Lithium Titanate Negative Electrode Plating Prevention
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Solution Overview
Problem
Conventional lithium-ion batteries face issues with lithium plating, leading to decreased capacity and potential internal shorts, particularly in batteries with carbon-based negative active materials, which require excessive negative electrode capacity and complex design rules to mitigate, resulting in increased size, cost, and lower energy density.
Innovation Solution
The use of lithium titanate as a negative active material with a higher average potential versus Li/Li+ reduces the likelihood of lithium plating, allowing for simpler battery designs where negative electrodes do not need to extend beyond positive electrodes, thereby reducing materials and manufacturing costs while maintaining effective lithium intercalation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If carbon-based negative active materials are used, then battery capacity is improved, but lithium plating occurs leading to decreased capacity and potential internal shorts
Solution Approach 1:
The patent changes the electrochemical potential parameter of the negative active material from carbon-based (lower potential) to lithium titanate-based (higher potential). This parameter change fundamentally alters the operating voltage window, preventing lithium plating while maintaining high capacity through the higher operating potential.
Solution Approach 2:
The patent employs lithium titanate as a composite negative active material that combines the benefits of high capacity with inherent protection against lithium plating. The lithium titanate structure provides both high lithium intercalation capability and structural stability that prevents plating-related failures.
2Reliability
If excess negative electrode capacity is provided to prevent lithium plating, then reliability is improved, but battery size increases and energy density decreases
Solution Approach 1:
By changing the potential parameter of the negative active material to a higher value (lithium titanate), the patent eliminates the need for excess negative electrode capacity. The higher potential inherently prevents lithium plating, allowing the negative electrode to be sized optimally without unnecessary material additions.
3Reliability
If negative electrodes extend beyond positive electrodes to compensate for plating, then reliability is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent simplifies the design by changing the electrochemical potential parameter of the negative active material. This eliminates the need for complex design rules requiring negative electrodes to extend beyond positive electrodes, as the higher potential inherently prevents plating regardless of precise electrode alignment.
4Productivity
If higher charging rates are implemented, then productivity is improved, but lithium plating risk increases
Solution Approach 1:
By changing the operating potential parameter to a higher value with lithium titanate, the patent enables higher charging rates. The higher potential provides a larger voltage window that accommodates faster lithium ion transport without reaching the plating threshold, thus decoupling charging speed from plating risk.
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
Lithium titanate materials enable higher charging rates, superior cycle life, and reduced risk of lithium plating, allowing for more flexible battery designs with improved energy density and manufacturing efficiency, and the ability to charge batteries quickly without decomposing organic solvents.
Implementation Method 1
The additional negative active material provides additional intercalation sites for the cyclable lithium originating with the positive active material
Implementation Method 2
During charging and discharging of the battery, lithium ions move between the positive electrode and the negative electrode
Data Source
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AI summary
A lithium-ion battery having a wound electrode configuration includes a wound cell element that includes a positive electrode and a negative electrode, the positive electrode including a current collector and a first active material and the negative electrode including a current collector and a second active material. The second active material has a potential that is greater than 0.2 volts versus a lithium reference electrode. The wound cell element includes a region where an edge of the positive electrode is provided proximate an edge of the negative electrode and the second active material near the edge of the negative electrode does not extend beyond the first active material near the edge of the positive electrode.