CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2019-0106976, filed on Aug. 30, 2019, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The following disclosure relates to a positive electrode for a Zn—Br battery, a Zn—Br battery including the same, and a method of manufacturing the positive electrode for a Zn—Br battery.

BACKGROUND

With the recent increasing interest in inhibiting the generation of global-warming gases, power generation systems using renewable energy such as sunlight, wind power, and the like have been actively researched and distributed all over the world. However, because the renewable energy such as sunlight, wind power, and the like depend on natural energy having a high variability, it has a drawback in that it is difficult to respond to the variability of electric power and it is difficult to secure the stability of electric power supply. Therefore, stable energy storage technology for accepting the variability of renewable energy, smoothly supplying electric power, and making efficient use of power generation facilities is needed.

Much research on redox flow batteries using an electrochemical method as the stable energy storage technology has been conducted. In particular, Zn—Br batteries have come into the spotlight due to their advantages such as price competitiveness, a high discharge voltage, and the like.

RELATED ART DOCUMENTS

Patent Documents

KR 10-2019-0072124 A (Jun. 25, 2019)KR 10-1862368 B1 (May 23, 2018)

SUMMARY

An embodiment of the present invention is directed to providing a positive electrode for a Zn—Br battery capable of avoiding, reducing or minimizing crossover of brominated anions from a positive electrode to a negative electrode to improve current efficiency and voltage efficiency of a Zn—Br battery and showing excellent charge/discharge cycle stability as well, and a method of manufacturing the same.

In one general aspect, a positive electrode for a Zn—Br battery is provided, which includes a carbon body doped with pyridinic nitrogen.

The Zn—Br battery may be a membraneless flowless Zn—Br battery.

The carbon body doped with pyridinic nitrogen may be a microporous carbon body including micropores.

The micropores may have an average pore size of 0.2 to 3 nm.

The pyridinic nitrogen may be present at 30 atom % or more with respect to the total nitrogen content of the nitrogen-doped carbon body.

The pyridinic nitrogen may be positively charged pyridinic nitrogen.

The carbon body doped with pyridinic nitrogen may further include a porous carbon body substrate, and the porous carbon body substrate and the carbon body doped with pyridinic nitrogen may be integrated with each other.

Adsorption energies of the carbon body doped with pyridinic nitrogen and the brominated anions may satisfy the following Expression 1:
EAd-CN/EAd-C>5  [Expression 1]

(Wherein EAd-CNrepresents an adsorption energy of a carbon body doped with pyridinic nitrogen and brominated anions, and EAd-Crepresents an adsorption energy of a carbon body and brominated anions).

In another general aspect, a Zn—Br battery is provided, which includes a negative electrode including a transition metal coated with zinc, the positive electrode according to an exemplary embodiment of the present invention, and an electrolyte, wherein a pH of the electrolyte is in a range of 1.5 to 5.

A drop in open circuit voltage of the Zn—Br battery may last for 40 hours or more.

The Zn—Br battery may have an energy efficiency of 70% or more for 1,000 charge/discharge cycles.

In still another general aspect, a method of manufacturing a positive electrode for a Zn—Br battery is provided, which includes:

(S1) subjecting a porous carbon body substrate to hydrophilic surface treatment;

(S2) immersing the hydrophilized porous carbon body substrate in a solution including a metal precursor and an organic ligand precursor;

(S3) drying the immersed porous carbon body substrate to coat the porous carbon body substrate with nanocrystalline polyhedrons including metal-organic frameworks (MOFs); and

(S4) carbonizing the porous carbon body substrate coated with the nanocrystalline polyhedrons.

The metal-organic frameworks may be zeolitic-imidazolate frameworks (ZIFs).

The carbonization process of the step (S4) may be performed at 500 to 1,200° C.

The hydrophilic surface treatment process of the step (S1) may be performed at 400 to 800° C. under an oxidizing atmosphere.

