Pre-Lithiated Negative Electrode Material for Uniform SEI Formation
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Solution Overview
Problem
Conventional lithium secondary batteries face challenges in achieving high initial efficiency and cycle life due to irreversible SEI film formation on carbon electrodes, leading to lithium ion consumption and capacity degradation.
Innovation Solution
A method involving the preparation of a lithium composite negative electrode active material by extruding a mixture of lithium metal and carbonaceous materials, immersing the pellets in an electrolyte containing SEI film forming additives like fluoro ethylene carbonate and vinylene carbonate, and subsequent pulverization and drying to create a uniform SEI film, enhancing initial efficiency and cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pre-lithiated carbon electrode is used as a negative electrode, then initial efficiency is improved, but the process complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-lithiating the carbon electrode before battery assembly. Specifically, lithium metal is mixed with carbonaceous material and compressed into pellets, which are then immersed in electrolyte to allow controlled lithium insertion. This pre-lithiation step is performed outside the battery structure, simplifying the overall manufacturing process while achieving the desired initial efficiency improvement.
Solution Approach 2:
The patent uses an intermediary approach by introducing SEI film forming additives into the electrolyte during the pre-lithiation process. These additives mediate the interaction between lithium and the carbon electrode, enabling controlled SEI film formation that stabilizes the electrode structure while maintaining manufacturing simplicity. The additives act as intermediaries that facilitate uniform lithium distribution without requiring complex processing equipment.
2Productivity
If a large amount of lithium is incorporated into the negative electrode active material in a short time, then pre-lithiation efficiency is improved, but structural change in the negative electrode active material occurs
Solution Approach 1:
The patent applies parameter changes by controlling the pre-lithiation process through electrolyte composition and immersion time. By adjusting the concentration of SEI film forming additives and the duration of electrolyte immersion, the patent achieves controlled lithium insertion rates that prevent structural damage to the carbonaceous material while maintaining high pre-lithiation efficiency. The extrusion process also controls particle morphology to facilitate uniform lithium distribution.
Solution Approach 2:
The patent uses local quality by creating uniform lithium distribution throughout the carbon electrode structure through the extrusion and electrolyte immersion process. The carbonaceous material is thoroughly mixed with lithium metal before compression, ensuring homogeneous local composition. During electrolyte immersion, lithium ions are uniformly distributed across all carbon particles, preventing localized structural stress and maintaining overall structural stability.
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 method results in improved initial efficiency and extended cycle life of lithium secondary batteries by ensuring uniform lithium doping and stable SEI film formation, reducing irreversible capacity loss.
Implementation Method 1
a second step of immersing the pellet in an electrolyte containing an SEI film forming additive (S20)
Implementation Method 2
a second step of immersing the pellet in an electrolyte containing an SEI film forming additive (S20)
Implementation Method 3
a first step of preparing a pellet by extruding a mixture of lithium metal and a negative electrode active material (S10)
Implementation Method 4
a third step of pulverizing, washing and drying the pellet to prepare a powder of the lithium composite negative electrode active material (S30)
Data Source
AI summary
A method for manufacturing negative electrode active material including the steps of manufacturing a pellet by extruding a mixture of lithium metal and negative electrode active material, immersing the pellet in an electrolyte comprising an SEI film-forming additive, and manufacturing the pellet into powder form by grinding, washing and drying same. A negative electrode and a lithium rechargeable battery manufactured using the lithium-active material powder has an SEI film that is uniformly formed by having lithium uniformly doped in the negative electrode. During initial charging, the SEI film is stably formed, and thus an effect is achieved whereby the initial efficiency of the lithium rechargeable battery is improved.