Lithium Secondary Battery Electrode Pairing for Fast Charge Stability
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Solution Overview
Problem
Existing lithium secondary batteries face limitations in improving energy density, efficiency, and cycle life within a limited space due to the use of high-capacity positive and negative electrode materials, which lead to thermal instability, increased resistance, gas generation, and irreversible capacity loss.
Innovation Solution
A lithium secondary battery design that combines a positive electrode with a lithium composite transition metal compound and a negative electrode with silicon oxide, where the Si crystal grain size is 10% or less of the positive electrode's crystal grain size, along with specific dopants and a carbon layer to enhance stability and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel content in the positive electrode active material is increased to increase capacity, then energy density is improved, but thermal stability deteriorates and resistance increases
Solution Approach 1:
The patent changes the chemical composition parameters of the positive electrode active material by substituting nickel with cobalt and manganese, and by controlling the oxidation state (average valence) of transition metals. This allows maintaining high capacity while improving thermal stability through compositional optimization rather than simply increasing nickel content.
Solution Approach 2:
The patent uses composite positive electrode active materials containing multiple transition metals (nickel, cobalt, manganese) in specific ratios. This composite approach combines the high capacity of nickel-based materials with the thermal stability of cobalt and manganese, achieving both high energy density and reliability.
2Quantity of substance
If non-carbon-based negative electrode materials (silicon, tin, oxides) are used to increase capacity, then energy density is improved, but initial efficiency decreases and irreversible capacity loss increases
Solution Approach 1:
The patent optimizes the particle size parameters of the negative electrode active material, controlling the D50 value within specific ranges (0.1-10 μm for silicon, 0.1-5 μm for tin). This particle size control reduces volume expansion stress and improves initial efficiency while maintaining high capacity.
Solution Approach 2:
The patent applies different surface treatments to different regions of the negative electrode particles. A protective coating (carbon layer or amorphous silicon oxide layer) is applied to the particle surface, creating a core-shell structure that protects the high-capacity material while improving initial efficiency and reducing irreversible capacity loss.
3Volume of moving object
If the battery is designed in a limited space to meet size requirements, then compactness is improved, but energy density and high-output performance cannot be simultaneously increased
Solution Approach 1:
The patent changes the physical parameters of the electrode materials, specifically controlling particle sizes and layer thicknesses to optimize space utilization. By reducing particle sizes and optimizing the thickness of functional layers (coatings, current collectors), the battery achieves high energy density within a compact volume.
4Reliability
If graphite is used as the negative electrode active material, then initial efficiency is maintained, but capacity per unit mass is limited
Solution Approach 1:
The patent creates composite negative electrode materials by combining high-capacity materials (silicon, tin, or their oxides) with graphite or amorphous carbon. This composite structure maintains the good initial efficiency and conductivity of carbon-based materials while incorporating the high capacity of silicon and tin, achieving both properties simultaneously.
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 improves rapid charging performance, efficiency, and energy density while reducing swelling and cycle degradation, enhancing battery life and performance in confined spaces.
Implementation Method 1
electrical energy is produced by oxidation/reduction reactions at a time when lithium ions are intercalated/deintercalated into/from the positive electrode and the negative electrode
Data Source
AI summary
The present invention relates to a lithium secondary battery, a battery module, and a battery pack. The lithium secondary battery comprises: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; a separator disposed between the positive electrode and the negative electrode; and an electrolyte, wherein the positive electrode active material includes a lithium composite transition metal compound containing nickel (Ni), cobalt (Co), and manganese (Mn), the lithium composite transition metal compound contains single particles, the negative electrode active material includes a silicon oxide, and the grain size of Si in the silicon oxide is at most 10% of the grain size of the lithium composite transition metal compound.