Lithium Composite Oxide Surface Manganese Enrichment for High Voltage Stability
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Solution Overview
Problem
Existing methods for enhancing the capacity retention rate of lithium-ion secondary batteries with high voltage operation, such as doping, forming protective films, and modifying the active material composition, face challenges including reduced lithium storage capacity, increased electrical resistance, and limited industrial scalability or effectiveness.
Innovation Solution
A specific treatment process that increases the manganese composition ratio in the superficial layer of lithium composite metallic oxides with a lamellar rock-salt structure, altering the crystal structure and heterogeneous strains, leading to improved stability and resistance against degradation during high voltage operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If doping is performed to enhance capacity retention rate, then resistance to high voltage is improved, but lithium storage capacity is reduced
Solution Approach 1:
The patent applies local quality by creating a superficial layer with high manganese composition ratio on the surface of the lithium composite metallic oxide particles, while the interior maintains a different composition optimized for lithium storage. This superficial layer specifically addresses high voltage resistance where needed, while the interior preserves lithium storage capacity.
Solution Approach 2:
The patent segments the particle structure into distinct regions: a superficial layer with high manganese content for stability and voltage resistance, and an interior region with composition optimized for capacity. This segmentation allows each region to fulfill its specific function without compromising the other.
2Reliability
If protective film is formed to enhance capacity retention rate, then resistance to electrolytic solution is improved, but electrical resistance increases
Solution Approach 1:
Instead of adding a separate protective film layer, the patent changes the compositional parameters of the superficial layer by increasing the manganese composition ratio. This compositional change provides both protection and maintains electrical conductivity, avoiding the energy loss associated with film formation.
3Reliability
If active material composition is modified to enhance capacity retention rate, then high voltage resistance is improved, but manufacturing complexity increases
Solution Approach 1:
The patent modifies composition locally in the superficial layer rather than throughout the entire particle. This localized modification can be achieved through surface treatment processes that are scalable and do not require complete reprocessing of the bulk material, thus maintaining manufacturing feasibility.
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 treated lithium composite metallic oxides exhibit a satisfactory capacity retention rate even under high voltage conditions, with enhanced stability and corrosion resistance, effectively addressing the limitations of previous methods.
Implementation Method 1
lithium composite metallic oxides with a lamellar rock-salt structure
Implementation Method 2
a specific treatment process that increases the manganese composition ratio in the superficial layer
Data Source
AI summary
An active material expressed by a general formula; LiaNibCocMndDeOf (where 0.2≤“a”≤1, “b”+“c”+“d”+“e”=1, 0≤“e”<1, “D” is at least one element selected from the group consisting of Li, Fe, Cr, Cu, Zn, Ca, Mg, Zr, S, Si, Na, K and Al, and 1.7≤“f”≤2.1) includes a high manganese portion, which is made of a metallic oxide including Ni, Co and Mn at least and of which the composition ratio between Ni, Co and Mn is expressed by Ni:Co:Mn=b2:c2:d2 (note that “b2”+“c2”+“d2”=1, 0<“b2”<1, 0<“c2”<“c”, and “d”<“d2”<1), in a superficial layer thereof.