CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of Korean Patent Application Nos. 10-2016-0092243, filed on Jul. 20, 2016, and 10-2016-162291, filed on Nov. 30, 2016, in the Korean Intellectual Property Office, the entire content of each of which is incorporated herein by reference.

BACKGROUND

1. Field

One or more aspects of embodiments of the present disclosure relate to a nickel-based active material for a lithium secondary battery, a method of preparing the same, and a lithium secondary battery including a positive electrode including the nickel-based active material.

2. Description of the Related Art

As portable electronic devices and communication devices are developed, there is a high need for development of a lithium secondary battery having a high energy density.

A lithium nickel manganese cobalt composite oxide, a lithium cobalt oxide, or the like may be used as a positive active material in a lithium secondary battery. However, when such a positive active material is used, cracks may be formed in the positive active material as charge/discharge cycling is repeated. As a result, a lithium secondary battery containing such a material may have a shorter long-term lifespan, higher resistance, and unsatisfactory capacity characteristics. Therefore, improvements in positive active materials are desirable.

SUMMARY

One or more aspects of embodiments of the present disclosure are directed toward a nickel-based active material for a lithium secondary battery and a method of preparing the nickel-based active material, the lithium secondary battery having improved lifespan characteristics and reduced battery resistance due to suppression or reduction of crack formation during charge/discharge cycling.

One or more aspects of embodiments of the present disclosure are directed toward a lithium secondary battery including a positive electrode including the nickel-based active material, the lithium secondary battery exhibiting improved cell performance.

Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments.

One or more example embodiments of the present disclosure provide a nickel-based active material for a lithium secondary battery including at least one secondary particle comprising an aggregate of two or more primary particles, wherein at least a portion of the secondary particle has a radial alignment structure, and a hetero-element compound is positioned between the primary particles.

In some embodiments, the hetero-element compound is a compound containing at least one hetero-element selected from zirconium (Zr), titanium (Ti), aluminum (Al), magnesium (Mg), tungsten (W), phosphorus (P), and boron (B). For example, the hetero-element compound may be an oxide including at least one hetero-element selected from Zr, Ti, Al, Mg, W, P, and B.

In some embodiments, an interior portion of the secondary particle of the nickel-based active material has a larger pore size than an outer portion of the secondary particle.

One or more example embodiments of the present disclosure provide a method of preparing a nickel-based active material for a lithium secondary battery, the method including:

obtaining a nickel-based active material particle A by performing a first heat treatment on a mixture of a lithium precursor and metal hydroxide in an oxidative gas atmosphere; and

mixing a raw material containing the nickel-based active material particle A with a hetero-atom and performing a second heat treatment thereon,

wherein the second heat treatment is performed at a higher temperature than the first heat treatment, and

the prepared nickel-based active material includes at least one secondary particle comprising an aggregate of two or more primary particles, wherein at least a portion of the secondary particle has a radial alignment structure.

One or more example embodiments of the present disclosure provide a lithium secondary battery including a positive electrode including the nickel-based active material, a negative electrode, and an electrolyte between the positive electrode and the negative electrode.

