[Complete Battery Mastery](33) Three Key Keywords to Compete with LFP... Single Crystal, High Voltage, Mid-Nickel

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Song Hojun, CEO of Ecopro, said in his New Year's address this January, "I hope this year will be one where we advance High Nickel technology further and develop Mid Nickel and Lithium Iron Phosphate (LFP) technologies to trigger a 'technology coup d'?tat.'"

Then, in the early February earnings conference call, Kim Sunju, CFO of Ecopro, stated, "We plan to expand the proven high-nickel single-crystal mass production technology to high-voltage mid-nickel and pursue securing new clients among automakers and cell manufacturers within the year."

At the '2024 InterBattery Awards' held last March, LG Energy Solution received the highest innovation award for its 'Mid Nickel Pure NCM (Nickel-Cobalt-Manganese).' The Mid Nickel Pure NCM is a laptop battery made from mid-nickel (NCM613) material capable of operating at high voltage.

LG Energy Solution's Mid-Nickel Pure NCM (613) laptop battery, awarded the Grand Prize for Overall Innovation at the 2024 InterBattery Awards. Photo by Kang Hee-jong

This battery applies single-crystal cathode material. LG Energy Solution announced plans to expand the application of mid-nickel batteries to more applications through the development of more advanced next-generation mid-nickel batteries. This means broadening applications beyond IT devices to electric vehicles and energy storage systems (ESS).

The keywords connecting these two cases are 'single-crystal,' 'high voltage,' and 'mid-nickel.'

As the electric vehicle market expands, automakers are seeking affordable batteries to produce mid- to low-priced electric vehicles. Alongside this, concerns about electric vehicle fire safety are growing, prompting countries to strengthen thermal propagation (TP) regulations.

This is why the adoption of Chinese-made LFP, which has relatively superior thermal safety and lower cost compared to the ternary batteries such as NCM and NCA (Nickel-Cobalt-Aluminum) that Korean battery companies mainly produce, is increasing.

In response, domestic companies are promoting high-voltage mid-nickel batteries with single-crystal particles as their trump card. High-voltage mid-nickel batteries, which can compete with LFP in price and offer performance comparable to high-nickel NCM, are emerging as a new contender.

Strengthening TP Regulations... "What to do with Nickel?"

According to the battery industry, major automakers in the US and Europe have recently increased demands for thermal stability. This is due to the rise in electric vehicle fire incidents and the announcement of stricter safety regulations worldwide.

Battery safety regulations began to gain attention after the UN GTR (Global Technology Regulation) first issued recommendations in 2018. UN-GTR stipulates that "there must be at least a 5-minute warning before fire or explosion situations that could threaten passenger safety inside electric vehicles."

Research so far indicates that electric vehicle fires caused by batteries occur due to thermal runaway (TR) and thermal propagation (TP). Thermal runaway refers to the rapid temperature rise and explosion of a battery cell, the basic unit of a battery, caused by internal or external thermal factors or chemical reactions. The explosion then propagates to adjacent cells, leading to fire, which is thermal propagation.

To meet UN-GTR recommendations, a 5-minute delay time between the initial thermal runaway and thermal propagation is required. The electric vehicle and battery industries expect that the second-phase recommendations, to be announced around 2024-2025, will demand a longer delay time of 15 to 30 minutes. Furthermore, regulations are expected to tighten to a level where thermal propagation must not occur at all by 2030.

Following the UN-GTR recommendations, the US and Europe are also reportedly establishing battery safety regulations. In preparation for these moves, automakers are proactively demanding batteries with enhanced thermal stability from battery companies.

The battery industry believes that the recent expansion of Chinese-made LFP battery adoption by major electric vehicle manufacturers, including Tesla, is closely related to this background. Losses from recalls due to electric vehicle fires in recent years by automakers such as GM and Ford have also increased the demand for electric vehicle safety.

To prevent thermal propagation, automakers manage heat through the Battery Management System (BMS) or apply special materials to battery packs and modules, but fundamentally, reducing the risk of ignition within the cell itself is considered crucial.

Korean companies' strength lies in ternary batteries using NCM (Nickel-Cobalt-Manganese) and NCA (Nickel-Cobalt-Aluminum) cathode active materials. NCM and NCA cathode materials use nickel (Ni) as a core raw material. Increasing the nickel content in cathode active materials allows more lithium ions to be stored, increasing energy density and extending driving range per charge. Cathode materials with nickel content above 80% are called high-nickel batteries.

However, nickel oxidizes to +4 during lithium-ion battery charging. The oxidized Ni4+ ion is highly unstable and reacts with the electrolyte to form nickel oxide. Also, because the bond energy between nickel and oxygen is weak, it tends to release heat to stabilize. This is why higher nickel content results in lower thermal stability. Korean battery companies address this issue by doping aluminum or coating cathode particles. Cathode materials with nickel content above 90% are also commercialized.

Nevertheless, global automakers and other customers reportedly still feel uneasy about high-nickel batteries. Moreover, high-nickel batteries are expensive, making it difficult to lower electric vehicle prices. This is why customers are turning to LFP batteries.

As an alternative to LFP, domestic cathode material and battery companies emphasize high-voltage mid-nickel batteries. High-voltage mid-nickel means lowering nickel content to 50-70% but increasing voltage to raise energy density. Reducing the expensive nickel content enhances safety and lowers cost. Also, high-voltage mid-nickel cathode materials use cheaper lithium carbonate instead of lithium hydroxide.

Technological Regression?... Similar Yet Different Mid Nickel

Cathode material companies have focused on increasing nickel content. They have evolved from NCM523 (nickel 50%, cobalt 20%, manganese 30%) to NCM622, NCM811, and NCM9-half-half (1/2, 1/2). Because of this, mid-nickel might be perceived as a technological regression in batteries.

However, the high-voltage mid-nickel currently discussed in the battery industry is fundamentally different from past mid-nickel.

The product that won the highest innovation award at the 2024 InterBattery Awards by LG Energy Solution is NCM613. Compared to previous mid-nickel, it reduces cobalt content and increases manganese proportion. This reportedly reduces cost by 10% and improves thermal stability by 30% compared to existing high-nickel batteries.

Generally, cobalt in NCM cathode materials is responsible for power output, which refers to the ability to deliver instantaneous power. However, cobalt is expensive and its use is being reduced internationally due to child labor issues at the mineral extraction stage. These are called cobalt-free or cobalt-less cathode materials.

Conversely, development is progressing toward manganese-rich cathode materials, which increase manganese content. Manganese is cheaper than nickel and cobalt and advantageous for high-voltage implementation. In lithium-ion batteries, manganese provides structural stability.

Reducing nickel content decreases energy capacity. To solve this, the battery industry is developing high-voltage mid-nickel batteries. Since energy density = capacity × voltage, increasing voltage can offset the reduced capacity.

The battery industry is currently developing to raise the charging voltage from 4.2-4.3V to 4.4-4.5V. Each 0.1V increase in charging voltage reportedly increases energy density by more than 5mAh/g. In fact, the cathode material industry recognizes that the energy density of high-voltage mid-nickel (single-crystal unimodal) batteries is superior to that of high-nickel (polycrystalline bimodal) batteries.

However, increasing charging voltage is a very challenging task. While raising voltage improves energy density, it can cause cracks or fractures within the material. There are limits to increasing manganese content to enhance stability because higher manganese content increases resistance, which degrades battery performance.

Applying doping materials or coating particle surfaces can suppress cracks, but finding suitable materials is difficult and can increase costs.

The battery industry is looking for answers in single-crystal technology. Single-crystal technology began as a method to extend the life and capacity of high-nickel cathode materials but is now gaining attention as an excellent solution for mid-nickel cathode materials as well.

Single-crystal means that the material's unit particle forms a single crystal structure. In lithium-ion batteries, it refers to materials where metals such as nickel, cobalt, and manganese are combined into one particle shape (one body).

Image source=LG Chem [LG Chemtopia]

Currently, lithium-ion batteries use polycrystalline cathode materials, where multiple crystals form one particle. Polycrystalline cathode materials are prone to breakage during rolling processes. Especially with repeated charging and discharging, cracks develop between materials, allowing electrolyte penetration, causing side reactions and gas generation.

In contrast, single-crystal products have particles as a single unit, preventing cracks and improving stability and lifespan. Single crystals do not break under high pressure, making them advantageous for implementing solid-state batteries or dry electrodes. The battery industry analyzes that single-crystal cathode materials improve capacity by 10% and lifespan by 30% compared to polycrystalline.

Meanwhile, cathode materials are classified by particle size into large particle size (10-20 micrometers, ㎛) and small particle size (5㎛ or less). To reduce voids between particles, cathode materials mix large and small particles, called bimodal. Typically, large and small particles are mixed in an 8:2 or 7:3 ratio.

The industry expects to initially use large particle polycrystalline and small particle single-crystal materials together, then evolve to using only small particle single-crystal materials in a unimodal approach.

Can Mid Nickel Compete with LFP?

Domestic battery cell and material companies are pursuing a two-track strategy: developing LFP batteries targeting the affordable electric vehicle and ESS markets, while simultaneously developing single-crystal high-voltage mid-nickel cathode materials.

LG Chem produced Korea's first high-nickel single-crystal cathode material in June 2023 and is currently developing both high-voltage mid-nickel and LFP cathode materials. Ecopro BM also plans to expand single-crystal technology to high-voltage mid-nickel.

POSCO Future M produced single-crystal cathode materials with nickel content above 86% last year and supplied them to Ultium Cells, a joint venture between LG Energy Solution and GM in the US. The company is also developing high-voltage mid-nickel materials with single-crystal particle structures.

L&F, which holds single-crystal high-nickel technology, is also reportedly developing high-voltage mid-nickel technology. Cosmo Advanced Materials produces high-nickel small particle single-crystal cathode materials.

It is difficult to gauge how much impact the recently spotlighted high-voltage mid-nickel will have on the electric vehicle market. Market research firms have yet to provide definitive forecasts.

Market Outlook for Lithium-Ion Battery Cathode Materials. Source: SNE Research 2024 NGBS Seminar.

The market still predicts LFP dominance in the lithium-ion battery market. According to market research firm SNE Research, LFP accounted for 37% of the total cathode material market (including electric vehicles, ESS, and IT) last year. The ternary share was 49%, including high-nickel NCM (16%), mid-nickel (NCM523, NCM622, 22%), and NCA (11%).

By 2030, LFP's share is expected to exceed half at 54%, while mid-nickel's share will drop to 10%. This suggests that existing mid-nickel cathode materials will be outpaced by LFP in the mid- to low-priced electric vehicle market.

Of course, these forecasts can change significantly depending on how powerful the upcoming high-voltage mid-nickel cathode materials prove to be. If a new form of mid-nickel cathode material that balances price, performance, and safety emerges, it could create a storm in the electric vehicle market.

WAGU Research, Expansion of Battery Thermal Management System Demand, 2023.6.25
LG Energy Solution, [All about Battery] Why is Nickel a Core Material in Cathode Materials?, 2023.7.27
LG Chem, [LG Chemtopia] FOCUS ON ? High-Nickel Single-Crystal Cathode Materials, 2024.2.19
POSCO Newsroom, Next-Generation Cathode Material Technology Led by POSCO Future M, 2024.3.7