There are 5 significant requirements for light electric vehicle applications:
1. Low cost
2. High safety
3. Wide temperature range
4. Long life cycle
5. High rate
At the beginning, the LEV (light electric vehicle) market was occupied by lead-acid batteries, which have a low cost and high safety.
Due to the pollution problem caused by heavy metals Pb (Lead), Cd (Cadmium) from LAB (lead-acid battery), the Chinese government published the new GB17761-2018 standard to limit the maximum weight of electric scooters to 55 kg, which leaves no room for LAB in this market due to their low energy density. (Launched on April 15, 2019, activated on April 15, 2024, with a 5-year transition period)
Currently, the LEV market is full of nickel-manganese-cobalt (NMC) lithium-ion batteries, thanks to their high energy density, light weight, long range, and advanced chemistry.
With over 21,000 incidents of fire or explosion involving NMC LIB electric scooters (lithium-ion battery) occurring in China in 2023, especially during the summer period, 80% of which were due to thermal runaway of the lithium battery during charging, the government launched GB 43854—2024 on April 25 and will implement it on November 1, 2024, which requires that the LEV battery pass the NAIL PENETRATION test without fires or explosions before being installed in vehicles.
The LiFePO4 LFP LIB chemistry will replace most NMC LIB batteries on the Chinese LEV market thanks to the new policy, as they are much safer and have a good life cycle, but their low temperature and high-speed performance are not good.
One of the LTO LIB Li4Ti5O12 batteries with a very high chemical potential has almost all the advantages needed for LEVs, such as high safety, wire temperature range, long cycle life, high speed, but the high cost of raw materials, low energy density, and low platform voltage have prevented its mass use in the LEV market.
The latest option concerns sodium-ion batteries, which have abundant raw materials, no pollution from mining activity, and low carbon emissions.
SIB (sodium-ion battery) is generally safer than LIB but not as safe as LAB (acid battery); all the advantages are present for SIB, only the price needs to be improved through industrialization.
There are generally 3 technical paths for SIB, Layered Oxide (LO) which is like NMC, a similar combination of 3 transition metals with high nickel to support its high energy density. LO shares a similar production line with NMC LIB, therefore most Chinese SIB cell manufacturers are paving this way, with HiNa Battery Technology Co., Ltd. leading the way.
But consistently producing a good LO SIB is a tough job, as gas generation is a common problem during charging and discharging, which makes the internal chemistry unstable and can lead to potentially low lifespan or a rocket-like flight when the mass releases the internal gas.
The wide voltage range for LO (Layered Oxide) from 4 V to 1.5 V represents a further challenge for accessories and applications that must adapt to it; some people use smart BMS and DCDC to manage the voltage discrepancy, but I believe this is not the ultimate solution for commercialization.
The Prussian Blue/White SIB series is a traditional route, in which researchers are seeking the solution to remove crystalline water and minimize the risk of toxic precursors for humans. Natron Energy in the USA is a leader in this field with its aqueous PB (Prussian Blue), which has an ultra-long cycle life, high power, and non-flammable chemistry, but the low energy density of 20-30 WH/KG has determined its narrow usable market and low possibility of commercialization.
When talking about Polyanion Compounds SIB (NFPP), it is difficult not to mention its pioneer Tiamat Energy in France, which produced its first 18650 fast-charging, long-life, and superior safety power cell for SIB PCs in 2016, later widely used in power tool applications requiring high continuous output power in 2023 with C-level MWh sample status. In the meantime, it has moved on to the Gen 2 LO energy cell to expand its market opportunities thanks to higher energy density.
The fact is that the current cost of polyanionic SIB NFPP is about 67% higher than that of LFP (based on a lithium carbonate price of 100,000 RMB/ton), while the energy density is 40% lower compared to the FC46120P 3.2 V 24 Ah 173 Wh/kg model of the same size, which is estimated to be improved to the same BOM cost and ED level by 34% less in 2025, 30% cheaper while ED is 25% less in 2026.
Key technologies of the product strategy: Aluminum shell material + laser sealing + borderless design.
Product advantages with high PPM in cylindrical cell for large capacity, high consistency, more automatic production. Less swelling and potentially lower costs.
The BYD NFPP 46120 SIB cell has passed various safety tests, such as short circuit, overcharge, over-discharge, impact, drop, NAIL PENETRATION. With 60 degrees Celsius storage for 7 days, better capacity retention and recovery compared to LFP, 7-day maintenance charge, better capacity retention and recovery compared to LFP.
At 1.5 V-3.6 V, 100% DOD 0.5C/1C, the BYD NFPP 46120 SIB estimate will have a lifespan of over 8,000 cycles at 80% SOH at room temperature, while 4,000 cycles at 45 degrees.
At room temperature, the ability to maintain discharge at 10C is over 95%, at -20°C the discharge temperature increases by 4°C within 20 degrees, the retention capacity is even better compared to a lower temperature, and at 0.2C the ability to maintain discharge at -40°C is over 70%.
Based on the current high price, the rental mode could be a good way to split the cost from its Product Lifecycle Management, just like renting the 20,000-30,000 cycle life of LTO over 20-30 years of daily cost. NFPP 46120 SIB by BYD is running a pilot project on swappable E-scooter stations for the food delivery market.
Overall, NFPP is a high-potential SIB chemistry, which will also be widely used in BESS later on with its potentially 10,000 cycle lifespan and a lower cost compared to LFP. Let's get ready.
