The present invention provides an electrode having a surface layer of niobium-containing metal oxide disposed on a secondary active electrode material. The niobium-containing metal oxide may be a Nb.sub.2O.sub.5 polymorph, NbO.sub.2 or Nb.sub.2O.sub.3, or it may be a mixed metal oxides such as niobium tungsten oxide, titanium niobium oxide or niobium molybdenum oxide. Also provide is an electrochemical cell comprising the electrode, and the use of the cell, for example in a lithium ion battery, at elevated or reduced temperatures.

A method of preparing an electrode material includes heating a substrate with a bonding agent to form a self-assembled monolayer-containing material; and depositing a polymer coating onto the self-assembled monolayer-containing material under an elevated temperature to form a layered material. An electrode material and an electrode incorporating the electrode material is also provided.

Provided is a positive electrode material which can impart a lithium secondary battery with excellent low temperature output characteristics, excellent high temperature cycle characteristics and excellent durability against high voltage. A positive electrode material of a lithium secondary battery disclosed here includes a positive electrode active substance particle, a Li-free first coating at the surface of the positive electrode active substance particle, and a Li-containing second coating at the surface of the positive electrode active substance particle. The first coating contains a titanium oxide represented by TiO.sub.2 or Ti.sub.nO.sub.2n-1, wherein n is an integer of 3 or more. The second coating contains a composite oxide containing Li and Ti, wherein the ratio of the number of atoms of Li relative to the number of atoms of Ti is at least 0.1 and at most 3.

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

A silicon-based powder suitable for use in a negative electrode of a battery. The silicon-based powder comprises silicon-based particles and non-silicon-based particles. The silicon-based particles have a number-based particle size distribution with a d.sub.S50 value, being at most 200 nm. The silicon-based powder has an oxygen content of at most 20% by weight and comprises one or more elements M from a group of metals that have a Standard Gibbs free energy of formation at a temperature T of the oxide from their zerovalent state which is lower than the Standard Gibbs free energy of formation at the same temperature T of SiO.sub.2 from zerovalent silicon. The temperature T is equal to or higher than 573K and lower than 1373K. The content of said one or more elements M in the silicon-based powder is at least 0.10% of the content of Si by weight in said silicon-based powder.

Presented in the present disclosure are nanocomposites and rechargeable batteries which are resistant to thermal runaway and are safe, reliable, and stable electrode materials for rechargeable batteries operated at high temperature and high pressure. The nanocomposites include a plurality of transition metal oxide nanoparticles, a plurality of ultrathin sheets of a first two-dimensional (2D) material, and a plurality of ultrathin sheets of a different 2D material, which act in synergy to provide an improved thermal stability, an increased surface area, and enhanced electrochemical properties to the nanocomposites. For example, rechargeable batteries that include the nanocomposites as an electrode material have an enhanced performance and stability over a broad temperature range from room temperature to high temperatures. These batteries fill an important need by providing a safe and reliable power source for devices operated at high temperatures and pressures such as downhole equipment used in the oil industry.

Here is described an aluminum-ion battery technology having an electrolyte comprising an aluminum trichloride (Al—Cl3)/trimethylamine hydrochloride ionic liquid, aluminum metal as the anode material, and a compatible cathode active material. A wide variety of applications ranging from energy storage in consumer electronics to electric vehicles and to grid storage is also considered.

Provided are a composite negative electrode material, a preparation method therefor and a lithium battery. The composite negative electrode material comprises silicon-containing particles and a carbon coating layer coating at least part of the surface of silicon-containing particles. In Raman spectrum, the composite negative electrode material has a silicon characteristic peak A between 450 cm.sup.−1-550 cm.sup.−1, a carbon characteristic peak B between 1300 cm.sup.−1-1400 cm.sup.−1, a carbon characteristic peak C between 1530 cm.sup.−1-1630 cm.sup.−1, and a graphene structure characteristic peak D between 2500 cm.sup.−1-2750 cm.sup.−1. The preparation method comprises: in protective atmosphere, introducing reaction gas to react with silicon-containing particles, the reaction temperature being 700° C.-1450° C., and the reaction gas comprising a carbon-containing gas, so that at least part of the surface of silicon-containing particles form a carbon coating layer, so as to obtain the composite negative electrode material.

The power storage device comprises an electrode assembly including a positive electrode, a separator, and a negative electrode, and an electrolyte solution. The negative electrode comprises a negative electrode current collector and a negative electrode active material layer. The active material layer comprises a surplus region A not facing the positive electrode active material layer, an end region B facing a region in the positive electrode active material layer, the region extending from an end of the positive electrode active material layer toward a center of the positive electrode active material layer by a length of 5% of a length from the center to the end, and a center region C. A negative electrode potential VA and a negative electrode potential VC after the positive electrode and the negative electrode are short-circuited satisfy Formulas below: (1): VA≤2.0 V, (2): VC≤1.0 V, (3): VA/VC≥0.7.

The present disclosure relates to a composite anode and a secondary battery including the same, the composite anode including a silicon-containing structure; a first carbon material; a second carbon material; and a conductive material, wherein the first carbon material has a specific surface area (BET) value of 1.5 m.sup.2/g or less, a rate of change of the specific surface area (m.sup.2/g) to an increase in particle size (μm) is −0.07 to −0.04 m.sup.2/μm.Math.g, and an area occupied by pores in a cross-section of the first carbon material is 10% or less.