Journal Article

β-Nickel hydroxide cathode material for nano-suspension redox flow batteries

Yue LI;Cheng HE;Javier PARRONDO;Vijay RAMANI;Elena V. TIMOFEEVA;Yujia DING;Carlo SEGRE

2017

Overview

As part of an effort to build a prototype flow battery system using a nano-suspension containing β-Ni（OH）2 nanoparticles as the cathode material, nano-sized β-Ni（OH）2 particles with well-controlled particle size and morphology were synthesized via the one-step precipitation of a NiCl2 precursor. The composition and morphology of the nanoparticles were characterized by scanning electronic microscopy （SEM） and X-ray diffraction （XRD）. The XRD patterns confirmed that β-Ni（OH）2 was successfully synthesized, while SEM results showed that the particle sizes range from 70 to 150 nm. To ensure that Ni（OH）2 could be employed in the nano-suspension flow battery, the electrochemical performance of the synthesized 13-Ni（OH）2 was initially tested in pouch cells through charge/discharge cycling. The phase transformations occurring during charge/discharge were investigated using in-situ X-ray absorption spectroscopy to obtain the shift in the oxidation state of Ni （X-ray adsorption near edge structure, XANES） and the distances between Ni and surrounding atoms in charged and discharged states （extended X-ray absorption fine structure, EXAFS）. XANES results indicated that the electrode in the discharged state was a mixture of phases because the edge position did not shift back completely. XAFS results further proved that the discharge capacity was provided by β-NiOOH and the ratio between β-Ni（OH）2 and γ-NiOOH in the electrode in the discharged state was 71：29. Preliminary nano-suspension tests in a lab-scale cell were conducted to understand the behavior of the nano-suspension during charge/discharge cycling and to optimize the operating conditions.

• Publisher: Higher Education Press,Springer Nature B.V
• Subject: Absorption spectroscopy / Cathodes / Cycles / Diffraction patterns / Discharge / Electrochemical analysis / Electrochemistry / Electrode materials / Electrodes / Electrons / Energy / Energy Systems / extended X-ray absorption fine structure (EXAFS) / Fine structure / Morphology / nano-suspension flow battery / Nanoparticles / Nickel / Nickel compounds / Oxidation / Particle size / Phase transitions / Research Article / Scanning electron microscopy / scanning electronic microscopy (SEM) / Spectroscopy / Synthesis / Ultrastructure / Valence / X ray absorption / X-ray absorption spectroscopy / X-ray adsorption near edge structure (XANES) / X-ray diffraction / X-ray diffraction (XRD) / X-rays / X射线吸收近边结构 / β-Ni(OH) 2 / β-NiOOH / β-氢氧化镍 / 悬浮液 / 扩展X射线吸收精细结构 / 正极材料 / 液流电池 / 纳米颗粒