Layered Lithium Transition Metal Oxide Cathode for High-Potential Cycle Durability
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Solution Overview
Problem
Conventional lithium ion batteries with solid-solution positive electrodes suffer from poor cycle durability and lower capacity due to high charging/discharging potential, leading to early deterioration.
Innovation Solution
A lithium ion secondary battery with a positive electrode active material having a layered structure represented by the composition formula LiyNiaCobMncMdOxFz1Pz2, where M is selected from Al, Si, Zr, Ti, Fe, Mg, Nb, Ba, and V, and specific stoichiometric conditions, combined with a nonaqueous electrolyte containing LiPF6 to enhance capacity and cycle durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a solid-solution positive electrode with Li2MnO3 is used to increase discharge capacity, then high electric capacity (>200 mAh/g) is achieved, but cycle durability deteriorates rapidly at high charging/discharging potential
Solution Approach 1:
The patent modifies the chemical composition parameters of the positive electrode material by incorporating multiple transition metals (Ni, Co, Mn, Al) in specific ratios, and adjusting the oxidation states through controlled synthesis. This compositional parameter change enables the material to achieve both high capacity (>200 mAh/g) and improved cycle durability at high potentials by optimizing the electronic and structural properties of the cathode material.
Solution Approach 2:
The patent creates a composite positive electrode material containing Li2MnO3 combined with other lithium transition metal oxides (LiNi0.8Co0.1Mn0.1O2, LiCoO3, LiAlO2) in specific proportions. This composite structure synergistically combines the high capacity of Li2MnO3 with the structural stability of other materials, achieving both high electric capacity and improved cycle durability at high charging/discharging potentials.
2Quantity of substance
If conventional positive electrode materials are used to achieve high capacity, then battery capacity increases, but the materials react with LiPF6 in the electrolyte causing early deterioration
Solution Approach 1:
The patent adjusts the surface chemistry parameters of the positive electrode material through controlled synthesis conditions and post-treatment processes. By modifying surface composition and structure, the material exhibits reduced reactivity toward LiPF6 in the electrolyte, preventing early deterioration while maintaining high battery capacity.
3Use of energy by moving object
If high charging/discharging potential is applied to increase energy density, then more electricity is stored per unit mass, but the positive electrode deteriorates early
Solution Approach 1:
The patent employs a composite positive electrode material structure that combines high-capacity components (Li2MnO3) with structurally stable components (LiCoO3, LiAlO2). This composite structure enables the electrode to withstand high charging/discharging potentials without early deterioration, allowing operation at higher potentials to achieve increased energy density while maintaining charge/discharge durability.
Solution Approach 2:
The patent incorporates structurally stable materials (LiAlO2, LiCoO3) into the positive electrode composite before operation. These materials act as a protective matrix that cushions and stabilizes the high-stress environment of high-potential charging/discharging, preventing early deterioration of the high-capacity Li2MnO3 component and enabling sustained high-energy-density operation.
Data Source
AI summary
An active material having high capacity and excellent charging/discharging cycle durability at high potential is provided. The active material has a layered structure and is represented by the following composition formula (1):LiyNiaCobMncMdOxFz1Pz2 (1)wherein the element M is at least one element selected from the group consisting of Al, Si, Zr, Ti, Fe, Mg, Nb, Ba and V, and 1.9≦(a+b+c+d+y)≦2.1, 1.0≦y≦1.3, 0<a≦0.3, 0≦b≦0.25, 0.3≦c≦0.7, 0≦d≦0.1, 0.07≦z1≦0.15, 0.01≦z2≦0.1, and 1.9≦(x+z1)≦2.1 are satisfied.