Lithium-Rich Manganese Oxide Cathode Structure for Voltage Decay
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Solution Overview
Problem
Lithium-rich manganese oxide cathode materials face challenges with low first-cycle coulombic efficiency, discharge capacity, energy efficiency, rate performance, and cycle performance due to severe voltage decay, poor rate performance, and unstable electrolyte under high voltage during cycling.
Innovation Solution
A lithium-rich manganese oxide cathode material with a chemical composition of xLi[Li1/3(Mn1-aMa)2/3]O2·(1−x)LiMn1-bM′bO2, where M and M′ are specific elements, is developed, and a two-stage heating sintering process is used to achieve a stable solid solution composite structure, enhancing electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium-rich manganese oxide cathode materials are used to achieve high specific capacity and low cost, then energy density is improved, but voltage decay and cycle performance deteriorate
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core region and outer shell region have different compositions and properties. The core contains Li2MnO3-rich composition for high capacity, while the shell has modified composition to improve stability and reduce voltage decay, thus resolving the contradiction between high specific capacity and good cycle performance.
Solution Approach 2:
The patent uses composite materials by combining Li2MnO3 with other lithium manganese oxide phases to form a composite cathode material. This composite structure leverages the high capacity of Li2MnO3 while the other phases provide structural stability and reduce voltage decay, simultaneously achieving high specific capacity and improved cycle performance.
2Quantity of substance
If high voltage operation is used to increase discharge capacity, then energy efficiency is improved, but electrolyte stability deteriorates
Solution Approach 1:
The patent applies beforehand cushioning by pre-modifying the cathode material surface and structure before electrochemical cycling. The surface coating and structural optimization are performed in advance to cushion against the harmful effects of high voltage operation on the electrolyte, enabling high discharge capacity while maintaining electrolyte stability.
3Reliability
If multi-element doping is used to improve cycle performance, then reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by systematically varying the doping element types, concentrations, and distribution patterns to optimize cycle performance. By controlling compositional parameters and processing conditions, the patent achieves improved reliability while managing manufacturing complexity through parameter optimization rather than complex multi-element combinations.
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 cathode material exhibits high first-cycle efficiency, high discharge capacity, high energy efficiency, good rate performance, and excellent cycle performance, with improved crystallinity and atomic arrangement, leading to enhanced electrochemical performance and prolonged cycle life.
Implementation Method 1
performing a two-stage heating sintering on the mixed material, to obtain the lithium-rich manganese oxide cathode material
Implementation Method 2
heating from room temperature to a first sintering temperature at a first heating rate to perform a first sintering, and heating to a second sintering temperature at a second heating rate to perform a second sintering
Data Source
AI summary
The present disclosure relates to the technical field of lithium-ion batteries, and discloses a lithium-rich manganese oxide cathode material, a preparation method and use thereof, and a positive electrode plate and use thereof. The cathode material has a chemical composition of xLi[Li1/3(Mn1-aMa)2/3]O2·(1−x)LiMn1-bM′bO2. An XRD spectrum of the cathode material has a diffraction peak P(1) in a range of a diffraction angle 2θ1 satisfying [43.5(1−x)+44x]°≤2θ1≤[44(1−x)+45x]°; and the XRD spectrum of the cathode material has a diffraction peak P(2) in a range of a diffraction angle 2θ2 satisfying [17.7(1−x)+18.3x]°≤2θ2≤[19.2(1−x)+19.8x]°, where 0.35≤x≤0.63. The cathode material has high first-cycle efficiency, high discharge capacity, high energy efficiency, high rate performance, and high cycle performance.