Lithium batteries? Coming into the mainstream?

It is only about 10,000 tons of lithium iron phosphate ordered in 2014, and the National order for lithium iron phosphate raw materials is expected to increase 14-fold in 2015. "Sunliqing, an associate professor at the Institute of Machinery and Vehicle at Beijing University of Technology, opened the conference on energy conservation and the development of the new energy automotive industry.

The oil is not pure, the car runs up and gasps; The batteries are flawed, and electric cars are naturally inefficient.

This is the worry of new energy vehicles in China. Despite the hype in capital markets and the applause of policy support, technical problems are back to square one.

Battery, as the core part of electric vehicle, is responsible for the long range of electric vehicle. So, what kind of battery is the darling of the market, and who is the future leader, is the topic of general concern.

Lithium batteries will be mainstream

Domestic battery types of electric vehicles are: lead-acid batteries, lithium iron phosphate batteries, lithium cobalt acid batteries and three polymer lithium batteries.

Sunliqing introduced to the author, power cells have experienced lead-acid batteries, nickel-cadmium batteries, nickel-metal hydrogen cells, lithium cells, fuel cells era. Lead acid batteries currently occupy more than 80 % of the market share of secondary batteries, and are mainly used in the electric vehicle market and energy storage market. Nickel-cadmium batteries are mainly used in power tools, but lead-acid batteries and nickel-cadmium batteries contain heavy metal elements that are easily contaminated. Therefore, the degree of promotion is limited.

Nickel-metal hydride batteries are currently mainly used in hybrid electric vehicles, but their performance can not meet the current demand for pure electric vehicles and plug-in hybrid vehicles. Such electric vehicles require more than 200 kilometers of mileage, which is 10 times the pure electric mileage provided by nickel-metal hydride batteries.. Although the performance of fuel cells is very good, the technology is very difficult.

Lithium battery has become the first choice for electric vehicle batteries in the next ten years because of its superior performance and mature technology. Its advantage is that it has a higher energy mass ratio and energy volume ratio. It can currently reach 100-125 Wh / kg and 240-300 Wh / L, which is twice that of nickel-cadmium batteries and 1.5 times that of nickel-metal hydrogen batteries. Not only that, but the small self-discharge indicates that it can be stored for a long time. The self-discharge rate after 1 month of storage of the charged lithium battery is about 10 %, which is much lower than 25-30 % of the nickel-cadmium battery and 30-35 % of the nickel-metal hydride battery. This is the most prominent advantage of lithium batteries; In addition, no memory effect, long life, can be quickly charged, pollution-free features for consumers to provide more convenient.

Three-yuan material or a star of tomorrow

Positive materials are the most critical raw materials for lithium batteries. In the production of the four major materials, the cathode material is the core of the lithium battery, accounting for more than 30 % of the cost of the lithium battery, with the largest proportion. The quality of the cathode material directly determines the various performance indicators of the lithium battery, such as energy density performance, specific power, temperature range and safety performance.

Three-dimensional material is the trend of future development. At present, all the ternary materials on the market are mainly based on NMC and NCA. At the same time, they contain the synergistic effects of nickel, cobalt, and manganese. They have the advantages of high capacity and high voltage, and gradually become the mainstream of electric vehicle applications. In the next 3-5 years, the high-end ternary system as a power lithium battery will be in short supply.

At present, domestic power lithium batteries are still dominated by lithium iron phosphate. Domestic lithium batteries and electric vehicle companies can form mature battery technology within 2-3 years through the mastery of lithium iron phosphate materials. Then slowly transition to the three-element material for the positive lithium battery industrialization development on the road. "At present, China's positive electrode materials are dominated by lithium iron phosphate and will gradually change to ternary and its mixed material system with lithium manganate; The negative electrode material is dominated by graphite and both lithium titanate.”Dr. Wang Fang, senior engineer of the New Energy Laboratory at the Automotive Experimental Research Institute of the China Automotive Technology Research Center, told the author.

EV Breakthrough Focus on Battery

In fact, due to the cost pressure after mass production, luxury electric vehicles such as BMW 530Le with a starting price of 698,600 Yuan and Tesla with a price of close to one million Yuan are not available to the general public. High battery costs have become a key factor.

It is understood that Tesla uses a 18650 lithium cobalt acid battery. This battery has high power, high energy density, and high consistency, but the cost is also relatively high, so it is not widely adopted by other manufacturers.

However, BYD(002594, bar) uses its own battery technology, lithium iron phosphate battery, which has better battery performance and stability, but at low temperatures, lithium iron phosphate battery performance loss is large, conductivity may be affected.

Song Jian, deputy director of the State Key Laboratory of Automobile Safety and Energy Conservation, said publicly that car companies need to break through the bottleneck of battery technology. Although local car companies have not been able to make money from new energy vehicles, if they continue to develop and break through battery technology, they will be equal to breaking through.

Wang Fang told the author whether the safety meets the consumer's expectations, whether the life span can really meet the service life of 5-10 years, whether the continuous mileage can be increased, whether consumers can accept the cost of battery replacement and maintenance, and whether it affects consumers 'use in different seasons. These are ongoing concerns for consumers. She believes that the evaluation of power batteries should be based on the collection of vehicles and practical applications. Through in-depth and effective testing and evaluation of batteries, well-performing batteries should be superimposed through integrated technologies to further improve their safety and comprehensive performance. Promote the rapid development of the power battery industry and promote the industrialization of electric vehicles.

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