What are the differences between ternary lithium, lithium iron phosphate, sodium-ion, and solid-state batteries?

The names of power batteries for new energy vehicles are varied and numerous, including Qilin, Shenxing, Xiaoyao, Blade, and Jinzhuan. These are simply commercial brands used by battery manufacturers or automakers.

Regardless of the name, the fundamental difference lies in the chemical composition of the battery’s internal components.

Currently, the mainstream batteries on the market are ternary lithium batteries and lithium iron phosphate batteries, while sodium-ion batteries and solid-state batteries are also rapidly under development and undergoing vehicle testing. So, what are the differences between them?

The “ternary” in ternary lithium batteries refers to the three metallic elements: nickel (Ni), cobalt (Co), and manganese (Mn). They use lithium nickel cobalt manganese oxide (LiNiCoMnO₂) as the positive electrode and graphite as the negative electrode for cyclic charging and discharging.

Currently, ternary lithium batteries can achieve an energy density of 200-300 Wh/kg, while lithium iron phosphate batteries can only achieve 140-200 Wh/kg. Ternary lithium batteries have a higher energy density, therefore providing a longer driving range for the same weight.

Ni in ternary lithium batteries increases energy density; the higher the nickel content, the greater the energy storage capacity. However, excessively high nickel content can lead to poor structural stability and affect safety. China relies on imports for 80% of its nickel materials, and the price of one ton of nickel exceeds 140,000 yuan.

Cobalt plays a role in improving stability, significantly improving battery cycle life and conductivity. However, China relies on imports for 95% of its cobalt, and it is expensive; 99.8% purity electrolytic cobalt costs over 400,000 yuan per ton. Manganese itself doesn’t contribute significantly to battery energy storage; its main function is as a safety framework. Manganese effectively suppresses the instability introduced by nickel, improving the battery’s thermal stability and safety.

The advantages of ternary lithium batteries are high energy density, long driving range, and relatively good power retention in low-temperature environments. However, ternary lithium batteries are relatively expensive and have relatively poor safety. This is because ternary material crystals are prone to decomposition at temperatures reaching 200 degrees Celsius, producing oxygen (oxygen supports combustion), and flammable materials combined with oxygen can easily ignite.

However, there’s no need to be overly anxious. Battery companies such as CATL, Zhongchuang Xinhang, EVE Energy, and BYD have largely mitigated the flammability risk through battery management technology, heat dissipation technology, and thermal insulation materials.

The positive electrode material of lithium iron phosphate (LiFePO₄) batteries is lithium iron phosphate (LiFePO₄), and the negative electrode material is graphite (carbon). China’s production of phosphorus and iron is among the world’s leading, not only in terms of quantity but also in terms of low price.

The unique olivine structure of lithium iron phosphate forms a stable three-dimensional framework. Therefore, lithium iron phosphate batteries exhibit excellent stability, with better cycle life and thermal stability than ternary lithium batteries.

The phosphorus-oxygen bonds in lithium iron phosphate are extremely strong, making it less prone to overheating at high temperatures. Furthermore, it does not produce oxygen internally, making it less flammable and thus resistant to puncture and fire, resulting in relatively higher safety.

Lithium iron phosphate (LFP) batteries have a lower energy density compared to ternary lithium batteries, resulting in shorter battery life under the same conditions, with the reduction being more pronounced in low-temperature environments. Low cost and safety are the core competitive advantages of LFP batteries.

This year, sodium-ion batteries have been just as popular as solid-state batteries. Sodium-ion batteries rely on the movement of sodium ions between the positive and negative electrodes. Sodium is readily available; seawater salt (NaCl) is rich in sodium, making it virtually inexhaustible and inexpensive.

Sodium-ion batteries charge quickly and retain power well in extremely cold conditions, operating normally at -40°C. Their biggest advantage is their extremely high safety; they are not prone to fire, and their cost is very low.

Currently, the energy density of sodium-ion batteries is relatively low, only reaching 100-160 Wh/kg, and their cycle life is also not very high, approximately 2000-4000 cycles. With continued investment in research and development, the application prospects of sodium-ion batteries are believed to be very broad.

Solid-state batteries are widely considered the ultimate form of automotive power batteries because of their high energy density, reaching over 500Wh/kg. They have a longer cycle life than ternary lithium, lithium iron phosphate, and sodium-ion batteries, reaching up to 10,000 cycles, and exhibit good energy retention at both low and high temperatures (-40°C to 60°C). Most importantly, solid-state batteries are inherently non-flammable, making them extremely safe.

Solid-state batteries use solid conductive materials to replace liquid electrolytes and separators. Because the solid conductive materials isolate the positive and negative electrodes, the risk of spontaneous combustion is greatly reduced.

There are three main development paths for solid conductive materials in solid-state batteries. First, sulfides, which offer high conductivity and strong performance, but require stringent manufacturing environments and can produce toxic hydrogen sulfide gas when exposed to water. Toyota, Samsung, and CATL are currently developing such materials. Second, oxides, which offer good stability, high safety, and high hardness, but are brittle and difficult to process. Third, polymers, which offer good flexibility, ease of processing, and low cost, but have low conductivity and typically require temperatures above 60 degrees Celsius to operate.

TAICO has become a leader in the industrialization of solid-state batteries through its battery management technology, heat dissipation technology, and thermal insulation materials, fully utilizing solid-state batteries in home energy storage, industrial and commercial energy storage, and power batteries.