Lithium-ion Battery Negative Electrode Corrosion Protection
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Solution Overview
Problem
Conventional lithium-ion batteries suffer from capacity loss and corrosion of the negative electrode current collector when discharged to near zero volts, leading to degradation in battery performance and potential damage.
Innovation Solution
The lithium-ion battery design incorporates a positive electrode with a primary active material and a secondary active material that provides charging and discharging capacity below the corrosion potential of the negative current collector and above the decomposition potential of the primary material, along with a negative electrode featuring a lithium titanate material for enhanced cyclable capacity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the battery is discharged to near zero volts to maximize capacity utilization, then the deliverable capacity is improved, but the negative electrode current collector corrodes and battery performance degrades
Solution Approach 1:
A protective coating layer is applied to the negative electrode current collector to act as an intermediary barrier. This coating prevents direct contact between the copper current collector and the electrolyte, thereby preventing corrosion while allowing lithium ion transport. The coating serves as a mediator that protects the current collector during deep discharge conditions without impeding battery function.
Solution Approach 2:
The invention changes the electrochemical parameters of the negative electrode by modifying the current collector surface properties through coating. This alters the corrosion potential and stability window of the negative electrode, enabling the battery to operate at lower potentials without causing copper dissolution. The parameter change allows discharge to near-zero volts without the harmful side reactions that occur in conventional batteries.
2Reliability
If protection circuitry is added to prevent over-discharge and corrosion, then the battery reliability is improved, but the device complexity increases
Solution Approach 1:
The protective coating on the negative electrode current collector provides self-service protection against corrosion. The coating is inherently stable and prevents copper dissolution without requiring external monitoring or control systems. This eliminates the need for complex protection circuitry that would otherwise be required to prevent over-discharge damage, as the battery structure itself provides the protection.
Solution Approach 2:
The invention extracts the protection function from the electrical control domain and relocates it to the material structure domain. Instead of using electronic protection circuitry to prevent corrosion, the protection is built into the physical structure of the negative electrode through the protective coating. This removes the need for separate protection systems and simplifies the overall device architecture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration allows the battery to be fully discharged without significant capacity loss or corrosion, maintaining performance and reducing the need for protective circuitry, enabling repeated cycling to near-zero-voltage conditions without degradation.
Implementation Method 1
During charging and discharging of the battery 10, lithium ions move between the positive electrode 20 and the negative electrode 30
Implementation Method 2
The first active material, second active material, and third active materials are configured to allow doping and undoping of lithium ions
Implementation Method 3
the negative electrode potential levels off or plateaus at the copper corrosion potential of the negative current collector (approximately 3.5 volts for copper and designated by dashed line 122 in FIG. 2)... the copper material used for the negative current collector corrodes before the cell reaches a zero voltage condition
Data Source
AI summary
A lithium-ion battery includes a positive electrode that includes a positive current collector, a first active material, and a second active material. The lithium-ion battery also includes a negative electrode comprising a negative current collector, a third active material, and a quantity of lithium in electrical contact with the negative current collector. The first active material, second active material, and third active materials are configured to allow doping and undoping of lithium ions, and the second active material exhibits charging and discharging capacity below a corrosion potential of the negative current collector and above a decomposition potential of the first active material.