Differences between Lithium Iron Phosphate Generation 3/Generation 4/Generation 4.5 Products: The Code of Technological Iteration in the High-Tap-Density Era

In the new energy battery sector, lithium iron phosphate (LFP) cathode materials have continuously evolved around three core objectives: enhancing energy density, optimizing costs, and balancing performance. Today, Generation 3, Generation 4, and Generation 4.5 products coexist in the market. Significant differences exist from technical specifications to mass production, which directly determine a battery's range, fast-charging capability, and application scenarios. As a technical professional with years of industry experience, this article will break down the core distinctions between each generation in plain language, demystifying the logic of technological upgrades driven by high tap-density.

I. Core Performance Indicators: Comprehensive Advancement Centered on Compaction Density

The industry's generational classification of lithium iron phosphate products is essentially based on the gradient upgrade of powder compaction density. This indicator directly determines the active material content per unit battery volume and is the key to improving energy density. Simultaneously, each generation of products achieves interconnected optimizations in indicators such as capacity, fast charging, and cycle life. The specific differences are as follows.

1.Generation 3 Products (Current Market Mainstream)  

The standard powder compaction density is about 2.50 g/cm³, and the electrode compaction density can reach around 2.65 g/cm³, corresponding to a cell energy density of approximately 180-200 Wh/kg. It is primarily suited for traditional power and energy storage applications, with a typical fast-charging capability of around 2C, a low-temperature (-20°C) capacity retention rate of about 70%, and a cycle life of up to 3,000 cycles or more. This product offers balanced performance and controllable costs, making it the main choice for entry-to-mid-level passenger vehicles and energy storage power stations. It boasts the highest technological maturity and supply chain stability.  

2.Generation 4 Products (High-Compaction Mainstream)  

As the entry-level product for high-compaction lithium iron phosphate, the powder compaction density is ≥2.60 g/cm³, and the electrode compaction density is increased to 2.75 g/cm³, with cell energy density exceeding 210 Wh/kg. By optimizing particle gradation and crystal structure, electronic conductivity is significantly improved, enabling fast-charging capabilities of 4C-6C. Coupled with an 800V high-voltage platform, it can achieve an 80% charge in 30 minutes, while low-temperature capacity retention is enhanced to over 75%. At the same time, the cycle life remains stable at over 4,000 cycles, making it suitable for high-end energy storage, ride-hailing, taxi services, and other high-frequency fast-charging scenarios. It has now achieved large-scale mass production, with leading companies gradually increasing their shipment share.

3.Generation 4.5 Products (Transitional High-End Model)  

There is no unified industry standard, and it is commonly defined as a transitional product with a powder compaction density of around 2.65 g/cm³ and an electrode compaction density of 2.80 g/cm³. Compared to the fourth generation, impedance is further reduced through optimizations such as metal ion doping (e.g., magnesium, zinc) and carbon coating processes, enabling fast-charging capabilities of 6C–8C. The low-temperature (-20°C) capacity retention rate approaches 80%, and the energy density can reach 220–230 Wh/kg. This product primarily addresses the performance gap between the fourth and fifth generations and is suitable for high-end new energy passenger vehicles and large-scale energy storage power stations. Currently, it is mainly supplied through customized orders from leading companies and is in the production ramp-up stage.

Additional Note: The theoretical density of lithium iron phosphate is 3.60 g/cm³, indicating that currentGeneration 4.5 products still have significant room for improvement. Meanwhile, fifth-generation products (≥2.70 g/cm³) have entered the laboratory trial production stage and will become the focus of the next generation of technological competition.

II. Process Flow: The Evolution from "Single Sintering" to "Precision Temperature Control + Secondary Optimization"

The performance differences among various generations of products are fundamentally rooted in the iterative upgrades of their process flows. The current mainstream processes are all based on the ferric phosphate route (as the ferrous oxalate route is gradually being phased out due to issues like high gas generation and limited compaction density). The core distinctions primarily lie in the number of sintering cycles, particle gradation, and doping techniques.

1. Third-Generation Product Process (Primarily Traditional Solid-State Method)  

The core process is "raw material mixing → grinding → spray drying → primary sintering → crushing → de-ironing and sieving." Conventional ferric phosphate and lithium sources are used as raw materials. After mixing, a single sintering is conducted in a roller hearth kiln (temperature: 750–800°C, duration: 8–10 hours). The particle gradation mainly consists of a single particle size, requiring only basic carbon coating to enhance conductivity. This process is simple, has high yield, and features lower cost per ton. However, it carries a higher risk of particle agglomeration, making it difficult to achieve higher compaction density.

2. Fourth-Generation Product Process (Optimized Single Sintering / Initial Adoption of Secondary Sintering)  

Two mainstream technological pathways have emerged:  

First, the "Ferric Phosphate Single Sintering Method," represented by companies like Longpan Technology, which simplifies the process through precision temperature-controlled sintering (temperature: 800–850°C, duration: 6–8 hours) and combines particle gradation technology of different sizes to ensure crystallinity while reducing energy consumption.  

Second, the "Ferric Phosphate Secondary Sintering Method," adopted by companies such as Fulin Precision and Hunan Yuneng. After the initial sintering, the material undergoes crushing and grading, followed by secondary sintering (temperature: 780–820°C, duration: 4–6 hours) to optimize the crystal structure and reduce lattice defects, enabling stable compaction density exceeding 2.60 g/cm³. Some enterprises further enhance fast-charging performance through mild ion doping.

3. Generation 4.5 Product Process (Refined Secondary Sintering + Enhanced Doping)  

Building upon the secondary sintering of Generation 4, additional steps of "precursor precise modification" and "multi-stage particle gradation" are incorporated. During the precursor stage, the Fe/P ratio and particle size distribution of the ferric phosphate are controlled. The sintering process employs stepwise temperature control technology to precisely regulate heating rates and dwell times, reducing carbon residue and impurity content. Simultaneously, composite doping technology (such as synergistic magnesium and zinc doping) is introduced to optimize the olivine crystal structure, lower lithium-ion migration resistance, and achieve breakthroughs in both compaction density and conductivity when combined with an ultra-thin, uniform carbon coating process. This process demands extremely high precision in parameter control and has a slightly longer production cycle compared to Generation 4 products.

III. Equipment Differences: Upgrades from "General-Purpose" to "Precision-Controlled" Equipment

The iteration of process flows directly drives upgrades in production equipment. The requirements for equipment precision and automation levels gradually increase across product generations, with core differences primarily concentrated in sintering, crushing, and inspection equipment:

1. Third-Generation Product Equipment (General-Purpose Equipment)  

Sintering employs conventional roller hearth kilns, where temperature control precision within ±5°C meets requirements. Crushing relies on standard jet mills, requiring only control over particle size distribution ranges. Inspection equipment focuses on basic physical performance testing, such as compaction density testers and particle size analyzers. The entire equipment setup has a low investment threshold, is suitable for large-scale mass production, with an annual production capacity of up to 100,000 tons per production line and high equipment utilization rates.

Generation2. Fourth-Generation Product Equipment (Precision-Oriented Upgrades)  

Sintering equipment is upgraded to high-precision intelligent roller hearth kilns, with temperature control precision improved to ±2°C, equipped with atmosphere control systems (precisely adjusting nitrogen/argon ratios) to reduce oxidation risks. Crushing equipment adopts graded jet mills, enabling precise grading and proportioning of large and small particles. New crystal structure inspection equipment (such as XRD diffractometers) is added to monitor crystal integrity in real-time during sintering. The secondary sintering process also requires additional intermediate crushing and grading equipment, increasing investment per production line by 15%–20% compared to third-generation equipment.

3. Generation 4.5 Product Equipment (High-End Customized Equipment)  

High-precision mixing and stirring equipment is added during the precursor preparation stage to achieve molecular-level uniform mixing of raw materials. Sintering equipment adopts segmented temperature-controlled roller hearth kilns, supporting precise regulation of multi-stage heating, holding, and cooling curves. High-resolution electron microscopes and electrochemical performance testing systems are introduced in the inspection phase to monitor doping uniformity, carbon coating thickness, and fast-charging performance in real-time. Some companies also equip automated parameter adjustment systems to optimize process parameters in real-time. Equipment investment increases by an additional 10%–15% compared to fourth-generation products, but product premium capability is significantly enhanced (with a premium of 1,000–2,000 yuan per ton).

IV. Intergenerational Upgrade Transition: Path Selection from "Process Optimization" to "Full-Chain Transformation"  

Enterprises upgrading from Generation 3 to Generation 4 or Generation 4.5 must consider their existing production capacity, cost constraints, and technological capabilities to select the appropriate path. The core challenge lies in balancing "upgrade costs" with "market returns." Specific transition strategies are outlined below:

1. Generation 3 → Generation 4: Focus on Low-Cost Retrofitting for Rapid Entry into the High-Compaction Track  

If adopting the optimized single-sintering path, no core equipment additions are necessary. Retrofitting mainly involves upgrading the temperature control system of existing roller hearth kilns (to high-precision modules), optimizing particle gradation and sintering parameters, and pairing with improved raw materials (such as high-purity ferric phosphate). This can increase compaction density from 2.50 g/cm³ to above 2.60 g/cm³. The retrofitting cost per production line is relatively low, with a timeline of 1–2 months, making it suitable for small and medium-sized enterprises seeking a quick transition.  

If opting for the secondary sintering path, additional intermediate crushing, grading equipment, and a second sintering line are required, leading to higher investment. However, this approach ensures more stable product performance and aligns with the demands of leading battery manufacturers.

2. Generation 4 → Generation 4.5: Refined Upgrades Focused on the High-End Market  

The key lies in "process refinement" and "breakthroughs in doping technology." Large-scale equipment replacement is unnecessary, with upgrades focusing on three main areas:  

First, enhancing the segmented temperature control functionality of sintering equipment to optimize heating and holding curves.  

Second, introducing precursor modification equipment to improve raw material uniformity.  

Third, adding composite doping systems to precisely control the dosage and distribution of doping elements.  

Additionally, detection capabilities must be strengthened by incorporating equipment for crystal structure and electrochemical performance testing to ensure product stability. The upgrade cycle typically takes 3–4 months, making it suitable for enterprises already proficient in Generation 4 technology with sufficient R&D capabilities, enabling them to capture premium pricing in the high-end market.

3. Key Considerations for Upgrades  

First, raw material enhancement is fundamental. Stable Fe/P ratios, high purity, and controllable particle size in ferric phosphate precursors are essential to avoid performance fluctuations caused by material inconsistencies.  

Second, process parameters require iterative adjustments, particularly for secondary sintering and doping processes, to balance compaction density, conductivity, and cycle life.  

Finally, equipment and processes must be optimized synergistically to avoid mismatches such as "high-end equipment paired with outdated processes," which could lead to increased costs without achieving the desired performance standards.

V. GenerationGenerationV. Summary: High Compaction Remains the Core Direction for Future IterationGenerationGeneration

From Generation 3 to Generation 4.5, the evolution of lithium iron phosphate (LFP) is fundamentally a process of "centering on compaction density to jointly enhance energy density, fast-charging performance, and stability." The process has advanced from simple to complex, equipment from general-purpose to precision-oriented, and products from mass-market to high-end. In the future, with the ongoing development of fifth-generation products (≥2.70 g/cm³) and breakthroughs in lithium manganese iron phosphate (LMFP) technology, LFP materials will continue to make strides in three key dimensions: "high compaction, high voltage, and low cost." Enterprises that master core processes and possess equipment adaptation capabilities will hold a competitive edge in the ongoing industry reshuffle.

For downstream enterprises, the choice of product generation should align with application scenarios: third-generation products offer a balance of cost and performance for standard energy storage and entry-to-mid-level vehicle models; fourth-generation products are prioritized for high-end energy storage and high-frequency fast-charging vehicle models; high-end passenger vehicles may consider adopting Generation 4.5 products to gain an early technological advantage.