Provided is a negative electrode active material that is applied in an aqueous secondary battery in which is used an aqueous electrolyte containing water and a lithium salt. The negative electrode active material contains hardly-graphitizable carbon, and the hardly-graphitizable carbon has a C—F bond group on the surface thereof. In an XPS spectrum obtained through X-ray photoelectron spectroscopy, when the peak intensity near 688 eV originating from C—F bonds of the hardly-graphitizable carbon is denoted by I688eV, the peak intensity near 284 eV originating from C—C bonds is denoted by I284eV, a ratio of the peak intensity I688eV to the peak intensity I284eV (value of I688eV/I284eV) is denoted by X, and the BET specific surface area (m2/g) is denoted by Y, the X and Y satisfy Y<(−0.3X+3.75), 0.1≤X≤5, and Y≥2.

The present invention provides a non-aqueous electrolytic solution which can be handled industrially stably, and which allows for achieving a good durability performance, particularly, a good capacity retention rate during repeated charging and discharging, of an energy device typified by a non-aqueous electrolytic solution secondary battery. The non-aqueous electrolytic solution contains a compound(s) represented by the following general formula(e) (A1) and/or (A2). In formula (A1), X.sup.1 represents a halogen atom; each of R.sup.1, R.sup.2, R.sup.5 and R.sup.6 independently represents a hydrogen atom, a halogen atom, or a hydrocarbon group having 10 or less carbon atoms optionally substituted with a halogen atom; and each of R.sup.3 and R.sup.4 independently represents a halogen atom, or a hydrocarbon group having 10 or less carbon atoms optionally substituted with a halogen atom; wherein at least two of R.sup.1 to R.sup.6 may be bonded to each other to form a ring. In formula (A2), each of X.sup.2 and X.sup.3 independently represents a halogen atom; and each of R.sup.7 to R.sup.14 independently represents a hydrogen atom, a halogen atom, or a hydrocarbon group having 10 or less carbon atoms optionally substituted with a halogen atom; wherein at least two of R.sup.7 to R.sup.14 may be bonded to each other to form a ring.

##STR00001##

The present disclosure relates to an electrolyte comprising: a) a sodium salt; b) an additive comprising at least one additional metallic/metalloid cation having a standard reduction potential which is at least 2.5V more positive than that of sodium cation; wherein said sodium salt and said additive are dispersed in a solvent comprising at least one alkyl carbonate, and wherein the concentration of said metallic/metalloid cation in the electrolyte is 15 mM to 250 mM. The present disclosure also relates to a sodium-sulfur cell comprising a sodium anode, a microporous sulfur cathode, and the electrolyte as described herein. The present disclosure further provides a method of improving cycling life of a sodium-sulfur cell, wherein the sodium-sulfur cell comprising a sodium anode, a sulfur cathode, and an electrolyte containing a sodium salt dispersed in an alkyl carbonate solvent.

Provided is a non-aqueous electrolyte solution that achieves a favorable balance between suppressing an increase in resistance and improving metallic Li precipitation resistance in an embodiment that contains LiPO.sub.2F.sub.2. The non-aqueous electrolyte solution disclosed here is used in a non-aqueous electrolyte secondary battery, and contains lithium difluorophosphate and a Cs cation-containing compound. When the total amount of the non-aqueous electrolyte solution is taken to be 100 mass %, the content of the lithium difluorophosphate is 1.0 mass % or less and the content of the Cs cation-containing compound is 0.1 to 0.5 mass %.

Described is a lithium-sulfur electrochemical cell in which the anode and the cathode are each equipped with a respective solid-electrolyte interphase (SEI) layer that inhibits lithium side reactions. On the cathode side, the SEI layer inhibits the shuttle effect by retaining soluble polysulfides within a cathode active layer while releasing and admitting lithium ions to and from the electrolyte. The cathode SEI is deposited, during cell formation, by depositing a layer of an anode reductant (e.g., metallic lithium) on the surface of the cathode. The resultant electrically conductive layer allows electrons to reduce adjacent electrolyte and form the cathode SEI from electrolyte decomposition products.

An object of the present invention is to provide a non-aqueous electrolytic solution secondary battery capable of improving low-temperature output characteristics.

The problem is solved by a secondary battery including a non-aqueous electrolytic solution containing fluorosulfonic acid ions, difluorophosphate ions, and bisoxalate borate ions, in which [FSO.sub.3.sup.−]>[PO.sub.2F.sub.2.sup.−]>[BOB.sup.−] is satisfied in the non-aqueous electrolytic solution.

A system and method for optimizing electrochemical cells including electrodes employing coordination compounds by mediating water content within a desired water content profile that includes sufficient coordinated water and reduces non-coordinated water below a desired target and with electrochemical cells including a coordination compound electrochemically active in one or more electrodes, with an improvement in electrochemical cell manufacture that relaxes standards for water content of electrochemical cells having one or more electrodes including one or more such transition metal cyanide coordination compounds.

The present invention relates to an electrochemical device comprising a) a positive electrode, b) a negative electrode, c) a separator, and d) a liquid electrolyte, wherein at least one of said positive electrode and said negative electrode is a gelled electrode comprising an electronic conductive substrate and directly adhered onto the electronic conductive substrate, at least one layer of a gelled electrode-forming composition, and wherein the d) liquid electrolyte comprises at least one organic carbonate and/or at least one ionic liquid, and at least one metal salt. The present invention also relates to a process for manufacturing an electrochemical device comprising at least one gelled electrode.

The present invention generally relates to electrolytes for use in various electrochemical devices. In some cases, the electrolytes are relatively safe to use; for example, the electrolytes may be resistant to overheating, catching on fire, burning, exploding, etc. In some embodiments, such electrolytes may be useful for certain types of high-voltage cathode materials. In some cases, the electrolytes may include ion dissociation compounds that can dissociate tight ion pairs. Non-limiting examples of ion dissociation compounds include trialkyl phosphates, sulfones, or the like. Other aspects of the invention are generally directed to devices including such electrolytes, methods of making or using such electrolytes, kits including such electrolytes, or the like.

A rechargeable lithium battery includes a positive electrode including a positive active material; a negative electrode including a negative active material; and an electrolyte including a non-aqueous organic solvent, a lithium salt, and an additive represented by Chemical Formula 1, wherein a volume of the rechargeable lithium battery is about 5 cm.sup.3 to about 200 cm.sup.3.

##STR00001##

Details of Chemical Formula 1 are as described in the specification.