Negative Electrode Additives for Low-Temperature Li-Ion Output
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Solution Overview
Problem
Lithium secondary batteries experience deteriorated output at low temperatures due to issues such as delamination of graphite-based active materials and increased charge transfer resistance from nano-structured negative electrode active materials.
Innovation Solution
Incorporating specific additives like LATP, LAGP, LLTO, and LLZO in a range of 1.8 to 3.2 parts by weight with negative electrode active material particles improves lithium ion conductivity and diffusion, minimizing capacity deterioration and resistance increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If propylene carbonate is included in the non-aqueous electrolyte to improve low-temperature performance, then low-temperature output is improved, but graphite-based active material interlayer delamination occurs and battery performance deteriorates
Solution Approach 1:
The patent introduces a solid electrolyte additive layer containing Li1+xAlxTi2-x(PO4)3 (LATP) or Li1+xAlxTi2-xZr1-yMby(PO4)3 (LAGP) as an intermediary between the graphite-based active material and the non-aqueous electrolyte. This intermediary layer prevents the harmful interaction between propylene carbonate and graphite while maintaining low-temperature ionic conductivity, thus resolving the contradiction between low-temperature output improvement and prevention of interlayer delamination
Solution Approach 2:
The patent modifies the chemical composition parameters of the solid electrolyte additive layer by controlling the x and y values in the formulas Li1+xAlxTi2-x(PO4)3 and Li1+xAlxTi2-xZr1-yMby(PO4)3. By optimizing these compositional parameters, the additive layer achieves appropriate ionic conductivity at low temperatures while providing sufficient structural stability to prevent graphite interlayer delamination
2Area of stationary object
If nano-structured negative electrode active material is used to increase surface area, then reactivity is improved, but charge transfer resistance increases due to polycrystalline nature and battery performance deteriorates
Solution Approach 1:
The solid electrolyte additive layer acts as an intermediary between the nano-structured graphite particles and the non-aqueous electrolyte. This intermediary layer provides continuous ionic conduction pathways that compensate for the high charge transfer resistance inherent in polycrystalline nano-structures, thereby maintaining battery performance while utilizing the high surface area benefits of nano-structuring
Solution Approach 2:
The patent utilizes the porous structure of the solid electrolyte additive layer to facilitate lithium ion transport. The porous morphology provides multiple conduction pathways that reduce the effective charge transfer resistance at the electrode-electrolyte interface, allowing the system to benefit from nano-structured graphite's high surface area without suffering from its inherent high resistance
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
Enhances low-temperature output properties of lithium secondary batteries by improving lithium ion conductivity and diffusion, particularly at temperatures below -10°C, while maintaining battery capacity and reducing resistance.
Implementation Method 1
the diffusion rate and conductivity of lithium ions may be improved
Implementation Method 2
the diffusion rate and conductivity of lithium ions may be improved
Data Source
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AI summary
The present invention relates to a negative electrode and a secondary battery including the same, the negative electrode including a negative electrode active material layer containing negative electrode active material particles and an additive, wherein the additive is included in an amount of 1.8 parts by weight to 3.2 parts by weight based on 100 parts by weight of the negative electrode active material particles, and the additive includes at least one selected from the group consisting of LATP, LAGP, LLTO, and LLZO.