# Principles for Optimal Electrode Design and Operation for Desalination with Electrochemical Ion Pumping

## TL;DR

This paper explores how to design and operate electrodes for efficient desalination using electrochemical ion pumping.

## Contribution

The study provides systematic principles for optimizing electrode design and operation in electrochemical ion pumping.

## Key findings

- Optimal performance requires balancing ion mobility through the polymer phase and electronic conductivity from the carbon phase.
- Desalination performance remains stable over a wide range of electrode capacity but declines at very low capacity.
- EIP's specific energy consumption is consistent across different cycle times if electrolysis is prevented.

## Abstract

Electrochemical ion pumping (EIP) is an emerging electrochemical
separation form that eliminates solution mixing in conventional capacitive
deionization and enables pseudocontinuous desalination with unidirectional
ion flux. In this work, we systematically investigate electrode design
and operational parameters governing the performance of EIP desalination
using both experiments and modeling. We first evaluated the effect
of carbon and polymer fractions on ionic and electronic transport
within the cation-shuttling electrodes, demonstrating that optimal
performance requires balancing ion mobility through the polymer phase
and the electronic conductivity and ion storage capacity provided
by the carbon phase. We then assessed the impact of electrode capacity
and conductivity on EIP performance by varying the ratio of activated
carbon and carbon black, showing that desalination performance is
relatively stable over a wide range of capacity and is only undermined
at extremely low capacity. Finally, we analyze the role of cycle time
and show that EIP has similar specific energy consumption with very
different cycle times as long as electrolysis is prevented. Overall,
these results establish guiding principles for rational electrode
design and operation to achieve optimal EIP performance.