Analysis of main parameters of lithium ion battery

The main parameter index

Lithium ion batteries have high energy density, high conversion efficiency, long cycle life, no memory effect, no charge and discharge time delay, low self-discharge rate, width, and environment friendly advantages such as working temperature range, thus it becomes an ideal carrier of electric power and has been widely used in various fields.

In general, we in the use of lithium ion battery, it will focus on some technical indicators, as the main factor to measure its performance "and". So, what is we need at the time of use, should give special attention to?

Capacity of 1.

This is one of the biggest concerns of all parameters. Smartphones have already spread, we in the use of smart phones, the most worried about is the battery is low, need frequent charging, sometimes can't find the local charge. Early the function of the machine, under normal use, filled the battery could be standby 3 ~ 5 days, some products can even standby more than 7 days. But in the smartphone era, standby time is horrible. It's very important for one reason, is the power consumption is more and more big, the mobile phone and battery capacity is not same proportion of growth.

Capacity of the unit is commonly "mAh" (mAh) or "Ah" (Ann), when use with rated capacity and the difference between the actual capacity. Nominal capacity refers to the lithium ion battery filled under laboratory conditions (temperature and humidity environment of ideal), with a certain discharge ratio (C - rate) discharge to the cut-off voltage, are able to provide the total power. Actual capacity is generally is not equal to the rated capacity, it is directly related to temperature, humidity, charge and discharge rate, etc. Under normal circumstances, the actual capacity is smaller than the rated capacity, sometimes even much smaller than the rating capacity, the winter in the north, for example, if in outdoor use of cell phones, battery capacity drops rapidly.

2. The energy density

Energy density, refers to the unit volume or weight of the battery, can store and release electricity, the unit has two kinds: Wh/kg and Wh/L, respectively than energy and volume weight. The power, here is the above mentioned capacity (Ah), and the integral working voltage (V).At the time of application, the energy density of this index given more has guiding significance.

Based on the current lithium ion battery technology, can achieve the level of energy density about 100 ~ 200 wh/kg, the value is low, have had many occasions to become the bottleneck of lithium ion battery applications. The problem also appeared in the field of electric vehicles, the volume and weight are tightly restricted conditions, determines the electric car battery energy density of single maximum mileage, then appeared the characteristic of the term "range anxiety". If you want to make electric cars single mileage reached 500 kilometers, and the traditional fuel car quite), the energy density of battery monomer must reach more than 300 wh/kg.

Lithium ion battery energy density of ascension, it is a slow process, of Moore's law is far lower than the integrated circuit industry, this can make the performance of electronic products with battery energy density between ascension a scissors, and increasing with time.

3. The charge and discharge rate

This index will affect the lithium ion battery work when continuous current and peak current, its unit is commonly C (C - rate of abbreviations), such as C, 1/10 1/5 C, 1 C and 5 C, 10 C, etc. As an example to elaborate the specific meaning of ratio index, a the capacity of the battery is 10 ah, if the nominal charge and discharge ratio is 1 c, that means this type of battery, can with 10 a current, repeated charge and discharge, until the cut-off voltage of charging or discharging. If the maximum discharge ratio is 10 c @ 10 s, maximum charging ratio 5 c @ 10 s, then the battery can be in the current of 100 a discharge for 10 seconds, for a 50 current charging for 10 seconds.

Charge and discharge rate corresponding to the current value multiplied by the working voltage, can be concluded that the lithium ion battery for power and peak power indicator. Charge and discharge ratio index defined more detailed, when used for guiding significance. Especially as lithium ion battery of electric vehicle power supply, need rules under different temperature conditions of continuous and pulse rate index, to ensure that the lithium ion battery used in a reasonable range.

4. The voltage

Lithium ion battery voltage, there is open circuit voltage and working voltage, charging by some parameters such as voltage, discharge cut-off voltage, this paper no longer separate one by one, but make an explanation.

Open circuit voltage, just as its name implies, is the battery outside don't pick up any load or power, measuring the potential difference between a battery is negative, this is the open circuit voltage of the battery.

Working voltage, external load is the battery or power, in working status, when we have current flow through measuring the potential difference between is negative. In general, as a result of the existence of battery internal resistance, working voltage is lower than the open circuit voltage of discharge state, the working voltage of charging is higher than the open circuit voltage.

Charge/discharge cut-off voltage, refers to the highest and lowest battery allows to achieve working voltage. Exceeded the limit, can produce some irreversible damage to the battery, resulting in a loss of battery performance, serious when even fire, explosion and other accidents.

Open circuit voltage and working voltage of battery, there are certain corresponding relationship with the capacity of the battery.

Life of 5.

Lithium ion battery life will gradually decay with use and storage, and there will be more obvious. Still in smart phones, for example, used mobile phones for a period of time, can clearly feel the phone battery "durable", may be charged only once a day, beginning may need to charge twice a day later, and this is the embodiment of the battery life constantly attenuation.

The life of the lithium ion battery is divided into cycle life and the two parameters of the calendar life. For the unit with the number of cycle life in general, represent the number of batteries can be circulation charge and discharge. Here is conditional, of course, are usually under the ideal temperature and humidity, rated in the depth of the charge and discharge current charge and discharge (100% DOD or 80% DOD), calculation of battery capacity attenuation to 80% of the rated capacity, the cycles.

Working voltage, external load is the battery or power, in working status, when we have current flow through measuring the potential difference between is negative. In general, as a result of the existence of battery internal resistance, working voltage is lower than the open circuit voltage of discharge state, the working voltage of charging is higher than the open circuit voltage.

Charge/discharge cut-off voltage, refers to the highest and lowest battery allows to achieve working voltage. Exceeded the limit, can produce some irreversible damage to the battery, resulting in a loss of battery performance, serious when even fire, explosion and other accidents.

Open circuit voltage and working voltage of battery, there are certain corresponding relationship with the capacity of the battery.

Life of 5.

Lithium ion battery life will gradually decay with use and storage, and there will be more obvious. Still in smart phones, for example, used mobile phones for a period of time, can clearly feel the phone battery "durable", may be charged only once a day, beginning may need to charge twice a day later, and this is the embodiment of the battery life constantly attenuation.

The life of the lithium ion battery is divided into cycle life and the two parameters of the calendar life. For the unit with the number of cycle life in general, represent the number of batteries can be circulation charge and discharge. Here is conditional, of course, are usually under the ideal temperature and humidity, rated in the depth of the charge and discharge current charge and discharge (100% DOD or 80% DOD), calculation of battery capacity attenuation to 80% of the rated capacity, the cycles.

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