Single-Crystal Cathode Composition With Tungsten Oxides for Li-Ion Capacity
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Solution Overview
Problem
Existing positive electrode active materials for lithium-ion rechargeable batteries have low initial discharge capacity and high irreversible capacity, as seen in KR 2019/0078991, which limits their electrochemical performance.
Innovation Solution
A positive electrode active material comprising Li, Co, Mn, A, and Ni, with specific molar ratios and including Li2WO4 and WO3 compounds, forming a single-crystalline powder with a controlled tungsten content, optimized for improved electrochemical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mixture of lithium transition metal oxide and lithium tungsten oxide compounds is used as positive electrode active material, then the battery can operate with lithium-ion rechargeable system, but the initial discharge capacity is low and irreversible capacity is high
Solution Approach 1:
The patent changes the chemical composition parameters by introducing a specific multi-element doping system (Co, Mn, A, Ni) with precisely controlled molar ratios. The Li/(Co+Mn+Ni+A) ratio is maintained between 0.900-1.100, and tungsten content is controlled at 0.20-2.50 wt%, which optimizes the electrochemical performance and resolves the contradiction between reliability and discharge capacity
Solution Approach 2:
The patent creates a composite material system combining lithium tungsten oxide (Li2WO4) and tungsten oxide (WO3) compounds with transition metal oxides. This composite structure leverages the complementary properties of different materials to achieve both high initial discharge capacity and low irreversible capacity, resolving the technical contradiction
2Stability of the object's composition
If tungsten oxide compounds are added to lithium transition metal oxide, then electrochemical stability is improved, but initial discharge capacity decreases
Solution Approach 1:
The patent applies local quality by introducing tungsten oxide compounds at specific locations within the material structure through controlled doping. The tungsten content is precisely controlled at 0.20-2.50 wt% to provide local electrochemical stability enhancement without significantly impacting the overall initial discharge capacity of the bulk material
Data Source
AI summary
A positive electrode active material for lithium-ion liquid electrolyte 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.