New battery technology in lithium ion battery industry
The development of electric vehicles is in full swing. As one of the most important parts, the development of lithium ion car battery plays a decisive role in the endurance and safety of electric vehicles. Recently, we often hear some terms of new battery technology, such as solid state battery, SVOLT jelly battery, NIO Nickel 55 battery, MI doped with silicon lithium and CTP/CTC technology, etc.
In fact, with so many technical directions, the fundamental purpose is to improve the energy density and safety of the battery. In this article, we will take you through the path associated with new battery technology.
Paths of new battery technology: increase energy density and safety
If a person goes on an adventure in the wild and his backpack is full of food, how does one make the food supply last longer? The easiest way to think about it is to pack as many foods as possible in terms of calories and density, such as compressed biscuits and chocolate. And another aspect is to allocate the layout of the bag so that you can pack as much food as possible.
Engineers are trying to develop new battery technology to improve the energy density of battery pack by using two similar paths: increasing cell density and increasing system density.
Increasing cell density is equivalent to making the food itself more caloric; The increase in system density is equivalent to carrying more food in a backpack. Of course, while improving energy density, safety is always a top priority.
What efforts are being made and what new battery technology is emerging to improve battery density and safety? Now let’s talk about it in the context of recent news.
Making the food more caloric? The new battery technology for increasing cell energy density
The cell is composed of three parts, the cathode, the anode and the electrolyte between the cathode and anode. The energy density is improved from these three aspects in new battery technology. Let’s look at them one by one.
New battery technology for cathode – nickel 55 and single crystal material
Nickel 55
Recently, NIO released 100kWh battery pack, which is the “only smoke does not fire” battery previously announced by CATL, without changing the size of the battery pack shell and almost no weight gain, energy density increased by 37%, and range is greatly increased.
The new battery’s nickel 55 ternary cell is an important factor in the increase in energy density. Its cathode material is a high voltage single crystal material. What is a single crystal? Before answering this question, let’s take a look at the technical direction of cathode materials.
The so-called ternary lithium battery refers to the cathode materials of nickel, cobalt and manganese (NCM). Nickel is used to increase capacity, cobalt is used to stabilize structure, and manganese is used to reduce cost and improve structural stability. The higher the proportion of nickel and the less the proportion of cobalt and manganese, the higher the energy density, but the lower the safety.
To improve the energy density, the NCM ratio was increased from “111 (N:C:M=1:1:1)” to “523” and then to “811”. This new battery technology route has always been the mainstream direction of the development of ternary cathode materials.
Single crystal material
The opposite direction of new battery technology is the single crystal path. The cathode of the newly released cell uses a 5 series single crystal material. Single crystal materials are more suitable for high voltages.
At present, most of the commercial ternary cathode materials are secondary spherical polycrystalline materials about 10 microns formed by the nanometer level primary particle agglomeration. Polycrystalline and single crystal are both silica, quartz sand is polycrystalline material, glass can be considered as a single crystal material.
There are a lot of grain boundaries in polycrystalline NCM. In the process of battery charging and discharging, due to anisotropic lattice changes, polycrystalline NCM is prone to grain boundary cracking, leading to secondary particle breakage, rapid increase in specific surface area and interface side reactions, resulting in increased battery impedance and rapid decline in performance.
However, new battery technology use single crystal ternary materials have no internal grain boundaries, which can effectively deal with grain boundary breakage and performance degradation. Therefore, the single crystal structure can achieve higher voltage, not only that, but also improve the cycle stability of ternary materials, greatly improving battery safety.
This is the cathode material. Now let’s look at the new battery technology for anode.
New battery technology for anode – Silicon-doped and Prelithiation
Recently, it was reported that IM Motor and CATL are jointly developing a new battery technology of silicon-doped and prelithiation, and the two sides will share this new battery technology patents.
IM Motor said the energy density of battery is now industry leading level higher than 30-40%, the highest can achieve approximately 1000 km range, 200000 km and attenuation, the battery will be sent to you by batteries insulation flame retardant materials formula optimization, group technology, and the whole cast aluminum battery pack shell packaging technology, the BMS end cloud coordinated management ensure the safety of the battery.
The energy density of the battery is 30-40% higher than the current industry-leading level, and it can achieve a maximum range of about 1000km and a maximum attenuation of 200,000km.
This battery will be insulated and flame-retardant through the optimization of the battery material formula and insulated and fire-retardant of pack technology, as well as the all-cast aluminum battery shell packaging technology, combined with BMS end-cloud collaborative management to ensure battery safety.
What is the new battery technology of “Silicon-doped and Prelithiation”?
The graphite anode density of traditional lithium ion battery is low. In order to pursue high density, new anode materials silicon carbon and silicon oxygen have become the new hot spots pursued by enterprises. However, silicon oxygen will have low efficiency for the first time and need to refilling lithium(prelithiation).
In the first charge and discharge process of liquid lithium ion battery, the electrode material reacts with electrolyte on the solid-liquid interface, forming a passivation layer covering the electrode material surface. This passivation layer is an interfacial layer that has the characteristics of a solid electrolyte and is an electron insulator but an excellent conductor of Li+.
Li+ can be embedded and released freely through this passive layer, so this passive film is called “solid electrolyte interface film” (SEI film for short) (there are also films formed on the cathode, but at present it is believed that its influence on the battery is far less than the SEI film on the anode surface).
The new battery technology of silicon carbon anode prelithiation technology,the silicon carbon anode is precoated with a layer of lithium metal, which is in close contact with the anode. After the electrolyte is poured, the coating reacts with the anode and is embedded in the anode particle.
A part of lithium ions are stored in the anode, so as to make up for the Li ions consumed by the formation or repair of SEI film during the first charge and discharge or cycle.
Compared to the difficult, high investment of the anode prelithiation, cathode prelithiation is more simple, the typical cathode prelithiation is in the process of the anode homogenate, add a small amount of high capacity anode material, in the process of charging, redundant Li elements emerge from these rich lithium battery anode materials, embedded in the cathode of complement the irreversible capacity of the charge and discharge for the first time.
Through this complex prelithiation process, the density of the anode material can be increased. It is not yet known what kind of new battery technology IM Motor will use, but it is almost certain that IM Motor will use this high-end lithium battery.
Finally, consider the electrolyte, the final link in the cell’s energy density increase.
New battery technology for electrolytes – Solid State batteries and Jelly batteries
Solid State batteries
QuantumScape, a startup backed by Volkswagen and Bill Gates, unveiled its latest solid-state battery on Tuesday, saying it will be in production by 2024. Such solid-state batteries offer a significant improvement over conventional lithium-ion batteries: they can increase the range of electric cars by 80%. Let’s take a look at what this new battery technology is and what their benefits are.
While improving the energy density of the battery, the safety of the battery has to be considered for every new battery technology. To eliminate the hidden danger of lithium ion battery fundamentally lies in the improvement of battery material safety.
But for cathode materials, these two aspects are contradictory. For example, as mentioned earlier, increasing the nickel content increases the energy density, but increasing the nickel content means less safety.
What could be done to enhance battery safety in other ways that would increase energy density more safely? That’s when you start thinking about electrolytes.
A large number of studies have shown that liquid electrolyte is involved in most of the reactions in the process of thermal runaway of batteries, and greatly reduces the initial reaction temperature of batteries, that is, the threshold of thermal runaway becomes lower. Therefore, improving electrolyte safety is one of the most effective methods to achieve battery safety.
The physical characteristics of liquid electrolyte make it impossible to avoid leakage, and at the same time, it is not conducive to reduce the battery volume and improve the energy density. Therefore, in order to improve the energy density and safety, solid electrolyte has become a trend.
New Battery Technology Solid-state batteries are those that have solid electrodes and electrolytes. Solid-state batteries without liquid inside the cell are not only safer, but also can be assembled after series and parallel, which reduces the material used for packaging and shell. Pack design is greatly simplified, which also improves the energy density after battery pack.
Like conventional lithium-ion batteries, solid-state batteries consist of a cathode, a anode and an electrolyte. Its structure is simpler than that of a conventional lithium-ion battery, with the solid electrolyte acting as both an electrolyte and a diaphragm.
The cathode material is not fundamentally different from the traditional lithium battery. The anode materials are lithium metal anode materials, carbon group anode materials and oxide anode materials.
For solid-state batteries, the research and development of solid-state electrolytes in this new battery technology is the most important. There are many kinds of materials, including oxides, sulfides, polymers and composite solid electrolytes.
Jelly batteries
In addition to the large-scale use of liquid lithium batteries and solid-state batteries under research, a new battery technology, a semi solid battery called jelly battery – is coming into view. In December 2020, SVOLT was the first to release jelly batteries and take pre-orders.
The jelly battery is a new battery technology that uses a new jelly-like electrolyte that fits well with the surface of the electrode material. It is self-healing, flame retardant and prevents thermal diffusion with little loss of conductivity. Jelly battery is a transition from liquid battery to solid battery.
How to pack more? The new battery technology for pack with increased system density
In addition to increasing the energy density of batteries, one way of new battery technology to increase the energy density of batteries is to pack more cells into a pack of the same size and weight. Here is a brief introduction to the current relatively new battery technology for battery pack.
New battery technology for removing internal packaging – (CTP)
Generally, batteries not only have battery packs externally, but also have “modules” formed by a group of cells internally. The new battery technology that so-called CTP is de-modular, and the cells are packaged directly.
Currently, it is a major choice for enterprises to improve energy density. CATL, BYD, SVOLT have launched de-modular new battery technology. The hot BYD blade battery is based on lithium iron phosphate battery, using a de-modular design to improve space utilization.
New battery technology for removing internal and outside packaging -(CTC)
On Tesla’s battery Day, a structural battery was proposed, which was directly built into the structure of the ca. This structured new battery technology is similar to the CTC technology previously proposed by CATL, which integrates the battery cell and chassis together, and then integrates the motor, electric control and vehicle high voltage system together through an innovative architecture, and optimizes power distribution and reduces energy consumption through intelligent power domain controller.
Conclusion
Through the above introduction, I believe that you have a certain understanding of the related new battery technology. Although we still need to wait patiently for the commercial use of all-solid-state batteries, we believe new battery technology that has already developed like semi-solid-state batteries, cathode single-crystal materials and silicon-doped prelithiation technology can be experienced in the near future.
