Lithium Composite Oxide Gradient Doping for Battery Stability
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Solution Overview
Problem
Conventional lithium composite oxides for lithium secondary batteries face issues with structural stability, high-temperature storage, and lifespan characteristics due to limitations in resource availability, thermal safety, and cation mixing, which affects the battery's capacity and rate characteristics.
Innovation Solution
A lithium composite oxide with a concentration gradient of doping metal elements in primary particles that decreases toward the center of secondary particles, combined with a lithium alloy oxide at the interface and surface of secondary particles, enhancing structural stability and lithium ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiCoO2 is used as positive electrode active material, then excellent lifespan characteristics and charge/discharge efficiency are achieved, but high cost due to resource limit of cobalt occurs
Solution Approach 1:
The patent applies local quality by creating a concentration gradient of doping metal elements (such as Al, Ti, Zr, B, Be) within the LiNi0.8Co0.1Mn0.1O2 particles, where the doping concentration varies from the surface to the center. This allows different regions of the material to have optimized properties: the surface region has higher doping concentration for stability, while the interior maintains higher Ni content for capacity, thus achieving both lifespan characteristics and cost-effectiveness without relying on expensive cobalt.
2Quantity of substance
If lithium manganese oxides are used, then excellent thermal safety and low costs are achieved, but small capacity and poor high-temperature characteristics occur
Solution Approach 1:
The patent employs composite materials by combining LiNi0.8Co0.1Mn0.1O2 with doping metal elements (Al, Ti, Zr, B, Be) to create a composite oxide structure. This composite approach integrates the high capacity of Ni-based materials with the thermal stability provided by the doping elements, achieving both cost-effectiveness and improved high-temperature characteristics while maintaining excellent lifespan properties.
3Quantity of substance
If LiNiO2-based positive electrode active material is used, then high discharge capacity is achieved, but cation mixing between Li and transition metal occurs making synthesis difficult
Solution Approach 1:
The patent applies local quality by implementing a concentration gradient of doping metal elements that varies spatially within the particles. The doping concentration is higher at the surface and decreases toward the center, which suppresses cation mixing at the surface where it occurs most frequently during synthesis, while preserving the high Ni content in the interior for maximum discharge capacity. This gradient structure makes synthesis more controllable and reproducible.
4Manufacturing precision
If cation mixing intensifies, then synthesis difficulty increases, but large amount of Li by-products are generated causing gelation and gas generation
Solution Approach 1:
The patent applies preliminary anti-action by pre-doping the LiNi0.8Co0.1Mn0.1O2 material with specific metal elements (Al, Ti, Zr, B, Be) at controlled concentrations, particularly higher concentrations at the surface region. This preliminary doping creates a protective effect that suppresses subsequent cation mixing during synthesis and battery operation, thereby preventing the formation of Li by-products such as LiOH and Li2CO3 that would otherwise cause gelation and gas generation.
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 improves high-temperature storage stability and lifespan characteristics of lithium secondary batteries by maintaining structural integrity and efficient lithium ion diffusion, leading to enhanced capacity retention and discharge efficiency.
Implementation Method 1
a lithium secondary battery storing electrical energy due to a difference in chemical potential when lithium ions are intercalated/deintercalated into/from a positive electrode and a negative electrode
Implementation Method 2
A lithium composite oxide with a concentration gradient of doping metal elements in primary particles that decreases toward the center of secondary particles, combined with a lithium alloy oxide at the interface and surface of secondary particles, enhancing structural stability and lithium ion conductivity
Data Source
AI summary
The present invention relates to a lithium composite oxide, a positive electrode active material for a lithium secondary battery including the lithium composite oxide, and a lithium secondary battery using a positive electrode including the positive electrode active material.