Lithium-Mediated Ammonia Electro-Synthesis: Effect of CsClO₄ on Lithium Plating Efficiency and Ammonia Synthesis

Abstract

Electro-reduction of nitrogen aided by lithium offers a new route for ammonia synthesis. In this novel approach, the first step of lithium plating plays a determining role in faradaic efficiency (FE) of the electro-synthesis process. It was found that the simple addition of cesium salt in a conventional organic electrolyte enhanced Li plating performance (FE of 82.3% for ammonia synthesis) to a substantial extent. This improvement appeared to have a lot to do with a Cs-caused change in morphology of Li deposit, which brought about the suppression of parasitic side reactions between metallic Li and propylene carbonate. This study proves that FE enhancement can be made possible via a simple change in electrolyte composition, an approach that is collectively called electrolyte engineering, and this approach can serve as effective means for making the best of Li-mediated ammonia synthesis.

Electrochemical approaches for selective recovery of critical elements in hydrometallurgical processes of complex feedstocks

“…When the competitive deposition was further carried out in the presence of silver, copper, and lead, the removal efficiency of lead (>80%) was much higher than the removal efficiency of copper (<20%), which was contrary to expectations based solely on reduction potentials ( Paul Chen and Lim, 2005 ). This result indicates that standard reduction potentials alone do not determine the composition of the deposit; other factors, such as metal concentration, pH, ionic strength, additives, the kind of substrate, chelating agents, mode of electrodeposition (chronoamperometry or chronopotentiometry), applied current signal, temperature, and fluid-dynamic conditions, all work together to determine the characteristics of deposition ( Banthia et al., 2017 ; Ibañez and Fatás, 2005 ; Kim et al., 2018a ; Maarof et al, 2017 ).…”

“…Owing to the reactivity of lithium with water, most of the lithium electrodeposition studies (e.g., lithium metal anode in battery applications) have been investigated in non-aqueous electrolyte ( Sun et al., 2020 ). To recover lithium ions from aqueous streams, researchers have used lithium-ion-conducting glass-ceramics (Li 2+2x Zn 1−x GeO 4 or Li 1+x+y Ti 2-x Al x P 3-y Si y O 12 ), which separate an aqueous compartment from an organic electrolyte and thus protect deposited lithium from the exposure to the aqueous electrolyte ( Bae et al., 2016 ; Kim et al., 2018a , 2018b ; Wang and Zhou, 2010 ). The lithium-ion-conducting glass-ceramics allow for the migration of lithium ions only, without the passage of other cations (e.g., Na, Mg, Ca, and K) and the permeation of water ( Hoshino, 2015 ; Kim et al., 2018b ).…”

Strategies in cell design and operation for the electrosynthesis of ammonia: status and prospects

“…To achieve this, the electrolysis must occur under the coexistence of Li salt, N 2 supply, and a proton donor. However, many kinetic and thermodynamic aspects of such multicomponent systems are not fully elucidated, which is further complicated by practical issues such as Li under/over plating, 108–110 electrolyte decomposition, 108,124 electrode passivation with a solid–electrolyte interphase (SEI), 103,108,125,126 and insufficient mass transport of N 2 or protons. 36,65,102,127 Nevertheless, progress has been made in characterizing and optimizing the composition and interaction among the gas, liquid, and solid phases under continuous operation.…”

Preliminary economics for green ammonia synthesis via lithium mediated pathway

“…RSTOIC blocks to simulate reactions with known stoichiometry. The NRR Faradaic efficiency in the electrochemical model was a fixed point 22 at 80% based on recent lithium mediated research 15 where FE values as high as 82.3% were obtained after minimizing parasitic side reactions F I G U R E 1 Process flow diagram for the electrochemical synthesis of ammonia using Li + conductive membrane. The nitrogen generation section of the process was adapted from Gomez et al 22 [Colour figure can be viewed at wileyonlinelibrary.com] via electrolyte variation.…”

“…The most significant development in this research direction has been the attainment of high faradaic efficiencies. 12,15,16 However, there are known technical issues facing this electrochemical route on the laboratory scale [17][18][19][20] that prompts further study into its economic viability on the industrial level. Some of these challenges include low ammonia production rates <10 −10 mol cm −2 s −1 and lack of publications 13,21 that focus on the process from a continuous standpoint.…”