An electroactive material for use in an electrochemical cell, like a lithium ion battery, is provided. The electroactive material comprises silicon or tin and undergoes substantial expansion during operation of a lithium ion battery. A polymeric ultrathin conformal coating is formed over a surface of the electroactive material. The coating is flexible and is capable of reversibly elongating by at least 250% from a contracted state to an expanded state in at least one direction to minimize or prevent fracturing of the negative electrode material during lithium ion cycling. The coating may be applied by vapor precursors reacting in atomic layer deposition (ALD) to form conformal ultrathin layers over the electroactive materials. Methods for making such materials and using such materials in electrochemical cells are likewise provided.

The present invention is directed to a silicon-containing particle for use as a negative-electrode active material of a non-aqueous electrolyte secondary battery, wherein a crystal grain size is 300 nm or less, the crystal grain size being obtained by a Scherrer method from a full width at half maximum of a diffraction line attributable to Si (111) and near 2θ=28.4° in an x-ray diffraction pattern analysis, and a true density is more than 2.320 g/cm.sup.3 and less than 3.500 g/cm.sup.3. The invention provides silicon-containing particles for use as a negative-electrode active material of a non-aqueous electrolyte secondary battery that enable manufacture of a non-aqueous electrolyte secondary battery having an excellent cycle characteristics and a higher capacity compared with graphite types.

A calcium-based secondary cell including a negative electrode that includes a negative-electrode active material, a positive electrode that includes a positive-electrode active material, an electrolyte arranged between the negative electrode and the positive electrode, and a temperature control element. The negative-electrode active material is capable of accepting and releasing calcium ions, and the positive-electrode active material is capable of accepting and releasing calcium ions. The electrolyte includes calcium ions and an electrolyte medium, and is not solid at a temperature of about 20° C. and a pressure of about 1 atm. The electrolyte medium includes a non-aqueous solvent.

A secondary battery includes a cathode; an anode; and (1) a first polymer compound layer disposed between the cathode and the anode and being adjacent to the cathode, (2) a second polymer compound layer disposed between the cathode and the anode and being adjacent to the anode, or (3) the first polymer compound layer and the second polymer compound layer. One or both of the first polymer compound layer and the second polymer compound layer contain a polymer compound containing fluorine (F) as a constituent element and a conductive material dispersed in the polymer compound.

Improved anodes and cells are provided, which enable fast charging rates with enhanced safety due to much reduced probability of metallization of lithium on the anode, preventing dendrite growth and related risks of fire or explosion. Anodes and/or electrolytes have buffering zones for partly reducing and gradually introducing lithium ions into the anode for lithiation, to prevent lithium ion accumulation at the anode electrolyte interface and consequent metallization and dendrite growth. Various anode active materials and combinations, modifications through nanoparticles and a range of coatings which implement the improved anodes are provided.

Improved anodes and cells are provided, which enable fast charging rates with enhanced safety due to much reduced probability of metallization of lithium on the anode, preventing dendrite growth and related risks of fire or explosion. Anodes and/or electrolytes have buffering zones for partly reducing and gradually introducing lithium ions into the anode for lithiation, to prevent lithium ion accumulation at the anode electrolyte interface and consequent metallization and dendrite growth. Various anode active materials and combinations, modifications through nanoparticles and a range of coatings which implement the improved anodes are provided.

Improved anodes and cells are provided, which enable fast charging rates with enhanced safety due to much reduced probability of metallization of lithium on the anode, preventing dendrite growth and related risks of fire or explosion. Anodes and/or electrolytes have buffering zones for partly reducing and gradually introducing lithium ions into the anode for lithiation, to prevent lithium ion accumulation at the anode electrolyte interface and consequent metallization and dendrite growth. Various anode active materials and combinations, modifications through nanoparticles and a range of coatings which implement the improved anodes are provided.

Improved anodes and cells are provided, which enable fast charging rates with enhanced safety due to much reduced probability of metallization of lithium on the anode, preventing dendrite growth and related risks of fire or explosion. Anodes and/or electrolytes have buffering zones for partly reducing and gradually introducing lithium ions into the anode for lithiation, to prevent lithium ion accumulation at the anode electrolyte interface and consequent metallization and dendrite growth. Various anode active materials and combinations, modifications through nanoparticles and a range of coatings which implement the improved anodes are provided.

An electrochemical device is claimed and disclosed, including a method of manufacturing the same, comprising an environmentally sensitive material, such as, for example, a lithium anode; and a plurality of alternating thin metallic and ceramic, blocking sub-layers. The multiple metallic and ceramic, blocking sub-layers encapsulate the environmentally sensitive material. The device may include a stress modulating layer, such as for example, a Lipon layer between the environmentally sensitive material and the encapsulation layer.

Li-ion batteries are provided that include a cathode, an anode comprising active particles, an electrolyte ionically coupling the anode and the cathode, a separator electrically separating the anode and the cathode, and at least one hydrofluoric acid neutralizing agent incorporated into the anode or the separator. Li-ion batteries are also provided that include a cathode, an anode comprising active particles, an electrolyte ionically coupling the anode and the cathode, and a separator electrically separating the anode and the cathode, where the electrolyte may be formed from a mixture of an imide salt and at least one salt selected from the group consisting of LiPF.sub.6, LiBF.sub.4, and LiClO.sub.4. Li-ion battery anodes are also provided that include an active material core and a protective coating at least partially encasing the active material core, where the protective coating comprises a material that is resistant to hydrofluoric acid permeation.