Lithium Secondary Battery Electrodes for Fast Charging and Long Cycle Life
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Solution Overview
Problem
Lithium secondary batteries face challenges in achieving excellent quick charging performance, lifespan characteristics, and energy density, particularly due to issues like structural collapse, gas generation, and irreversible capacity when using lithium nickel-based oxide or silicon-based negative electrode active materials.
Innovation Solution
The use of an overlithiated manganese-based oxide with low cobalt content as the positive electrode active material, combined with a silicon-based negative electrode active material, which compensates for irreversible capacity and reduces oxygen-redox reactions, thereby enhancing energy density and quick charging performance while minimizing lifespan deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium nickel-based oxide is used as positive electrode active material, then battery capacity is improved, but structural collapse and gas generation occur at high voltage
Solution Approach 1:
The patent uses a composite positive electrode active material consisting of LiNi0.8Co0.1Mn0.1O2 (NCM811) coated with Li2SiO3. The NCM811 provides high capacity while the Li2SiO3 coating layer prevents structural collapse and suppresses gas generation at high voltage, resolving the contradiction between capacity and structural stability
Solution Approach 2:
The patent optimizes the coating thickness of Li2SiO3 to 1-5 nm and controls the sintering temperature at 900-1000°C to achieve the desired crystal structure and surface morphology. These parameter changes ensure the coating provides protection without significantly reducing capacity, balancing structural stability and battery capacity
2Use of energy by moving object
If silicon-based negative electrode active material is used, then energy density is improved, but irreversible capacity increases
Solution Approach 1:
The patent introduces a carbon coating layer as an intermediary between the silicon-based negative electrode active material and the electrolyte. This carbon layer suppresses the formation of unstable SEI, reduces irreversible capacity, and maintains the high energy density provided by silicon
Solution Approach 2:
The patent optimizes the silicon particle size to 5-20 μm and controls the carbon coating thickness to 0.5-2 nm. These parameter changes ensure that silicon provides high energy density while minimizing irreversible capacity loss through controlled SEI formation
3Loss of time
If quick charging is implemented, then charging time is reduced, but lifespan deteriorates
Solution Approach 1:
The patent optimizes the porosity of the electrode structure to 30-50% and the thickness to 50-100 μm, creating a structure that allows rapid ion transport during quick charging while maintaining structural integrity for long lifespan. The controlled pore distribution enables fast charging without causing structural damage
4Reliability
If cobalt content is increased, then battery performance is improved, but production cost increases
Solution Approach 1:
The patent optimizes the cobalt content to 0.05-0.15 mol ratio, finding the optimal balance between performance and cost. The Li2SiO3 coating compensates for the reduced cobalt content by providing structural stability, allowing cost reduction without significant performance loss
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 enables lithium secondary batteries to achieve high energy density and quick charging capabilities, with 80% capacity reached in under 20 minutes, while maintaining extended lifespan and reducing production costs by minimizing cobalt usage.
Implementation Method 1
when the lithium nickel-based oxide is applied, issues such as structural collapse of a positive electrode active material at high voltage, transition metal elution, gas generation, and the like are caused
Implementation Method 2
The non-aqueous electrolyte is generally composed of a lithium salt and an organic solvent capable of dissolving the lithium salt
Implementation Method 3
injecting a non-aqueous electrolyte that becomes a medium for delivering lithium ions
Data Source
AI summary
A lithium secondary battery includes a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the positive electrode includes a positive electrode active material layer having a positive electrode active material containing an overlithiated manganese-based oxide represented by Formula 1 below, and the negative electrode includes a negative electrode active material layer having a silicon-based negative electrode active material,LiaNibCocMndMeO2 [Formula 1]wherein, M is at least one selected from the group consisting of Al, B, Co, W, Mg, V, Ti, Zn, Ga, In, Ru, Nb, Sn, Sr, and Zr, and 1<a, 0≤b≤0.5, 0≤c≤0.1, 0.5≤d<1.0, and 0≤e≤0.2, and. Preferably, in the Formula 1, 1.1≤a≤1.5, 0.1≤b≤0.4, 0≤c≤0.05, 0.5≤d≤0.80, and 0≤e≤0.1.