Hierarchical One-Dimensional Ammonium Nickel Phosphate Microrods for High-Performance Pseudocapacitors.

Kumar Raju,Kenneth I Ozoemena

doi:10.1038/srep17629

Kumar Raju, Kenneth I Ozoemena

Open Access

https://doi.org/10.1038/srep17629

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Abstract

High-performance electrochemical capacitors will drive the next-generation portable, flexible and wearable electronics. Unlike the conventional all-carbon supercapacitors (electric double layer capacitors, EDLC) with high power but poor energy density, pseudocapacitors capitalize the high energy density inherent to reversible redox reactions and provide a facile means to enhancing the energy ratings of supercapacitors. The high length-to-diameter ratio and anisotropic character of 1-D architecture makes them suitable for use in energy storage. For the first time, we report 1-D microrod structures (~ 36 nm width) of ammonium nickel phosphate hydrate (ANPmr) as a pseudocapacitor with high energy rating and power handling. To confirm the data, the ANPmr-based pseudocapacitor was subjected to various configurations (i.e., half-cell, symmetric, asymmetric, and flexible all-solid-state) and in each case it gave excellent values compared to any accessible literature to date. We clearly demonstrate that a flexible all-solid-state ANPmr-based pseudocapacitor achieved high areal capacitance of 66 mF cm−2 with extra-ordinary energy (21.2 mWh cm−2) and power (12.7 mW cm−2) densities. This work opens doors for a facile, robust and scalable preparation strategy for low-cost, earth-abundant electrode materials for high-performance pseudocapacitors.

Highlights

A considerable amount of research attention has continued to be devoted to renewable and clean energy technologies globally
The small diameter of the 1-D architecture is important as it allows for enhanced accommodation of possible large volume changes, preventing possible cracking or fracturing of the structures usually observed in bulk or micron-sized materials
It is without doubt that an important strategy for achieving high-performance Phosphate-rich materials (PRMs) is the preparation of their hierarchical 1-D architectures such as the wire-like or rod-like morphology

Summary

Introduction

A considerable amount of research attention has continued to be devoted to renewable and clean energy technologies globally. An extraordinary storing of electrical energy with exceptional power has been projected to increase the awareness and development of important technologies such as hybrid electric vehicles, portable electronics and power-saving units It is well-established that the performance of supercapacitor-driven technologies is dependent on the physicochemical properties of their electrode materials[8]. The small diameter of the 1-D architecture is important as it allows for enhanced accommodation of possible large volume changes, preventing possible cracking or fracturing of the structures usually observed in bulk or micron-sized materials. It is possible for ions and electrons to be simultaneously integrated into 1-D architectures, thereby making them ionically and electronically conductive. We show that when subjected to various experimental conditions from half-cell and symmetric to asymmetric and flexible all-solid-state configurations, the NH4NiPO4 microrods still maintained excellent performance

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