Walking into the National Demonstration Power Station of Wind and Solar Storage and Transmission in Zhangbei County, you can see rows of white wind turbines and gleaming blue photovoltaic panels on the green grassland.

This is the largest wind-solar storage and transmission demonstration project in my country. It adopts the world’s first wind-solar storage and transmission combined power generation construction ideas and technical routes. It is a comprehensive new energy demonstration project integrating wind power, photovoltaics, energy storage devices and smart power transmission. .

This power station can “store” the wind and solar resources that are “difficult to predict, difficult to control, and difficult to dispatch”, and convert them into high-quality and reliable green electric energy for input into the grid, and can operate in “smooth fluctuations” and “peak shaving and filling valleys” Flexible switching between modes. In the case of loss of external power supply from the power grid, the energy storage power station can maintain the normal operation of the power grid through the internal self-starting capability.

The development of energy storage technology is one of the key core technologies to promote new energy generation and improve the security and stability of the power grid. Among various types of electrochemical energy storage technologies, lithium titanate batteries have the characteristics of long cycle life and good safety performance, which are well suited to the application scenarios of grid energy storage. However, the high cost of lithium titanate batteries is not conducive to Large-scale energy storage applications.

In this regard, the China Electric Power Research Institute has united with a number of units to jointly form a project team “Development of low-cost lithium titanate batteries for energy storage and development and application of system integration technology”. After years of research, the project team, based on the original lithium titanate battery, proposed a lithium titanate battery material system and production process reconstruction principles and technical solutions to meet the needs of energy storage applications, and developed sub-micron level Lithium titanate material. The lithium titanate battery for energy storage developed by the project maintains the intrinsic characteristics of a long life, while the cost is greatly reduced. In the 2017 Beijing Science and Technology Awards, the project won the second prize.

The next outlet for new energy

Energy storage is considered to be the next outlet for new energy. As a forward-looking technology to promote the development of the new energy industry in the future, the energy storage industry will play a huge role in new energy grid connection, new energy vehicles, smart grids, microgrids, distributed energy systems, and home energy storage systems.

“The reason for the development of energy storage is that photovoltaic and wind power generation are intermittent and unstable. Therefore, the cooperation of energy storage systems is needed to provide stable and reliable power.” Director of Energy Storage Battery Ontology Research Office, China Electric Power Research Institute Yang Kai told reporters.

The use of large-scale energy storage technology can promote the development of renewable energy, improve the safety and stability of the power grid, improve the quality of power supply, and effectively alleviate the contradiction between power supply and demand.

Large-scale energy storage systems run through all aspects of power system generation, transmission, distribution, and use. Its application can not only improve the performance of traditional power systems, but also bring revolution to the planning, design, layout, operation and management and use of power grids. In this sense, energy storage technology is a technological commanding height with national strategic significance, and the development of energy storage technology is actually “storing the future.”

A “wonderful flower” in lithium-ion batteries

It is understood that energy storage technology is mainly divided into mechanical energy storage, electrochemical energy storage, electromagnetic energy storage and phase change energy storage. In recent years, electrochemical energy storage technology represented by lithium-ion batteries has the characteristics of large energy scale, flexible location selection, and fast response speed, which meets the technical requirements of power systems and the development trend of smart grids, and has been regarded as the research focus by research institutions in various countries. Become the fastest growing power system energy storage technology. Lithium-ion battery is a kind of “rocking chair battery”. The positive and negative electrodes are composed of two compounds or simple substances that can deintercalate lithium multiple times. When charging, the positive electrode material is delithified, and lithium ions enter the electrolyte and penetrate the separator to be embedded in the negative electrode. The positive electrode undergoes an oxidation reaction. The opposite is true during discharge.

Lithium-ion battery technology has been in a state of rapid development with the research of battery electrode materials. It has now expanded from lithium cobalt oxide batteries to ternary systems, lithium manganate, lithium iron phosphate, lithium titanate and other battery systems coexisting. The new lithium-ion battery with lithium titanate as the negative electrode breaks through the inherent limitations of graphite as the negative electrode, and has significantly better performance than traditional lithium-ion batteries, making it one of the most promising energy storage batteries. To this end, Yang Kai introduced to reporters four major advantages of lithium titanate batteries that can stand out:

Good safety and stability. Because the lithium titanate anode material has a high lithium insertion potential, the generation and precipitation of metallic lithium are avoided during the charging process. And because its equilibrium potential is higher than the reduction potential of most electrolyte solvents, it does not react with the electrolyte and does not form a solid —The passivation film on the liquid interface avoids the occurrence of many side reactions, thus greatly improving the safety. “Energy storage power stations are the same as electric vehicles, and safety and stability are the most important indicators.” Yang Kai said.

Excellent fast charging performance. Too long charging time has always been an obstacle that is difficult to overcome in the development of electric vehicles. Generally, slow-charging pure electric buses are used, and the charging time is at least 4 hours, and the charging time of many pure electric passenger cars is as long as 8 hours. The lithium titanate battery can be fully charged in about ten minutes, which is a qualitative leap from traditional batteries.

Long cycle life. Compared with the graphite materials commonly used in traditional lithium-ion batteries, lithium titanate materials hardly shrink or expand in the framework structure during the process of charging and discharging lithium. / The problem of electrode structure damage caused by cell volume strain when intercalating lithium ions, so it has very excellent cycle performance. According to experimental data, the average cycle life of ordinary lithium iron phosphate batteries is 4000-6000 times, while the cycle life of lithium titanate batteries can reach more than 25000 times.

Good performance in wide temperature resistance. Generally, electric vehicles will have problems when charging and discharging at -10°C. Lithium titanate batteries have good wide temperature resistance and strong durability. They can be charged and discharged normally at -40°C to 70°C, no matter in the frozen North country, Still in the hot south, the vehicle will not affect the work due to battery “shock”, eliminating the worries of users.

It is precisely based on these advantages that lithium titanate batteries have become a dazzling “wonder” in the development of lithium-ion battery technology.