A binder for preparing a positive electrode of a lithium secondary battery, and a method for preparing a positive electrode using the same. The binder includes two or more different lithium-substituted polyacrylic acids with different molecular weights. The lithium-substituted polyacrylic acids include two different lithium-substituted polyacrylic acids differing in weight average molecular weight by 500,000 or more from each other.

The present disclosure relates to prelithiated Si electrodes, methods of prelithiating Si electrodes, and use of prelithiated electrodes in electrochemical devices are described. There are several characteristics of electrode prelithiation that enable the superior battery performance. First, a prelithiated silicon anode is already in its expanded state during SEI formation, and therefore less of the SEI layer breaks down and reforms during cycling. Second, the prelithiated anode has a lower anode potential, which may also help the cycle performance of an electrochemical device. A silicon-based electrode, for use in energy storage devices, may have prelithiated silicon active material with a prelithiation level of above 0% to about 30%, with a lithium source within the energy storage devices providing excess lithium for contributing at least a portion of the prelithiation of the silicon active material.

According to one embodiment, an electrode includes a current collector and an active material layer. The active material layer is disposed on at least one of faces of the current collector. The active material layer comprises active materials which include at least a cobalt-containing oxide and a lithium nickel manganese oxide. A ratio of a weight of the cobalt-containing oxide to a total of weights of the cobalt-containing oxide and the lithium nickel manganese oxide is 5 wt % or more and 40 wt % or less.

This application discloses a secondary battery and a device containing the secondary battery. A positive active material of the secondary battery includes one or more of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and a modified material thereof. A negative active material of the secondary battery includes a silicon-oxygen compound and graphite. A separator of the secondary battery includes a substrate and a coating layer. The secondary battery satisfies:

[00001]$7.5\le \frac{3460}{ED}-\left(D50-D_{C}50\times 0.75-\frac{T}{18}\right)\le 11.5,$

where ED≥270 Wh/Kg, 11 μm≤D50≤18.5 μm, 11 μm≤D.sub.C50≤20 μm. The secondary battery according to this application achieves relatively high cycle performance while achieving a relatively high energy density concurrently.

Composite carbon particles including a porous carbon material and a silicon component, the composite carbon particle having an average aspect ratio of 1.25 or less, and a ratio (I.sub.Si/I.sub.G) of a peak intensity (I.sub.Si) in the vicinity of 470 cm.sup.−1 to a peak intensity (I.sub.G) in the vicinity of 1580 cm.sup.−1 as measured by Raman spectroscopy of 0.30 or less, wherein the porous carbon material satisfies V.sub.1/V.sub.0>0.80 and V.sub.2/V.sub.0<0.10, when a total pore volume at a maximum value of a relative pressure P/P.sub.0 is defined as V.sub.0 and P.sub.0 is a saturated vapor pressure, a cumulative pore volume at a relative pressure P/P.sub.0=0.1 is defined as V.sub.1, a cumulative pore volume at a relative pressure P/P.sub.0=10.sup.−7 is defined as V.sub.2 in a nitrogen adsorption test, and has a BET specific surface area of 800 m.sup.2/g or more.

Provided is a positive electrode for a lithium-sulfur secondary battery comprising a positive electrode active material, an electrically conductive material, a binder, and a multivalent metal salt. The multivalent metal salt comprises a cation of a metal selected from a group consisting of metals having 3 to 6 of an effective nuclear charge of outermost electrons in the 3rd and 4th periods. The positive electrode for the lithium-sulfur secondary battery can improve the performance of the lithium-sulfur secondary battery by introducing a multivalent metal salt and thus effectively inhibiting the leaching of lithium polysulfide when applied to the battery while not significantly increasing the weight of the electrode and not significantly lowering the conductivity of the electrode.

An electrochemical cell comprises an anode, a cathode and an electrolyte composition, wherein the anode comprises as anode active material a combination of at least a carbon material and a silicon material; and the electrolyte composition comprises a solvent, from 0.5 wt. % to 70 wt. %, based on the total weight of the electrolyte, of a fluorinated acyclic carbonate compound, from 0.5 wt. % to 10 wt. %, based on the total weight of the electrolyte, of a fluorinated cyclic carbonate compound; and an electrolyte salt.

A lithium ion battery includes a cathode, which has a composite cathode active material, and an anode, which has an anode active material. The composite cathode active material includes at least a first and a second cathode active material, wherein the second cathode active material is a compound having an olivine structure, and wherein at least a lithiation degree of the first cathode active material differs from a lithiation degree of the second cathode active material. Prior to electrolyte filling or the first discharging and/or charging process of the lithium ion battery, the lithiation degree of the first cathode active material is higher than the lithiation degree of the second cathode active material. Prior to electrolyte filling or the first discharging and/or charging process of the lithium ion battery, the anode active material is pre-lithiated. A method for producing a lithium ion battery of this kind is also described.

Manufacturing a lithium-ion battery includes assembling the lithium-ion battery; and performing an initial charging on the lithium-ion battery. The lithium-ion battery includes a positive electrode, a negative electrode, and an electrolyte; the negative electrode contains a negative electrode active material containing a precursor of a silicon material, the precursor having a composition represented by SiO.sub.x where a relationship of 0<x<2 is satisfied. The initial charging includes a first step where the charging is performed to an intermediate voltage at a first current rate, and a second step where the charging is performed from the intermediate voltage to a maximum voltage at a second current rate. The first current rate is lower than 0.5 C; the second current rate is higher than the first current rate; and the intermediate voltage is 3.75 V or higher.

The present nonaqueous electrolyte secondary battery positive electrode comprises a positive electrode core, and a positive electrode composite material layer formed on the surface of the positive electrode core. The positive electrode composite material layer includes at least a positive electrode active material, and lithium phosphate. The positive electrode active material includes a first positive electrode active material wherein the Ni content relative to the total molar amount of metal elements other than Li is 50-65 mol%, and a second positive electrode active material wherein the Ni content relative to the total molar amount of metal elements other than Li is 45 mol% or less. The ratio of the first positive electrode active material to the second positive electrode active material in the positive electrode composite material layer is, by mass ratio, from 80:20 to 50:50.