Cathode Coating Composition for Stable High-Nickel Li-Ion Batteries
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Solution Overview
Problem
Existing layered positive electrode active materials like LiNiO2 suffer from structural collapse during charging and discharging, low thermal stability, and high initial resistance, making them unsuitable for high-capacity and high-energy density batteries.
Innovation Solution
A positive electrode active material for lithium secondary batteries is developed with a coating layer containing B, LiOH, and Li2SO4 on lithium metal oxide particles, where B is in the range of 10-5000 ppm, LiOH in 100-10000 ppm, and Li2CO3 in 1000-5000 ppm, formed through a method involving a co-precipitation process, heat treatments, and internal reaction of Li2CO3, with nickel content of 85 mol% or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If LiNiO2 is used as a high-capacity positive electrode active material, then the battery capacity increases, but the material undergoes structural collapse and has low thermal stability
Solution Approach 1:
A coating layer comprising Li2SiO3, Li2CO3, and LiOH is applied on the surface of the lithium metal oxide particles. This coating layer acts as an intermediary protective barrier between the LiNiO2 core material and the external environment, preventing direct exposure to water and air, thereby maintaining structural stability and thermal performance while preserving high capacity
Solution Approach 2:
The positive electrode active material is designed as a composite structure with a LiNiO2 core and a multi-component coating shell containing Li2SiO3, Li2CO3, and LiOH. This composite architecture combines the high capacity of LiNiO2 with the protective and stabilizing properties of the coating layer, achieving both high performance and reliability
2Quantity of substance
If LiNiO2 is used to achieve high capacity, then the energy density increases, but the initial resistance and resistance increase rate are high
Solution Approach 1:
The coating layer comprising Li2SiO3, Li2CO3, and LiOH serves as an intermediary conductive interface between the LiNiO2 particles and the electrolyte. This coating improves wettability and facilitates lithium ion transport, thereby reducing initial resistance and resistance increase rate while maintaining high energy density
3Quantity of substance
If LiNiO2 is used for high capacity, then the battery performance improves, but the thermal stability decreases
Solution Approach 1:
The coating layer acts as a thermal barrier and protective intermediary between the LiNiO2 core and the external environment. It prevents direct contact with water and air, suppressing exothermic reactions and maintaining thermal stability while preserving the high capacity of the underlying LiNiO2 material
Solution Approach 2:
The coating layer creates an inert protective environment around the LiNiO2 particles, isolating them from reactive species in the external environment. This inert barrier prevents degradation reactions and maintains thermal stability, enabling the high-capacity material to operate safely under various temperature conditions
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 material achieves high capacity, excellent high-temperature life characteristics, and significantly decreased initial resistance and resistance increase rate, suitable for electric vehicles.
Implementation Method 1
a coating layer placed on at least a part of a surface of the lithium metal oxide particles, wherein the coating layer includes B, LiOH, Li2CO3, and Li2SO4
Implementation Method 2
The Li2CO3 may come from an internal reaction, without introducing a lithium raw material separately
Data Source
AI summary
The present disclosure relates to a positive electrode active material for a lithium secondary battery including lithium metal oxide particles; and a coating layer placed on at least a part of a surface of the lithium metal oxide particles, wherein the coating layer includes B, LiOH, Li2CO3, and Li2SO4.