Self-discharge mitigation in a liquid metal displacement battery

TL;DR

This paper introduces a method to reduce self-discharge in Liquid Displacement Batteries by adding PbO to the electrolyte, improving efficiency and power output without compromising voltage efficiency.

Contribution

It demonstrates that adding PbO acts as a barrier to lead ion diffusion, enhancing battery performance and mitigating self-discharge in a novel liquid metal battery system.

Findings

Coulombic efficiency increased from 92% to 97%.

Limiting current density rose from 575 to 831 mA cm$^{-2}$.

Limiting power improved from 2.53 to 3.66 W.

Abstract

Recently, a disruptive idea was reported about the discovery of a new type of battery named Liquid Displacement Battery (LDB) comprising liquid metal electrodes and molten salt electrolyte. This cell featured a novel concept of a porous electronically conductive faradaic membrane instead of the traditional ion-selective ceramic membrane. LDBs are attractive for stationary storage applications but need mitigation against self-discharge. In the instant battery chemistry, Li|LiCl-PbCl$_2$|Pb, reducing the diffusion coefficient of lead ions can be a way forward and a solution can be the addition of PbO to the electrolyte. The latter acts as a supplementary barrier and complements the function of the faradaic membrane. The remedial actions improved the cell's coulombic efficiency from 92% to 97% without affecting the voltage efficiency. In addition, the limiting current density of a 500 mAh cell increased from 575 to 831 mA cm$^{-2}$ and the limiting power from 2.53 to 3.66 W. Finally, the effect of PbO on the impedance and polarization of the cell was also studied.