23 Years' Battery Customization

Overview of lithium battery material technology development trends

Mar 27, 2019   Pageview:571

Thanks to the development of new energy vehicles, power batteries are at the high-speed development, and the development of new energy vehicles is also putting forward higher requirements for the performance of power batteries. The Action Plan for Promoting the Development of Automotive power battery Industry proposes mentions: by 2020, the specific energy of the new lithium-ion power battery cell will exceed 300wh/Kg, and by 2025, the specific energy of the new system power battery will reach 500wh/Kg.

 

Under the dual driving of policy and market, the power battery must develop toward high energy density, high cycle performance, high safety performance, etc., which requires research institutions and enterprises to make improvements in cathode materials, anode materials and electrolytes. The direction of solid-state batteries, silicon-carbon anodes, high-nickel ternary materials and lithium-rich manganese anodes is considered to be the mainstream technology route developed by enterprises in recent years.

 

Lithium-rich manganese-based positive electrode: ideal material with low precious metal content

 

In 2025, the technical goal of the single cell is to achieve a specific energy efficiency of 400Wh/kg. It is a research hotspot to develop and replace the existing defective cathode material with a new type of cathode material that is more efficient and energy-saving. Among the known positive electrode materials, the lithium-rich manganese-based positive electrode material has a specific discharge capacity of 250mAh/g or more, which is almost twice the actual capacity of the currently commercialized positive electrode material; and the material is cheaper manganese. Mainly, the precious metal content is small, compared with the commonly used lithium cobalt oxide and nickel cobalt manganese ternary cathode materials, not only low cost, but also good safety. Therefore, lithium-rich manganese-based cathode materials are considered as ideal materials for next-generation lithium-ion batteries.

 

How long does it take to achieve 500wh/Kg? Overview of lithium battery material technology development trends

 

Many companies, including Dangsheng Technology, Jiangte Electric, and AVIC Lithium, are stepping up research and development of lithium-rich manganese-based cathode materials. The Institute of Physics of the Chinese Academy of Sciences has improved the voltage decay of the lithium-rich manganese-based positive electrode cycle, reaching the target of reducing the voltage attenuation to less than 2% after 100 weeks, and made significant progress. The Peking University team first developed a lithium-rich manganese-based positive electrode with a specific capacity of 400mAh/g, which can reach the target of 400Wh/kg.

 

At present, the full application of the lithium-rich manganese-based positive electrode has the technical problems of reducing the first irreversible capacity loss, improving the rate performance and the cycle life, and suppressing the voltage decay of the cycle process.

 

High nickel ternary material: 2018 is the first year of development

 

According to the starting point research, the output of 2018 nickel-cobalt-manganese will reach 47GWh, which will be 32% higher than last year, while the output of lithium cobalt oxide will be only 19GWh, only 5% higher than last year. Constrained by the scarcity of cobalt and the rising price of cobalt, battery companies actively promote the high nickel content of ternary materials, and reduce the cost of cobalt in the battery. The cobalt content of NCM811 is only 6.06%.

 

Nickel-cobalt-manganese materials have high energy density, stable electrochemical performance, high capacity and low cost, and will gradually replace lithium iron phosphate and ordinary ternary batteries in the future. At present, Dangsheng Technology, Shanshan, Betray and other enterprises already have the mass production conditions of NCM811, and 2018 is considered to be the first year of high-nickel ternary material development.

 

Solid-state battery: solid material replaces diaphragm and electrolyte

 

All solid-state batteries are recognized in the industry and academic circles as one of the mainstream directions for battery development in the next step.

 

How long does it take to achieve 500wh/Kg? Overview of lithium battery material technology development trends

 

On the one hand, all-solid-state battery technology is the only way for the battery to be miniaturized and thinned. The volume of the diaphragm and electrolyte add up to almost 40% of the battery's volume. If the diaphragm and electrolyte are replaced by solid materials, the distance between the positive and negative electrodes can be shortened to a few microns, and the thickness of the battery is greatly reduced.

 

On the other hand, compared with the general lithium battery, the energy density of the all-solid battery is greatly increased, which can reach 300-400Wh/kg, while the lithium-ion battery is generally 100-220Wh/kg. High safety is also one of the important driving factors for the development of all-solid-state batteries. From a safety point of view, the traditional lithium battery electrolyte is an organic liquid, which will oxidize and decompose to generate gas at high temperatures, which is prone to combustion and greatly increases. Unsafe, if the electrolyte is replaced by a solid material, the battery safety performance is greatly improved.

 

At present, the polymer solid-state battery developed by Qingdao Energy Research Institute of the Chinese Academy of Sciences has an energy density of 300Wh/kg. The inorganic solid lithium battery developed by the Ningbo Institute of Materials of the Chinese Academy of Sciences has an energy density of 240Wh/kg. In addition, the agency is cooperating with Yanfeng Lithium Industry. Its industrialization, product plans to mass production in 2019. In the industry, battery-leading companies including Toyota, Panasonic, Samsung, Mitsubishi, and Ningde Times have invested in R&D and deployment of solid-state batteries.

 

Solid-state batteries are undoubtedly one of the mainstream technology routes in the future. However, there are still problems such as high cost, complicated preparation process, and insufficient maturity. The battery's rate performance is low overall, internal resistance is large, and the voltage drop is high when discharging at high rate. Problems such as fast charging and unreality also need to be resolved. There is still a way to go to achieve large-scale commercialization.

 

Silicon carbon negative electrode: two or three years will usher in an outbreak

 

Silicon carbon material is currently the most commercial high-energy density new anode material. SPIR expects that the silicon-carbon material industry will begin to face the large-scale stage of lithium battery anode materials in the second half of 2018, and will also be in the next two to three years. It is bound to usher in a major outbreak and the industry has broad prospects.

 

How long does it take to achieve 500wh/Kg? Overview of lithium battery material technology development trends

 

The ultra-high theoretical energy density of silicon-carbon composites can significantly increase the monomer specific capacity, and it has the advantages of low deintercalation lithium voltage and environmental friendliness. It is considered to be the ideal anode material for replacing graphite in the next generation. With the development of new energy vehicles, the specific energy of power batteries is constantly demanding higher requirements, and graphite will be gradually replaced by silicon carbon anode materials in the future.

 

As of December 2017, the top 8 anode material companies in China are basically expanding their production capacity of silicon-carbon materials, and many new entrants across industries are involved in the layout of silicon-carbon anode materials. The new capacity will be in 2018-2019. BYD, Ningde Times, Guoxuan Hi-Tech, Betray, Shanshan, lishen, BAK, Wanxiang, etc. have launched the layout of silicon carbon anode materials.

 

Although the current silicon carbon anode materials still have problems such as high cost, technical difficulty and imperfect supporting industries, the prospect of realizing large-scale applications is still promising.

 

The page contains the contents of the machine translation.

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