LR726 battery.Energy storage battery usage scenarios

　　Clean energy + energy storage + intelligence is the development direction of the energy Internet. In the future, the development of clean energy and smart energy is inseparable from energy storage. 2017 is the first year of energy storage in my country. The issuance of the "Command Opinions on Promoting the Development of Energy Storage Technology and Industry" marks the arrival of the spring of energy storage. Although the weather in early spring turns warm and cold, the energy storage industry has begun to sprout and blossom. Energy storage projects, especially energy storage battery projects, are springing up like mushrooms after a rain in the fields of power generation, grid side, user side, microgrid, communication energy storage, emergency power supply, etc. The spring of energy storage has arrived.

　　Energy storage technologies include physical energy storage (pumped hydro energy storage, compressed air energy storage, flywheel energy storage, seawater energy storage, superconducting energy storage), chemical energy storage (hydrogen storage, carbon storage), electrochemical energy storage (battery energy storage There are four major types: supercapacitor energy storage) and heat and cold storage. Among various types of energy storage technologies, battery energy storage is the fastest growing and most concerned energy storage technology direction. By the end of 2017, a total of 1,210.3MW of global battery energy storage projects had been put into operation, and the cumulative scale entered the GW era for the first time.

　　1. Energy storage battery usage scenarios

　　(1) Renewable energy grid integration

　　Low temperature lithium iron phosphate battery 3.2V 20A -20℃ charging, -40℃ 3C discharge capacity ≥70%

　　Charging temperature: -20~45℃ -Discharge temperature: -40~+55℃ -40℃ Supports maximum discharge rate: 3C -40℃ 3C discharge capacity retention rate ≥70%

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　　The intermittent and variability of renewable energy power generation, as well as the continuous increase in penetration rate, pose severe challenges to the normal operation and dispatch of the existing power grid system. In recent years, in order to utilize as much renewable energy as possible and improve the reliability and efficiency of power grid operations, various energy storage technology research and engineering demonstration projects have developed rapidly. Large-capacity battery energy storage technology is used in wind power and photovoltaic power generation. It can smooth power output fluctuations, reduce its impact on the power system, improve the power station's ability to track planned output, and provide backup energy for the construction and operation of renewable energy power stations.

　　(2) Grid auxiliary services

　　Grid auxiliary services are divided into capacity-type and power-type services. Capacity-type services include grid peak shaving, load following and black start, etc. The energy storage scale needs to reach a certain volume, generally between 1~500MW, and the discharge time is greater than 1 hour; power Services such as frequency modulation auxiliary and voltage support require the battery to have a large power or voltage output in a short period of time (minute level). In terms of improving the grid's frequency regulation capability, energy storage battery technology can reduce the losses of traditional frequency modulation power supplies caused by frequent switching; in terms of improving the grid's peak regulation capability, the energy storage system can respond promptly and reliably to changes in power supply and load. Scheduling instructions and changing its output level according to the instructions.

　　(3)Power grid transmission and distribution

　　Energy storage battery systems can improve power distribution quality and reliability. When the distribution network fails, it can be used as a backup power supply to continue supplying power to users; in terms of improving power quality, it can be used as a system controllable power supply to manage the power quality of the distribution network, eliminate voltage sag, harmonics and other problems, while reducing the main Invest in network expansion and save expansion funds.

　　Low temperature high energy density 18650 3350mAh-40℃ 0.5C discharge capacity ≥60%

　　Charging temperature: 0~45℃ Discharge temperature: -40~+55℃ Specific energy: 240Wh/kg -40℃ Discharge capacity retention rate: 0.5C Discharge capacity ≥ 60%

　　(4) Distributed and micronet

　　The microgrid system requires an energy storage device, and the energy storage device is required to do the following: 1) provide short-term uninterrupted power supply when it is off-grid and the distributed power supply cannot supply; 2) be able to meet the microgrid peak load regulation demand; 3) can improve the power quality of the microgrid; 4) can complete the black start of the microgrid system; 5) balance the output of intermittent and fluctuating power supplies, and effectively control the electrical load and thermal load. The energy storage battery system has the characteristics of dynamically absorbing energy and releasing it in a timely manner. As a necessary energy buffer link of the microgrid, it can improve power quality, stabilize network operation, optimize system configuration, and ensure the safe and stable operation of the microgrid.

　　(5) User side

　　User-side energy storage mainly includes industrial and commercial peak-shaving and valley-filling and demand-side response. Batteries combined with power electronics technology can provide users with reliable power and improve power quality; and use the difference in peak and valley electricity prices to save users money.

　　(6) Energy supply system of electric vehicle VEG mode

　　The development of the new energy automobile industry must be coordinated with the energy storage industry. In order to meet the demand for safe and fast charging of electric vehicles in the future, it is necessary to establish distributed energy stations similar to gas stations. The energy stations are equipped with low-cost, long-life megawatt-level energy storage batteries, which can charge and store electricity from the power grid and provide electricity to electric vehicles. Cars can be charged quickly; at the same time, the energy station can also interact with the power grid for power peak shaving or frequency modulation.

　　2. Types of energy storage batteries

　　The complexity of energy storage usage scenarios determines the diversified development direction of energy storage battery technology. Selecting appropriate energy storage battery technology for specific scenarios will be the main theme of the energy storage market for a long time in the future. The research and development direction of new energy storage battery technologies in the future should also follow this rule, and amplify its advantages for specific scenarios to gain future success. Possibility of commercial use.

　　There are many characteristic parameters that characterize the performance of energy storage batteries, the most important of which are the power characteristics and capacity characteristics of the battery. Therefore, energy storage batteries can be roughly divided into three types based on the different requirements for battery power capacity ratio (W: Wh, referred to as C) in different energy storage usage scenarios: capacity type (≤0.5C), energy type (≈1C ) and power type (≥2C). The larger the ratio, the higher the power density of the battery, but the lower the capacity density and the higher the price per unit capacity.

　　For example, power peak shaving, off-grid photovoltaic energy storage or peak-to-valley price difference energy storage on the user side generally require the energy storage battery to continue charging or discharging for more than two hours, so it is suitable for the use of capacity batteries; regarding power frequency regulation or smoothing In energy storage scenarios where renewable energy fluctuates, the energy storage battery needs to be charged and discharged quickly in seconds to minutes, so it is more suitable for the use of power batteries; in some usage scenarios where frequency regulation and peak shaving are required at the same time, Energy-type batteries are more suitable. Of course, power-type and capacity-type batteries can also be used together in this scenario.

　　Among the current types of energy storage batteries, flow batteries and lithium slurry batteries are typical capacity batteries, while lithium titanate batteries among lithium-ion batteries are a typical power battery. This is due to the characteristics of the above batteries. Determined by essential attributes, it is difficult to change. For other types of batteries, the properties of other types of batteries can be adjusted to a certain extent by changing the battery materials and processes to adapt to different energy storage usage scenarios.

　　3. Technical connotation of energy storage battery

　　In the future, large-capacity batteries for power peaking energy storage and high-power batteries for power frequency regulation energy storage still need technological innovation breakthroughs. The technical content of energy storage batteries mainly includes six aspects: material technology, structural technology, manufacturing technology, use technology, repair technology and recycling technology.

　　(1)Material technology

　　Battery core materials include positive electrode materials, negative electrode materials and electrolyte materials, and accessory materials also include separators, current collectors and battery case materials. In the past thirty years, the research and development of lithium-ion battery materials has mainly focused on improving the energy density, cycle life and safety performance of the materials, and developing low-cost material preparation technology; the research and development of flow battery materials has mainly focused on electrolytes and separators. Modification of materials. In 2006, the lead-acid battery category began to select and modify carbon material additives in negative electrode paste to develop long-life lead-carbon batteries for energy storage.

　　Throughout the research history of energy storage battery technology, although the advancement of materials can bring about significant improvements in battery performance, the process of material innovation that can have practical effects is actually very slow. In particular, the material properties reported in laboratory papers are not equivalent to the performance of actual batteries, and there is often a considerable gap between the two. Therefore, although battery materials are critical, they are not all aspects of battery technology research. At present, the establishment of technical engineering projects in the field of energy storage places too much emphasis on the materials research work of the laboratory and ignores the connection with actual use scenarios, resulting in a large disconnect between scientific research work and industrial development needs, which should be given sufficient attention.

　　(2) Structural technology

　　Not all batteries can be called energy storage batteries. Those with system power above 1KW can be called energy storage batteries; batteries with system power ≥1MW and used in energy storage power stations are called power energy storage batteries.

　　Energy storage battery structure technology includes battery cell internal structure technology and external system structure technology. Different from batteries for small consumer electronics, the structure of energy storage batteries is more complex, with system series and parallel requirements and the characteristics of high power and capacity.

　　Existing energy storage and power lithium-ion batteries are developed from micro-sized lithium-ion batteries such as mobile phone batteries. Whether they are cylindrical or square batteries, from the internal structure, all types of lithium-ion batteries use The bonded thin film electrode structure brings fundamental structural problems to the design of consistent performance of lithium-ion batteries for energy storage. In addition, when the battery is scrapped and recycled, all the bonded electrodes can only be crushed, and the internally cracked aluminum foil, copper foil materials, Co, Li elements, etc. must be recycled metallurgically, resulting in high recycling costs and the presence of acid and alkali waste liquid pollution. Resolve risks. Therefore, the structural design of lithium-ion batteries for energy storage must learn from the structural ideas of large-scale batteries such as lead-acid batteries and flow batteries, and transform them from petite and rich that are prone to problems to safe and reliable, big and bulky, so as to be suitable for large currents. High-power energy storage usage scenarios.

　　In the future, the research and development of large-scale energy storage batteries will also consider the integrated design of the internal structure and external structure of the battery. Regarding power energy storage, end-user customers are concerned about system cost, system efficiency, system life and system safety, rather than the energy density of a single battery or the cycle life of a single battery. Therefore, as the research and development side of battery technology, we should proactively consider the innovative integration of the internal structure of the cell and the external structure of the system, and reduce the cost and safety pressure faced by the external system through subversive design of the internal structure. This will be an important direction for future research on energy storage battery structure technology.

　　(3) Manufacturing technology

　　Energy storage battery manufacturing technology is closely related to battery structural design. The series-parallel characteristics of the energy storage battery system require that the batteries must have good consistency, so intelligent management and control of the processing technology is particularly important. How to manufacture high-performance energy storage batteries with low-cost equipment and processes? This is a contradictory issue, and it is also a key issue in the current development of energy storage battery manufacturing technology.

　　The existing lithium-ion battery processing technology is a transition from the past tape manufacturing process to adapt to the accuracy requirements of battery film coating pole pieces. In addition, the variety of battery product models and the lack of specifications have led to low material utilization in the battery processing process. , The product qualification rate is low, the equipment operation rate is low, and the manufacturing cost is high. Therefore, in the future, it is necessary to combine the subversive design of battery structure to fundamentally reduce the complexity of energy storage battery processing technology and the parameter requirements of processing equipment, and at the same time promote the integrated development of big data, Internet of Things technology and energy storage battery processing equipment and manufacturing technology. , through intelligent manufacturing upgrades, standardize manufacturing process standards, strictly control product quality, improve product final inspection efficiency, and reduce the manufacturing cost of energy storage batteries.

　　(4)Use technology

　　Energy storage battery application technologies mainly refer to bMS, pCS and EMS. bMS (battery management system) is the link between the battery body and the user. The main object is the secondary battery. The purpose is to improve the utilization rate of the battery and prevent the battery from overcharging and over-discharging. pCS (battery energy storage system energy control device) is a system that is matched with the energy storage battery pack and is connected between the battery pack and the grid to store the grid power into the battery pack or feed the battery pack energy back to the grid. EMS (Energy Management System) is the general term for modern power grid dispatching automation systems, including: computers, operating systems and EMS support systems, data collection and monitoring, automatic power generation control and planning, and network usage decomposition.

　　At present, many energy storage demonstration projects are implemented directly between battery processing suppliers and power grid companies, and there is a lack of responsibility identification standards and usage technical standards, which brings difficulties to later system operation and maintenance and possible accident identification. In the future, there should be independent energy storage battery system service providers with technology development as the core. They will be responsible for the design and planning, leasing, operation and maintenance, and scrap recycling of the energy storage system. They will also cooperate with insurance companies and promise to be responsible for the service life and operation of the system. Safety.

　　(5) Repair technology

　　The repair technology of energy storage batteries includes electrical repair technology and online regeneration technology of battery systems. The former includes environmental corrosion repair, electrical insulation aging test, electrical connection test, temperature and pressure sensing maintenance and battery inspection technology, etc. The latter is a new technical direction proposed for new energy storage lithium-ion batteries. Because theoretically, in addition to the internal lattice disorder of the battery's active particles and the corrosion and shedding of the current collector, other interface problems of the energy storage lithium-ion battery may be maintained and extended through online regeneration. After the battery has been used for a period of time, the battery performance can be reactivated through in-situ repair of the SEI film on the surface of the positive and negative electrode materials, and the replenishment and replacement of the electrolyte to extend the actual calendar service life of the energy storage lithium-ion battery. For example, the slurry-thick electrode morphology of lithium slurry batteries gives them the possibility of online regeneration during their lifetime.

　　(6)Recycling technology

　　Any battery has a lifespan. There are currently hundreds of millions of small consumer batteries in use in China, and most of them are small in size. The utilization value of waste batteries is low, and their use is scattered. Most of them are treated as domestic waste, posing potential pollution risks. Scrapped energy storage batteries cannot be discarded in the environment like small consumer batteries and must be recycled.

　　Energy storage battery recycling technology includes waste battery replacement technology, safe transportation technology, recycling technology and resource reuse technology. At present, the recycling and regeneration technology of lead-acid batteries is relatively mature, but there is a risk of contamination due to non-standardized recycling processes. The recycling process and technology of lithium-ion batteries are not yet mature. It needs to be combined with material technology and structural technology to develop new energy storage battery technology that is convenient for recycling and regeneration. Innovation and improvement should be made in product design, and battery recycling solutions should be considered in advance from the processing end. link in order to realize the sustainable development of resources in the energy storage lithium-ion battery industry, which is of important strategic significance.

　　4. Development goals of energy storage battery technology

　　The spring of energy storage has arrived, but the summer of booming industry development is far from coming. Various energy storage technologies have been put into commercial or demonstration use, demonstrating the advantages of energy storage in use, but also gradually exposing some problems, especially batteries. Energy storage technology is still a long way from the development goals of low cost, long life, high safety, and easy recycling, and needs innovation and breakthrough.