New progress has been made in lithium - sulfur battery technology

OFweek lithium power grid comprehensive reports: at present, the main international chemical energy storage technologies including sodium sulfur batteries, the lithium battery, flow batteries, lead-acid batteries, lithium iron phosphate batteries and so on. Dalian institute of chemical physics, Chinese academy of sciences, researchers say, as the renewable energy industry and the development of electric vehicle industry, by countries attach great importance to energy storage technology and industry, all kinds of new type of electrochemical energy storage battery research and development of technology progress. Among them, the more representative include flow batteries, lithium battery and lithium air batteries, etc., but its technology development is faced with some real challenges.

Flow battery energy storage technology

Flow battery is usually done by liquid active substances REDOX reaction energy and chemical energy conversion, so as to realize electrical energy storage and release of electrochemical energy storage device. Because of its power and capacity are independent of each other, can the depth of the charge and discharge, security, good such outstanding advantages, has become one of the best choice for energy storage areas.

Flow batteries since was invented in the 1970 s, it took from the lab to the enterprise, from prototype to standard products, from the model is applied to the commercial promotion function, scale since the childhood, from single to comprehensive, there are hundreds of all kinds of projects implementation, accumulative total installed capacity of about 40 gigawatts.

All vanadium flow batteries installed capacity of 35 mw, is currently the most widely used flow battery. In Dalian institute of chemical physics of Chinese academy of sciences for technical support of Dalian and energy storage technology development co., LTD. (hereinafter referred to as the "melting secco energy storage) and Dalian chemical institute of cooperation, realize the total vanadium flow batteries of key materials and mass production. The electrolyte products have been exported to Japan, South Korea, the United States, Germany and Britain. Develop high selectivity, high durability, low cost of fluorine ion conduction membrane performance is better than that of perfluorinated sulfonic acid ion exchange membrane, the price was only about 10% of the latter, break through the entire real vanadium flow batteries cost "bottleneck".

Through structural optimization and application of new materials, vanadium flow batteries electric pile rated current density has increased from the original 80 ma/c ㎡ to 120 ㎡ and ma/c keep the same performance, electricity costs plunged nearly 30%, single pile specification of 32 kw, has been exported to the United States and Germany. Designed and built in May 2013, the world's biggest 5 mw / 10 mw stream all vanadium battery energy storage system in Guodian Longyuan lie NiuShi 50 mw wind farms parallel operation success. Since then successively implemented in Jinzhou with 3 mw / 6 megawatts of wind power grid energy storage projects and Guodian peace is 2 mw / 4 mw energy storage projects, also is our country to explore the importance of energy storage business models.

All vanadium flow batteries another leader is Japan's sumitomo electric field. In 2010, the company to restart the flow battery business, will be completed in 2015, 15 mw/total vanadium flow batteries when 60 mw power station, is used to solve local Hokkaido large-scale solar power grid pressure load and power quality, successful implementation of this project will be another milestone all vanadium flow batteries. In 2014, the United States UniEnergy Technologies, LLC (UET) companies in the U.S. department of energy and clean fund support in Washington, established the 3 mw / 10 mw stream all vanadium battery energy storage system. UET company will for the first time in the project application and the mixed acid electrolyte technology, the energy density increases by about 40%, and can broaden the vanadium flow batteries use window of temperature and voltage range, reduce the energy consumption of thermal management.

At present, improving flow battery energy efficiency and system reliability, reduce the cost is an important topic of the flow cell mass to popularize and apply. Development of high performance battery materials, optimization of structural design, reduce the battery internal resistance is a key technology. Recently, Zhang hua and his team through the battery material innovation and structure innovation, make the total vanadium flow batteries of the single battery in 80 ma / / c ㎡ working current density, charge and discharge energy efficiency increased to 93% from 81% a few years ago, fully prove that it has a broad space for development and prospects.

Lithium-ion battery technology

In recent years, the traditional lithium ion batteries technology continues to advance, but the battery than energy still can't meet the requirements of application, battery technology is still the biggest bottleneck of the development of portable electronic devices and electric vehicles. To achieve high energy battery technology innovative breakthrough, researchers will breakthrough direction choice for higher energy density of lithium battery and lithium metal air batteries, such as air and made a certain progress. Some new battery technology has already seen signs of actual application.

According to the latest news, scientists in the United States has breached the lithium-sulfur battery faces major obstacles -- electrolyte solution problem, solve the lithium-sulfur battery failure quickly, the breakthrough is expected to greatly improve lithium sulfur batteries market competitiveness. In published in the British royal society journal of Nanoscale paper, university of California, riverside bourns college of engineering, researchers have announced recently successfully developed a Nanoscale sulfur particles, with the combination of silicon dioxide formed by the cathode material, can prevent the lithium battery electrolyte, the dissolution of a significant boost battery performance.

Lithium sulfur batteries is sulfur elements as the anode, metal lithium as negative electrode of a battery, its theory than the energy density of 2600 wh/kg, the actual energy density up to 450 wh/kg. Elemental sulfur low price at the same time, yield rich, environmental friendly, is the most close to the industrialization of high energy battery technology.

Internationally, some typical R&D manufacturer of lithium sulfur batteries are American SionPower, Polyplus, Moltech, British Oxis and South Korea's Samsung, etc., of which SionPower results are most representative of the company. In 2010, SionPower company applying lithium sulfur batteries on the unmanned aerial vehicle (uav), by solar batteries during the day, night discharge power, created the unmanned aerial vehicle (uav) flight record of 14 days in a row, is more successful application example of lithium sulfur batteries. At home, lithium battery research mainly concentrated in Dalian by compound of Chinese academy of sciences, China institute of chemical defense, Beijing institute of technology and other scientific research units, obtained the rapid development in recent years. At present, the domestic development of lithium sulfur batteries has become a world leader in the energy density (> 450 wh/kg), but the normal charge and discharge after dozens of times, the energy density is greatly attenuation, is of great importance to improve its cycle life.

Lithium sulfur batteries are all over the world compete to research and development of cutting-edge technology, its industrialization prospect widely. How to raise the battery charge and discharge cycle life, use safety, will become the key to the development of industrialization of lithium sulfur batteries.

Metal air batteries

At present, the metal lithium air batteries especially - air battery has caused the attention of people, and many major progress was made.

Lithium air batteries with metal lithium as negative electrode, the oxygen in the air as the positive active material, through electrochemical reaction between lithium and oxygen, realize mutual conversion of electrical energy and chemical energy. The battery energy density theory is about 3500 wh/kg, 10 times for lithium ion batteries, and gasoline. Focusing on potential applications of lithium air batteries, countries around the world have to carry out the related research work. IBM has been committed to "battery 500" project, expect to achieve the goal of the electric car charging a range of 500 miles. And of the enterprise such as Japanese agms join will push the diaphragm and the electrolyte.

Lithium - air battery is not a new concept, its first in 1976 by researchers at the lockheed. In 1996, Abraham put forward by organic electrolytic liquid system, create a new situation the study of lithium air batteries. At present, lithium - air battery research mainly focus on the positive, it directly decides the technical specifications of the battery. Energy density, the most representative is the graphene materials. Researchers in the United States Pacific northwest national laboratory, the preparation of a kind of layered graphene material of bubble structure, to achieve the discharge specific capacity of about 15000 mAh/g, far more than the existing lithium-ion batteries.

However, battery charging and discharging lithium - air generated in the process of oxygen intermediates products will react with carbon material, electrolyte, resulting in a large number of the formation of by-products, such as lithium carbonate, etc.), greatly affect the cell cycle, is the bottleneck problem of its development. Bruce porous gold and titanium carbide and others will be used in the anode, which can effectively restrain the adverse event, a 100 - cycle capacity retention rate is more than 95%.

High energy density is the main advantage of lithium air batteries, and cycle stability is the key to the development of its technology and problems., on the other hand, the cathode protection and purification of metallic lithium and lithium dendrite inhibition in the process of charging and discharging, highly active cathode catalytic component and the selectivity of air film development, battery structure design integration technology and so on all is the practical application process need to effectively solve the problem.

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