Nickel-Rich Cathode Material With Grain-Boundary Ti/Nb Stabilization
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Solution Overview
Problem
Existing positive electrode active materials for lithium-ion batteries with high nickel ratios face a trade-off between thermal stability and cost, with a need for improved thermal stability at lower costs and ease of industrial-scale production.
Innovation Solution
A positive electrode active material containing lithium-nickel-manganese composite oxide with specific distributions of titanium and niobium, segregated at grain boundaries, and controlled particle sizes, achieving high volume resistivity and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the nickel ratio in lithium-nickel-manganese composite oxide is increased to enlarge battery capacity, then the battery capacity is improved, but the thermal stability decreases
Solution Approach 1:
The patent applies local quality by segregating titanium and niobium elements specifically at the grain boundaries between primary particles, rather than uniformly distributing them throughout the material. This localized placement at critical interfaces provides enhanced thermal stability and short-circuit resistance precisely where needed, while maintaining the high nickel ratio (0.80≤b≤0.88) in the bulk material for high capacity.
Solution Approach 2:
The patent creates a composite material system by combining lithium-nickel-manganese composite oxide with titanium and niobium elements. The multi-element composition (Li:Ni:Mn:Co:Zr:Ti:Nb=a:b:c:d:e:f:g) with specific ratios forms a composite structure that integrates the high capacity of nickel-rich materials with the thermal stability provided by titanium and niobium at grain boundaries.
2Reliability
If niobium is added to lithium-metal composite oxide to improve thermal stability, then the thermal stability is improved, but the production cost increases
Solution Approach 1:
The patent reduces cost by localizing niobium (an expensive element) specifically at grain boundaries where it provides maximum benefit for thermal stability, rather than distributing it uniformly throughout the entire material. This localized approach minimizes the total amount of expensive niobium required (0.001≤g≤0.010) while maintaining effective thermal protection.
Solution Approach 2:
The patent merges the functions of multiple elements (titanium and niobium) working together at grain boundaries to achieve thermal stability. This combination allows for reduced overall content of expensive elements while maintaining or enhancing performance, as the synergistic effect of Ti and Nb provides thermal stability more efficiently than either element alone.
3Quantity of substance
If high nickel ratio composite oxide is used to achieve high capacity, then the battery performance is improved, but the short-circuit resistance decreases
Solution Approach 1:
The patent addresses short-circuit resistance by placing titanium and niobium elements specifically at grain boundaries, creating localized regions with enhanced electrical resistance properties. This local modification at interfaces between primary particles provides barriers to electron transport pathways that could lead to internal short circuits, while the high nickel content in the bulk material maintains high capacity.
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 material achieves extremely high thermal stability and can be produced industrially at lower costs, suppressing oxygen release during overcharge and enhancing battery performance.
Implementation Method 1
niobium is segregated at a grain boundary between primary particles of the lithium-nickel-manganese composite oxide
Implementation Method 2
a volume resistivity, as determined by powder resistivity measurement, when compressed to 4.0 g/cm3 is 5.0×102Ω·cm or more and 1.0×105 Ω·cm or less
Data Source
AI summary
The positive electrode active material for a lithium ion secondary battery contains a lithium-nickel-manganese composite oxide, in which metal elements constituting the lithium-nickel-manganese composite oxide include lithium (Li), nickel (Ni), manganese (Mn), cobalt (Co), titanium (Ti), niobium (Nb), and optionally zirconium (Zr), an amount of substance ratio of the elements is represented as Li: Ni: Mn: Co: Zr: Ti: Nb =a: b: c: d: e: f: g (provided that, 0.97≤a≤1.10, 0.80≤b≤0.88, 0.04≤c≤0.12, 0.04≤d≤0.10, 0≤e≤0.004, 0.003<f≤0.030, 0.001<g≤0.006, and b+c+d+e+f+g=1), and in the amount of substance ratio, (f+g)≤0.030 and f>g are satisfied.