China's 300whkg power battery has been developed; Solid-state battery is not rare

What makes Tesla Model 3 limited to dystocia is its famous power battery 2170, which is said to have a specific energy of about 280 watt-hours/kg.

The latest news is that China's high-nickel ternary lithium battery , with a specific energy of more than 300 watt-hours/kg, has been researched and developed. Ouyang Minggao, executive vice president of the China Electric Vehicle 100-member Association and academician of the Chinese Academy of Sciences, clearly pointed out that several teams including Ningde Times, Tianjin Lishen and Guoxuan Hi-Tech have basically realized the development of 300 watt-hour/kg power battery.

Ouyang Minggao pointed out that the country originally planned to achieve a mass production target of 300 watt-hours/kg of power battery in 2020. It is certain that there is even a chance to impact the energy of 350 watt-hours/kg.

On January 7, 2018, at a media conference held by the China Electric Vehicles 100-members, the executive vice-president of the organization, Ouyang Minggao, gave a speech on the technical route, phased goals of the global power battery from 2018 to 2030. Hot issues are elaborated.

Some important points are summarized as follows:

1. In 2020, the industrialized 300 watt-hour/kg power battery achieved a substantial breakthrough. The monomer specific energy reached 350 watt-hours/kg and the system 260 watt-hours/kg was our goal.

2. The Ningbo Institute of Materials of the Chinese Academy of Sciences cooperates with Yanfeng Lithium Industry Co., Ltd., and is promoting industrialization. It plans to mass-produce solid-state lithium-ion batteries in 2019.

3. What Toyota does is not an all-solid lithium metal battery. It is a solid-state lithium-ion battery. Its negative electrode is graphite (so the difficulty is much smaller).

4. In terms of lithium-sulfur and lithium-air batteries, progress at home and abroad is relatively slow. In 2017, no breakthrough progress was seen.

5, all solid state lithium batteries will make a breakthrough between 2025-2030.

For more details, please see the full text of Mr. Ouyang Minggao’s speech:

I will also represent the overall expert group and make technical reports at this year's annual meeting (January 21). There are so many technical problems, and I now focus on three issues: battery, power consumption, and charging.

First, the component level, core technology level I think the power battery is definitely the key, fuel cell is of course also very important, I am now picking the biggest progress in the year, because the technology is too much progress.

Second, the whole vehicle technology: I am not concerned about mileage this year, it is the power consumption of electric vehicles, which is the core issue of the current vehicle integration technology. I will also talk about this issue at this year's annual meeting.

Thirdly, from the perspective of system engineering for the promotion and application of new energy vehicles, charging technology is experiencing a period of great growth in demand and development of technology. Need to focus on.

So I will probably talk about these three questions at the annual meeting of the 100-members, but today I only pick one question, which is the battery problem of pure technology.

First, the main technical progress of domestic power batteries.

In the first aspect, the 300 watt-hour/kg power battery to be industrialized in 2020 has made a substantial breakthrough.

At present, there are three teams in the special energy vehicle special: one is the new energy in Ningde era, one is Tianjin Lishen, and the other is Hefei Guoxuan. The technical routes basically adopted by these three teams are similar, the positive electrode is high in nickel and the negative electrode is silicon carbon. This battery technical indicator is close to the application requirements, and it can be said that there is significant progress.

The specific energy has reached the target. The energy density of the Ningde era reached 304 watt-hours/kg, and the other two were similar. In terms of cycle life, the Ningde era is basically about 1,000 times. Of course, some enterprise safety standards have not yet been fully satisfied, and the safety of Ningde era has also passed.

300 watt-hours/kg of monomer can probably make a battery system of 200-210 watt-hours/kg because they are basically soft-packed batteries , not square batteries.

At the end of 2017 and the beginning of 2018, the monomer energy density is about 230 watt-hours/kg, and the system is about 150 watt-hours/kg.

In 2018 and 2019, we still need to increase the temperature by 50~70 watts/kg. I think this can be done. As for 2020, the monomer specific energy reaches 350 watt-hours/kg and the system 260 watt-hours/kg is our goal.

In the second aspect, by 2025, it is hoped to hit the industrialization goal of 400 watt-hours/kg of single cells.

The monomer is 300 watt-hours/kg, and the negative electrode changes from carbon to silicon carbon. To reach 400 watt-hours/kg, we have to change the positive electrode. At present, there are several kinds of anodes that can be selected. The breakthrough of our "new energy vehicle major projects" is high-capacity lithium-rich manganese-based cathode materials.

Two units have undertaken the frontier basic projects, and one is the Institute of Physics of the Chinese Academy of Sciences, which has improved the voltage attenuation of the lithium-rich manganese-based positive electrode cycle. The indicator reached is that the voltage decay drops to less than 2% after 100 weeks, which should be said to be a major development.

The other is a team from Peking University. For the first time, a lithium-rich manganese-based positive electrode with a specific capacity of 400 mAh/g has been developed. It should be no problem for 400 watt-hour/kg, or even higher.

The third aspect, more cutting-edge, is the solid state battery.

There are many research institutes and industrial units in the domestic solid-state battery, including Qingdao Institute of Energy, Chinese Academy of Sciences, Ningbo Institute of Materials, Chinese Academy of Sciences, Institute of Physics, Chinese Academy of Sciences, etc., including Ningde Era New Energy and AVIC Lithium.

Recently, the Ningbo Institute of Materials of the Chinese Academy of Sciences has cooperated with Yanfeng Lithium Industry to promote industrialization. It plans to mass-produce solid-state lithium-ion batteries in 2019.

It should be said that solid-state batteries are undoubtedly the hottest technical term in the global battery field in 2017, so I will introduce the global power battery technology hotspots with solid-state batteries as an example.

Second, the global battery technology hotspot: overview of all solid state lithium battery technology

All solid-state lithium batteries, each of these words cannot be less, cannot be changed, for example, "all solid state" is not the same as "solid state", "lithium battery" and "lithium ion battery" is not a concept.

The so-called "all-solid lithium battery" is a kind of lithium battery that is solid in the working temperature range and the electrolyte material is solid and does not contain any liquid component. Therefore, we are all called "all solid electrolyte lithium battery".

This all-solid lithium battery is divided into an all-solid lithium primary battery and an all-solid lithium secondary battery.

Primary batteries are already useful, and all-solid lithium secondary batteries are divided into all-solid lithium-ion batteries and lithium-metal batteries. These two concepts have to be distinguished. The so-called all-solid metal lithium battery is that its negative electrode is made of lithium metal. We now know that the negative electrode is made of carbon or silicon carbon or lithium titanate.

The concept of an all-solid-state lithium battery is earlier than that of a lithium-ion battery. Everyone knows that lithium-ion batteries have only appeared for about 25 years. They were invented by the Japanese. In the past 25 years, they have been used in cars for more than 10 years, so they are very young but progress very fast.

The all-solid lithium battery in the early days refers to the all-solid metal lithium battery with lithium metal as the negative electrode. Therefore, it is often said that the whole solid state is lithium metal as the negative electrode.

There are several potential technical advantages to an all-solid-state lithium battery:

First, for example, security is high. Because there is no organic solvent as an electrolyte to initiate the electrolyte burning problems.

Second, the energy density is high. It should be noted that the density and usage of the solid electrolyte are higher than that of the liquid electrolyte. When the positive and negative materials are the same, his advantage is not obvious. But if there is no electrolyte leakage after the solid electrolyte, it can be stacked all together, unlike we have to make a soft bag, so the volume ratio energy will be higher.

Third, the range of choice of positive electrode material is wide. Since the negative electrode is lithium metal, the positive electrode does not contain lithium. Also, the voltage window of the electrolyte will be wider, the selection range of the positive electrode material will be larger, and the specific energy can be increased.

Fourth, the system is higher than energy. Since the electrolyte has no fluidity, it is convenient to form a high voltage monomer through the internal series, which is advantageous for the battery system group efficiency and energy density.

But the problem is also there.

The first problem is that the ionic conductivity of the solid electrolyte material is low.

There are now three solid electrolytes, one being a polymer, one being an oxide, and one being a sulfide. Polymer electrolyte, in fact, this battery has been, and now used in some cars in France, its problem is to heat, the battery should be heated to 60 degrees, the ionic conductivity is up, the battery can work properly.

At present, the conductivity of oxide electrolytes is generally much lower than that of liquids.

Only the solid electrolyte of sulfides is now similar to the liquid state. For example, Toyota uses the solid electrolyte of this sulfide, so the solid electrolyte is a breakthrough. The main breakthrough is the solid electrolyte of sulfide.

The second problem is the poor contact and stability of the solid/solid interface.

The combination of liquid and solid is very easy and penetrates. However, the contact and stability of solids and solids are not very good, which is a big problem. Although the lithium ion conductivity of the sulfide electrolyte has been improved, there are still problems of interface contact and stability.

The third problem is the problem of the chargeability of metallic lithium.

In solid electrolytes, there are also problems with chalking and dendrite growth on the lithium surface. Its cycle, even safety still needs to be studied.

Of course, there is still a problem, that is, the manufacturing cost is high.

Based on the above problems, especially the solid interface interfaciality/stability and the chargeability problem, the true all-solid metal lithium battery technology is still immature, and there are technical uncertainties.

At present, there are breakthroughs in performance, and there are performance advantages and industrialization prospects, mainly solid-state lithium-ion batteries.

What is the difference between a solid-state lithium-ion battery and an all-solid-state lithium battery? Solid-state batteries are not necessarily all solid electrolytes, that is to say, there is still a little liquid, which is mixed with liquid and solid, and the ratio of mixing is large.

In solid-state lithium-ion batteries, the electrolyte is solid, but there is a small amount of liquid electrolyte in the cell; the so-called semi-solid is half of the solid electrolyte and the liquid electrolyte, or half of the cell is solid and half is liquid. Therefore, there are quasi-solid ones, which are mainly solid and a small amount is liquid.

About solid state lithium battery at home and abroad

Solid-state lithium batteries continue to heat up, and the United States, Europe, Japan, South Korea, and China are all investing. The mentality of each country is not the same.

For example, in the United States, small companies and entrepreneurial companies are the mainstays. There are two companies in the United States that are good, both start-ups and Sakti3. The driving range can reach 500 kilometers, and it is still in its infancy. Another one is called SolidPower, which was invested by several big companies such as BMW. The United States is mainly a small company, a startup company, based on disruptive technology.

In Japan, it is basically a solid-state lithium-ion battery. The most famous Toyota will be commercialized in 2022.

Let's see what Toyota is doing? What Toyota does is not an all-solid lithium metal battery. It is a solid-state lithium-ion battery. Its negative electrode is graphite, sulfide electrolyte, high-voltage positive electrode. When the single-cell battery has a capacity of 15 amps, the voltage is more than ten V. The realization of commercialization in 2022 is reliable.

So in Japan, there is no subversion, or lithium-ion batteries, the positive and negative can also be used before. South Korea is also a graphite-based anode, not a lithium-metal anode, similar to Japan.

The situation in China, Japan and Korea is similar, because we already have a large industrial chain of lithium-ion batteries, and we do not want to reinvent them.

Third, comprehensive review and outlook

First, lithium-ion power batteries are expected to achieve the 300 watt-hour/kg target by 2020.

At present, technology research and development at home and abroad are basically at the same level, but safety research needs to be strengthened. The core of this battery is safety.

Second, as two new types of systems to achieve long-term goals, lithium-sulfur and lithium-air batteries are currently making slow progress at home and abroad. In 2017, no breakthrough progress was seen.

In principle, the weight-to-weight ratio of lithium-sulfur battery is basically equal to that of volume-to-volume, so it is quite difficult to increase the volume-to-volume energy.

The demand for volumetric energy in passenger cars and cars may be more important than the weight ratio energy. Although there are 400 watt-hours/kg per kilogram, the volumetric energy is only 400 watt-hours/liter. It’s not good to talk about it.

Lithium-ion batteries generally have a weight ratio of 300 watt-hours/kg, for example, and a volume ratio of 600 watt-hours/liter.

Lithium-air batteries should be said to have all the difficulties of integrating zinc-air batteries, hydrogen fuel cells, and lithium secondary batteries. In contrast, hydrogen fuel cells are more competitive.

Third, the research and development industrialization of all-solid-state lithium batteries continues to heat up, but it is constrained by the two problems of solid/solid interface stability and metal lithium negative electrode chargeability. The true all-solid lithium metal anode battery is not mature yet, but inorganic Lithium-ion batteries with sulfide as a solid electrolyte should be said to have a breakthrough.

Looking at the path of solid-state battery development in general, the electrolyte may be mixed from liquid, semi-solid, solid-liquid to solid, and finally to all solid state.

As for the negative electrode, it will be from the graphite negative electrode to the silicon carbon negative electrode. We are now transforming from the graphite negative electrode to the silicon carbon negative electrode, and finally it is possible to go to the metal lithium negative electrode, but there is still technical uncertainty.

Fourth, China has made some breakthroughs in 2017 in terms of high-capacity lithium-rich cathode materials. Innovative lithium-ion batteries based on high-capacity lithium-rich cathodes and high-capacity silicon-carbon anodes are more feasible than lithium-sulfur and lithium-air batteries.

According to the above progress analysis, our expert group made an optimization of iteration on the development trend of technology battery technology (not based on the national battery technology roadmap, for reference only), as follows:

1. In 2020, the specific energy is 300 watt-hours/kg, the specific power is 1000 watt-hours/liter, the cycle is more than 1000 times, and the cost is less than 0.8 yuan/watt hour. This is certain.

What is the corresponding material? High nickel three yuan. We all know that we are now moving from nickel:cobalt:manganese ratio 3:3:3 to 6:2:2, which is high nickel, nickel becomes 6, then converts to 8:1:1, nickel becomes 8, cobalt further Drop to 1, even cobalt is further reduced to 0.5. The negative electrode should be transformed from a carbon negative electrode to a silicon carbon negative electrode. This is our current technological change.

2. By 2025, the cathode material will further improve its performance. For example, the lithium-rich manganese-based materials that we have made important breakthroughs this year will of course have other materials.

From 2020 to 2025, from 300 watt-hours/kg to 400 watt-hours/kg, the cost per watt-hour is reduced from 8 cents to less than 6 cents. At this time, our general price-performance pure electric car has a reasonable mileage of 300-400 kilometers.

3. By 2030, there is hope for breakthrough in electrolytes, that is, the biggest breakthrough in 2025~2030 may be in electrolytes, that is, all-solid-state lithium batteries will be industrialized in scale, and battery cells are expected to hit 500 watt-hours/kg.

In 2030, the regular price-performance model should be able to reach more than 500 kilometers. Of course, the cooperation of other technologies is required.