An electrolyte composition comprising (i) a block copolymer, (ii) an organic electrolyte (e.g. an ionic liquid), and (iii) a lithium salt, wherein the block copolymer comprises a non-ionic block and an ionic block, the non-ionic block comprising polymerised residues of hydrophobic monomers, and the ionic block comprising polymerised monomer residues having covalently coupled thereto (a) a pendant organic ionic liquid cation, the pendant organic ionic liquid cation having a counter anion, (b) a pendant anionic moiety, the pendant anionic moiety having a counter cation, or (c) a combination thereof, and the electrolyte composition has at least two glass transition temperature (Tg) values.

A system for electrical energy production from chemical reagents in a compartmentalized cell includes: at least two electrodes, comprising at least one anode and at least one cathode; at least one separator, that separates the anodes and the cathodes; and an ionic liquid electrolyte system. The system can be a battery or one or more cells of a battery system. The ionic liquid electrolyte system comprises an ionic liquid solvent; an ether co-solvent, comprising a minority fraction, by weight, of the electrolyte; and a lithium salt. In preferred variations, the anode is a lithium metal anode and the cathode is a metal oxide cathode and the separator is a polyolefin separator.

A flexible Zn film electrode with ionic and electronic networks has been designed by utilizing ionic liquid based gel polymer as the binder, which can minimize the interface resistance between electrode and electrolytes. Ionic liquid electrolytes are good candidates for high surface area Zn anode due to their good electro(chemical) stability. Ionic liquid based gel polymer electrolytes (GPEs) are good candidates to replace liquid electrolytes or separators in some special applications, like surface coating structure batteries.

A separator for a battery formed from a polymer gel electrolyte that is disposed within the pores of a polymer mesh. The polymer gel electrolyte is formed from a crosslinked ion-conducting polymer and an ionic liquid. The separator is formed from a gel loaded with an electrolyte, which prevents issue with electrolyte leakage. The polymer mesh provides stability to the polymer gel electrolyte, allowing for use of thin films of the polymer gel electrolyte and use of soft polymer gel electrolytes.

There is provided a lithium ion battery for use in a power tool. The lithium ion battery includes a carbon-based negative electrode containing a certain weight content of silicon-based material, a positive electrode including a lithium metal oxide containing nickel, and a non-flammable electrolyte placed between the negative electrode and the positive electrode. The weight content of silicon-based material in the negative electrode is no less than 5%. A composition of nickel of the lithium metal oxide is no less than the composition of other metals of the lithium metal oxide.

Disclosed is a calcium salt, Ca(HMDS).sub.2, where HMDS is the hexamethyldisilazide anion (also known as bis(trimethylsilyl)amide), enables high current densities and high coulombic efficiency for calcium metal deposition and dissolution. These properties facilitate the use of this salt in batteries based on calcium metal. In addition, the salt is significant for batteries based on metal anodes, which have higher specific energies than batteries based on intercalation anodes, such as LiC.sub.6. In particular, a calcium based rechargeable battery includes Ca(HMDS).sub.2 salt and at least one solvent, the solvent suitable for calcium battery cycling. The at least one solvent can be diethyl ether, diisopropylether, methyl t-butyl ether (MTBE), 1,3-dioxane, 1,4-dioxane, tetrahydrofuran (THF), tetrahydropyran, glyme, diglyme, triglyme or tetraglyme, or any mixture thereof.

According to one embodiment, provided is a secondary battery including a positive electrode, a negative electrode, and an electrolyte. The negative electrode includes a niobium-titanium composite oxide having fluorine atoms on at least part of a surface the niobium-titanium composite oxide. An abundance ratio A.sub.F of fluorine atoms, an abundance ratio A.sub.Ti of titanium atoms, and an abundance ratio A.sub.Nb of niobium atoms on a surface of the negative electrode according to X-ray photoelectron spectroscopy satisfy a relationship of 3.5≤A.sub.F/(A.sub.Ti+A.sub.Nb)≤50.

A system for electrical energy production from chemical reagents in a compartmentalized cell includes: at least two electrodes, comprising at least one anode and at least one cathode; at least one separator, that separates the anodes and the cathodes; and an ionic liquid electrolyte system. The system can be a battery or one or more cells of a battery system. The ionic liquid electrolyte system comprises an ionic liquid solvent; an ether co-solvent, comprising a minority fraction, by weight, of the electrolyte; and a lithium salt. In preferred variations, the anode is a lithium metal anode and the cathode is a metal oxide cathode and the separator is a polyolefin separator.

A printed energy storage device includes a first electrode including zinc, a second electrode including manganese dioxide, and a separator between the first electrode and the second electrode, the first electrode, second, electrode, and separator printed onto a substrate. The device may include a first current collector and/or a second current collector printed onto the substrate. The energy storage device may include a printed intermediate layer between the separator and the first electrode. The first electrode, and the second electrode may include 1-ethyl-3-methylimidazolium tetrafluoroborate (C.sub.2mimBF.sub.4). The first electrode and the second electrode may include an electrolyte having zinc tetrafluoroborate (ZnBF.sub.4) and 1-ethyl-3-methylimidazolium tetrafluoroborate (C.sub.2mimBF.sub.4). The first electrode, the second electrode, the first current collector, and/or the second current collector can include carbon nanotubes. The separator may include solid microspheres.

Electrolytes and polymers for a lithium battery can include a fluorinated aryl sulfonimide salt or fluorinated aryl sulfonimide polymer.