Positive Electrode Active Material Water Control for Solid-State Batteries
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Solution Overview
Problem
Existing all-solid lithium ion batteries face increased resistance due to trace amounts of water reacting with halide solid electrolytes, leading to deterioration and high internal resistance.
Innovation Solution
A positive electrode material comprising a complex oxide represented by LiNi x Me 1-x O 2 with controlled water content (2.9 to 44.7 ppm) and a halide solid electrolyte, where x is between 0.5 and 1, and Me includes Mn, Co, or Al, is used to minimize water interaction and maintain electrolyte conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If trace amounts of water are present in the active material, then the manufacturing process is simpler, but the halide solid electrolyte deteriorates and internal resistance increases
Solution Approach 1:
The patent applies preliminary action by controlling the water content in the active material before assembling the battery. By pre-drying the active material to maintain water content within 2.9-44.7 ppm, the harmful reaction between water and halide solid electrolyte is prevented from occurring in the first place, ensuring low internal resistance without requiring complex post-assembly treatments
Solution Approach 2:
The patent applies parameter changes by precisely controlling the water content parameter of the active material within a specific range (2.9-44.7 ppm). This parameter control strikes a balance between ease of manufacture (allowing some water content) and reliability (preventing electrolyte deterioration), resolving the contradiction between manufacturing simplicity and battery performance
2Reliability
If water content in active material is reduced, then electrolyte deterioration is prevented, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by defining a specific water content range (2.9-44.7 ppm) for the active material. This range is optimized to prevent harmful reactions with halide solid electrolyte while remaining achievable through conventional drying processes, thus maintaining electrolyte stability without excessive manufacturing complexity
Solution Approach 2:
The patent references conventional drying processes and existing manufacturing techniques to achieve the target water content, rather than requiring entirely new manufacturing methods. This allows the solution to be implemented using adapted existing processes, limiting the increase in manufacturing complexity
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
This configuration results in a battery with reduced internal resistance by preventing electrolyte deterioration and maintaining high conductivity, enabling low resistance and improved charge/discharge characteristics.
Implementation Method 1
contains water in an amount of 2.9 ppm by mass or more and 44.7 ppm by mass or less generated during heating at 180°C in Karl Fischer titration
Data Source
Figure 1~2
AI summary
The positive electrode active material of the present disclosure includes a complex oxide represented by a formula (1): LiNixMe1-xO2 as a main component and contains water in an amount of 2.9 ppm by mass or more and 44.7 ppm by mass or less. Here, x satisfies 0.5 ≤ x ≤ 1, and Me is at least one element selected from the group consisting of Mn, Co, and Al.