Various implementations of a method of forming an electrochemical cell include providing a first electrode, a second electrode, a separator between the first and second electrodes, and an electrolyte in a cell container. The first electrode can include silicon-dominant electrochemically active material. The silicon-dominant electrochemically active material can include greater than 50% silicon by weight. The method can also include exposing at least a part of the electrochemical cell to CO.sub.2, and forming a solid electrolyte interphase (SEI) layer on the first electrode using the CO.sub.2.

Electrolytes and electrolyte additives for energy storage devices comprising a sulfonate ester compound are disclosed. The energy storage device comprises a first electrode and a second electrode, wherein at least one of the first electrode and the second electrode is a Si-based electrode, a separator between the first electrode and the second electrode, an electrolyte, and at least one electrolyte additive selected from a sulfonate ester compound.

A negative electrode for a lithium secondary battery, a lithium secondary battery including the negative electrode, and a method for manufacturing the lithium secondary battery, where the negative electrode includes a negative electrode current collector; and a negative electrode active material layer on at least one surface of the negative electrode current collector. The negative electrode active material layer includes a Si-containing negative electrode active material, a conductive material and a first binder polymer. The Si-containing negative electrode active material has cracks formed after activation, and a second binder polymer is present in the cracks. The first binder polymer and the second binder polymer are heterogeneous (e.g., different from each other). The lithium secondary battery shows improved life characteristics.

Systems and methods for configuring anisotropic expansion of silicon-dominant anodes using particle size may include a cathode, an electrolyte, and an anode, where the anode may include a current collector and an active material on the current collector. An expansion of the anode during operation may be configured by utilizing a predetermined particle size distribution of silicon particles in the active material. The expansion of the anode may be greater for smaller particle size distributions, which may range from 1 to 10 μm. The expansion of the anode may be smaller for a rougher surface active material, which may be configured by utilizing larger particle size distributions that may range from 5 to 25 μm. The expansion may be configured to be more anisotropic using more rigid materials for the current collector, where a more rigid current collector may comprise nickel and a less rigid current collector may comprise copper.

A non-aqueous electrolyte secondary battery according to an aspect of the present disclosure is provided with a negative electrode having: a negative electrode collector: a first negative electrode mixture layer provided on the surface of the negative electrode collector; and a second negative electrode mixture layer provided on the surface of the first negative electrode mixture layer. Each of the first negative electrode mixture layer and the second negative electrode mixture layer contains graphite particles. The ratio (S2/S1) of the inter-particle porosity (S2) of the graphite particles in the second negative electrode mixture layer to the inter-particle porosity (S1) of the graphite particles in the first negative electrode mixture layer is 1.1-2.0. The ratio (D2/D1) of the filling density (D2) of the second negative electrode mixture layer to the filling density (D1) of the first negative electrode mixture layer is 0.9-1.1.

A nonaqueous electrolyte secondary battery that is an aspect of the present disclosure comprises a positive electrode, a negative electrode, and a nonaqueous electrolyte solution. The negative electrode comprises a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector. The negative electrode active material layer contains graphite particles A and graphite particles B as negative electrode active materials. The graphite particles A have an internal void ratio of 5% or less. The graphite particles B have an internal void ratio of 8-20%. When the negative electrode active material layer is divided in half in the thickness direction, the region of the half to the side of the outer surface contains more graphite particles A than the region of the half to the side of the negative electrode current collector.

The non-aqueous electrolyte secondary cell according to an embodiment of the present disclosure has a positive electrode, a negative electrode, and a non-aqueous electrolytic solution. The negative electrode has a negative electrode collector and a negative electrode active material layer provided on the negative electrode collector. The negative electrode active material layer contains graphite particles A and graphite particles B as negative electrode active materials. The graphite particles A have an internal void rate of 5% or below. The graphite particles B have an internal void rate of 8 to 20%. When the negative electrode active material layer is halved in the thickness direction, a region on the half closer to the outer surface contains more graphite particles A than a region on the half closer to the negative electrode collector.

Disclosed is a method of fabricating an anode for a lithium-ion battery, including milling a mixture of nano-silicon, one or more carbonaceous materials and one or more solvents, wherein the mixture is retained as a wet slurry during milling. The mixture is carbonised to produce a silicon thinly coated with carbon (Si@C) material. Further milling occurs of a second mixture of the Si@C material, one or more graphite, one or more second carbonaceous materials and one or more second solvents, wherein the second mixture is retained as a second wet slurry during milling. The second mixture is carbonised to produce a Si@C/graphite/carbon material. The anode is formed from the Si@C/graphite/carbon material.

Embodiments described herein relate to electrochemical cells and production thereof under high pressure. In some aspects, a method of producing an electrochemical cell can include disposing a cathode material onto a cathode current collector to form a cathode, disposing an anode material onto an anode current collector to form an anode, and disposing the anode onto the cathode in an assembly jig with a separator positioned between the anode and the cathode to form an electrochemical cell, the assembly jig applying a force to the electrochemical cell such that a pressure in the cathode material is at least about 3,500 kPa. In some embodiments, the cathode material can be a first cathode material, and the method can further include disposing a second cathode material onto the first cathode material. In some embodiments, the first cathode material can include silicon. In some embodiments, the second cathode material can include graphite.

A bilayer-structured silicon carbon composite anode material, a method of preparing the same, and a secondary battery including the same is provided. The method of preparing the anode material includes: drying a first mixture including graphite balls, a nano-silicon slurry, pitch, and flake graphite to prepare a dried product; sintering the dried product to prepare a sintered product including a hard coating layer formed on an outermost surface thereof and containing amorphous hard carbon; mixing the sintered product with a carbon precursor, followed by heat treatment to form a soft coating layer on an outer circumferential surface of the sintered product; and forming a carbon nanotube layer on an outer circumferential surface of the soft coating layer.