The largest Chinese battery manufacturer - Contemporary Amperex Technology Co., Ltd. (CATL) - has announced today the first generation of sodium-ion batteries.
The sodium-ion batteries are not new. The concept emerged atn a similar time as the lithium-ion batteries, as both types have a similar working principle.
"Sodium ions also shuttle between the cathode and anode. However, compared with lithium ions, sodium ions have a larger volume and higher requirements regarding structural stability and the kinetic properties of materials. This has become a bottleneck for the industrialization of sodium-ion batteries."
The lower energy density of sodium-ion batteries limited interest in this type over the years, but it might return as this chemistry has its own, specific advantages. CATL was working on this chemistry for a long time.
Here is how the company describes the cells:
"CATL has been dedicated to the research and development of sodium-ion battery electrode materials for many years. In terms of cathode materials, CATL has applied Prussian white material with a higher specific capacity and redesigned the bulk structure of the material by rearranging the electrons, which solved the worldwide problem of rapid capacity fading upon material cycling. In terms of anode materials, CATL has developed a hard carbon material that features a unique porous structure, which enables the abundant storage and fast movement of sodium ions, and also an outstanding cycle performance."
The first-generation model is expected to deliver a decent energy density, very fast charging capability, and especially strong performance at low temperatures.
- energy density of up to 160 Wh/kg
(the target for the second generation is 200 Wh/kg)
- fast charging up to 80% SOC in 15 minutes at room temperature
- excellent thermal stability
- great low-temperature performance
at -20°C, the sodium-ion battery has a capacity retention rate of more than 90%
- system integration efficiency can reach more than 80%
(cells consist more than 80% of the pack weight and/or volume)
Compared to the lithium-ion LFP (lithium iron phosphate) chemistry, the sodium-ion also does not contain cobalt or nickel and is expected to be similarly affordable at scale.
Sodium-ion chemistry actually beats LFP in low-temperature performance, fast charging, cycle-life and system integration efficiency, but are currently less energy-dense.
"The first generation of sodium-ion batteries can be used in various transportation electrification scenarios, especially in regions with extremely low temperatures, where its outstanding advantages become obvious. Also, it can be flexibly adapted to the application needs of all scenarios in the energy storage field."
According to Chinese media reports, sodium-ion cells should start at 500 CNY ($77) per kWh at a small scale, while at a volume scale the cost will be halved to 200-300 CNY ($31-$47) per kWh, which potentially would be very competitive.
Hybrid battery pack - CATL AB
The specifics of the sodium-ion batteries makes them perfect for cold climates. On the other hand, they might be used together with other types (higher energy-dense lithium-ion) in a single battery pack.
CATL proposes an AB battery system solution - a hybrid battery pack - with two battery cell types. In a combination with smart BMS, the vehicle could take advantage of the low-temperature performance of the sodium-ion battery or high energy density, depending on the need.
"In terms of battery system innovation, CATL has made another breakthrough in battery system integration and developed an AB battery system solution, which is to mix and match sodium-ion batteries and lithium-ion batteries in a certain proportion and integrate them into one battery system, and control the different battery systems through the BMS precision algorithm.
The AB battery system solution can compensate for the current energy-density shortage of the sodium-ion battery, and also expand its advantages of high power and performance in low temperatures. Thanks to this innovative structure system, application scenarios for the lithium-sodium battery system are expanded."
For example, there would be no limitations on regenerative braking in the winter.
One of the most important things is that the sodium-ion can be produced using the production equipment and processes used for lithium-ion cells.
CATL is starting industrial deployment and by 2023 should achieve a scale. The company invites partners to support the development of the chemistry.
"Dr. Qisen Huang, deputy dean of the CATL Research Institute, said that sodium-ion battery manufacturing is perfectly compatible with the lithium-ion battery production equipment and processes, and the production lines can be rapidly switched to achieve a high-production capacity.
As of now, CATL has started its industrial deployment of sodium-ion batteries, and plans to form a basic industrial chain by 2023. CATL invites upstream suppliers and downstream customers, as well as research institutions to jointly accelerate the promotion and development of sodium-ion batteries."