Lithium Battery Cathode High Density Stability
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Solution Overview
Problem
Lithium secondary batteries face challenges in achieving high operational stability and reliability due to the trade-off between high power and thermal/mechanical stability, where high-density lithium metal oxides compromise lifespan and reliability.
Innovation Solution
A cathode for lithium secondary batteries is designed with a current collector and a first cathode active material layer of lithium-transition metal composite oxide particles, with a pressed ratio of 25% or less and an electrode density of 3.4 g/cc or more, incorporating a combination of nickel, cobalt, and manganese to maintain capacity and power while reducing deformation and breakage, and optionally a second cathode active material layer with larger particles to enhance electrode density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal oxide is designed to have high density for high power and high capacity, then energy density is improved, but thermal and mechanical stability deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the pressed ratio of the current collector (20-30%) and electrode density (3.2-3.6 g/cc) to achieve optimal balance between energy density and stability. By adjusting these physical parameters within specific ranges, the invention resolves the contradiction between high energy density and thermal/mechanical stability.
Solution Approach 2:
The patent uses composite materials by combining lithium-transition metal composite oxide particles with a binder and conductive agent to form a cathode active material layer. This composite structure allows the electrode to maintain high density while the binder and conductive network provide mechanical integrity and thermal stability, resolving the contradiction between energy density and stability.
2Quantity of substance
If lithium metal oxide is designed to have high density for high power and high capacity, then energy density is improved, but lifespan property deteriorates
Solution Approach 1:
The patent applies parameter changes by controlling the pressed ratio within 20-30% and electrode density within 3.2-3.6 g/cc, which prevents excessive mechanical stress on the electrode structure during cycling. This optimized parameter range maintains high energy density while ensuring the electrode structure remains intact over extended cycling, thereby improving lifespan.
Solution Approach 2:
The patent applies beforehand cushioning by incorporating a binder and conductive agent in the cathode active material layer before electrode assembly. These components provide a cushioning effect that absorbs mechanical stress and prevents particle detachment during repeated charging-discharging cycles, protecting the high-density electrode structure and extending battery lifespan.
3Quantity of substance
If lithium metal oxide is designed to have high density for high power and high capacity, then energy density is improved, but operational reliability deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the pressed ratio (20-30%) and electrode density (3.2-3.6 g/cc) to achieve optimal operational reliability. These parameter controls prevent electrode deformation and maintain consistent electrochemical performance over time, ensuring reliable operation while maintaining high energy density.
Solution Approach 2:
The patent uses composite materials with binder and conductive agent to create a robust cathode structure that maintains high density while ensuring operational reliability. The composite structure provides mechanical strength and electrical conductivity throughout the electrode, preventing failure modes that would compromise reliability in high-density electrodes.
Data Source
AI summary
A cathode for a lithium secondary battery is provided. The cathode for a lithium secondary battery includes a current collector, and a first cathode active material layer formed by being pressed on at least one surface of the current collector. The first cathode active material layer includes first lithium-transition metal composite oxide particles. A pressed ratio of the current collector is 25% or less, and an electrode density is 3.4 g/cc or more.