Layered Positive Electrode Material with Plane-Specific Conductors
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Solution Overview
Problem
Conventional positive electrode materials for lithium secondary batteries have high resistance, which limits their performance and stability, particularly during charge and discharge cycles and overcharge conditions.
Innovation Solution
A positive electrode material with a layered structure, where a lithium conductor is predominantly disposed at planes other than the (003) plane and an electronic conductor is predominantly disposed at the (003) plane, or both are used in combination to reduce resistance, enhance cycle characteristics, and suppress temperature rises during overcharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional positive electrode materials are used, then the battery structure is simple, but the resistance is high which limits performance and stability
Solution Approach 1:
The patent applies composite materials by combining positive electrode active material particles with two distinct coating layers: an electronic conductor layer (containing cobalt, nickel, and manganese oxides) and a lithium conductor layer (containing lithium phosphate, lithium silicate, or lithium tungstate). This composite structure simultaneously improves battery performance and stability while managing the increased structural complexity through systematic material integration.
2Reliability
If a coating layer is added to increase performance, then battery resistance decreases, but the manufacturing process becomes more complex
Solution Approach 1:
The patent implements preliminary action by performing the coating process during the initial sintering stage of positive electrode active material particle formation. The coatings are applied before electrode assembly, allowing simultaneous formation of the active material and conductive layers in one manufacturing step, thereby reducing overall process complexity despite the multi-layer structure.
Solution Approach 2:
The dual-coating structure with specific material compositions (electronic conductor containing cobalt/nickel/manganese oxides and lithium conductor containing lithium phosphate/silicate/tungstate) enables optimized electrical properties while the coatings are integrated into the sintering process, balancing performance improvement with manufacturing feasibility.
3Speed
If lithium ions enter and leave at planes other than (003), then lithium ion transport efficiency improves, but electronic conductivity at these planes decreases
Solution Approach 1:
The patent applies local quality by providing different coating compositions at different crystallographic planes of the positive electrode active material particles. The electronic conductor layer and lithium conductor layer are strategically positioned to provide localized electronic conductivity enhancement at planes where lithium ion transport occurs, thereby simultaneously improving both lithium ion transport efficiency and electronic conductivity at the interface.
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
This configuration significantly reduces battery resistance, improves cycle performance, and effectively mitigates temperature increases during overcharge, achieving a synergistic effect that surpasses the benefits of using either conductor alone.
Implementation Method 1
a lithium conductor disposed at planes other than the (003) plane of the positive electrode active material particles
Implementation Method 2
an electronic conductor disposed at the (003) plane of the positive electrode active material particles
Implementation Method 3
positive electrode active material particles each having a layered structure... capable of occluding and releasing lithium ions
Data Source
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AI summary
Provided is a positive electrode material that allows reducing the resistance of a lithium secondary battery. The positive electrode material for lithium secondary batteries disclosed herein contains positive electrode active material particles each having a layered structure; and at least one conductor selected from the group consisting of a lithium conductor and an electronic conductor, and disposed on a surface of the positive electrode active material particles. In a case where the positive electrode material contains the lithium conductor, the proportion of the lithium conductor disposed at planes other than the (003) plane of the positive electrode active material particle, with respect to the total amount of the lithium conductor, is not less than 50% and not more than 100%. In a case where the positive electrode material contains the electronic conductor, the proportion of the electronic conductor disposed at the (003) plane of the positive electrode active material particle, with respect to the total amount of the electronic conductor, is not less than 50% and not more than 100%.