Dual-Active Positive Electrode Plate for Fast-Charge Rate Tolerance
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Solution Overview
Problem
Conventional nickel-cobalt-manganese (NCM) system materials for lithium-ion battery positive electrodes exhibit poor rate tolerance boundaries at low voltages, affecting fast charge capability and available capacity.
Innovation Solution
A positive electrode plate is designed with a dual active material system, comprising LiaNibCocM1dM2eOfR′g and Li1+xM3Mn1−yA′yP1−zEzO4, where the mole ratios and resistance of elements A′, Ni, Mn, and R are optimized to broaden rate tolerance boundaries and enhance fast charge and cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional NCM system materials are used for positive electrode, then high energy density is achieved, but rate tolerance boundaries at low voltages deteriorate
Solution Approach 1:
The patent uses a composite positive electrode active material comprising LiCo1/3Mn1/3Ni1/3O2 and LiMn0.8Fe0.1Ni0.1O2 in a weight ratio of 95:5 to 5:95. This composite structure combines the high energy density characteristics of NCM materials with the improved rate tolerance and voltage stability of the secondary material, resolving the contradiction between energy density and rate tolerance boundaries.
Solution Approach 2:
The patent modifies the chemical composition parameters of the positive electrode active material by controlling the ratios of Ni, Co, Mn, and other elements in the dual-phase composite. By adjusting these compositional parameters, the material achieves both high energy density and improved rate tolerance boundaries at low voltages.
2Speed
If fast charge capability is improved, then charging speed increases, but cycling performance deteriorates
Solution Approach 1:
The patent optimizes the compositional parameters of the dual-phase composite material, specifically controlling the ratio of NCM to secondary material and the doping elements, to achieve a balance between fast charge capability and cycling performance. The modified composition enables faster charging while maintaining structural stability over multiple cycles.
Solution Approach 2:
The patent introduces localized modifications to the positive electrode material composition, creating regions with different functional characteristics. The dual-phase composite structure provides local areas optimized for fast charge acceptance while other regions maintain structural integrity for cycling stability.
Data Source
AI summary
A positive electrode plate, a secondary battery, and an electric apparatus are described The positive electrode plate includes a positive electrode active material layer that includes a first positive electrode active material and a second positive electrode active material. The first positive electrode active material includes LiaNibCocM1dM2eOfR′g, where 0.75≤a≤1.2, 0<b<1, 0<c<1, 0<d<1, 0≤e≤0.2, 1≤f≤2.5, 0≤g≤1, f+g≤3, and M1 is element Mn and/or element Al. The second positive electrode active material includes Li1+xM3nMn1−yA′yP1−zEzO4, where −0.100≤x≤0.100, 0≤n≤1.1, 0.001≤y≤1, 0≤z≤0.100, and A′ includes one or more elements of Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ga, Sn, Sb, Nb, and Ge. The positive electrode plate satisfies:0.001≤n(A′)n(N)+n(Mn)+n(A′)R≤0.50,where n(A′), n(Ni), and n(Mn) are molar amounts of A′, Ni, and Mn in the positive electrode plate respectively, measured in mol; and R is resistance of the positive electrode plate at 25° C., measured in Q.