Lithium-ion batteries have high internal resistance because their electrolyte is a gel rather than an aqueous solution. Furthermore, the extremely low water content and chemically stable electrode materials allow lithium-ion batteries to operate safely over a wide temperature range. Some lithium-ion batteries can operate at temperatures as low as -55°C and as high as +150°C. The rated output voltage of lithium-ion batteries is 2.7–3.6V.
Electrode materials for lithium-ion batteries
Different electrode materials impart different characteristics to lithium-ion batteries, which are mainly reflected in the following aspects:
● Rated voltage, minimum voltage, and maximum voltage;
●Initial discharge current, average discharge current, and maximum discharge current;
●Continuous discharge performance and intermittent discharge performance;
● Voltage fluctuations and discharge time when connected to minimum and maximum loads (non-continuous);
●Lifespan;
●Ambient temperature range;
●Maximum discharge current at the lowest operating temperature;
●The shortest time for the voltage to rise to the lower limit;
●Storage time and storage conditions;
There are many types of lithium-ion batteries, the most common being lithium-polyethylene, lithium-manganese dioxide, lithium-thionyl chloride, lithium-sulfur dioxide, and lithium iodide-ion batteries. (See table below for details)
Polyethylene batteries have an output voltage of 2.8V and a relatively high bulk density. Cylindrical polyethylene batteries use a spiral cathode and are sealed with artificial corrugated rubber. Although this structure is relatively robust, under certain special conditions, the rubber sealing material may age and break down before the battery life is exhausted, causing leakage of active materials and leading to accidents.
Compared to polyethylene lithium-ion batteries, LiMnO2 batteries offer advantages in structural strength, bulk density, safety, and output capacity, but their lifespan is only half that of the former. These batteries have lower internal resistance than other types, making them ideal for devices requiring continuous (or short-term) high-current power.
Lithium iodide-ion batteries use entirely solid-state active materials, making them the safest option. These batteries have an internal insulating layer that self-heals if the outer casing is damaged by external impact. The biggest drawback of lithium iodide-ion batteries is their high internal resistance, making them unsuitable for low-load devices.
LiSO2 batteries are the most widely used in special/aerospace fields. However, this type of battery has a lower bulk density than LiMnO2 and polyethylene batteries, and its lifespan and bulk density are only half that of LiSOCl2 batteries.
Among all lithium-ion batteries, LiSOCl2 batteries have the highest energy density and an unparalleled lifespan of 15-20 years. This type of battery is particularly suitable for devices requiring low continuous current supply but high short-term current supply. Due to its long lifespan and low self-discharge, this battery also exhibits excellent environmental resistance.
There are two common internal structures for LiSOCl2 batteries: one is helical winding, and the other is stacked winding. In addition, the PulsesPlus battery also employs a composite structure, incorporating a composite capacitor within the stacked winding structure.
In fact, apart from the stacked winding structure of LiSOCl2 batteries, other lithium-ion batteries all use a helical winding structure. The helical winding structure can improve load capacity, but compared to the stacked winding structure, its capacity is smaller and its self-discharge is more significant.
LiSOCl2 batteries with a stacked and wound structure are particularly suitable for devices with low load current because they have high energy density, low self-discharge rate, and a lifespan of over 10 years. These batteries offer large capacity, small size, and can withstand temperatures ranging from -55°C to +150°C, as well as excellent resistance to pressure, temperature, and shock.
