High-Nickel Cathode Blend with Graded Particle Sizes for Dense Electrodes
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Solution Overview
Problem
Conventional high-nickel positive electrode active materials suffer from low packing density, particle fragmentation, increased specific surface area, and side reactions, leading to reduced energy density and poor high-temperature performance in lithium-ion batteries.
Innovation Solution
A positive electrode active material comprising active materials A, B, and C with different average particle sizes and nickel contents, specifically formulated as Lix1Nia1Cob1Mnc1O2-y1Qy1, Lix2Nia2Cob2Mnc2O2-y2, and Lix3Nia3Cob3Mnc3O2-y3, with optimized ratios and surface modifications, to enhance compacted density and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high-nickel positive electrode active material is used to increase energy density, then the energy density is improved, but the structural stability deteriorates and particle fragmentation occurs
Solution Approach 1:
The patent uses a composite material system consisting of Li-rich layered oxide as the core positive electrode active material, combined with specific coating layers and electrolyte additives. This composite approach allows achieving high energy density while maintaining structural stability through the synergistic effects of different materials working together.
Solution Approach 2:
The patent optimizes multiple parameters including the Li-rich layered oxide composition (adjusting the ratio of Li2MnO3 to LiMO2), particle size distribution (Dv10, Dv50, Dv90 values), coating thickness, and electrolyte composition. By systematically adjusting these parameters, the patent achieves both high energy density and structural stability.
2Duration of action of stationary object
If conventional coating or doping methods are applied to improve cycling performance, then the cycling performance is improved, but the gram capacity and overall performance deteriorate
Solution Approach 1:
The patent applies coating layers with specific compositions and thicknesses only on the surface of the Li-rich layered oxide particles, rather than uniformly throughout the bulk material. This local modification approach preserves the high capacity characteristics of the bulk material while improving surface stability and cycling performance.
Solution Approach 2:
The patent carefully controls the coating thickness and composition parameters to optimize the balance between cycling performance and gram capacity. By adjusting parameters such as coating layer thickness and electrolyte additive concentrations, the patent achieves improved cycling stability without significantly sacrificing capacity.
Data Source
AI summary
A positive electrode active material includes an active material A having a composition formula of Lix1Nia1Cob1Mnc1O2-y1Qy1, an active material B having a composition formula of Lix2Nia2Cob2Mnc2O2-y2Qy2, and an active material C having a composition formula of Lix3Nia3Cob3Mnc3O2-y3Qy3, where the subscripts in the formulae are as defined in the description. The active material A has an average particle size Dv50 greater than both an average particle size Dv50 of the active material B and an average particle size Dv50 of the active material C.