Lithium iron phosphate VS ternary lithium batteries

01 Development background of lithium-ion batteries 

With the continuous progress of modern society and the rapid development of industrial economy, the global energy shortage and environmental pollution problems are becoming increasingly serious. In order to deal with the increasingly serious energy crisis and environmental pollution problems, most countries in the world have begun to formulate relevant sustainable development strategies, one of which is the electrification of the transportation system, mainly including the development and application of battery electric vehicles (BEVs), hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs). In recent years, the development of new energy vehicles has been advancing all the way, and the market share has been rising, as shown in Figure 1. According to the data released by the Ministry of Public Security of China, by the end of 2022, the number of new energy vehicles in China has exceeded 13.1 million vehicles, accounting for 4.1% of the total number of vehicles, with a year-on-year increase of 67.13%, among which the number of pure electric vehicles is 104.5 million vehicles, accounting for 79.77% of the total number of new energy vehicles. In 2021, the sales of new energy vehicles in China reached 3.521 million vehicles, a year-on-year increase of 1.6 times, ranking first in the world for seven consecutive years. In the foreseeable future, new energy vehicles will continue to maintain a high rate of development. 

Figure 1 Changes in the number of new energy vehicles in China from 2018 to 2022

The high growth rate of new energy vehicles also drives the rapid development of the power battery industry. As the core component of electric vehicles, the performance of power batteries directly determines the development and popularization of electric vehicles. For vehicle power batteries, it mainly focuses on battery energy density, power density, cycle life, safety and other performance. In recent years, with the development of energy storage technology, the commonly used energy storage devices for electric vehicles can be divided into five categories, namely: lead-acid batteries, nickel-metal hydride batteries, lithium-ion batteries, super capacitors and fuel cells. Based on the existing data, this paper compares the key performance of these five types of energy storage devices, as shown in Table 1.

Table 1 Comparison of key performance of commonly used energy storage devices for electric vehicles

As can be seen from the comparison in Table 1, lithium-ion batteries have excellent performances such as high energy density, large capacity, no memory effect, small internal resistance and long cycle life, making it the best energy storage device with the best comprehensive performance at present. With many enterprises, scientific research institutions and efficient participation in the research and development of lithium-ion batteries, the development of lithium-ion batteries has made a qualitative leap. 

02 Classification and performance comparison of lithium-ion batteries

The differences in anode and cathode materials, electrolyte materials and production processes of lithium-ion power batteries make the batteries show different performances and have different names. At present, the lithium-ion power batteries on the market are named according to the cathode materials. Figure 4 compares four different cathode materials of lithium-ion batteries, namely lithium manganate lithium-ion battery (LMO), lithium iron phosphate lithium-ion battery (LFP), nickel-cobalt-manganese ternary lithium-ion battery (NCM), nickel-cobalt-aluminum ternary lithium-ion battery (NCA). It is not difficult to see that in terms of energy density, the ternary system (i.e. NCM and NCA) performs better, and higher energy density can effectively increase the range of electric vehicles; in terms of safety performance and cycle life, LFP performs best, so the battery is widely used in some heavy-duty electric machinery or electric bus field; in terms of cost of use, except for NCA, other lithium-ion batteries with other material systems perform better. At present, domestic and foreign enterprises and users are most concerned about the battery's range, safety and service life and other performance. Therefore, ternary lithium-ion batteries and LFP are the mainstream products in the current power battery market. 

03 lithium iron phosphate and ternary route 

Based on the above mentioned, as the mainstream products in the current power battery market, the installed proportion of lithium-iron phosphate and ternary lithium batteries is increasing. Therefore, the current battle of lithium-ion battery is the battle between ternary and lithium iron phosphate. Table 2 gives the advantages and disadvantages of the two lithium-ion batteries. At the same time, based on the public installed data of power batteries, this section summarizes the installed proportion of lithium-ion batteries using different cathode materials from 2017 to 2022, as shown in Figure 5. 

Table 2 Comparison of the advantages and disadvantages of ternary lithium-ion batteries and lithium iron phosphate batteries

Figure 5 The installed proportion of different cathode materials from 2017 to 2022

It is easy to see from the figure that in 2018, the installed proportion of ternary lithium-ion batteries exceeded that of lithium iron phosphate batteries, and in the subsequent three years, the market proportion of ternary lithium-ion batteries in the field of electric vehicles has been higher than that of lithium iron phosphate batteries. The main reason is the Notice on Adjusting and Improving the Financial Subsidy Policy for the Promotion and Application of New Energy Vehicles issued by the Ministry of Finance in 2018. The document takes the endurance mileage as the subsidy standard for new energy passenger vehicles, as shown in Table 3.Compared with lithium iron phosphate batteries, ternary lithium-ion batteries have higher energy density and longer endurance mileage, so they are favored by most new energy vehicles and users during this period. Table 3 Subsidy standards for new energy passenger vehicles in the Notice on Adjusting and Improving the Financial Subsidy Policy for the Promotion and Application of New Energy Vehicles issued by the Ministry of Finance in 2018 

However, in 2021, the installed proportion of lithium iron phosphate batteries again achieved overshoot, and in the subsequent few years the proportion remained high, the main reasons are as follows: 

New energy vehicles subsidy policy changes. In 2020, the Ministry of Finance in the "Notice on improving the promotion and application of new energy vehicles subsidy policy" document mentioned to extend the new energy vehicle subsidy period, gentle subsidy retreat strength and rhythm, the policy will be ternary lithium ion batteries and lithium iron phosphate batteries back to the same starting line. 

New energy vehicles spontaneous combustion accidents occur frequently, enterprises and users' focus gradually shifted to safety. Figure 6 shows the statistics of electric vehicle fires in China in 2019, it can be found that in many electric vehicle fire accidents, the proportion of electric vehicles using lithium iron phosphate batteries is the smallest. At the same time, relevant experiments have proved that lithium iron phosphate batteries have greater advantages than ternary lithium batteries in thermal stability, such as puncture does not explode, overcharge is not flammable.

Figure 6 Statistical analysis of electric vehicle fires in China in 2019

Compared with ternary lithium ion batteries, lithium iron phosphate batteries have lower cost and higher cost performance. The average cost of the battery industry shows that lithium iron phosphate batteries are 0.6 rmb/Wh, and ternary lithium ion batteries are 0.8 rmb/Wh.  In addition , affected by the supply chain, the price of nickel and cobalt metals has risen greatly in recent years, resulting in the cost of ternary lithium-ion batteries soaring, so the cost of relatively low lithium iron phosphate batteries gradually sought after by people. 

04 Conclusion

In summary, as the two mainstream battery technology routes in the global electric vehicle industry, the "war" between lithium iron phosphate batteries and ternary lithium-ion batteries has never stopped. From the performance point of view, lithium iron phosphate batteries and ternary lithium-ion batteries have their own advantages and disadvantages. Ternary lithium-ion batteries have high energy density and good low-temperature performance; lithium iron phosphate batteries have low cost, long life and good safety performance. Therefore, in the future, ternary lithium-ion batteries and lithium iron phosphate batteries will coexist for a long time, there is no complete crush or substitution relationship, only a phased ebb and flow.