The application scenarios of batteries are different, and practical applications have different requirements for their performance, service life, etc., which has led to a differentiation in the manufacturing field of batteries. Lithium ion batteries can be classified into consumer, power, and energy storage batteries according to their application fields.

The consumer lithium battery market is becoming saturated and entering stock competition, with the rise of power and energy storage batteries. In 1991, Sony released the first commercial lithium battery, marking the beginning of the commercial application of lithium-ion batteries. After 2001, the rapid development of portable electronic devices such as mobile phones and MP3 players has driven the growth of demand in the lithium battery industry. According to JuDa Lithium, in 2011, the global shipment of smartphones was only 491 million units; By 2016, the total global sales of smartphones had reached 1.47 billion units. The rapid popularity of smartphones has expanded the demand for lithium batteries. However, after the rapid growth of smartphones in the past few years, the market has approached saturation, with a year-on-year growth rate of only 2% in 2016, far lower than the 10.4% growth rate in 2015. Consumer electronics such as digital cameras and tablets are also similar, with year-on-year growth gradually slowing down after a significant initial increase. Instead, emerging markets such as electric vehicles and energy storage have emerged.

1. Different application scenarios

At present, power batteries and energy storage batteries are the most promising areas for the future development of lithium batteries. Batteries used for electric vehicles and energy storage devices are essentially energy storage batteries. At present, there is no difference in technical principles between energy storage batteries and power batteries, but due to different application scenarios, practical applications have different requirements for their performance, service life, etc.

Power and energy storage battery system products can be divided into battery cells, modules, and battery packs according to different product forms. The battery cell is the core basic component unit of power battery products. A certain number of battery cells can form modules and be further assembled into a complete set of battery packs. The final form of application in new energy vehicles is the battery pack.

Figure 1: Power Battery and Energy Storage Battery Industry Chain

Table 1: Differences between power batteries and energy storage batteries

2. There are differences in system structure and cost composition

The complete electrochemical energy storage system mainly consists of battery packs, battery management systems (BMS), energy management systems (EMS), energy storage converters (PCS), and other electrical equipment. The battery pack is the most important component of an energy storage system; The battery management system is mainly responsible for monitoring, evaluating, protecting, and balancing batteries; The energy management system is responsible for data collection, network monitoring, and energy scheduling; The energy storage inverter can control the charging and discharging process of the energy storage battery pack, and perform AC/DC conversion.

Figure 2: Schematic diagram of the structure of electrochemical energy storage system

In the cost composition of energy storage systems, batteries are the most important component, accounting for 60% of the cost; Next is energy storage inverters, accounting for 20%, EMS (Energy Management System) costs account for 10%, BMS (Battery Management System) costs account for 5%, and others account for 5%.

Figure 3: Schematic diagram of the structure of electrochemical energy storage system

Power battery PACK refers to the battery pack of new energy vehicles that provides energy for the overall operation of the vehicle. The car power battery PACK is basically composed of the following five systems: battery module, battery management system, thermal management system, electrical system, and structural system.

Figure 4: Power Battery System

Table 2: Components of Power Battery System

The cost of a power battery system consists of comprehensive costs such as battery cells, structural components, BMS, casing, accessories, and manufacturing expenses. Cells account for about 80% of the cost, while packs (including structural components, BMS, casing, accessories, manufacturing costs, etc.) account for about 20% of the entire battery pack cost.

Figure 5: Cost composition of power battery system

3. Differences in BMS

In the battery pack, BMS (Battery Management System) is the core, which determines whether the various components and functions of the battery pack can be coordinated and consistent, and directly affects whether the battery pack can provide safe and reliable power output for electric vehicles. Of course, the connection process, spatial design, structural strength, system interface, and other factors of structural components also have a significant impact on the performance of battery packs.

The energy storage battery management system is similar to the power battery management system, but the power battery system is located on a high-speed moving electric vehicle, which has higher requirements for the power response speed and power characteristics of the battery, SOC estimation accuracy, and the number of state parameter calculations. The relevant adjustment functions also need to be implemented through BMS.

Table 3: Differences between Energy Storage Battery and Power Battery BMS

4. There is a significant difference in cycle life between energy storage batteries and power batteries, which is related to materials, compaction density, and other factors.

There is a significant difference in the requirements for cycle life between power batteries and energy storage batteries. Taking electric vehicles as an example, the theoretical lifespan of a ternary lithium iron phosphate battery pack is 1200 times. In terms of usage frequency, it can be fully charged and discharged once every three days and 120 times a year. The calendar lifespan of a ternary lithium battery can reach ten years. Energy storage batteries are charged and discharged more frequently, and have higher requirements for cycle life under the same 10-year calendar life. If energy storage power stations and household energy storage are charged and discharged at a frequency of once a day, the cycle life of energy storage lithium batteries is generally required to be greater than 3500 times. If the charging and discharging frequency is increased, the cycle life requirement is usually required to reach 5000 times or more.

From the perspective of battery structure, factors such as material type, positive and negative electrode compaction density, moisture content, and coating film density can all affect the cycling performance of the battery.

Table 4: Factors affecting the cycle life of lithium-ion batteries