Cathode Composition for Low-Temperature Resistance in Li-Ion Batteries
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Solution Overview
Problem
Medium-nickel low-cobalt or cobalt-free lithium-nickel-manganese ternary layered oxide positive electrode materials face challenges with high direct-current internal resistance at low temperatures and low State of Charge (SOC), and rapid increase in cycle direct-current internal resistance, which affects battery performance and cost efficiency.
Innovation Solution
A battery design incorporating a positive electrode with a specific composition and mixing ratio of medium-nickel low-cobalt or cobalt-free layered positive electrode material and high-nickel ternary layered positive electrode material, utilizing transition metal oxides in single crystal or single crystal-like morphology, optimized for energy density, low-temperature low-SOC direct-current internal resistance, and cycle stability, while controlling the H2-H3 phase transition to ensure stable high-voltage cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If medium-nickel low-cobalt or cobalt-free layered positive electrode material is used, then cost is reduced and safety is improved, but direct-current internal resistance increases at low temperature and low-SOC
Solution Approach 1:
The patent uses a composite positive electrode material comprising medium-nickel low-cobalt or cobalt-free layered oxide and high-nickel ternary layered oxide in a weight ratio of 97:3 to 70:30. This composite structure combines the cost and safety advantages of medium-nickel materials with the low-temperature performance of high-nickel materials, resolving the contradiction between cost reduction and internal resistance increase.
Solution Approach 2:
The patent optimizes the composition parameters by controlling the nickel content (0.50≤x<0.70), cobalt content (0≤y<0.20), and manganese content (0.20<z≤0.45) in the medium-nickel material, while also controlling the nickel content (0.70≤x2<0.95) in the high-nickel material. These parameter adjustments allow balancing cost, safety, and electrical resistance performance.
2Reliability
If medium-nickel low-cobalt or cobalt-free layered positive electrode material is used, then cost is reduced, but cycle direct-current internal resistance increases rapidly
Solution Approach 1:
The composite structure of medium-nickel low-cobalt or cobalt-free layered oxide combined with high-nickel ternary layered oxide maintains cost efficiency while the high-nickel component provides structural stability that prevents rapid increase in cycle direct-current internal resistance, thereby improving cycle stability.
Solution Approach 2:
The patent applies local quality by having different regions of the positive electrode material serve different functions: the medium-nickel low-cobalt or cobalt-free layered oxide provides cost efficiency and baseline stability, while the high-nickel ternary layered oxide specifically addresses cycle stability by maintaining low internal resistance throughout cycling.
3Quantity of substance
If high-nickel ternary positive electrode material is used, then energy density is improved, but cost increases and long-term stability decreases
Solution Approach 1:
The patent creates a composite where high-nickel ternary layered oxide (providing high energy density) is combined with medium-nickel low-cobalt or cobalt-free layered oxide (providing long-term stability). The specific weight ratio range of 97:3 to 70:30 optimizes the balance between energy density and long-term stability, preventing the degradation issues of pure high-nickel materials.
Data Source
AI summary
The present disclosure belongs to the technical field of secondary batteries, and in particular, to a battery and an electric device. A capacity voltage difference ratio of the battery in a capacity test at 45° C. and 1/1C, which is the ratio of an intensity maximum value Q1 between a high-nickel H2-H3 phase transition peak 3.9-4.2 V to an intensity Q2 at 3.9 V of the battery satisfies 1<Q1:Q2≤1.6; a positive electrode sheet of the battery comprises a positive electrode active material, and the positive electrode active material comprises a transition metal oxide A: Lia1(Nix1Coy1Mnz1Gb1)O2-c1Dc1, and a transition metal oxide B: Lia2(Nix2Coy2Mnz2Mb2)O2-c2Ec2. The positive electrode active material provided in the present disclosure can take into account lower costs, low-temperature dynamic performance, high-temperature cycle performance and high-temperature storage performance.