A method for interfacial formation of large-capacity liquid metal batteries

Abstract

The invention belongs to the technical field related to electrochemical energy storage, and discloses a large-capacity liquid metal battery interface formation method, which includes the following steps: (1) heating the battery to the working temperature; (2) detecting the voltage of the battery, and waiting for the battery After the voltage is stable, put it aside for a predetermined time; (3) discharge the battery at a constant current; (4) after putting the battery on hold, charge the battery with a constant current until it is fully charged; (5) charge the battery at a constant voltage until the current density is lower than 50mA / After cm2, put the battery on hold; (6) Go to step (3) to cycle for 5 to 10 cycles; (7) Discharge the battery at a constant current; (8) After putting the battery on hold, charge the battery at a constant current to fully charge Finally, put the battery on hold; (9) go to step (7) to cycle until the coulombic efficiency of the battery meets the requirements, and the interfacial formation is completed. The short-circuit failure of the battery is avoided by the above method, the service quality of the battery is improved, and the influence of the internal resistance polarization of the battery on the formation of the interface is reduced.

Description

technical field [0001] The invention belongs to the technical field related to electrochemical energy storage, and more specifically relates to an interface forming method for a large-capacity liquid metal battery. Background technique [0002] Liquid metal battery is a new type of battery energy storage technology for grid-level energy storage applications proposed by Professor D.R. Sadoway of MIT in 2007. Liquid metal batteries usually operate at a high temperature of 300-700°C, the positive and negative electrodes are liquid metal, and the electrolyte is inorganic liquid or semi-solution molten salt. When the battery is running, its metal electrodes and inorganic salt electrolyte melt into a liquid state at high temperature, and automatically stratify according to the difference in density. When discharging, the negative electrode metal loses electrons, and the electrons do work through the external circuit. After the negative electrode metal is ionized, it migrates to t...

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Problems solved by technology

[0004] However, compared with small-capacity liquid metal batteries, the amount of positive and negative active materials in large-capacity liquid metal batteries increases, and the electrochemical reaction interface area between the positive and negative electrodes of the battery and the electrolyte will also increase. During the conduction process of a large number of negative electrode metal ions at the negative electrode-electrolyte-positive electrode three-layer interface, its rate and distribution uniformity are difficult to control, and it is easy to enrich at the reaction interface to form refractory substances. With the continuous accumulation of refractory substances , the battery will gradually short-circuit and fail, so a reasonable formation method is needed to promote the establishment and stable formation of the three-layer reaction interface in the initial stage of operation of the large-capacity liquid metal battery.

At present, small-capacity battery cells generally use constant current deep charge and discharge (generally 80% DOD) mode for interface formation. This method can effectively promote the electrochemical reaction interface when the amount of battery materials is small and the three-layer interface area is small. However, after the battery capacity is enlarged, with the increase of metal ions in the negative electrode and the increase of the interface area, simply charging and discharging the battery with a constant current can no longer promote the balanced distribution of a large number of metal ions under the large-area reaction interface, and it is difficult to complete effectively Interface formation

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