Layered Cathode Active Material for High-Voltage Crystal Stability
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Solution Overview
Problem
Existing cathode active materials for lithium secondary batteries face challenges in maintaining crystal structure stability under high-voltage and high-temperature conditions, leading to structural collapse during charge/discharge cycles, and require costly and time-consuming manufacturing processes.
Innovation Solution
A cathode active material with a layered crystal structure and a partially regular mixed structure is developed, where lithium and transition metal layers are alternately arranged, with controlled atomic ratios and pH conditions, to enhance stability and reduce volume variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional cathode active materials are used, then manufacturing process is simpler, but crystal structure stability deteriorates under high-voltage and high-temperature conditions
Solution Approach 1:
The patent applies preliminary action by controlling the pH value during the coprecipitation process to pre-form a specific mixed structure in the cathode active material. This preliminary structural control during manufacturing ensures crystal structure stability under high-voltage and high-temperature conditions without requiring complex post-processing steps. The pH control during synthesis pre-determines the stable layered structure with reduced cation mixing.
2Reliability
If conventional cathode active materials are used, then initial manufacturing cost is lower, but structural collapse occurs during charge/discharge cycles
Solution Approach 1:
The patent applies parameter changes by optimizing the pH value parameter during the coprecipitation process. By controlling pH within a specific range (10.5-11.5), the method achieves improved cycle stability and reduced structural collapse while maintaining manufacturing simplicity. This parameter optimization ensures stable lithium ion diffusion paths and prevents cation mixing during charge/discharge cycles.
3Use of energy by moving object
If conventional cathode active materials are used, then manufacturing time is shorter, but initial capacity is lower under high-voltage conditions
Solution Approach 1:
The patent applies preliminary action by controlling the coprecipitation process parameters (pH 10.5-11.5, temperature 60-80°C, aging time 12-24 hours) to pre-form a stable layered structure with optimized lithium ion diffusion paths. This preliminary structural optimization during manufacturing enables high initial capacity under high-voltage conditions (4.3-4.5V) without requiring additional post-processing steps or extended manufacturing time.
4Stability of the object's composition
If conventional cathode active materials are used, then manufacturing process is simpler, but volume variation is larger during charging
Solution Approach 1:
The patent applies parameter changes by optimizing the pH value (10.5-11.5) and aging conditions (60-80°C for 12-24 hours) during coprecipitation. These parameter optimizations create a stable layered structure with reduced cation mixing, which significantly reduces volume variation during charging (maintaining unit cell volume variation below 5% at 4.5V) while keeping the manufacturing process relatively simple.
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 new cathode active material maintains structural integrity under high-voltage and high-temperature conditions, improving initial capacity and long-term cycle stability, while reducing manufacturing costs and time.
Implementation Method 1
a cathode active material for a lithium secondary battery... serves to provide the lithium ions to an anode during a charging process of the secondary battery
Implementation Method 2
preparing a coprecipitation compound by mixing a metal salt aqueous solution including a first metal including nickel, cobalt, and manganese and optionally a second metal, a chelating agent, and a basic aqueous solution
Implementation Method 3
preparing an active material precursor by drying or heat-treating the coprecipitation compound
Implementation Method 4
preparing lithium composite metal oxide by mixing and sintering the active material precursor and lithium salt
Data Source
AI summary
The positive electrode active material according to the present invention may: comprise lithium, a transition metal, and oxygen; comprise a layered crystalline structure in which a lithium layer comprising the lithium and a transition metal layer comprising the transition metal are alternately and repeatedly arranged; and have provided, in the lithium layer or the transition metal layer, a partially regular mixed structure in which a unit arrangement is repeatedly provided in one direction, the unit arrangement having any one of the transition metal and the lithium arranged twice in a row in the one direction, and then the other arranged one time in the one direction.