How to Fast-Charge Lithium Batteries Without Damaging Them

This patent describes a three-phase method for quickly charging lithium-ion batteries while carefully controlling voltages to prevent harmful lithium metal buildup and electrolyte damage.

What it covers

The patent outlines a method for fast-charging lithium batteries, like those in electric vehicles, by carefully managing the charging process in three phases to avoid damage. In a first phase, the battery is charged as fast as possible, limited only by the battery or charger's capabilities (Claim 1). Next, in a second phase, the charging current is gradually reduced to ensure the "anode potential" (the voltage of the negative battery terminal) stays above a specific safe level, preventing "lithium plating" (Claim 1). Lithium plating is when lithium metal forms on the anode, which can damage the battery. Finally, in a third phase, the charging continues while keeping the overall "cell potential" (the battery's total voltage) below a maximum limit to stop the electrolyte from breaking down (Claim 1). The patent also describes a way to detect lithium plating by looking for sudden changes in the charging current's rate of change (its derivative), which helps fine-tune the safe charging limits (Claim 8). For example, an electric car could use this method to quickly charge its battery without shortening its lifespan.

What it doesn't cover

• —Does not cover fast-charging methods that do not specifically manage the anode potential to prevent lithium plating (Claim 1).
• —Does not cover fast-charging methods that do not control the cell potential to prevent electrolyte oxidation (Claim 1).
• —Does not cover lithium plating detection methods that do not involve analyzing the derivative of the charging current for discontinuities (Claim 8).
• —Does not cover charging methods that use only a single constant current or constant voltage phase without the specific three-phase approach (Claim 1).
• —Does not cover batteries that are not lithium-ion based, as the claims specifically refer to "lithium battery" and "lithium ion-containing electrolyte" (Claim 1).

The clever bit

The cleverness lies in the precise, multi-phase control of both anode and cell potentials during charging, specifically by decreasing current to maintain the anode potential above the lithium plating threshold. Additionally, the method for detecting lithium plating by analyzing the derivative of the charging current provides a way to dynamically optimize these thresholds.

Why it matters

Fast-charging is crucial for electric vehicles and other portable electronics, but it can degrade lithium-ion batteries by causing lithium plating or electrolyte breakdown. This patent provides a structured approach to achieve faster charging speeds while protecting the battery's health and lifespan. By preventing lithium plating, it helps maintain battery capacity and safety over many charge cycles. This is vital for consumer confidence and the widespread adoption of electric vehicles, where charging time is a significant concern.

Real-world examples

• 1.Electric vehicle fast-charging stations
• 2.Smartphone fast chargers
• 3.Laptop fast charging capabilities
• 4.Battery management systems in grid-scale energy storage