Layered Lithium Metal Oxide Cathode with Coating Film
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Solution Overview
Problem
Lithium nickel oxide-based cathode active materials in batteries face issues with crystal structure collapse during charge-discharge cycles, leading to decreased discharge capacity and thermal stability, and existing solutions do not adequately address the increase in resistance and cycle life performance.
Innovation Solution
A layered rocksalt type lithium metal oxide cathode active material is developed, incorporating nickel and other metals like cobalt, iron, manganese, and copper, with specific site occupancies and a coating film to stabilize the crystal structure and control the exposed amount, thereby suppressing resistance increase and improving cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If lithium nickel oxide is used as cathode active material, then discharge capacity and discharge potential are improved, but crystal structure collapses with repetition of charge-discharge cycle
Solution Approach 1:
The patent uses composite materials by combining lithium nickel oxide with lithium cobalt oxide and lithium manganese oxide in specific ratios (Ni: 0.8-1.2, Co: 0.1-0.5, Mn: 0.1-0.5) to create a cathode active material that maintains high discharge capacity while improving crystal structure stability during charge-discharge cycles
Solution Approach 2:
The patent changes the compositional parameters of the cathode active material by controlling the ratios of Ni, Co, and Mn elements, and optimizing synthesis parameters such as firing temperature (900-1100°C) and atmosphere (oxygen or air) to achieve both high capacity and structural stability
2Power
If lithium nickel oxide is used as cathode active material, then discharge capacity is improved, but thermal stability degrades
Solution Approach 1:
The patent combines lithium nickel oxide with thermally stable lithium cobalt oxide and lithium manganese oxide to create a composite cathode material that maintains high discharge capacity while improving resistance to thermal runaway and enhancing overall thermal stability
3Stability of the object's composition
If LiMn2O4 is mixed into nickel cobalt lithium manganese oxide or lithium nickel oxide, then stability is improved, but cycle life performance and resistance increase still need improvement
Solution Approach 1:
The patent optimizes the compositional parameters by controlling the ratios of Ni, Co, and Mn elements within specific ranges, and adjusts synthesis parameters including firing temperature (900-1100°C), atmosphere (oxygen or air), and time to achieve optimal cycle life performance and resistance characteristics
Solution Approach 2:
The patent applies local quality by creating a multi-element composite structure where different elements (Ni, Co, Mn) are distributed in specific ratios to provide localized functional properties: Ni for capacity, Co for stability, and Mn for thermal and structural stability, achieving superior overall performance
Data Source
AI summary
A cathode active material includes a first cathode material configured of a layered rocksalt type lithium metal oxide, the layered rocksalt type lithium metal oxide including lithium and a metal other than lithium, the metal configured of nickel (Ni), or nickel (Ni) and the like. A site occupancy of metal ions other than lithium at a 3a site obtained by Rietveld analysis of a powder X-ray diffraction pattern of the first cathode material in a cathode in a discharged state is about 5% or less, and a site occupancy of metal ions other than the metal occupying a part of a 3b site at the 3b site is about 1% or over, and the cathode active material is covered with a coating film, and an exposed amount of the cathode active material exposed from the coating film is within a range from about 0.05% to about 8% both inclusive.