Dual-Coated Ni-Mn Cathode Material for Low-Gas Li-Ion Batteries
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Solution Overview
Problem
The increasing demand for high-capacity, high-energy density rechargeable lithium batteries has led to a shortage of cobalt, a rare and expensive metal, necessitating the development of cobalt-free or low-cobalt positive electrode active materials that maintain high capacity and cycle-life characteristics.
Innovation Solution
A positive electrode active material is developed, comprising a core particle of layered lithium nickel-manganese-based composite oxide, with a first coating layer containing aluminium (Al) and a second coating layer containing nickel (Ni), enhancing capacity, efficiency, and cycle-life while reducing gas generation under high-voltage and high-temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cobalt is used in positive electrode active materials to achieve high capacity and long cycle-life, then battery performance is improved, but production cost increases and resource availability decreases due to cobalt being expensive and having limited reserves
Solution Approach 1:
The patent removes cobalt from the positive electrode active material composition, developing a cobalt-free lithium nickel-manganese-based composite oxide. This extraction of the expensive and scarce cobalt element while maintaining battery performance through alternative material composition directly addresses the contradiction between reliability and manufacturing cost.
Solution Approach 2:
The patent substitutes expensive cobalt with more abundant and cheaper metals (nickel and manganese) to create a cost-effective positive electrode active material. This replacement strategy reduces production cost while aiming to maintain acceptable cycle-life characteristics through optimized material composition and coating structures.
2Ease of manufacture
If cobalt is reduced or eliminated from positive electrode active materials, then production cost decreases and resource availability improves, but capacity and cycle-life characteristics may deteriorate
Solution Approach 1:
The patent creates a composite oxide structure combining lithium, nickel, and manganese elements in specific ratios (LiNi_xMn_yO2 where x+y=1). This composite material approach leverages the complementary properties of nickel (high capacity) and manganese (structural stability) to achieve both cost-effectiveness and reliable cycle-life characteristics without cobalt.
Solution Approach 2:
The patent applies different functional zones within the positive electrode active material structure, including core particles with optimized Ni:Mn ratios and surface coating layers with specific compositions. This local quality differentiation allows the material to simultaneously achieve high capacity in the bulk and long cycle-life through surface stabilization, resolving the contradiction between cost reduction and performance maintenance.
3Use of energy by moving object
If high-voltage and high-temperature conditions are applied to maximize battery capacity, then energy density increases, but gas generation problems worsen and cycle-life decreases
Solution Approach 1:
The patent converts the potential harm of high-voltage operation (which typically causes gas generation and degradation) into a benefit by developing a cobalt-free composite oxide with enhanced structural stability. The material's composition and surface coatings are designed to withstand high-voltage conditions without decomposing, thereby suppressing gas generation while maintaining high energy density.
Solution Approach 2:
The patent optimizes the chemical composition parameters of the positive electrode active material, specifically controlling the nickel and manganese ratios and applying surface coatings with controlled thickness and composition. These parameter changes enhance the material's thermal and electrochemical stability, allowing high-voltage operation without excessive gas generation.
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 proposed solution achieves suitably high initial charge/discharge capacity and efficiency, extends cycle-life, and effectively suppresses gas generation problems, thereby improving the performance and reliability of rechargeable lithium batteries under demanding conditions.
Implementation Method 1
a first coating layer provided on the surface of the core particle and including aluminium (Al), and a second coating layer provided on the first coating layer and including nickel (Ni)
Implementation Method 2
mixing a layered nickel-manganese composite hydroxide and a lithium raw material and performing a first heat treatment to obtain a lithium nickel-manganese-based composite oxide
Data Source
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AI summary
A positive electrode active material includes a core particle including a layered lithium nickel-manganese-based composite oxide, a first coating layer provided on the surface of the core particle and including Al, and a second coating layer provided on the first coating layer and including Ni. A method for preparing a positive electrode active material includes: mixing a layered nickel-manganese composite hydroxide and a lithium raw material and performing a first heat treatment to obtain a lithium nickel-manganese-based composite oxide, adding an aluminium (Al) raw material to an aqueous solvent, adding the lithium nickel-manganese composite oxide thereto and mixing them, then adding a nickel (Ni) raw material and mixing them, and drying the mixture and performing a second heat treatment.