There are many types of lithium-ion batteries, such as power lithium-ion batteries, capacity lithium-ion batteries, and consumer lithium-ion batteries. Power lithium-ion batteries and capacity lithium-ion batteries differ in the materials and processing technologies used, and their different discharge characteristics mean that their application ranges differ greatly. When purchasing lithium-ion battery packs, it is important to distinguish between these two types to avoid adverse effects on the load.
I. Differences between power-type lithium-ion batteries and capacity-type lithium-ion batteries
A power lithium-ion battery pack refers to a power source that provides power to tools, and today it often refers to lithium-ion battery packs that power electric vehicles, electric trains, and the like. Power-energy type lithium-ion battery packs emerged with the advent of plug-in hybrid electric vehicles. They require high battery energy storage to support a certain distance of pure electric driving, and also need good power characteristics to switch to hybrid mode when the battery is low.
1. Different voltage levels
In the battery industry, an increase in voltage leads to an increase in the corresponding output voltage, enabling power lithium-ion battery packs to meet the needs of high-power equipment. The direct effect of parallel connection is to increase the current of the entire battery pack. Since capacity is affected by the output current, the direct purpose of parallel connection is to increase the capacity of the lithium-ion battery pack. Battery packs connected in this way often have a larger capacity, which is the so-called capacity-type lithium-ion battery pack.
2. Different products are used
Some large pieces of equipment require higher voltages because low-power battery packs cannot power them; therefore, high-power lithium-ion battery packs must be used. For example, the electric bicycles we use daily often require a voltage of 48V, which is quite high for most everyday situations. Therefore, high-power lithium-ion battery packs are necessary to ensure the operation of electric bicycles.
High-capacity lithium-ion batteries are like endurance batteries for mountain climbing or running; they require high capacity to maintain low-power discharge for extended periods. They are commonly used in products that require low-current discharge but high capacity, such as power banks and outdoor flashlights.
3. Different internal resistances
The internal resistance of power lithium-ion batteries is lower than that of capacity lithium-ion batteries. Taking 18650 batteries as an example, good manufacturers with 3x discharge rate batteries usually include PDC and have an internal resistance of around 40; batteries with 5x discharge rate batteries generally do not include PDC and have an internal resistance of around 20.
4. Different discharge characteristics
The characteristic of power lithium-ion battery packs is high-current discharge, with a discharge rate generally above C, enabling instantaneous high current;
Capacity-type lithium-ion batteries are characterized by low-current discharge but large capacity, allowing them to continue providing stable power for a longer period of time.
II. How to distinguish between power lithium-ion battery packs and capacity-type lithium-ion batteries?
1. Compositional Materials
The key features of power lithium-ion battery packs are that the positive and negative electrode materials are smaller than those of capacity-type lithium-ion batteries, resulting in lower energy density. They also use separator materials and electrolytes with better conductivity, leading to superior overall performance.
2. Current magnitude
The power lithium-ion battery pack has more tab materials at the positive and negative terminals than the capacity lithium-ion battery (to reduce the internal resistance of the tabs and meet the requirements of larger currents).
3. Discharge rate
High-performance lithium-ion battery packs support high-current discharge, potentially reaching 30C, while typical 18650 lithium-ion batteries only support 1C discharge.
III. Analysis of Consumer Lithium-ion Batteries
As the consumer electronics market enters a phase of stagnant growth, the increase in consumer lithium-ion battery demand may slow down. Overall, with the global consumer electronics market reaching saturation, the proportion of demand for lithium-ion batteries will gradually decline. The aforementioned report predicts that by 2020, the proportion of lithium-ion battery demand from consumer electronics will fall to 30.5%. Demand in other emerging markets, particularly electric vehicles and energy storage, will rebound significantly.
With the growth rate of consumer electronics slowing down, the consumer lithium-ion battery market may be about to undergo a reshuffle. Some products with poor quality and low safety will be eliminated, while companies with technological accumulation and large production scale are expected to gain new opportunities.
Consumer lithium-ion batteries do not require long-term reliability and are generally not used in pairs or individually, so consistency requirements are not very high. However, due to the limited and precious space in consumer devices such as mobile phones and tablets, consumer lithium-ion batteries have strict requirements regarding size, capacity, and energy density. High-end consumer batteries use the most advanced technologies and materials, while power lithium-ion batteries require more advanced process control, consistency control, and quality management.
The above summarizes the differences between power lithium-ion batteries, capacity lithium-ion batteries, and consumer lithium-ion batteries. Each type of battery has different performance, structure, application scope, and parameters; therefore, you should choose according to your actual usage scenario!
