Ni-Rich Cathode Composition With Nb Additives for Low-Temperature Resistance
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Solution Overview
Problem
Lithium transition metal oxides with high Ni content experience increased battery resistance at low temperatures, and reducing cobalt content to suppress this resistance is costly and inefficient.
Innovation Solution
A positive electrode active material comprising a lithium transition metal oxide with a layered structure, incorporating Ni, Nb, and optionally Co, and coated with external additive particles of W, B, or Al, which stabilizes the structure and reduces resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high Ni content (90 mol% or more) is used in lithium transition metal oxide, then high battery performance is achieved, but battery resistance increases at low temperature
Solution Approach 1:
Nb elements are introduced as intermediary elements within the lithium transition metal oxide crystal structure to mediate between high Ni content and low-temperature resistance. The Nb elements replace some metal elements in the layered structure, creating a balanced composition that maintains high performance while suppressing resistance increase at low temperatures.
Solution Approach 2:
The composition parameters of the lithium transition metal oxide are precisely controlled within specific ranges: Ni content at 90-99.5 mol%, Nb at 0.05-5 mol%, and optional Co at 0-5 mol%. By adjusting these parameters within defined boundaries, the patent achieves optimal balance between high battery performance and low-temperature resistance characteristics.
2Reliability
If 5 mol% or more of Co is added to suppress battery resistance at low temperature, then resistance is reduced, but production cost increases due to expensive cobalt
Solution Approach 1:
The patent replaces expensive cobalt (used at 5 mol% or more in conventional solutions) with cheaper Nb elements and minimal Co (0-5 mol%). This substitution uses more economical materials to achieve the same resistance suppression effect, significantly reducing production costs while maintaining reliability.
Solution Approach 2:
The Co content parameter is reduced from the conventional 5 mol% or more to 0-5 mol% in the optimized composition formula, while Nb content is introduced at 0.05-5 mol%. This parameter change achieves resistance suppression through a more cost-effective elemental composition.
3Ease of manufacture
If Co content is reduced to suppress production cost, then cost decreases, but battery resistance increases at low temperature
Solution Approach 1:
Nb elements serve as intermediary substitutes for Co in the crystal structure. When Co content is reduced to minimize cost, Nb elements fill the structural roles previously performed by Co, maintaining the electrical and structural properties necessary for low-temperature performance while reducing reliance on expensive cobalt.
Solution Approach 2:
The patent creates a composite lithium transition metal oxide material combining multiple elements (Li, Ni, Nb, Co, Mn, Al) in optimized proportions. This composite structure leverages the synergistic effects of different elements to achieve low-temperature resistance suppression without relying heavily on expensive Co, thus resolving the cost-reliability trade-off.
Data Source
AI summary
This positive electrode active material contains: a lithium transition metal oxide that has a layered structure and contains Ni, Nb and a metal element other than Nb having a valence of at least four, as well as Co as an optional element; and external additive particles that contain at least one element selected from among W, B and Al and are adhered to the particle surface of the lithium transition metal oxide. The percentage of Ni, Nb and Co with respect to the total quantity of metal elements excluding Li in the lithium transition metal oxide satisfy the following ranges: 90 mol.% ≤ Ni < 100 mol.%, 0 mol.% < Nb ≤ 3 mol.%, and Co ≤ 2 mol.%. The percentages of W, B and Al in the external additive particles with respect to the total quantity of the lithium transition metal oxide fall within the range of 0.01 mol.% to 0.3 mol.%.