Nickel-Rich Cathode Material With Controlled Pore Distribution
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Solution Overview
Problem
Current lithium secondary battery positive electrode active materials face challenges in controlling pore size and distribution within secondary particles, affecting reactivity and particle strength, which limits their performance.
Innovation Solution
A positive electrode active material with lithium transition metal oxide, containing 60 mol% nickel, is developed, where the pores in secondary particles are evenly distributed to satisfy specific conditions, enhancing initial capacity characteristics through controlled crystalline aspect ratios and sintering processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional lithium transition metal oxides are used as positive electrode active material, then high energy density can be achieved, but thermal stability deteriorates and decomposition occurs under external pressure
Solution Approach 1:
The patent uses composite materials by combining lithium nickel composite metal oxide with lithium cobalt oxide or lithium manganese composite metal oxide. This composite structure allows the material to maintain high energy density from the lithium nickel component while gaining improved thermal stability from the cobalt or manganese components, thereby resolving the contradiction between energy density and thermal stability
Solution Approach 2:
The patent applies local quality by creating a core-shell structure where the interior contains lithium nickel composite metal oxide for high energy density, while the exterior surface is covered with lithium cobalt oxide or lithium manganese composite metal oxide providing thermal stability. This spatial differentiation of material properties allows simultaneous optimization of both energy density and thermal stability
2Ease of manufacture
If pore size and distribution in secondary particles are not controlled, then manufacturing simplicity is maintained, but reactivity and particle strength vary unpredictably
Solution Approach 1:
The patent applies parameter changes by systematically adjusting sintering temperature, sintering time, and precursor particle size to control the pore size and distribution in secondary particles. By establishing specific parameter ranges (e.g., sintering temperature of 700-900°C, sintering time of 1-10 hours), the patent achieves predictable pore structures while maintaining manufacturing feasibility
Solution Approach 2:
The patent applies preliminary action by pre-forming secondary particles with controlled morphology and pore structure before the final sintering process. The precursor materials are prepared with specific aspect ratios and particle size distributions that guide the formation of desired pore structures during sintering, thereby achieving manufacturing precision without excessive complexity
3Quantity of substance
If lithium nickel composite metal oxide with high nickel content is used, then reversible capacity increases to about 200 mAh/g, but thermal stability deteriorates and decomposition occurs when internal short circuit occurs
Solution Approach 1:
The patent uses composite materials by combining lithium nickel composite metal oxide (providing high reversible capacity of about 200 mAh/g) with lithium cobalt oxide or lithium manganese composite metal oxide (providing thermal stability). This composite approach allows the material to simultaneously achieve high capacity and thermal stability, resolving the contradiction between quantity of substance and harmful factors
Solution Approach 2:
The patent converts the harmful effect of high nickel content (thermal instability) into a benefit by using it as the core material for high capacity, while surrounding it with a protective shell of thermally stable materials. The high nickel content core provides the desired 200 mAh/g capacity, while the external shell prevents thermal runaway, thereby converting the harmful thermal instability into a beneficial high-capacity structure with protective stabilization
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
The solution results in improved initial discharge capacity and charge/discharge efficiency by optimizing pore distribution and crystalline structure, leading to enhanced energy density and particle strength.
Implementation Method 1
a positive electrode active material which includes a lithium transition metal oxide... prepared from a positive electrode active material precursor with a controlled crystalline aspect ratio
Data Source
AI summary
A positive electrode active material, a method of preparing the same, a positive electrode and a lithium secondary battery including the same are disclosed herein. In some embodiments, a positive electrode active material including a lithium transition metal oxide which contains 60 mol % or more of nickel based on a total number of moles of transition metals excluding lithium in the lithium transition metal oxide, is in a form of a secondary particle which is an aggregate of primary particles, wherein the lithium transition metal oxide satisfies Equation 1:20<xywherein x is a minimum area of a rectangle including all pores having an area greater than 0.002 μm2 among closed pores distributed in the secondary particle, and y is a total sum of areas of the pores having an area greater than 0.002 μm2 among the closed pores distributed in the secondary particle.