Dual-Shell Cathode Active Material for Stable Nickel-Rich Batteries
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Solution Overview
Problem
Nickel-based cathode active materials in lithium batteries suffer from degraded lifespan and poor thermal stability due to side reactions, leading to performance deterioration.
Innovation Solution
A composite cathode active material is developed, comprising a lithium transition metal oxide core coated with a first shell of specific metal compounds and a second shell of metal compounds and graphene, which inhibits side reactions and improves thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If nickel-based cathode active materials are used to achieve high capacity, then energy density is improved, but side reactions occur leading to degraded lifespan and poor thermal stability
Solution Approach 1:
A coating layer comprising a metal oxide layer and a metal hydroxide layer is applied to the surface of the nickel-based cathode active material. The metal oxide layer (e.g., Al2O3, TiO2, SiO2) serves as a stable barrier between the nickel-based material and the electrolyte, while the metal hydroxide layer (e.g., Al(OH)3, Ti(OH)4, Si(OH)4) provides additional protection. This intermediary coating prevents direct contact and side reactions, thereby improving lifespan characteristics while maintaining the high capacity of the nickel-based core material.
2Use of energy by moving object
If nickel-based cathode active materials are used to achieve high capacity, then energy density is improved, but thermal stability deteriorates
Solution Approach 1:
The dual-layer coating of metal oxide and metal hydroxide acts as a thermal barrier between the nickel-based cathode active material and the electrolyte. This intermediary structure prevents direct thermal interactions and side reactions that would otherwise occur at elevated temperatures, thereby maintaining thermal stability while preserving the high energy density characteristics of the nickel-based core material.
3Reliability
If a coating layer is applied to prevent side reactions, then lifespan characteristics are improved, but device complexity increases
Solution Approach 1:
A coating layer comprising a metal oxide layer and a metal hydroxide layer is applied to the surface of the nickel-based cathode active material. The metal oxide layer (e.g., Al2O3, TiO2, SiO2) serves as a stable barrier between the nickel-based material and the electrolyte, while the metal hydroxide layer (e.g., Al(OH)3, Ti(OH)4, Si(OH)4) provides additional protection. This intermediary coating prevents direct contact and side reactions, thereby improving lifespan characteristics while maintaining the high capacity of the nickel-based core material.
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 composite cathode active material enhances cycle characteristics, high-speed charging capabilities, and suppresses side reactions, thereby improving the overall performance and stability of lithium batteries at both low and high temperatures.
Implementation Method 1
a first shell and a second shell that are disposed on an outer side of a surface of the core... suppresses a side reaction between the composite cathode active material and an electrolyte solution
Data Source
AI summary
Provided are a composite cathode active material, a cathode and a lithium battery that include the same, and a method of preparing the composite cathode active material, the composite cathode active material comprising: a core; and a first shell and a second shell that are disposed on an outer side of a surface of the core, wherein the first shell includes at least one first metal compound represented by Formula XaOb (where 0<a≤3, 0<b≤4, and when a is 1, 2, or 3, b is an integer) or Formula Xa(OH)b (where 0<a≤3, 0<b≤4, and when a is 1, 2, or 3, b is an integer), the second shell includes at least one second metal compound represented by Formula YcOd (where 0<c≤3, 0<d<4, and when c is 1, 2, or 3, d is not an integer); and graphene, the at least one second metal compound is disposed in a graphene matrix, X and Y are each independently a metal selected from Groups 2 to 13, 15, and 16 of the Periodic Table of Elements.