CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a Divisional of Application No. 15/333,525 filed on Oct. 25, 2016, now U.S. Pat. No. 10,879,531, which claims the benefit of Korean Patent Application No. 10-2015-0148807, filed on Oct. 26, 2015, in the Korean Intellectual Property Office, the entire contents of all of which are expressly incorporated by reference into the present application.

TECHNICAL FIELD

The present disclosure relates to a negative electrode active material particle and a method for preparing the same.

BACKGROUND

Due to a rapid increase in the use of fossil fuels, there is a growing demand for the use of alternative or clean energy. The fields which are most actively being developed as part of this are those of electrical power generation and energy storage.

Currently, secondary batteries are a representative example of an electrochemical device that utilizes electrochemical energy, and the extent of the usage thereof is increasing. Recently, as technological advancements and the demand for mobile devices such as mobile computers, mobile phones, cameras, etc. have increased, there has been a rapid increase in demand for secondary batteries as sources of energy. Among such secondary batteries, much research has been done on lithium secondary batteries, which exhibit high energy densities and operating potentials, and have long cycle lifetimes and low self-discharge rates, and having been commercialized, are in wide use.

As interest in environmental issues has increased, much research has been devoted to electric vehicles, hybrid electric vehicles and the like which can replace fossil fuel powered vehicles such as gasoline powered vehicles and diesel powered vehicles, which are among the leading causes of air pollution. Nickel-metal hydride batteries have been the most widely used power source for such electric vehicles, hybrid electric vehicles and the like, but lithium secondary batteries, which have high energy densities and discharge voltages, are being actively researched for use in such vehicles, and have achieved a certain degree of commercialization.

Typically, lithium secondary batteries are composed of a positive electrode including a lithium transition metal oxide, a negative electrode including a carbon-based active material, and an electrolyte. Lithium ions released from a positive electrode active material are intercalated into a negative electrode active material such as a carbon particle by an initial charge, and during discharge, are deintercalated. Energy transfer occurs as the lithium ions travel back and forth between the two electrodes in this way, thus making charging/discharging possible.

Meanwhile, the carbon-based active material for negative electrodes has excellent stability and reversibility, but is limited in terms of capacity. Thus, in order to be used in mid- to large-scale energy storage systems and the like, the capacity must be at least two times the current capacity. Accordingly, a novel negative electrode active material is needed in order to achieve such mid- to large-scale energy storage systems.

Recently, negative electrode active materials capable of increasing the capacity by a factor of four or more are being developed using non-carbon-based materials such as silicon (Si) and tin (Sn)

However, such materials have a limitation in which the volume of the negative electrode and the secondary battery expand due to gas generated after a charge/discharge cycle, and thus are far from being commercialized.

DISCLOSURE OF THE INVENTION

Technical Problem

Accordingly, an aspect of the present disclosure is to provide a non-carbon-based negative electrode active material particle which has a high capacity and may suppress the generation of gas caused by side reactions.

Another aspect of the present disclosure is to provide a method for preparing the negative electrode active material particle.

Another aspect of the present disclosure is to provide a negative electrode including the negative electrode active material particle, and a secondary battery including the same.

Technical Solution

According to an aspect of the present invention, there is provided a negative electrode active material particle which includes SiOx(0<x≤2) and Li2Si2O5, and which includes less than 2 wt % of Li2SiO3and Li4SiO4.

The SiOx(0<x≤2) may include a nanocomposite structure in which Si and SiO2are mixed therein.

In accordance with another aspect of the present disclosure, a method for preparing a negative electrode active material is provided. The method includes forming a lithium-silicon composite oxide by mixing a silicon oxide represented by SiOx(0<x≤2) with a lithium precursor and then performing a first heat treatment (first step); and performing a second heat treatment on the lithium-silicon composite oxide (second step).

Here, the silicon oxide may include a nanocomposite structure in which Si and SiO2are mixed therein.

In accordance with another aspect of the present disclosure, a negative electrode which comprises a negative electrode composition including the negative electrode active material, and a secondary battery comprising the same are provided.

Advantageous Effects

A negative electrode active material according to the present disclosure includes SiOx(0<x≤2) and Li2Si2O5, and includes less than 2 wt % of Li2SiO3and Li4SiO4. As a result, reactions between a non-aqueous binder included in the negative electrode active material and side products are prevented, and thus there is an effect of suppressing the generation of gas from the negative electrode after charging/discharging. Therefore, a lithium secondary battery having enhanced stability may be manufactured.

