Switching to the electric vehicle industry, as the heart of its power lithium-ion batteries, the development of new technologies in battery material selection and technology research, providing higher energy density and achieving longer range, is currently a challenge and research hotspot faced by the industry.
According to Fang Kaizheng, an expert from the Power Lithium Battery Research Office of the Beijing Work Department of China Automotive Research Center, the increase in the production of new energy vehicles has led to an increase in the number of power lithium battery supporting batteries. In the first three quarters, the total number of power lithium battery supporting batteries exceeded 12.1 billion watt hours, of which 11 billion watt hours were for pure electric vehicle models and 1.1 billion watt hours were for plug-in hybrid models. Taking advantage of the development trend of the power lithium battery industry, industry researchers are also continuously researching and developing technology to improve the energy density of power lithium batteries and achieve their development goals of higher energy density, stronger power, and longer range.
Diversified technical routes
Tan Xinxin, Vice President of the Research Institute of Hunan Shanshan Energy Technology Co., Ltd., stated that as an important raw material supplier in the battery field, Shanshan will consider continuously improving the discharge specific capacity and charge discharge voltage of battery materials, as well as considering its power density and calendar life, including cycling, side reactions, and so on.
High nickel content of positive electrode material
On November 22nd, the Equipment Industry Department of the Ministry of Industry and Information Technology announced the "Standards and Conditions for the Automotive Power Lithium Battery Industry (2017)" (draft for soliciting opinions), intending to revise the "Standards and Conditions for the Automotive Power Battery Industry" (hereinafter referred to as the "Standards and Conditions") published and implemented in 2015. This provides a basis for power vehicle power battery companies to excel and strengthen, establish product specifications and quality assurance systems, strengthen technological and management innovation, improve product research and development and manufacturing levels, and improve product performance and quality.
According to Wu Hui, General Manager of the Investment Department of CCID Consulting, from January to October 2016, the total shipment volume of the top ten domestic power lithium battery companies reached approximately 11390.5MWh. With the rapid development of the pure electric drive vehicle industry and the increasing popularity of the power lithium battery industry, the energy density of power lithium batteries is developing towards higher and higher directions, which puts forward higher requirements for positive and negative electrode battery materials.
In terms of the development trend of power lithium batteries, there are basically three categories of positive electrode materials, with carbon materials as the main negative electrode material, and silicon carbon materials and hot spot materials are also being studied. Among them, lithium titanate is an important material choice for oxides.
Positive electrode materials will gradually transition to ternary materials, according to Chen Yanbin, the general manager of Dangsheng Technology. In the research and development of high-energy density ternary materials, Dangsheng Technology has always been at the forefront of the industry. Continuously increasing the energy density of batteries by increasing the content of nickel materials is a feasible technical route. However, the specific technical route adopted, such as whether to use high nickel or high voltage first, may vary depending on the company.
Chen Yanbin explained that from the overall international trend, the adopted route is to first focus on high power consumption and then on high voltage.
Nowadays, high energy density positive electrode materials are increasingly becoming the mainstream of the battery industry. It is reported that leading positive electrode material production companies in China have started researching and producing high nickel ternary materials. Some types of high nickel ternary materials, such as the 622 and 811 types, have also started small-scale production, and some companies have already conducted experimental applications in downstream companies. Moreover, the capacity ratios of the 622 and 811 models can reach 160mAh/g and 180mAh/g, respectively, which are somewhat improved compared to the current 532 and 111 models.
Chen Yanbin also mentioned that high nickel phase is still the preferred direction for high voltage. The ultimate goal of high nickel materials is 811 type, and 811 type materials also have more development prospects. When upgrading technology to achieve high energy density, it follows a high nickel based route and also produces high voltage batteries with medium to high nickel content. At the same time, it will also improve the lifespan and safety of batteries in terms of precursor, sintering, doping, surface treatment, and other aspects.
To make high nickel materials, it is necessary to address issues such as lifespan and storage safety, and optimize various aspects such as precursor, deliquescence, doping, and surface. Regarding the issue of the lifespan of high nickel plating, Chen Yanbin also stated that the research and development technology of Dangsheng Technology can ensure that the lifespan will not be affected when the capacity is increased by 20 milliamperes.
Increase research and development of negative electrode materials
How can power lithium batteries achieve high energy density and fast charging by 2025? In the field of fast charging negative electrode materials, Beiteri has been developing a composite high energy density negative electrode material. Through close cooperation between the battery factory and the vehicle factory, the battery energy ratio is 300Wh/kg, and the vehicle range is 500 kilometers. Yan Huiqing, Technical Director of Beiteri, answered this question.
Yan Huiqing also stated that Beiterui has developed four types of negative electrode materials, namely fast charging graphite negative electrode materials, fast charging soft/hard carbon materials, fast charging silicon series materials, and fast charging lithium carbonate negative electrode materials.
At present, the batteries developed by domestic battery companies are mainly lithium iron phosphate batteries, which are widely used in passenger cars, specialized vehicles, buses, etc. Yan Huiqing said: To improve the energy density of lithium iron phosphate, the first step is to do a good job in the negative electrode. We have been continuously developing negative electrode materials, and are making high energy density lithium iron phosphate ion batteries. From the perspective of the processing of the powder itself, the positive electrode, negative electrode, or ternary materials have similar technologies in improving the overall compaction density and capacity of the battery. Therefore, we are also developing high energy density lithium iron phosphate ion batteries, Strive to increase the battery capacity and compaction density. Especially the compaction density, therefore, we made spherical lithium iron phosphate. At the same time, we apply high-end negative electrode materials to improve the energy density of the entire lithium iron phosphate battery.
