SK On presents improved fast-charging battery and cold-proof LFP chemistry
The South Korean battery trade fair has been running since Wednesday at the Coex Convention & Exhibition Centre in Seoul. According to the company, the SF cell presented there by SK On has been improved, particularly in terms of energy density. The version of the cell with a high nickel content in the cathode presented in 2021 already offered a charging time of 18 minutes for the usual charging window of ten to 80 per cent. This charging time also applies to the 2024 version, although the energy density is said to be nine per cent higher – resulting in a longer range with the same battery size or a smaller and cheaper battery with the same range. However, SK On does not specify whether the statement refers to the volumetric or gravimetric energy density.
According to SK On, it has succeeded in “shortening the transport path of the lithium ions through a special coating process that drastically reduces the anode resistance, as well as through an anode alignment process”. In addition, an optimised fast charging protocol with analysis solutions was also used in the development of the ‘Advanced SF Battery’ in order to maximise the charging speed.
In addition to the ‘Advanced SF Battery’ with the same charging time but higher energy density, SK On has also developed in the other direction and is also exhibiting the ‘SF+ Battery’ in Seoul: This achieves a charging time of just 15 minutes, but there is no statement on energy density in the announcement.
To achieve a shorter charging time, the transport distance for the lithium ions in the ‘SF+ Battery’ has been reduced and their movement speed increased at the same time, as the Koreans explain. This was achieved by applying “high-capacity silicon with low-resistance graphite to the double-layer structure developed in-house”.
In addition to the two new variants of the SF cell, the ‘Winter Pro’ LFP cell was also presented at InterBattery. “Generally, a LFP battery suffers 50~70 per cent drop in driving range it can offer at a low temperature (-20℃). However, compared to the existing conventional LFP, the Winter Pro LFP Battery extends the charging and discharging capacity by 16 per cent and 10 per cent, respectively, while increasing the energy density by 19 per cent,” writes SK On about the new development. However, no further details were given.
At the battery trade fair, South Korean competitor Samsung SDI had also announced its intention to mass-produce solid-state batteries in 2027. Samsung SDI has been producing prototype cells with solid electrolyte since 2023, but had previously avoided making a statement on the start of mass production.
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