Efficient and durable multifunctional nickel-doped cobalt phosphate hydrate electrocatalysts for hybrid supercapacitors and zinc–air batteries

Obula Reddy Ankinapalli; B. N.Vamsi Krishna; Young Jun Lee; Logeshwaran Natarajan; Ramakrishna Reddy Ayyaluri; Jae Su Yu

doi:10.1039/d5qi01512j

Efficient and durable multifunctional nickel-doped cobalt phosphate hydrate electrocatalysts for hybrid supercapacitors and zinc–air batteries

Obula Reddy Ankinapalli
, B. N.Vamsi Krishna
, Young Jun Lee
, Logeshwaran Natarajan
, Ramakrishna Reddy Ayyaluri
, Jae Su Yu

Research output: Contribution to journal › Article › peer-review

1 Citation (Scopus)

Abstract

High-performance and long-life cycle supercapacitor (SC) electrodes and air cathodes are essential for the development of efficient hybrid SCs (HSCs) and rechargeable zinc–air batteries (ZABs). In this report, we developed a novel nickel (Ni)-doped cobalt phosphate hydrate ((Ni/Co)₃(PO₄)₂·8H₂O) material via a single-step hydrothermal process, which was employed in SC electrodes and bifunctional electrocatalysts. The doping of Ni metal into the material effectively enhanced its SC performance and electrocatalytic properties. The (Ni/Co)₃(PO₄)₂·8H₂O SC electrode exhibited an excellent specific capacity/capacitance of 220/1760 (mAh g⁻¹/F g⁻¹) with a superior rate capability of 74.5%. More importantly, the (Ni/Co)₃(PO₄)₂·8H₂O SC electrode exhibited an outstanding capacity retention of 92% after 100 000 cycles. The assembled (Ni/Co)₃(PO₄)₂·8H₂O//activated carbon HSC device exhibited high energy and power densities of 47.28 Wh kg⁻¹ and 5588.48 W kg⁻¹, respectively. Moreover, the prepared HSC exhibited an excellent capacitance retention of 95% after the completion of 100 000 cycles. The oxygen evolution reaction overpotential of (Ni/Co)₃(PO₄)₂·8H₂O was 310 mV, which is lower than those of Co₃(PO₄)₂·8H₂O (350 mV), RuO₂ (340 mV), and IrO₂ (330 mV) in 1 M KOH. (Ni/Co)₃(PO₄)₂·8H₂O showed decent onset (E_onset) and half-wave (E_1/2) potentials of 0.86 and 0.756 V, respectively. Specifically, the (Ni/Co)₃(PO₄)₂·8H₂O-based ZAB exhibited excellent open circuit voltage (1.425 V), specific capacity (733 mAh (g_Zn)⁻¹), and power density (160.385 mW cm⁻²) values compared to those of the Pt–C + RuO₂-based ZAB. The (Ni/Co)₃(PO₄)₂·8H₂O-based ZAB exhibited superior cycling stability of 70 h at 2 mA cm⁻². Following the above advantages, the SC and ZAB performances of the (Ni/Co)₃(PO₄)₂·8H₂O material create a novel path for efficient energy storage applications.

Original language	English
Pages (from-to)	575-591
Number of pages	17
Journal	Inorganic Chemistry Frontiers
Volume	13
Issue number	2
DOIs	https://doi.org/10.1039/d5qi01512j
Publication status	Published - 20 Jan 2026

Bibliographical note

Publisher Copyright:
This journal is © the Partner Organisations, 2026

Access to Document

10.1039/d5qi01512j

Cite this

@article{30f9e5eef3df429ebf10f517da48802f,

title = "Efficient and durable multifunctional nickel-doped cobalt phosphate hydrate electrocatalysts for hybrid supercapacitors and zinc–air batteries",

abstract = "High-performance and long-life cycle supercapacitor (SC) electrodes and air cathodes are essential for the development of efficient hybrid SCs (HSCs) and rechargeable zinc–air batteries (ZABs). In this report, we developed a novel nickel (Ni)-doped cobalt phosphate hydrate ((Ni/Co)3(PO4)2·8H2O) material via a single-step hydrothermal process, which was employed in SC electrodes and bifunctional electrocatalysts. The doping of Ni metal into the material effectively enhanced its SC performance and electrocatalytic properties. The (Ni/Co)3(PO4)2·8H2O SC electrode exhibited an excellent specific capacity/capacitance of 220/1760 (mAh g−1/F g−1) with a superior rate capability of 74.5\%. More importantly, the (Ni/Co)3(PO4)2·8H2O SC electrode exhibited an outstanding capacity retention of 92\% after 100 000 cycles. The assembled (Ni/Co)3(PO4)2·8H2O//activated carbon HSC device exhibited high energy and power densities of 47.28 Wh kg−1 and 5588.48 W kg−1, respectively. Moreover, the prepared HSC exhibited an excellent capacitance retention of 95\% after the completion of 100 000 cycles. The oxygen evolution reaction overpotential of (Ni/Co)3(PO4)2·8H2O was 310 mV, which is lower than those of Co3(PO4)2·8H2O (350 mV), RuO2 (340 mV), and IrO2 (330 mV) in 1 M KOH. (Ni/Co)3(PO4)2·8H2O showed decent onset (Eonset) and half-wave (E1/2) potentials of 0.86 and 0.756 V, respectively. Specifically, the (Ni/Co)3(PO4)2·8H2O-based ZAB exhibited excellent open circuit voltage (1.425 V), specific capacity (733 mAh (gZn)−1), and power density (160.385 mW cm−2) values compared to those of the Pt–C + RuO2-based ZAB. The (Ni/Co)3(PO4)2·8H2O-based ZAB exhibited superior cycling stability of 70 h at 2 mA cm−2. Following the above advantages, the SC and ZAB performances of the (Ni/Co)3(PO4)2·8H2O material create a novel path for efficient energy storage applications.",

author = "Ankinapalli, \{Obula Reddy\} and Krishna, \{B. N.Vamsi\} and Lee, \{Young Jun\} and Logeshwaran Natarajan and Ayyaluri, \{Ramakrishna Reddy\} and Yu, \{Jae Su\}",

note = "Publisher Copyright: This journal is {\textcopyright} the Partner Organisations, 2026",

year = "2026",

month = jan,

day = "20",

doi = "10.1039/d5qi01512j",

language = "English",

volume = "13",

pages = "575--591",

journal = "Inorganic Chemistry Frontiers",

issn = "2052-1545",

publisher = "Royal Society of Chemistry",

number = "2",

}

TY - JOUR

T1 - Efficient and durable multifunctional nickel-doped cobalt phosphate hydrate electrocatalysts for hybrid supercapacitors and zinc–air batteries

AU - Ankinapalli, Obula Reddy

AU - Krishna, B. N.Vamsi

AU - Lee, Young Jun

AU - Natarajan, Logeshwaran

AU - Ayyaluri, Ramakrishna Reddy

AU - Yu, Jae Su

PY - 2026/1/20

Y1 - 2026/1/20

N2 - High-performance and long-life cycle supercapacitor (SC) electrodes and air cathodes are essential for the development of efficient hybrid SCs (HSCs) and rechargeable zinc–air batteries (ZABs). In this report, we developed a novel nickel (Ni)-doped cobalt phosphate hydrate ((Ni/Co)3(PO4)2·8H2O) material via a single-step hydrothermal process, which was employed in SC electrodes and bifunctional electrocatalysts. The doping of Ni metal into the material effectively enhanced its SC performance and electrocatalytic properties. The (Ni/Co)3(PO4)2·8H2O SC electrode exhibited an excellent specific capacity/capacitance of 220/1760 (mAh g−1/F g−1) with a superior rate capability of 74.5%. More importantly, the (Ni/Co)3(PO4)2·8H2O SC electrode exhibited an outstanding capacity retention of 92% after 100 000 cycles. The assembled (Ni/Co)3(PO4)2·8H2O//activated carbon HSC device exhibited high energy and power densities of 47.28 Wh kg−1 and 5588.48 W kg−1, respectively. Moreover, the prepared HSC exhibited an excellent capacitance retention of 95% after the completion of 100 000 cycles. The oxygen evolution reaction overpotential of (Ni/Co)3(PO4)2·8H2O was 310 mV, which is lower than those of Co3(PO4)2·8H2O (350 mV), RuO2 (340 mV), and IrO2 (330 mV) in 1 M KOH. (Ni/Co)3(PO4)2·8H2O showed decent onset (Eonset) and half-wave (E1/2) potentials of 0.86 and 0.756 V, respectively. Specifically, the (Ni/Co)3(PO4)2·8H2O-based ZAB exhibited excellent open circuit voltage (1.425 V), specific capacity (733 mAh (gZn)−1), and power density (160.385 mW cm−2) values compared to those of the Pt–C + RuO2-based ZAB. The (Ni/Co)3(PO4)2·8H2O-based ZAB exhibited superior cycling stability of 70 h at 2 mA cm−2. Following the above advantages, the SC and ZAB performances of the (Ni/Co)3(PO4)2·8H2O material create a novel path for efficient energy storage applications.

AB - High-performance and long-life cycle supercapacitor (SC) electrodes and air cathodes are essential for the development of efficient hybrid SCs (HSCs) and rechargeable zinc–air batteries (ZABs). In this report, we developed a novel nickel (Ni)-doped cobalt phosphate hydrate ((Ni/Co)3(PO4)2·8H2O) material via a single-step hydrothermal process, which was employed in SC electrodes and bifunctional electrocatalysts. The doping of Ni metal into the material effectively enhanced its SC performance and electrocatalytic properties. The (Ni/Co)3(PO4)2·8H2O SC electrode exhibited an excellent specific capacity/capacitance of 220/1760 (mAh g−1/F g−1) with a superior rate capability of 74.5%. More importantly, the (Ni/Co)3(PO4)2·8H2O SC electrode exhibited an outstanding capacity retention of 92% after 100 000 cycles. The assembled (Ni/Co)3(PO4)2·8H2O//activated carbon HSC device exhibited high energy and power densities of 47.28 Wh kg−1 and 5588.48 W kg−1, respectively. Moreover, the prepared HSC exhibited an excellent capacitance retention of 95% after the completion of 100 000 cycles. The oxygen evolution reaction overpotential of (Ni/Co)3(PO4)2·8H2O was 310 mV, which is lower than those of Co3(PO4)2·8H2O (350 mV), RuO2 (340 mV), and IrO2 (330 mV) in 1 M KOH. (Ni/Co)3(PO4)2·8H2O showed decent onset (Eonset) and half-wave (E1/2) potentials of 0.86 and 0.756 V, respectively. Specifically, the (Ni/Co)3(PO4)2·8H2O-based ZAB exhibited excellent open circuit voltage (1.425 V), specific capacity (733 mAh (gZn)−1), and power density (160.385 mW cm−2) values compared to those of the Pt–C + RuO2-based ZAB. The (Ni/Co)3(PO4)2·8H2O-based ZAB exhibited superior cycling stability of 70 h at 2 mA cm−2. Following the above advantages, the SC and ZAB performances of the (Ni/Co)3(PO4)2·8H2O material create a novel path for efficient energy storage applications.

UR - https://www.scopus.com/pages/publications/105027725545

U2 - 10.1039/d5qi01512j

DO - 10.1039/d5qi01512j

M3 - Article

AN - SCOPUS:105027725545

SN - 2052-1545

VL - 13

SP - 575

EP - 591

JO - Inorganic Chemistry Frontiers

JF - Inorganic Chemistry Frontiers

IS - 2

ER -

Efficient and durable multifunctional nickel-doped cobalt phosphate hydrate electrocatalysts for hybrid supercapacitors and zinc–air batteries

Abstract

Bibliographical note

Access to Document

Other files and links

Fingerprint

Cite this