Multilayer Cathode Structure for High-Nickel Battery Gas Reduction
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Solution Overview
Problem
Existing lithium secondary batteries face challenges in achieving high energy density, stability, and safety, particularly due to the degradation of cathode active materials with high nickel content, which leads to gas generation and reduced lifespan.
Innovation Solution
A multilayer cathode structure is introduced, comprising a first layer with single-crystal lithium transition metal composite oxide particles and a second layer with secondary particle lithium transition metal composite oxide particles, optimized for nickel content and layer ratios, to enhance stability and reduce gas generation while maintaining high energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high nickel content lithium transition metal composite oxide is used to increase energy density, then battery capacity is improved, but gas generation increases and lifespan decreases
Solution Approach 1:
The cathode active material is segmented into two distinct layers: a first layer containing single-crystal lithium transition metal composite oxide particles and a second layer containing secondary particle lithium transition metal composite oxide particles. This segmentation allows each layer to perform specialized functions, with the single-crystal layer providing stability and low gas generation, while the secondary particle layer contributes to capacity, thereby resolving the contradiction between high capacity and long lifespan
Solution Approach 2:
The invention uses a composite structure combining two different types of lithium transition metal composite oxide particles with distinct morphologies (single-crystal and secondary particle) in a layered configuration. This composite material approach leverages the advantages of both particle types to achieve both high energy density and extended battery lifespan
2Quantity of substance
If high nickel content cathode active material is used, then energy density is improved, but gas generation increases
Solution Approach 1:
By segmenting the cathode active material into two layers with different particle structures, the invention isolates the gas-generation-prone secondary particle material from direct contact with the substrate, while the single-crystal layer acts as a barrier, thereby maintaining high energy density while suppressing gas generation
Solution Approach 2:
The single-crystal lithium transition metal composite oxide layer serves as an intermediary between the substrate and the secondary particle layer, preventing direct interaction that would cause gas generation and substrate damage, thus enabling high nickel content materials to be used without excessive gas generation
3Reliability
If single-crystal lithium transition metal composite oxide particles are used, then storage performance is improved, but manufacturing complexity increases
Solution Approach 1:
The invention segments the cathode structure into two functional layers, placing the single-crystal particles in the first layer directly on the substrate to maximize storage performance, while accepting the increased manufacturing complexity as a necessary trade-off for achieving superior battery reliability and reduced gas generation
Data Source
AI summary
A cathode for a lithium secondary battery and a lithium secondary battery including the same are provided. The cathode for a lithium secondary battery includes a cathode current collector, a first cathode mixture layer disposed on at least one surface of the cathode current collector, and including a first cathode active material being a lithium transition metal oxide particle having a single-crystal structure, and a second cathode mixture layer disposed on the first cathode mixture layer, and including a second cathode active material being a lithium transition metal oxide particle having a secondary particle structure.