【Technical Field】
The present invention relates to a positive electrode active material for a sulfide-based
all-solid-state battery.
The present application claims the benefit of priority based on Korean Patent
Application No. 10-2021-0127344 dated September 27, 2021, and all contents published in the
10 literature of the Korean patent application are incorporated as a part of this specification.
【Background Art】
A lithium all-solid-state battery is a battery that can directly convert chemical energy
into electrical energy by using a sulfide-based or oxide-based solid electrolyte and oxidizing or
reducing lithium ions through an all-solid material. In particular, due to the advantages such as
15 eco-friendliness, safety, and high energy density capacity storage, the problems of low energy
density, high cost and toxicity, which are limitations of currently commercial lithium secondary
batteries, can be solved by a sustainable secondary battery, and thus there is an increasing
demand for the sustainable secondary battery.
However, the all-solid-state battery has problems such as irreversible properties due to
20 interfacial side reactions between the sulfide-based or oxide-based solid electrolyte and the
positive electrode during the charging and discharging reaction; and a decrease in battery
2
capacity due to non-uniform distribution of electrode charges due to interfacial resistance and
space-charge layer formation. In addition, the low ionic conductivity of the all-solid material
itself hinders the commercialization of lithium all-solid-state batteries, which are next-generation
batteries.
In order to solve these problems, posi 5 tive electrode active materials using lithium metal
sulfide or the like as a medium have been developed. However, the positive electrode active
material, which has been developed to date, has a problem that, while charge-discharge
performance and the like are greatly increased in terms of capacity as compared with an oxidebased
positive electrode active material as a new positive electrode active material, the capacity
10 retention rate at the time of charge and discharge is significantly lower than that of an existing
oxide-based positive electrode active material or negative electrode active material.
In addition, although a technique has been developed in which a positive electrode
active material is surface-treated with a metal oxide or the like to be applied to an all-solid-state
battery, the effect of improving the charging and discharging performance is insignificant, or
15 there is the effect of improving the charging and discharging performance, but there is a
limitation that is unsuitable for commercialization due to the high cost of a raw material to be
used.
Related Art
Korean Patent Registration No. 10-1582394
20 Summary
An object of the present disclosure is to provide a positive electrode active material for a
sulfide-based all-solid-state battery in which the mobility of lithium ions is improved by
preventing the occurrence of cracks that may be generated between the positive electrode active
3
material and the solid electrolyte or the induction of side reactions therebetween.
In order to solve the above-mentioned problem,
in one embodiment , the present disclosure provides a positive electrode active material
for an all-solid-state battery, including:
a core containing a lithium m 5 etal oxide represented by the following Chemical Formula
1; and
a shell adsorbed on the surface of the core and including metal sulfide (M2S) particles,
the metal sulfide particles have an average particle size of 0.1 nm to 40 nm,
[Chemical Formula 1]
Lix[NiyCozMnwM1
10 v]Ou
wherein,
M1 is one or more elements selected from the group consisting of W, Cu, Fe, V, Cr, Ti,
Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, and
x, y, z, w, v and u are 1.0≤x≤1.30, 0.1≤y<0.95, 0.01