Why Do Lithium Batteries Lose Capacity Over Time?

Lithium batteries are the backbone of modern energy storage, powering everything from smartphones to electric vehicles. But over time, they lose capacity due to chemical and mechanical changes. Understanding these processes helps both users and manufacturers optimize battery performance and extend service life.

Main Reasons for Lithium Battery Capacity Loss

1. Solid Electrolyte Interphase (SEI) Growth

The SEI layer forms on the anode during the first charge. Over time, it thickens, consuming active lithium and reducing capacity. Studies show SEI growth contributes to 20–40% of total capacity fade after 500 cycles.

2. Lithium Plating

At low temperatures or high charging rates, metallic lithium can plate onto the anode, reducing available lithium and increasing short-circuit risk.

3. Cathode Degradation

Repeated cycling changes the cathode structure (e.g., NMC, LFP). Transition metal dissolution reduces efficiency. High-Ni cathodes may lose ~15% capacity within 1000 cycles at elevated temperatures.

4. Electrolyte Decomposition

High temperatures and over-voltage accelerate electrolyte breakdown, increasing cell impedance. Continuous use above 45°C nearly doubles the rate of capacity loss.

5. Mechanical Stress and Microcracks

Expansion and contraction of electrode materials cause microcracks, isolating active material and reducing capacity.

Factors Accelerating Capacity Loss

How to Slow Down Capacity Loss

• Keep battery SOC between 20–80% for daily use.
• Store at cool, dry conditions (15–25°C ideal).
• Use a robust Battery Management System (BMS).
• Choose quality packs from trusted manufacturers like Huawen New Power.