Single-Crystal Cathode Composition for High-Voltage Cycle Retention
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Solution Overview
Problem
Traditional positive electrode active materials in solid state batteries suffer from limited capacity retention after repeated charge-discharge cycles at higher temperatures and voltages.
Innovation Solution
A positive electrode active material comprising Li, M′, and O, where M′ includes Co, Mn, and A, with specific molar ratios and a combination of Li2WO4 and WO3 compounds, forming a single-crystalline powder with a defined tap density, enhancing stability and electrochemical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional compounds are used as positive electrode active materials in solid state batteries, then the battery can operate at higher temperatures and voltages, but capacity retention is limited after repeated charge-discharge cycles
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molar ratios of metal elements (Ni: 0.8-0.95, Mn: 0.02-0.1, Co: 0.02-0.05, A: 0.01-0.05) in the positive electrode active material. This compositional parameter optimization enhances capacity retention while maintaining stability during repeated charge-discharge cycles at elevated temperatures and voltages.
Solution Approach 2:
The patent employs composite materials by combining multiple metal elements (Ni, Mn, Co, and A) in specific proportions to create a multi-element positive electrode active material. This composite approach leverages the synergistic effects of different metals to improve both capacity retention and cycle life, overcoming the limitations of traditional single-compound electrodes.
2Quantity of substance
If the positive electrode active material uses higher metal content to increase capacity, then energy density improves, but capacity leakage increases
Solution Approach 1:
The patent resolves this contradiction through parameter changes by optimizing the Li/(Co+Mn+Ni+A) molar ratio to be between 0.9 and 1.1. This precise parameter control allows high metal content (improving energy density) while minimizing capacity leakage through balanced stoichiometry and controlled synthesis conditions.
Data Source
AI summary
A positive electrode active material for solid state rechargeable batteries, whereby the positive electrode active material is a powder which comprises Li, M′, and O, wherein M′ consists of Co in a content x superior or equal to 2.0 mol % and inferior or equal to 35.0 mol %, Mn in a content y superior or equal to 0 mol % and inferior or equal to 35.0 mol %, A in a content m superior or equal to 0 mol % and inferior or equal to 5 mol %, whereby A comprises at least one element of the group consisting of: Al, Ba, B, Mg, Nb, Sr, Ti, W, S, Ca, Cr, Zn, V, Y, Si, and Zr, Ni in a content of 100-x-y-m mol %, a first compound which comprises Li2WO4 and a second compound which comprises WO3, whereby the powder is a single-crystalline powder, whereby the positive electrode active material comprises Li in a molar ratio of Li/(Co+Mn+Ni+A) of at least 0.9 and at most 1.1, whereby the positive electrode active material has a tap density which is at least 1.0 gr/cm3 and at most 3.0 g/cm3.