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Li-SOCl2 and Li-MnO2 batteries are mainly used in industrial-grade IoT devices which are designed to be maintanence-free during its entire life time, battery reliability is crucial to those applications.

When device is in the design stage, it is important for our clientrs to have some basic but fundamental knowledge on these types of battery in order to make the right choice on battery selection, at CELL MAJIK, we are happy to assist with our expertise.

1) The electrochemical mechanism behind the Li-SOCL2 battery

Li-SOCL2 battery is composed by metal lithium foil (Li) as anode active material and SOCL2 which serves as both cathodic active material and solvent for electrolyte, bewteen the anode and cathod electrode, there is a seperator made by glass fiber paper that segregates them physically. the overall chemical reaction is as below:

4Li + 2SOCl2 → 4LiCl + SO2 + S

Among the end-products, the LiCL is a tiny crystal format element that adheres onto the surface of Lithium foil, forming a passivation layer that hinders the further chemical reaction between anode and cathod material, thus makes this battery has a very low self-discharge rate and a long storage time, in parallel, this passivation layer also create a TMV hassle when the battery is set to be operated, this is especially true when battery is stored for sometime then applied for GSM/GPRS high pulse drain areas.

2) The advantages of Li-SOCL2 batteries

Lithium thionyl chloride (LiSOCl2) batteries (primary cell)
Service life, 10 years +;

Self-discharge, not more than: 1% per year;

Operating temperature range: -55…+85 °С

Contact design: flexible axial leads/plates/connectors of any type

Charging characteristics: any charging is prohibited

Lithium batteries CELL MAJIK, ER series have a long service life – at least 10 years, a very high energy density and operate with minimal losses even at extreme temperatures (operating range: -55C … + 85C).

The self-discharge of the cells is less than 1% per year at room temperature.

The main areas of application of our batteries.
– flow measuring and heat metering equipment;

– wireless sensors of the radio channel of security and fire equipment;

– high temperature drilling and drilling rigs;

– non-volatile memory of any purpose;

– marine and navigational equipment;

– vending machines and ATMs;

– medical equipment, automotive electronics;

– military electronics, ASKUE equipment;

– GPS/tracking;

3) How passivation comes and how to de-passivate

 

 

 

 

 

 

 

 

 

 

 

 

Passivation layer comes from the natural chemical reaction between anode Li and Cathode SOCL2, they are tiny crystal shape elements clung to the surface of Lithium foil that hinders the further chemical reaction of anode and cathod, the passivation layer starts to occur simultaneously once the cell is filled with electrolyet SOCl2 and it grows thicker by time during battery storage period, when the storage temperature is elevated, its growth rate is accelerated.

Passviation is an intrinsic character of Li-SOCl2 battery, it is highly desired since it reserves the battery power in a maximum possible way, on the other hand, it generates TMV ( transient minimum voltage ) to the battery especially when the battery experiences the initial high pulse current when installed into the device after some time storage, which is a reflection of the peel- off of passivation layer internally.

With some additive during the cell production, passivation effect can be reduced, but as exchange, it would bring a higher self-discharge rate to the cell.

To de-passivate, or to peel off the passivation layer, one can use physical force by knocking the passivated cell, but this is not a recommended method as it may damage the cells by some extent leve, CELL MAJIK suggests to do a pre-discharging process with a varity of constant load at a certain time, depending on the passivation level and cell model, please consult CELL MAJIK, info@cellmajik.com for details.

One of the ideal ways to avoid passivation effect is to place super capacitor onto the cell, making a battery pack combination of bobbin cell plus super capactior, in this design, CELL MAJIK provide bobbin cell ER18505H+super capacitor SPC1520, ER26500H+SPC1520 ER34615H+SPC1520 ER18505H+super capacitor SPC1550, ER26500H+SPC1550 ER34615H+SPC1550, super capacitor can be provided serperately too if needed.

4) Temperature influence on Li-SOCL2 battery

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