voltage cathode. The electrolyte has a mixture of a cyclic carbonate of ethylene carbonate (EC) or mono-fluoroethylene carbonate (FEC) co-solvent, ethyl methyl carbonate (EMC), a flame retardant additive, a lithium salt, and an electrolyte additive that improves compatibility and performance of the lithium-ion battery with a high voltage cathode. The lithium-ion battery is charged to a voltage in a range of from about 2.0 V (Volts) to（範囲）about 5.0 V (Volts)." (Abstract)

"Lithium-ion (“Li-ion”) cells typically include a carbon (e.g., coke or graphite) anode intercalated with（挿入）lithium ions to form Li_xC; an electrolyte consisting of a lithium salt dissolved in one or more（一種類以上の）organic solvents; and a cathode made of（から成る、作製、作られた、構成）an electrochemically active material, typically an insertion compound, such as LiCoO₂. During cell discharge, lithium ions pass from the carbon anode, through the electrolyte to the cathode, where the ions are taken up（引き出す？）with the simultaneous release of electrical energy. During cell recharge, lithium ions are transferred back to the anode, where they reintercalate into（再挿入）the carbon matrix."

"Future NASA missions aimed at exploring Mars, the Moon, and the outer planets require rechargeable batteries that can operate effectively over a wide temperature range (−60° C. (Celsius) to +60° C. (Celsius)) to satisfy the requirements of various applications, including: Landers (lander spacecraft), Rovers (surface rover spacecraft), and Penetraters (surface penetrator spacecraft). Some future applications typically（典型）will require high specific energy batteries that can operate at very low temperatures, while still providing adequate（十分な）performance and stability at higher temperatures. In addition, many of these applications envisioned（想定、計画、予測）by the ESRT (Exploration Systems Research and Technology) program will require improved safety, due to their use by humans. Lithium-ion rechargeable batteries（複数形；一般）have the demonstrated characteristics of high energy density, high voltage, and excellent cycle life. Currently, the state-of-the-art lithium-ion system（定冠詞、断定的；不定冠詞だと変に具体的になって聞き手、読み手の好奇心を下手にくすぐるのではないか？）has been demonstrated to operate over a wide range of temperatures (−40° C. to +40° C.), however, abuse（過酷な）conditions such as being exposed to high temperature, overcharge, and external shorting, can often lead to cell rupture and fire. The nature of the electrolyte can greatly affect the propensity of the cell/battery to（傾向、易さ）catch fire, given the flammability of the organic solvents used within. Therefore, extensive effort has been devoted recently to developing（近年、開発のため鋭意努力）non-flammable electrolytes to reduce the flammability of the cell/battery."

"Desired properties for Li-ion electrolytes can include high conductivity over a wide temperature range (e.g., 1 mS (milli-Siemens) cm⁻¹ from −60° C. to +60° C.); good electrochemical stability over a wide voltage range (e.g., 0 to 4.5V (volts)) with minimal oxidative degradation of solvents/salts; good chemical stability; good compatibility with a chosen electrode couple, including good SEI (solid electrolyte interface) characteristics on the electrode and facile lithium intercalation/de-intercalation kinetics; good thermal stability; good low temperature performance throughout the life of the cell, including good resilience to high temperature exposure and minimal impedance build-up with cycling and/or storage; and low toxicity. Since the flammability of the electrolyte solution in Li-ion batteries is a major concern, significant research has been devoted to developing electrolyte formulations with increased safety. Known electrolytes used in state-of-the-art Li-ion cells have typically comprised binary mixtures of organic solvents, for example, high proportions of ethylene carbonate, propylene carbonate or dimethyl carbonate, within which is dispersed a lithium salt, such as lithium hexafluorophosphate (LiPF₆). Examples may include 1.0 M (molar) LiPF₆ in a 50:50 mixture of ethylene carbonate/dimethyl carbonate, or ethylene carbonate/diethyl carbonate. More recently, electrolytes have also been developed which combine more than two solvents and/or have incorporated the use of electrolyte additives to address specific performance goals."