Pre-lithiating Negative Electrodes for Lithium Ion Batteries
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Solution Overview
Problem
Conventional lithium-ion batteries suffer from capacity fade due to the formation of a solid electrolyte interphase (SEI) layer on the negative electrode, leading to irreversible lithium loss and reduced energy density, which is not effectively counteracted by current methods.
Innovation Solution
A method of pre-lithiating the negative electrode by placing a lithium metal source in contact with a pre-fabricated negative electrode and heating it under pressure to transfer lithium, thereby replacing irreversibly lost lithium and enhancing battery capacity and life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lithium-ion batteries are used without pre-lithiation, then the battery structure is simple and manufacturing is straightforward, but capacity fade occurs due to SEI layer formation and irreversible lithium loss
Solution Approach 1:
The patent applies preliminary action by pre-lithiating the negative electrode before assembling the battery cell. This involves contacting the negative electrode with a lithium metal source and heating to transfer lithium onto the electrode surface in advance, compensating for the lithium that will be irreversibly lost during initial charging cycles due to SEI layer formation. This preliminary treatment ensures the electrode has sufficient lithium capacity from the start.
2Reliability
If extra lithium capacity is incorporated onto the positive electrode to compensate for initial lithium loss, then capacity fade is addressed, but energy density is reduced
Solution Approach 1:
The patent applies local quality by selectively adding lithium only to the negative electrode where it is needed to compensate for SEI layer formation, rather than uniformly distributing extra lithium throughout the entire battery. This localized pre-lithiation approach compensates for lithium loss without requiring additional lithium in the positive electrode, thereby maintaining the battery's energy density while improving capacity stability.
3Duration of action of stationary object
If pre-lithiation process is implemented with heating and compression, then initial lithium loss is compensated and battery life is extended, but manufacturing process complexity increases
Solution Approach 1:
The patent applies parameter changes by utilizing heat and pressure parameters to facilitate lithium transfer from the lithium metal source to the negative electrode. By controlling temperature and pressure parameters during the pre-lithiation process, efficient lithium transfer is achieved without requiring overly complex manufacturing equipment or multiple processing steps, thus extending battery cycle life while maintaining reasonable manufacturing simplicity.
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
The pre-lithiation process increases the initial capacity of lithium-ion batteries and improves long-term performance by compensating for initial lithium loss, resulting in extended battery life and maintained charge capacity.
Implementation Method 1
heating and compressing of the lithium metal source and the pre-fabricated negative electrode together at a temperature of greater than or equal to about 100° C.
Implementation Method 2
heating and compressing of the lithium metal source and the pre-fabricated negative electrode together
Data Source
AI summary
Methods for pre-lithiating negative electrodes for lithium-ion electrochemical cells (e.g., batteries) are provided. The methods include disposing a lithium metal source comprising a layer of lithium metal adjacent to a surface of a pre-fabricated negative electrode. The lithium metal source and electrode are heated (e.g., to a temperature of ≧about 100° C.) to transfer a quantity of lithium to the pre-fabricated negative electrode. This lithiation process adds excess active lithium capacity that enables replacement of irreversibly lost lithium during cell formation and cell aging, thus leading to increased battery capacity and improved battery life. The methods may be batch or continuous.