The solid-state battery technology that the new energy industry has been thinking about for many years has finally come true.

Recently, a pure electric sample vehicle equipped with solid-state battery system was debugged in BAIC new energy and went offline smoothly. This is the first time that China has disclosed a driveable solid-state battery sample car. Its offline also means that solid-state battery technology has taken a key step on the road of industrialization.

The pure electric prototype vehicle equipped with solid-state battery system has been debugged in BAIC new energy and successfully offline / BAIC group actually has no change in the structure of positive and negative electrodes, diaphragms and electrolyte of current mainstream batteries, but uses solid or semi-solid electrolyte instead of liquid electrolyte. After using solid electrolyte, the battery can not only improve the voltage platform, but also raise the upper limit of energy density; Because it is not easy to burn and produce gas, the safety of the battery is greatly improved.

Advantages of solid-state battery based on the above advantages, solid-state battery has always been the focus of the next generation lithium battery technology. At present, the main bottleneck of solid-state battery is the conductivity, internal resistance, interface impedance and compatibility of solid-state electrolyte. Therefore, the R & D focus of major enterprises at this stage is the design and preparation technology of solid polymer electrolyte and inorganic solid electrolyte, solid / solid interface construction and stabilization technology; On this basis, the research on battery production process and special equipment is improved to realize mass production of products.

In recent years, Toyota, Nissan, Renault, GM, BAIC, SAIC and other mainstream automobile enterprises at home and abroad have begun to step up the R & D and industrialization layout of solid-state batteries; On the other hand, battery enterprises such as Qingtao energy, Wanxiang 123, LG chemistry and Massachusetts solid energy have also begun to prepare for the construction of solid-state battery production plants, including many solid-state battery production lines that have been put into operation.

In addition to BAIC’s mass production of solid-state batteries, in March this year, Nezha automobile has released a new model equipped with solid-state batteries – Nezha U. According to Hezhong automobile, Nezha u plans to apply for the announcement of the Ministry of industry and information technology in October, and mass produce 500 units by the end of the year.

Obviously, in the field of new energy, a card battle based on solid-state batteries has quietly opened. According to the prediction of Dr. Li Zheng, general manager of Qingtao energy, a leading all solid-state battery developer in China, the solid-state battery will be used as an alternative in the field of passenger vehicles within three years, that is, a vehicle is being developed with the liquid battery scheme, and the solid-state battery version will replace some of its functions; Three years later, the forward development model based on solid-state battery will really go to the market and give full play to the characteristics of high safety and high energy density of solid-state battery.

Why solid state batteries?

According to made in China 2025, the development plan of power battery is defined: by 2020, the energy density of battery will reach 300wh / kg (watt hour / kg); In 2025, the energy density of the battery will reach 400wh / kg; By 2030, the energy density of the battery will reach 500wh / kg.

According to the existing liquid lithium ion power battery composed of ternary and graphite as positive and negative active materials, the weight and energy density limit is about 280wh / kg. Even if silicon-based alloy is introduced to replace pure graphite as negative electrode material, the upper limit of energy density can only reach 300-350wh / kg. This also means that lithium battery technology innovation is imperative to reach 400wh / kg and even break through higher energy density barriers.

In fact, there are many new battery technologies with great momentum in recent years. Concepts such as lithium rich manganese base, high-voltage spinel, cobalt free battery and quaternary battery emerge one after another. However, the battery technology pattern of ternary lithium battery, lithium iron phosphate battery and lithium manganate battery has not changed.

In this regard, Li Zheng explained that “limited by the voltage platform and safety of the current electrolyte, many new lithium battery materials with outstanding performance, such as lithium rich manganese base and high-voltage spinel, can not give full play to the advantages of high specific energy, making the technological innovation of lithium battery enter a bottleneck period.” At the same time, Li Zheng also pointed out that the application of solid electrolyte in high-voltage platform may open the “shackles” of new materials.

Because the solid electrolyte is actually only the battery electrolyte part from liquid to solid, there is no limit on its positive and negative materials. Therefore, theoretically, there are tens of millions of types of solid batteries, which can be either ternary lithium batteries or lithium iron phosphate batteries.

In addition, due to the characteristics of high safety and high voltage of solid electrolyte, many new battery materials are easier to be effectively applied. Once solid-state batteries are truly commercialized, many new lithium battery material applications based on solid-state batteries will follow. At that time, lithium battery technological innovation may usher in qualitative change.

Dr. Li Hong of the Institute of physics of the Chinese Academy of Sciences also pointed out that solid electrolyte is a general strategy. Once successfully developed, it can meet the needs of consumer electronics, UAV, power energy storage, aerospace, rail transit and many other fields with different anode and cathode materials.

Therefore, rather than regard solid-state battery as a new battery product, it should be regarded as a technical means to unlock the upper limit of battery material performance, which is the reason why the industry has high hopes for solid-state battery technology. At the same time, the change of safety properties brought by solid electrolyte is urgently needed by the current new energy industry.

Since the advent of new energy vehicles, safety anxiety has always haunted every new energy vehicle enterprise, and the biggest pain point comes from the spontaneous combustion of electric vehicles. The reason for the spontaneous combustion of electric vehicles is no more than that the thermal management is out of control after the internal short circuit of lithium battery, in which the flammable electrolyte plays an “important role”. The biggest feature of solid electrolyte is that it is not easy to burn, which avoids the thermal out of control of battery to a great extent.

However, it should be noted that there are many ways to form solid electrolytes, but not all solid electrolytes are difficult to burn. Li Hong made it clear, “we have recently published some articles to demonstrate the excellent thermal stability of oxide solid electrolyte (a kind of solid battery), but whether each solid electrolyte means thermal stability remains to be studied.”

Overall, the reason why solid-state batteries are highly expected is that they can be used as the basic strategy of battery technology innovation and have high safety. However, specific to each solid-state battery, it needs a lot of detailed research and development to ensure its performance and thermal stability.

When will the solid-state battery land?

Although solid-state batteries have various advantages, the progress of their industrialization is not smooth. In 2017, Fisk, Toyota and other car companies boasted their own solid-state battery technology, but the landing time of their mass-produced models was pushed again and again, which shows that the development of solid-state batteries is very difficult.

Recently, Keiji kaita, executive vice president of powertrain department and general manager of battery Department of Toyota Motor Corporation, said in an interview with automotive news that the original plan to launch its solid-state battery powered prototype vehicle at the 2020 Tokyo Olympic Games was postponed to 2021. However, Toyota is still expected to complete the production of solid-state batteries for electric vehicles by 2025.

2025 may be a watershed for the industrialization of solid-state batteries in the automotive field. According to the latest publicity of BMW, Toyota, Mercedes Benz, GM and start-ups, the landing time of solid-state batteries is basically locked around 2025.

Dr. Li Hong, Institute of physics, Chinese Academy of Sciences, said that the premise for vehicle enterprises to dare to develop solid-state battery vehicles is that the solid-state battery capacity should reach at least 1GWh. On this basis, considering the complete supply chain molding, mature process system, sufficient capacity construction and sufficient road test time, 2024 will be a relatively optimistic time node for large-scale application of semi-solid batteries, As for all solid state, it may be by 2030.

Relatively speaking, Li Zheng, general manager of Qingtao energy, made a more radical prediction. “At present, solid-state batteries have achieved mass production and application in consumer electronics and other fields. Solid-state batteries will be used instead in the field of passenger cars within three years. After three years (about three years of new car development), there will be real vehicles based on positive research and development of solid-state batteries for consumers.”

According to Li Zheng’s description, since last year, Qingtao energy has begun to test sample vehicles with several mainstream OEMs. Meanwhile, according to a person familiar with the matter, “there must be mass-produced electric vehicles equipped with solid-state batteries this year.”

It is worth mentioning that in July this year, Qingtao energy, which has just completed the e + round of financing, has officially put into production its solid-state battery mass production line in Yichun, with a capacity of 1GWh, which has met the vehicle R & D premise judged by Dr. Li Hong. Yichun solid state battery factory will face the passenger car power market and leave enough room for production expansion.

In addition to Qingtao energy, the 1GWh solid-state battery production line of Huineng technology is expected to start mass production next year, and the 2gwh all solid-state lithium battery production line of Xingying technology is expected to be put into operation in 2024. As the solid-state battery production line of battery enterprises is gradually put into operation, its commercialization in the automotive field will be faster and faster.

Editor in charge: Tzh

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