Improving Lithium Battery Life with a Built-in Lithium Source

This patent describes a method for building rechargeable lithium-based batteries with a special extra lithium source electrode inside that helps the main battery parts work better and last longer by giving them an initial charge of lithium ions.

What it covers

The patent outlines a method for forming an electrochemical cell, which is the basic unit of a battery. This cell includes at least one non-lithium negative electrode and at least one positive electrode, both designed to allow lithium ions to pass through. A key feature is a separate "lithium source electrode" placed within the cell, containing a specific amount of extra lithium ions (Claim 1). Microporous polymer separators are arranged to keep the electrodes apart while allowing ion flow. After introducing an electrolyte, a voltage is applied across the cell to "pre-lithiate" (fill with lithium ions) either the non-lithium negative electrode or the positive electrode, using lithium ions from the dedicated lithium source electrode (Claim 1). This process forms a rechargeable battery that can then be cycled, and the pre-lithiation can even be repeated to "re-lithiate" the electrodes later. For example, a graphite negative electrode could be pre-lithiated by applying a voltage between 0.005V and 2.0V (Claim 2).

What it doesn't cover

• —Batteries that are opened after the initial pre-lithiation step (Claim 3).
• —Batteries where the lithium source electrode contains less than 10% or more than 50% extra lithium ion capacity compared to the main electrodes (Claim 1).
• —Batteries where the lithium source electrode's projected area is less than 20% of the area of the main non-lithium negative or positive electrodes (Claim 1).
• —Battery manufacturing methods that do not include a separate, dedicated lithium source electrode within the cell.
• —Pre-lithiation processes that do not involve applying a voltage potential across the electrochemical cell (Claim 1).

The clever bit

The novelty lies in integrating a sacrificial, precisely sized lithium source electrode *inside* the sealed battery cell, allowing for controlled pre-lithiation and even re-lithiation without needing to open the cell. This addresses the problem of irreversible lithium loss during initial cycles by providing a convenient, in-situ lithium reservoir.

Why it matters

Pre-lithiation is a crucial technique for improving the performance and lifespan of lithium-ion batteries. Many electrode materials, especially silicon-based ones, lose a significant amount of lithium irreversibly during the very first charge-discharge cycles. This patent's method helps compensate for this initial lithium loss, leading to higher energy density and longer cycle life for the battery. This is particularly important for applications like electric vehicles, where long-lasting, high-capacity batteries are essential.

Real-world examples

• 1.High-energy density lithium-ion batteries for electric vehicles
• 2.Advanced lithium-ion batteries for grid energy storage
• 3.Next-generation consumer electronics batteries
• 4.Pouch cells, cylindrical cells, and coin cells (Claim 3)