Cathode Active Material Precursor with Concentration Gradient
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Solution Overview
Problem
Lithium rechargeable batteries face stability issues due to unstable crystal structures in cathode active materials, leading to poor thermal characteristics and reactivity with electrolytic solutions, which hinder their commercial development and application in high-capacity devices like electric vehicles.
Innovation Solution
A method for preparing a cathode active material precursor involving a concentration gradient distribution of nickel, cobalt, and manganese in a lithium rechargeable battery, where the concentrations of metallic salts in the core and shell parts are controlled to form a desired transition metal composition, ensuring excellent thermal stability by mixing metallic salt solutions with chelating agents and alkaline solutions, followed by drying and heating to create a stable active material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a portion of nickel is substituted with transition metal elements (Co, Mn) to increase exothermic start temperature, then thermal stability is improved, but charge-discharge characteristics and capacity are degraded
Solution Approach 1:
The patent applies local quality by creating a concentration gradient distribution where transition metal elements (Co, Mn) are concentrated in the outer shell region while the inner core maintains high nickel content. This spatial differentiation allows the outer shell to provide thermal stability while the inner core preserves high capacity and charge-discharge characteristics, resolving the contradiction between thermal stability and electrochemical performance
Solution Approach 2:
The patent creates a composite cathode active material with a core-shell structure consisting of a nickel-rich inner core and a transition metal-rich outer shell. This composite structure combines the high capacity benefits of nickel-based materials with the thermal stability benefits of cobalt and manganese, achieving both improved thermal stability and maintained charge-discharge characteristics
2Reliability
If uniform substitution of nickel with cobalt and manganese is performed to improve thermal stability, then thermal characteristics are improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by controlling the concentration gradient distribution of transition metal elements in the precursor material before the final sintering process. By pre-distributing Co and Mn in a gradient pattern in the precursor, the subsequent heat treatment naturally forms the desired core-shell structure without requiring complex multi-step manufacturing processes, thus improving thermal characteristics while keeping manufacturing relatively simple
3Reliability
If high concentration of transition metals is used throughout the cathode material to ensure thermal stability, then thermal stability is improved, but capacity and charging density are reduced
Solution Approach 1:
The patent concentrates transition metal elements (Co, Mn) specifically in the outer shell region rather than uniformly distributing them throughout the entire cathode material. This localized concentration provides thermal stability at the surface where it is most needed for safety, while the nickel-rich inner core maintains high capacity and charging density, thus achieving thermal stability without sacrificing charging density
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 method achieves a cathode active material with a continuous concentration gradient of transition metals, enhancing thermal stability and charge/discharge characteristics, thereby improving the performance and longevity of lithium rechargeable batteries.
Implementation Method 1
mixing an aqueous solution of Mn and Ni with an alkaline solution to co-precipitate Mn and Ni
Implementation Method 2
drying and heating a formed precipitate to prepare an active material precursor
Implementation Method 3
drying and heating a formed precipitate to prepare an active material precursor
Data Source
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AI summary
The present invention relates to a method of preparing a cathode active material precursor for a lithium rechargeable battery, the cathode active material precursor for the lithium rechargeable battery prepared thereby, and a cathode active material formed using the cathode active material precursor. According to the present invention, the method of preparing a cathode active material precursor for a lithium secondary battery controls the concentration of a concentration gradient part and a shell part in a precursor to obtain a desired concentration of a transition metal in the shell part. As a result, a metal composition is distributed in a continuous concentration gradient from the interface between the core part and the shell part to the surface of the cathode active material, thereby a cathode active material with excellent thermal stability.