Electrochemical behaviors of Li-B alloys in a LiCl-LiBr-KBr molten salt system

Li-B alloys present higher voltages and better power performances than those of conventional Li-Al and Li-Si anodes for thermal batteries. Herein, the electrochemical characteristics of the Li-B alloy in the LiCl-LiBr-KBr electrolyte, including the discharge mechanism, charge transfer coefficient an...

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Bibliographic Details
Published in:Physical chemistry chemical physics : PCCP 2022-11, Vol.24 (46), p.2825-28212
Main Authors: Wang, Chao, Zhang, Xicheng, Peng, Kaite, Cui, Yixiu, He, Ke, Zhang, Xu, Cao, Yong, Xu, Yichun, Jin, Xianbo
Format: Article
Language:English
Subjects:
Alloys
Aluminum
Anodes
Charge exchange
Charge transfer
Current density
Discharge
Electrochemical impedance spectroscopy
Electrolytes
Lithium
Lithium base alloys
Lithium chloride
Molten salts
Open circuit voltage
Silicon
Temperature
Thermal batteries
Voltammetry
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Summary:Li-B alloys present higher voltages and better power performances than those of conventional Li-Al and Li-Si anodes for thermal batteries. Herein, the electrochemical characteristics of the Li-B alloy in the LiCl-LiBr-KBr electrolyte, including the discharge mechanism, charge transfer coefficient and exchange current density, were investigated in the temperature range of 623-823 K by open circuit potential (OCP), cyclic voltammetry (CV), chronopotentiometry (CP), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) techniques. Consequently, the OCP of the Li-B alloy in the LiCl-LiBr-KBr electrolyte is close to that of pure lithium at the investigated temperatures. The discharge of the Li-B alloy electrode includes electrochemical dissolution of free lithium (Li → Li + ) and compounded lithium (LiB → Li + + B). The charge transfer coefficient in the anodic direction (Li → Li + ) is about 0.63 at 623 K, which slightly increases as the temperature increases. The exchange current density of the Li (Li-B)/Li + couple determined by the EIS method increases from 3.84 A cm −2 to 8.40 A cm −2 when the temperature increases from 623 to 823 K, corresponding to an activation energy of 16.4 kJ mol −1 . These results suggest that the Li-B anode allows ultrahigh-rate discharge in thermal batteries. Electrochemical behaviors of Li-B alloys in LiCl-LiBr-KBr molten salt are systematically measured and analyzed using a three-electrode system.
ISSN:1463-9076
1463-9084
DOI:10.1039/d2cp04125a