Highly Efficient Capacitive Deionization Enabled by NiCo₄MnO_8.5 Electrodes

Abstract

The shortage of fresh water resources is one of the major challenges facing this planet. Capacitive deionization (CDI) techniques that are deemed to be highly efficient and require low capital cost have attracted widespread attention in the last few decades. In this work, the cubic ternary metal oxides NiCo4MnO8.5 (Ni–Co–Mn–O) are synthesized by facile hydrothermal method for enhanced symmetrical CDI. Electrochemical measurements illustrate that the Ni–Co–Mn–O possesses low internal resistance and ion diffusion impedance. As a result, the salt removal capacity of the Ni–Co–Mn–O electrode increases from 26.84 to 65.61 mg g−1 by varying the voltage from 0.8 to 1.4 V in 1.0 × 10−2 m NaCl solution, while the charge efficiency stabilizes at ≈80%. After 20 cycles, the capacitance retained is 64.27%, which is due to the irreversibility of Co2+/Co3+ and Mn2+/Mn3+ and the release of Ni3+ from the Ni–Co–Mn–O electrode after long desalination/salination cycles.

Impact of Faradaic Interlayer Confinement and Carbon‐Centered Macrostructure Designs for Ion Capture and the Recovery of Elements

“…[114] Similarly, due to their suitability in aqueous solutions, faradaic electrodes, particularly transition metal oxides (such as NiO, Co 3 O 4 , and MnO 2 ), have received a lot of attention in the field of energy storage research. [138] In bimetallic oxide, spinel structure (MCo 2 O 4 ; M=Ni, Co, Zn) in regular tetrahedral and octahedral position occupied by M 2 + . [139] As a result, sodium ions from the electrolyte will combine with oxygen to form the NaÀ O bond, resulting in energy storage and separation with sodium ions.…”

Comprehensive Study on the Ion-Selective Behavior of MnOx for Electrochemical Deionization

“…With the support of theoretical calculations, vanadium hexacyanoferrate thermodynamically favored the intercalation of Ca 2+ rather than Na + , demonstrating a totally distinctive behavior. Besides PBAs, transition-metal ions also play an important role in the other series of materials in the field of ECDI, such as metal oxides, , MXenes, ,, and certain hybrid materials. − However, the number of articles related to the ion selectivity for these materials is relatively small, creating an empty space in this field that requires efforts to fulfill.…”