Embodiments described herein relate to electrodes containing yolk-sell electroactive materials. In some aspects, an anode can include a carbon shell having an outer surface and an inner volume, the carbon shell including a plurality of pinholes on the outer surface. The anode particle is disposed in the inner volume of the carbon shell, such that a portion of the inner volume includes a void space. The anode further includes a plurality of graphene flakes disposed on the outer surface of the carbon shell, the plurality of graphene flakes covering at least a portion of the pinholes. In some embodiments, at least about 50% of the inner volume of the carbon shell can include void space. In some embodiments, the plurality of graphene flakes can cover at least about 90% of the pinholes.

The present invention is directed to methods of transferring urea from an aqueous solution comprising urea to a MXene composition, the method comprising contacting the aqueous solution comprising urea with the MXene composition for a time sufficient to form an intercalated MXene composition comprising urea.

One variation of a battery unit includes: a substrate including silicon and defining a cell, wherein the cell includes a base encompassed by a continuous wall and a set of posts extending normal to the base; an electrolyte material coating vertical surfaces of each post, in the set of posts, and vertical surfaces of the continuous wall in the cell; a cathode material filling the cell over the electrolyte material, between posts in the set of posts, and between the set of posts and the continuous wall; a seal extending along a top of the continuous wall; and a cathode current collector bonded to the seal, electrically coupled to the cathode material, and cooperating with the substrate to enclose the cell to form a single-cell battery.

This invention relates to a negative electrode material for lithium-ion batteries comprising silicon and having a chemically treated or coated surface influencing the zeta potential of the surface. The active material consists of particles or particles and wires comprising a core comprising silicon, wherein the particles have a positive zeta potential in an interval between pH 3.5 and 9.5, and preferably between pH 4 and 9.5. The core is either chemically treated with an amino-functional metal oxide, or the core is at least partly covered with O.sub.ySiH.sub.x groups, with 1<x<3, 1≦y≦3, and x>y, or is covered by adsorbed inorganic nanoparticles or cationic multivalent metal ions or oxides.

Provided is a process for preparing an electrode comprising an iron active material. The process comprises first fabricating an electrode comprising an iron active material, and then treating the surface of the electrode with water to thereby create an oxidized surface. The resulting iron electrode is preconditioned prior to any charge-discharge cycle to have the assessable surface of the iron active material in the same oxidation state as in discharged iron negative electrodes active material.

A method for manufacturing a miniaturized electrochemical cell and a miniaturized electrochemical cell is provided. The method includes the following steps: a) forming a colloidal template of colloidal particles made of an electrically insulating material, on a substrate made of an electrically conducting material, b) depositing by electrodeposition in the void spaces of the colloidal template, at least three alternating layers forming a repeating unit, the alternating layers being made of an electron conducting material or a semi -conducting material, the intermediate layer(s) being made of a material M.sub.3 different from materials M.sub.1 and M.sub.2 constituting respectively the upper and lower layers, the material M3 having a standard potential lower than the standard potentials of the materials M.sub.1 and M.sub.2, c) removal of the material M.sub.3 of intermediate layer(s), and d) removal of the colloidal particles of the upper and lower layers to obtain the desired electrodes.

A nanofiber based micro-structured material including metal fibers with metal oxide coatings and methods are shown. In one example, nanofiber based micro-structured material is used as an electrode in a battery, such as a lithium ion battery, where the nanofibers of micro-structured material form a nanofiber cloth with free-standing, core-shell structure.

An anode of the lithium ion battery is provided. The anode of the lithium ion battery comprises a nanoporous copper substrate and a copper oxide nanosheet array. The copper oxide nanosheet array is disposed on one surface of the nanoporous copper substrate, and the nanoporous copper substrate is chemically bonded to the copper oxide nanosheet array.

A battery includes a cathode with a metal halide and an electrically conductive material, wherein the metal halide acts as an active cathode material; a porous silicon anode with a surface having pores with a depth of about 0.5 microns to about 500 microns, and a metal on the surface and in at least some of the pores thereof; and an electrolyte contacting the anode and the cathode, wherein the electrolyte includes a nitrile moiety.

An electrode, in particular for micro-batteries, produced in a plurality of layers with intermediate steps of masking a first layer leaving some parts of the latter exposed in order next to produce a removal of material eliminating defects. After removal of the masking layer, the second layer can be formed. Other layers can then follow in the same way.