Lithium Transport and Intermetallic Generation in Li-Bi Liquid Metal Batteries

Liquid metal batteries (LMBs) are a potential electrochemical energy storage technology. However, solid intermetallics could be generated during operation, which hinders the transport of the negative metal in the positive region. In this research, the operating processes of an existing Li||Bi LMB are simulated using a 2-D axisymmetric model considering intermetallic generation, mass transport and electrochemical reactions. The model simulates the lithium-ion transport and electrochemical reaction processes in the positive bulk with a calculation method for the intermetallic distribution. The battery performance evolution based on the positive composition development is investigated, and the losses caused by the different processes at different rates are compared. The large electrolyte ohm loss limits the operation of LMBs at a high rate, and the electrochemical performance is optimized by reducing the electrolyte thickness. However, a thin electrolyte leads to a risk of short circuits caused by predictable positive volume expansion and unpredictable contact. The model can be used to determine the minimum electrolyte thickness to prevent the LMBs from a positive volume expansion-induced short circuit. A plasma-sprayed MgO coating is suggested to be deposited on the bottom of the nickel foam to prevent unpredictable contact.