Introduction

The self-discharge rate of LiFePO₄ batteries (Lithium Iron Phosphate batteries) is the result of a combination of intrinsic material properties, manufacturing processes, and operating conditions.
Although LiFePO₄ chemistry is well known for its low self-discharge and high stability, abnormal capacity loss during storage or idle periods may still occur if key factors are not properly controlled.

This article systematically analyzes the main factors affecting LiFePO₄ battery self-discharge, helping users better evaluate battery quality, storage conditions, and system design.

Major Factors Affecting LiFePO₄ Battery Self-Discharge

1. Materials and Electrochemical System

Electrode Material Purity
Metal impurities (such as iron or copper) in cathode or anode materials can catalyze side reactions and even cause internal micro-short circuits, leading to abnormally high self-discharge.
Impact level: Very High (intrinsic factor)

Electrolyte Stability
Excess moisture or acidic components in the electrolyte may corrode current collectors (aluminum foil), generating gas and by-products that accelerate capacity loss.
Impact level: High

SEI Film Quality
An unstable, excessively thick, or non-uniform SEI (Solid Electrolyte Interphase) layer on the anode continuously consumes lithium ions and electrolyte, increasing self-discharge over time.
Impact level: High

2. Manufacturing Process and Quality Control

Production Cleanliness
Dust and contaminants introduced during cell manufacturing are a direct cause of internal micro-short circuits.
Impact level: Very High (critical control point)

Process Precision
Burrs on electrodes, poor separator alignment, or manufacturing defects significantly increase the risk of localized short circuits.
Impact level: High

Formation and Aging Process
Inadequate formation prevents stable SEI formation, while insufficient aging time fails to screen out defective cells.
Impact level: Medium

3. Operating and Environmental Conditions

Temperature
High temperature is the strongest “accelerator” of self-discharge. For every 10 °C increase, chemical reaction rates roughly double.
Low temperatures, on the other hand, suppress self-discharge.
Impact level: Very High (largest variable)

State of Charge (SOC)
Long-term storage at high SOC (e.g., 100%), over-charging, or over-discharging intensifies side reactions and structural degradation.
Impact level: High

Time and Aging
After long-term cycling or storage, material activity declines and the SEI layer thickens, causing a gradual and irreversible increase in self-discharge.
Impact level: Medium (long-term accumulation)

4. Battery Pack and System-Level Factors

Cell Consistency
In battery packs, voltage inconsistency among cells can create leakage currents through parallel paths, appearing as overall capacity loss.
Impact level: High (system-level issue)

BMS Power Consumption
Poorly designed Battery Management Systems (BMS) may have high standby power consumption, slowly draining the battery during storage.
Impact level: Medium (often overlooked)

Key Insights and Practical Recommendations