Ni-Rich Cathode Composition With Nb Grain-Boundary Thermal Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing positive electrode active materials for lithium-ion secondary batteries, particularly those with high nickel ratios, face a trade-off between increased battery capacity and decreased thermal stability, necessitating a material that achieves high thermal stability at a lower cost.
Innovation Solution
A positive electrode active material comprising lithium-nickel-manganese composite oxide with a hexagonal layered structure, containing secondary particles with aggregated primary particles, and incorporating specific amounts of titanium and niobium. Niobium is segregated at the grain boundary between primary particles, and the material exhibits a high volume resistivity when compressed, enhancing 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 deteriorates
Solution Approach 1:
The patent applies local quality by segregating niobium specifically at the grain boundaries between primary particles rather than uniformly distributing it throughout the material. This localized placement allows the grain boundaries to have enhanced thermal stability properties while the interior regions maintain high nickel content for capacity, thus resolving the contradiction between capacity and thermal stability.
Solution Approach 2:
The patent creates a composite material system by combining lithium-nickel-manganese composite oxide with niobium and titanium additives. The multi-element composite structure leverages the high capacity of nickel-rich materials while using niobium and titanium to provide thermal stability, achieving both high capacity and thermal stability simultaneously.
2Stability of the object's composition
If niobium is added to improve thermal stability, then the thermal stability is improved, but the manufacturing cost increases
Solution Approach 1:
By concentrating niobium at the grain boundaries rather than distributing it uniformly throughout the entire material, the patent reduces the total amount of expensive niobium required while still achieving the thermal stability benefits. This localized approach significantly lowers manufacturing cost compared to uniform doping.
Solution Approach 2:
The patent introduces titanium as an intermediary element that works synergistically with niobium. Titanium appears to facilitate the segregation of niobium to grain boundaries and may provide additional thermal stability functions, allowing for reduced niobium content while maintaining thermal stability performance.
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 proposed positive electrode active material achieves extremely high thermal stability at a lower cost, effectively suppressing oxygen release during overcharge and improving thermal runaway temperature, making it suitable for industrial-scale production.
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
Data Source
Figure 1
Figure 2(A)~2(B)
Figure 3
AI summary
A positive electrode active material that can achieve high thermal stability at low cost is provided. Provided is a positive electrode active material for a lithium ion secondary battery, the positive electrode active material containing 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.