Lithium iron phosphate (LFP) batteries are widely applied in new energy vehicles, advanced energy storage and other fields due to their high safety and low cost. However, their application is restricted in low‑temperature scenarios such as cold winter environments, high‑altitude regions, and aviation base stations, where their electrochemical performance degrades significantly.
Reduced operating temperatures greatly impair the electrochemical performance of lithium‑ion batteries, especially LFP batteries. Low temperatures exert varying degrees of adverse effects on the electrolyte bulk, electrode‑electrolyte interface, graphite anode and LFP cathode of the battery system.
The core causes of battery performance degradation at low temperatures include increased electrolyte viscosity, elevated internal impedance and polarization, and hindered lithium‑ion transmission. In particular, lithium batteries cannot support high charge‑discharge rates at low temperatures, and forced fast charging is highly likely to trigger lithium plating.
This article systematically summarizes the low‑temperature performance degradation mechanism of LFP batteries and corresponding optimization strategies in a clear itemized form for intuitive understanding.
I. Mechanism of Low‑Temperature Performance Degradation
LFP batteries suffer from severe performance degradation at low temperatures (especially below ‑20°C), mainly manifested as capacity attenuation, increased internal resistance and shortened cycle life. The specific mechanisms are as follows:
1. Deteriorated electrolyte performance
The stability of the electrode‑electrolyte interface declines at low temperatures, triggering increased side reactions that consume active lithium and electrolyte, resulting in irreversible capacity loss.
II. Low‑Temperature Performance Optimization Strategies
1. Electrode Material Modification
Material modification optimizes the structural characteristics of electrode materials to improve ionic and electronic conductivity, enhancing lithium‑ion migration efficiency at low temperatures.
Graphite Anode: Strategies such as nitrogen doping and macroporous structure construction are adopted to accelerate lithium‑ion diffusion. For example, dendritic nitrogen‑doped graphite tubes maintain a specific capacity of 222.5 mAh/g at ‑10°C; graphite anodes with penetrating macropores achieve a capacity of 352.9 mAh/g under 2C cycling at ‑30°C.
LFP Cathode: Carbon coating modification is applied to improve electronic conductivity and interfacial stability. Hydrothermally synthesized carbon‑coated LFP retains 75.1% of its room‑temperature capacity at ‑20°C. The uniform carbon coating effectively enhances the conductivity, lithium‑ion diffusion coefficient and surface stability of LFP composite materials. Dynanano is the core enterprise specializing in hydrothermal synthesis of LFP materials.
2. Electrolyte Optimization
Electrolyte optimization is the core approach to improve battery low‑temperature performance, covering solvent, lithium salt and functional additive modification.
Solvent Optimization: Low‑melting‑point and low‑viscosity solvents are adopted, including linear carbonates (DMC, DEC), carboxylate esters (MF, EA) and ethers (DOL, DME). Fluorinated solvents (MTFP) are also introduced to broaden the liquid temperature range and improve low‑temperature stability. Localized High‑Concentration Electrolyte (LHCE) reduces electrolyte viscosity while retaining the interfacial advantages of high‑concentration electrolytes via diluent introduction.
Lithium Salt Optimization: In addition to conventional LiPF₆, novel lithium salts such as LiBF₄, LiBOB and LiDFOB have attracted wide attention due to their excellent film‑forming performance and stable interfacial characteristics. Multi‑salt compounding has become a mainstream development trend for low‑temperature electrolytes.
Additive Optimization: Functional additives including FEC, Fluorosulfonyl Isocyanate (FI) and NaCl can form highly ionically conductive SEI/CEI films on electrode surfaces, inhibit lithium plating and side reactions, and improve low‑temperature cycling stability.
Adding 1% sodium chloride (NaCl) as an electrolyte additive forms a uniform Cathode Electrolyte Interphase (CEI) on the LFP surface, optimizing the lithiation and delithiation behavior during battery cycling.
3. Low‑Temperature Preheating Technology
Preheating technologies are divided into external heating and internal heating systems, which effectively raise battery temperature, reduce internal impedance and restore low‑temperature electrochemical activity.
External Heating
• Medium heating: Heat transfer is realized via air, liquid or phase change materials (SAT, STP). This technology features a simple structure but poor heating uniformity.
• Electric heating element heating: Adopts PTC resistors, metal resistance heating films and other components, delivering high heating efficiency while increasing the overall system volume.
Internal Heating
• Self‑heating: Built‑in nickel foil and other structures enable rapid self‑heating with high energy utilization efficiency.
• Current heating: Uses alternating current or pulse current to generate heat through internal resistance. Technologies such as mutual pulse heating and wireless charging heating systems achieve a heating rate of 8.5°C/min at ‑20°C.