Precise Manufacturing of Highly Porous Electrode Materials with Exceptional Durability for Use in Large-Scale Salt Water Battery Systems

Salt water battery (SWB) is a promising low-cost water desalting technique for brackish (moderately saline) water. However, the stability and regeneration of SWB electrodes have been major obstacles limiting the large-scale practical application of this technology. One of the key challenges is the oxidation of the electrodes during the repeated adsorption and desorption processes, which degrades their long-term performance. In this work, the researchers demonstrated the ability to design and fabricate SWB Electrodes with exceptionally stable performance. They used a one-step pyrolysis method to produce carbon materials doped with a controlled amount of nitrogen (NDCs). The optimized pyrolysis conditions allowed the fabrication of NDCs with a unique meso/microporous structure, high specific capacitance, and impressive salt adsorption capacity of up to 26.5 mg/g in single-pass desalination mode. Notably, all the NDC electrodes exhibited exceptional stability, retaining 100% of their desalination capacity over 150 consecutive charge/discharge cycles. This was achieved even under harsh operating conditions, such as 1.4 V charging voltage, in both aerated and deaerated solutions. Additionally, the NDC electrodes demonstrated charge efficiencies in the range of 40-60%. Analysis of the potential of zero charge (PZC) for the NDC electrodes revealed minimal shifts after the extensive stability tests, indicating negligible electrode oxidation. In comparison, commercially available activated carbon (AC) electrodes showed a significant decrease in salt adsorption capacity within just a few cycles under the same conditions. In summary, the researchers successfully developed a one-step pyrolysis method to fabricate nitrogen-doped carbon (NDC) electrodes with unprecedented cycling stability and desalination performance, addressing a key challenge in the practical application of SWB technology.