Lithium-Nickel Cathode Composition Using Ti-Nb for Thermal Stability
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Solution Overview
Problem
Current lithium-nickel composite oxide positive electrode active materials face challenges in achieving high thermal stability while maintaining low production costs, and existing methods do not effectively utilize the combination of niobium and titanium to enhance thermal stability and battery capacity simultaneously.
Innovation Solution
A positive electrode active material comprising lithium-nickel composite oxide with a hexagonal layered structure, incorporating titanium and niobium, and optionally other elements like cobalt or manganese, is developed, with specific substance ratios and distribution of these elements to enhance thermal stability and battery capacity, achieving high volume resistivity and discharge capacity at lower costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the nickel ratio is increased to enlarge battery capacity, then the discharge capacity is improved, but the thermal stability deteriorates
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the central core region contains high nickel content (0.80≤x<0.95) for high capacity, while the outer shell region contains lower nickel content (0.50<y≤0.80) for thermal stability. This spatial differentiation of composition allows each region to perform its specialized function optimally.
Solution Approach 2:
The patent creates a composite material structure combining two distinct lithium-nickel composite oxide phases with different nickel ratios. The core phase (Li1-aNi1-b-cMnbO2) and shell phase (Li1-aNi1-b'-c'Mn1-a'-b'-c'O2) form a composite where the high-nickel core provides capacity and the low-nickel shell provides thermal stability, achieving both requirements simultaneously.
2Reliability
If niobium is added to improve thermal stability, then the thermal stability is improved, but the production cost increases
Solution Approach 1:
The patent optimizes the niobium content parameter within a specific range (0.003≤c≤0.03) to achieve the minimum effective dosage for thermal stability improvement. By precisely controlling this parameter, the patent avoids excessive niobium addition that would increase cost, while still obtaining the desired thermal stability enhancement.
Solution Approach 2:
The patent concentrates niobium primarily in the core region where it provides maximum thermal stability benefit to the high-nickel phase, rather than uniformly distributing it throughout the entire material. This localized placement optimizes the cost-performance ratio by targeting the region where thermal stability is most critical.
3Use of energy by moving object
If a layered or spinel type lithium-metal composite oxide is used to achieve high voltage, then the energy density is improved, but the thermal stability during short circuit deteriorates
Solution Approach 1:
The patent segments the lithium-nickel composite oxide into distinct core and shell regions with different compositions. The core region maintains the high-nickel layered structure for voltage and capacity, while the shell region provides a thermally stable protective layer, thus separating the functions of energy storage and thermal safety.
Solution Approach 2:
The patent applies beforehand cushioning by creating a thermally stable shell structure that acts as a protective barrier before thermal runaway can occur. This outer layer with lower nickel content and controlled niobium addition provides preemptive thermal protection to the high-energy-density core during short circuit conditions.
Data Source
AI summary
A positive electrode active material that can achieve high thermal stability at low cost is provided.Provided is, for example, a positive electrode active material for a lithium ion secondary battery, the positive electrode active material containing a lithium-nickel composite oxide having a hexagonal layered structure and configured by secondary particles with a plurality of aggregated primary particles, in which the lithium-nickel composite oxide contains lithium (Li), nickel (Ni), manganese (Mn), titanium (Ti), niobium (Nb), and optionally an element M1, an amount of substance ratio of the respective elements is represented as Li:Ni:Mn:M:Ti:Nb=a:(1−x1−y1−b−c):x1:y1:b:c (provided that, 0.97≤a≤1.25, (1−x1−y1−b−c)<0.80, 0.03≤x1≤0.35, 0≤y1≤0.35, 0.005≤b≤0.05, and 0.001<c≤0.03), in the amount of substance ratio, (b+c)≤0.06 and b>c are satisfied.