Boron-Coated Positive Active Material for All-Solid-State Batteries
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Solution Overview
Problem
All-solid-state batteries face challenges in achieving long-term cycle-life characteristics and high capacity due to interface resistance between the positive active material and the solid electrolyte, which existing methods like sol-gel and atomic layer deposition are costly and limited for mass production.
Innovation Solution
A lithium nickel-based composite oxide positive active material with a boron coating on both the surface and inner grain boundaries, where the boron coating portions include boron oxide and lithium borate, are used to reduce interface resistance and maintain structural stability during charge and discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing coating methods (sol-gel, atomic layer deposition) are used to reduce interface resistance, then cycle-life characteristics are improved, but manufacturing cost increases and mass production becomes difficult
Solution Approach 1:
The patent changes the coating method from complex chemical processes (sol-gel, atomic layer deposition) to a simple thermal treatment process. By heating the positive active material at 400-800°C for 1-24 hours, boron compounds are formed on the surface and grain boundaries, reducing interface resistance without requiring expensive equipment or complex procedures, thus enabling mass production
Solution Approach 2:
The patent uses inexpensive boron compounds (boric acid, boron oxide, boron carbide) as coating materials instead of expensive precursors required by sol-gel or atomic layer deposition. These simple boron-based materials can be easily applied through thermal treatment, providing cost-effective protection against interface resistance while maintaining long cycle life
2Reliability
If boron coating is applied to reduce interface resistance, then cycle-life characteristics are improved, but excessive boron content increases resistance
Solution Approach 1:
The patent applies boron coating selectively to critical areas: the surface and grain boundaries of the positive active material particles. This localized coating approach ensures that boron is present where it is most needed (at interfaces with solid electrolyte) while avoiding excessive boron accumulation in the bulk material that would increase resistance and harm performance
Solution Approach 2:
The patent uses a controlled amount of boron compounds (0.1-5 wt% based on positive active material weight) to achieve sufficient coating coverage without over-application. This partial action approach provides just enough boron to reduce interface resistance and improve cycle life while preventing the harmful effects of excessive boron content
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 boron-coated lithium nickel-based composite oxide material enhances cycle-life characteristics and capacity while avoiding excessive boron resistance, enabling improved performance and practical mass production.
Implementation Method 1
the boron coating portions include boron oxide and lithium borate, are used to reduce interface resistance
Implementation Method 2
maintain structural stability during charge and discharge
Data Source
AI summary
A positive active material for an all-solid-state battery, a method of preparing the same, and an all-solid-state battery including the same. The positive active material includes a secondary particle in which a plurality of primary particles is aggregated and at least a portion of the primary particles is arranged radially, and includes a first boron coating portion on a surface of the secondary particle, and a second boron coating portion on a surface of the primary particles inside the secondary particle.