Research and judgment on six technical directions of power battery
- Cobalt-free of power battery
- Super fast charging of power battery
- Cell length thinning of power battery
- Power battery lamination technology
- Pre-lithium supplementation of power battery
- Predictability of power battery
The next generation of power battery technology is rapidly approaching. From system structure design to material system optimization, Chinese power battery companies have begun to demonstrate stronger and stronger underlying innovation capabilities.
In terms of system structure innovation, innovative technologies such as CTP, CTC, JTM, CTB, and One-Stop emerge in an endless stream.
In terms of material system innovation, cobalt-free batteries, fast-charging batteries, sodium-ion batteries, lithium-sulfur batteries, solid state battery, and high-manganese-iron-lithium batteries have all participated in the battery competition. At the same time, the diversification of power battery technology is also driving the complication and innovation of equipment technology.
Behind the innovation of power battery technology, there are not only the drive from the world energy reform and the upgrading of the new energy industry, but also the key weight for power battery companies to participate in the market competition.
Power battery is the cornerstone components of new energy vehicles, and technological breakthroughs are also closely related to the space for industrial upgrading. SVOLT summarizes the next-generation power battery technology into six major directions: cobalt-free, 4C fast charging, short-knife battery, lamination technology, pre-lithium supplementation, and predictability.
Cobalt-free of power battery
66% of the world’s cobalt production comes from the politically unstable Congo, and China’s cobalt reserves only account for about 1% of the world’s reserves. The scarcity of cobalt resources seriously threatens the security of the power battery supply chain. At the same time, cobalt accounts for an important part of the cost of cathode materials.
Taking the ternary 523 power battery system as an example, the material cost of cobalt accounts for 20%, and its price fluctuation will directly affect the cost of the power battery cell. Therefore, the “decobaltization” of power battery has become a global industry consensus, and the ternary system with high nickel and low cobalt is a popular technology.
But broadly speaking, as long as the cathode material of a lithium battery does not contain cobalt, it can be called a cobalt-free battery. In addition to low-cobalt ternary batteries, lithium iron phosphate, lithium iron manganese phosphate, etc. are also included in the cobalt-free system.
Experts said that in the future distribution of lithium battery products, the market share of “big cobalt-free” batteries will exceed 70%, which can cover A00-BC-class passenger cars with a range of 300-700 kilometers, as well as light power battery vehicles and commercial energy storage.
Different from the “less cobalt” batteries of other power battery companies, SVOLT’s layered cobalt-free power battery is a true zero-cobalt battery, and it is the first company in the world to successfully develop a cobalt-free battery. Compared with high-nickel ternary batteries of the same level, SVOLT cobalt-free batteries have the core advantages of high safety, high energy density, high cycle life and low cost. Box test and overcharge test at 140% SOC.
SVOLT will launch the second-generation layered cobalt-free power battery in 2023. The cost is expected to be close to that of lithium iron phosphate, and the power battery life can reach 800Km.
Super fast charging of power battery
In the first half of this year, the production and sales of new energy vehicles were booming, and the market penetration rate reached 21.6%. In order to alleviate the “range anxiety” and “energy replenishment anxiety” of electric travel, it is the general trend to deploy ultra-fast charging.
The fast charging of batteries based on the 800V high-voltage platform has become the focus of the current industry layout. With the launch of 800V models such as Jihu Alpha S, Avita 11, Xiaopeng G9 and Great Wall Mecha Dragon, 2022 will become the first year of mass production of 800V models.
However, a major challenge for ultra-fast charging is that the charging infrastructure is seriously imperfect. At present, the number of charging piles/stations that can match ultra-fast charging models is far from meeting the needs of establishing an ultra-fast charging ecosystem.
In addition to being restricted by the high investment cost in the early stage, the construction of supercharging stations is heavily dependent on the stability of the power grid. Supercharger stations suitable for 800V high-voltage fast charging require supercapacitor matching, and the strength and speed of the grid’s capacity transformation directly determines the penetration rate.
The peak power battery consumption caused by the overcharging station in the short term requires the support of a large number of efficient cable channels and other supporting facilities. It is a daunting renovation project. A wave of power battery cuts in southwest China in August this year has raised concerns about the stability of the power grid.
Therefore, although there are battery manufacturers in the industry that have mass-produced high-rate fast-charging batteries, from the perspective of the economy of the vehicle and charging facilities, and the stability of public power, 4C batteries can achieve better performance between mileage anxiety and actual equipment. balance.
In the short and medium term, 4C+800V is the optimal solution within the affordable range of the public power grid, and it can avoid unnecessary thermal management hazards. By the end of this year, SVOLT is expected to release a new power battery technology that achieves 4C+800v fast charging capability.
Cell length thinning of power battery
If cobalt-free is a manifestation of the acceleration of battery material innovation, then long and thin cells are an important direction in the field of battery structure innovation.
The long and thin cells reduce the thickness of the cells, increase the length of the cells, and at the same time cancel the module design, so that the cells are directly arrayed as structural components in the battery pack, thereby improving space utilization and improving power battery safety.
From the perspective of large-scale production and manufacturing, the biggest problems facing long and thin cells are the control of yield and the efficiency of large-scale manufacturing. The short-knife battery developed by SVOLT has found a relative balance between the length and the short, not only excellent in versatility and adaptability, but also in yield control and large-scale industrialized mass production.
In 2019, SVOLT first announced the L600 lithium iron phosphate short knife battery, which has been installed in a model of Great Wall Euler. Compared with the BYD blade battery with a length of more than one meter, the length of the L600 short blade battery of 574mm supports switching 590 standard modules.
It can be widely adapted to pure electric models such as Volkswagen MEB, Great Wall A30 and subsequent DE30, and achieve a driving range of more than 500km for models above A0 level. Compared with the traditional prismatic battery, the L600 short-blade battery has almost all the advantages of the blade battery: high volumetric energy density, CTP solution can be implemented as a structural component, cost reduction, easy heat dissipation, and good safety.
The design of the power battery cells with poles on both sides can support the use of upper and lower double water cooling technology in the pack link, achieve 2~4C fast charging performance, meet the application of high-end models with 800V high-voltage electrical architecture, and have a better match with the latest CTC technology.
SVOLT also proposed to extend the idea of short knife to various categories. The current mass-produced L300-L600 short-knife power battery can cover the 1.6-4C charging range; no cobalt, ternary, lithium iron phosphate global chemical system; and passenger cars, commercial vehicles, energy storage, and construction machinery.
Power battery lamination technology
Traditional square batteries generally choose the winding process for production, but long and thin cells are prone to wrinkle, deformation and other problems using the winding process. The lamination process not only improves the internal utilization rate of prismatic cells, but also has several performance advantages.
Higher battery energy density: The utilization rate of the winding space is lower than that of the lamination, and the lamination can make full use of the corner space, so the energy density is higher under the same volume.
More stable internal structure: Affected by the inconsistency of the internal stress of the inner and outer layers at the winding corner, the power battery will undergo wave-like deformation, resulting in uneven current distribution and accelerated internal structure instability. The lamination process keeps the cell interface flat.
Higher safety: Powder falling and burrs are prone to occur at the bends of the pole pieces at the lower ends of the winding, and in severe cases, the internal short circuit of the power battery will cause thermal runaway. The laminated battery is evenly stressed and safer.
Longer cycle life: The number of tabs of the laminated battery is twice that of the winding, the more the number of tabs, the shorter the electron transmission distance and the smaller the resistance, so the internal resistance of a battery can be reduced by 10%+, and the cycle life longer.
In the six short-knife battery production links of “homogenization, coating, rolling, die-cutting, lamination, and assembly”, the production efficiency and quality of laminations are crucial to the cell yield. However, the lamination process has always faced the shortcomings of low equipment efficiency, high equipment investment, low yield, and difficult control. The lamination machine technology has become the key to the growth of the penetration rate of the lamination process.
SVOLT has been leading the high-speed lamination process. In June of this year, its self-developed 0.125S/piece short-knife battery lamination 3.0 high-speed equipment has completed technical acceptance, and has been fully introduced into mass production, achieving a stand-alone production capacity of 0.9GWh.
This kind of equipment can stack eight pieces at a time, and at the same time completes online inspection of each piece to eliminate hidden dangers of quality. SVOLT’s next-generation 0.06S/piece ultra-high-speed lamination equipment with laser cutting technology has also begun project development.
Pre-lithium supplementation of power battery
Supplementing the electrode material with lithium by pre-lithiation can offset the irreversible lithium loss caused by the SEI film and improve the total capacity and energy density of the battery. Since the pre-lithium supplementation process is expected to solve the problem of the low coulombic efficiency of the silicon carbon anode for the first time, it often appears in the technical route of “silicon-doped lithium supplementation”.
In the whole machine factory, Tesla’s 4680 battery with silicon-based negative electrode adopts dry electrode + pre-lithiation at the technical level. BYD began to deploy lithium replenishment technology as early as 2004, and has applied for more than 20 patents related to lithium replenishment, with super technical reserves.
Battery manufacturers such as Gotion Hi-Tech, EVE and Envision have also laid out a large number of patents related to lithium supplementation, mainly involving the technical route of negative electrode pre-lithiation. Shanshan Energy and Zhuhai Guanyu are mainly involved in the technical route of cathode pre-lithiation.
The cathode material manufacturer Defang Nano is currently in the production capacity construction stage, and it is expected that some of the lithium supplementary capacity will be mass-produced in Q4 this year or Q1 next year. The cathode lithium supplement technology developed by SVOLT in the laboratory has achieved 10,000 cycles on the energy storage cells, and plans to challenge 12,000 cycles, that is, to achieve the same life as the photovoltaic system.
With the gradual release of silicon-based anodes and the demand for lithium supplementation for high-end power/storage batteries, pre-lithiation may become a major development direction of lithium batteries in the future.
Through the combination of pre-lithium supplementary lithium + short knife battery and superimposed new cooling and safety technology, SVOLT launched the CTR technical solution. The upgraded energy storage cells are around 325Ah, which is more than the mainstream 280Ah energy storage products on the market.
Predictability of power battery
From material innovation to structural innovation and manufacturing innovation, the multi-technology route of power battery has been continuously upgraded. However, no matter how perfect the technology is in theory, it cannot guarantee the safety of cells and battery packs 100%. In this reality, predictability becomes very important.
Through the early warning algorithm, monitoring + cloud computing, the potential risks of the battery cells are identified in advance and early warning is given. At the same time, online reports can be output for residual value assessment and space utilization.
The battery monitoring system launched by SVOLT, the bee cloud platform, can monitor the real-time running status of vehicles, and the battery cell data can be used to carry out subsequent battery performance analysis. As of the end of July 2022, more than 370,000 vehicles have been connected to monitoring, and the cumulative data has broken through 59.2 billion.
SVOLT said that they are integrating all key technologies such as fast charging, high energy density, and high security through a system integration solution. Combined with the innovative structure of SVOLT short-knife cells, they are forming an industry’s highest cost in the field of lithium iron phosphate.