Batteries are used to store electricity, from the application point of view, are energy storage, so it can be said that all lithium batteries are energy storage lithium batteries. Later, in order to distinguish applications, according to the scenario, they are divided into consumption, power and energy storage. Consumer applications are consumer products such as mobile phones, laptops, digital cameras, power applications in electric vehicles, energy storage applications in energy storage power stations.
Actually, power battery is also a kind of energy storage battery, which is mainly used in electric vehicles. Due to the limitation of the volume and weight of the vehicle and the requirement of starting and accelerating, power battery has higher performance requirements than ordinary energy storage battery. For example, the energy density should be as high as possible, the charging speed of the battery should be faster and the discharge current should be larger, but the requirement of ordinary energy storage battery is not so high. Standard, power battery capacity less than 80% can no longer be used in new energy vehicles, but slightly modified, can also be used in energy storage system.
From the application scenario, power lithium batteries are mainly used in electric vehicles, electric bicycles and other electric tools, while energy storage lithium batteries are mainly used in peak shaving and frequency modulation power auxiliary services, renewable energy grid-connected and micro-grid areas.
Due to the different application scenarios, the performance requirements of batteries are also different. First of all, as a mobile power supply, power lithium batteries require as high a volume (and mass) energy density as possible under the premise of safety, in order to achieve a more durable endurance. At the same time, users also hope that electric vehicles can be safely and quickly charged, so power lithium batteries have higher requirements for energy density and power density, just because for safety considerations, energy-based batteries with charging and discharging capacity of about 1C are widely used.
Most energy storage devices do not need to move, so there is no direct requirement for energy density of lithium battery. As for power density, different energy storage scenarios have different requirements.
For peak-shaving, off-grid photovoltaic energy storage or peak-valley price difference energy storage scenarios on the user side, energy storage batteries need to be charged or discharged continuously for more than two hours, so it is suitable to use capacity batteries with charge-discharge ratio less than 0.5C. For frequency-modulated or smooth renewable energy fluctuation scenarios, energy storage batteries need to charge and discharge quickly in the second to minute time intervals. Therefore, it is suitable for the application of batteries with power (> 2C). In some application scenarios where both frequency modulation and peak regulation are required, energy-based batteries are more suitable. Of course, in this scenario, power-based batteries can also be used with capacity-based batteries.
Compared with power lithium batteries, energy storage lithium batteries have higher requirements for service life. The life expectancy of new energy vehicles is usually 5-8 years, while the life expectancy of energy storage projects is generally expected to exceed 10 years. The cycle life of power lithium batteries ranges from 1000 to 2000 cycles, while the cycle life of energy storage lithium batteries is generally required to be more than 3500 cycles.
In terms of cost, power lithium batteries are facing competition with traditional fuel power sources, while energy storage lithium batteries need to face the cost competition of traditional peak shaving and frequency modulation technology. In addition, the scale of energy storage power plants is basically above megawatt level or even 100 megawatt level, so the cost requirements of energy storage lithium batteries are lower than that of power lithium batteries, and the safety requirements are higher.
There are some differences between power lithium batteries and energy storage lithium batteries, but from the point of view of the batteries, they are the same. They can use lithium iron phosphate batteries and ternary lithium batteries. The main difference is BMS battery management system. The power response speed and power characteristics of the batteries, SOC estimation accuracy, charging and discharging characteristics of the batteries can be realized on BMS.
Source: Author: Liu Jimao Source: Promoting Solar Energy