339results about How to "Reduce irreversible capacity" patented technology

The present invention provides a multiple-doped lithium metal oxide and a method of preparing same for use in the positive electrodes of lithium and lithium ion batteries. The intercalation compound of the invention has the formula LiNi.sub.1-x Co.sub.y M.sub.a M'.sub.b O.sub.2, wherein M is selected from the group consisting of Ti, Zr, and combinations thereof, and M' is selected from the group consisting of Mg, Ca, Sr, Ba, and combinations thereof. The elements in the compounds are present such that x=y+a+b, x is from greater than 0 to about 0.5, y is from greater than 0 to about 0.5, a is from greater than 0 to about 0.15, and b is from greater than 0 to about 0.15.

A lithium ion electrochemical cell having high charge/discharge capacity, long cycle life and exhibiting a reduced first cycle irreversible capacity, is described. The stated benefits are realized by the addition of at least one nitrate additive to an electrolyte comprising an alkali metal salt dissolved in a solvent mixture that includes ethylene carbonate, dimethyl carbonate, ethylmethyl carbonate and diethyl carbonate. The preferred additive is an organic alkyl nitrate compound.

A lithium ion electrochemical cell having high charge/discharge capacity, long cycle life and exhibiting a reduced first cycle irreversible capacity, is described. The stated benefits are realized by the addition of at least one nitrite additive to an electrolyte comprising an alkali metal salt dissolved in a solvent mixture that includes ethylene carbonate, dimethyl carbonate, ethylmethyl carbonate and diethyl carbonate. The preferred additive is an alkyl nitrite compound.

A positive active material is provided which can inhibit side reactions between the positive electrode and an electrolyte even at a high potential and which, when applied to a battery, can improve charge/discharge cycle performance without impairing battery performances even in storage in a charged state. Also provided are: a process for producing the active material; a positive electrode for lithium secondary batteries which employs the active material; and a lithium secondary battery which has improved charge/discharge cycle performance while retaining intact battery performances even after storage in a charged state and which can exhibit excellent charge/discharge cycle performance even when used at a high upper-limit voltage. The positive active material comprises: base particles able to dope and release lithium ions; and an element in Group 3 of the periodic table present on at least part of that part of the base particles which is able to come into contact with an electrolyte. It is produced by, e.g., a process which comprises: producing base particles containing lithium and able to dope and release lithium ions; and then imparting an element in Group 3 of the periodic table to the base particles so that the element can be present on at least part of that part of the base particles which is able to come into contact with an electrolyte.

A lithium ion electrochemical cell having high charge/discharge capacity, long cycle life and exhibiting a reduced first cycle irreversible capacity, is described. The stated benefits are realized by the addition of at least one dicarbonate additive to an electrolyte comprising an alkali metal salt dissolved in a solvent mixture that includes ethylene carbonate, dimethyl carbonate, ethylmethyl carbonate and diethyl carbonate. The preferred additive is an alkyl dicarbonate compound.

Disclosed is a positive active material for a rechargeable lithium battery and a rechargeable lithium battery including the positive active material. The positive active material includes a lithiated intercalation compound capable of reversibly intercalating and deintercalating lithium and a metal oxide represented by the following Chemical Formula 1.

Li_xM_yM′_1-yO₄  [Chemical Formula 1]

In the above Chemical Formula M, M′, x, and y are the same as defined in the detailed description.

The positive active material easily provides lithium needed for the irreversible chemical/physical reaction at a negative electrode during the initial charge reaction, and thus increases charge capacity of a battery, decreases its irreversible capacity, and resultantly improves its cycle life.

Provided are electrode compositions for lithium-ion electrochemical cells that include novel binders. The novel binders include lithium polysalts of carboxylic and sulfonic acids, lithium salts of copolymers of acids, lithium polysulfonate fluoropolymers, a cured phenolic resin, cured glucose, and combinations thereof.

The invention discloses a carbon nano tube/graphene composite negative pole material, a preparation method thereof and a lithium battery. The preparation method of the carbon nano tube/graphene composite negative pole material comprises the steps of placing graphene powder and a catalyst for carbon source splitting decomposition in a microwave reaction cavity, vacuumizing the microwave reaction cavity and leading protective gas into the microwave reaction cavity and using a microwave vapor deposition method to prepare the carbon nano tube/graphene composite negative pole material on a graphene base body growing carbon nano tube. A negative pole of the lithium battery contains the carbon nano tube/graphene composite negative pole material. The preparation method of the carbon nano tube/graphene composite negative pole material adopts the microwave vapor deposition method to perform in-situ preparation of the carbon nano tube/graphene composite negative pole material, does not needs a pre-synthesis process, reduces the production cost, adopts microwave heating and is efficient, low in energy consumption and short in production period. Due to the fact that the lithium battery contains the carbon nano tube/graphene composite negative pole material, embedding and taking-out of lithium are facilitated, the inreversible capacity of first-time charging and discharging is reduced, and the lithium battery is good in safety and high in power.

The invention discloses application of a high-molecular coating in an aluminium negative electrode, the aluminium negative electrode, a preparation method thereof and a secondary battery and relates to the field of electrochemical energy storage devices. For the application of the high-molecular coating in the aluminium negative electrode, the aluminium negative electrode is used as a negative current collector and a negative active material simultaneously. The aluminium negative electrode is used as the negative current collector and the negative active material simultaneously and is coated with the high-molecular coating; the secondary battery comprises the aluminium negative electrode. The application disclosed by the invention has the beneficial effects that the problems that the volume of the aluminium negative electrode used as the negative current collector and the negative active material is expanded and the capacity is attenuated due to an unstable solid electrolyte membrane are relieved; after the high-molecular coating is applied on the aluminium negative electrode, electrolytic solution and the aluminium negative electrode can be effectively isolated, the aluminium negative electrode can be prevented from being eroded and reacted, the coulombic efficiency is effectively improved, the irreversible capacity can be reduced, the cyclic stability of the battery can be improved, simultaneously certain role is played in inhibiting powdering of the aluminium negative electrode in the process of volume expansion, and the integrity of the aluminium negative electrode structure can be ensured.

The negative electrode or anode for a secondary electrochemical cell comprising a mixture of graphite or "hairy carbon" and a lithiated metal oxide, a lithiated mixed metal oxide or a lithiated metal sulfide, and preferably a lithiated metal vanadium oxide, is described. A most preferred formulation is graphite mixed with lithiated silver vanadium oxide or lithiated copper silver vanadium oxide.

The invention provides an anode material for lithium ion secondary battery using a coated graphite powder as a raw material. The coated graphite powder is coated with carbonized material of thermoplastic resin of a carbonization yield of not more than 20 wt % in a proportion of not more than 10 parts by weight the carbonized material per 100 parts by weight graphite powder. The graphite powder as coated with thermoplastic resin increases 5% or more in accumulative pore volume of the graphite powder having a pore size of 0.012 μm to 40 μm as measured by a mercury porosimeter method, as compared with the graphite powder before coated with the thermoplastic resin. The coated graphite powder has a mesopore volume defined by IUPAC of 0.01 cc/g or less as calculated with the BJH method as viewed from desorption isotherm, which is also equal to 60% or less of the pore volume of the graphite powder before coated with the thermoplastic resin, an average particle size ranging from 10 μm to 50 μm, as measured by a laser-scattering-particle-size-distribution measuring device, and a ratio of standard deviation to the average particle size (σ/D) of 0.02 or less.

To provide high energy density, good cycle properties and rate characteristics and long-term safety of a lithium ion battery containing at least an ionic liquid and a lithium salt. The above problems are solved by suppressing reduction and decomposition of the ionic liquid on an anode by using a graphite coated with an amorphous carbon or onto which an amorphous carbon is deposited as an anode active material.