Composite Electrode Material for High-Temperature Lithium Battery Stability

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Solution Overview

Problem

Lithium ion secondary batteries face challenges with capacity loss and charging/discharging performance, especially at elevated temperatures, with existing cathode materials like lithium iron phosphates and lithium cobalt oxides exhibiting suboptimal performance above 45°C in terms of cycle stability and C-rate capacity.

Innovation Solution

Development of electrode materials comprising a compound with the general formula Li(1+x)[NiaCObMncM1d](1-x)O2, a lithium iron-phosphorous compound in the form of a solid solution or domains, and carbon in electrically conductive modification, optimized through specific synthesis methods to enhance performance at high temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If lithium iron phosphate or lithium cobalt oxide is used as cathode material, then battery capacity is improved, but capacity loss increases at temperatures above 45°C

Engineering Contradiction:

Improvebattery capacityVSAvoidcycle stability at high temperature

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent employs a composite cathode material consisting of lithium iron phosphate (LFP) combined with lithium cobalt oxide (LiCoO2) or lithium nickel cobalt manganese oxide (NCM). This composite structure allows the material to benefit from the high capacity of LFP while incorporating the high-temperature stability of LiCoO2 or NCM, thereby resolving the contradiction between capacity and high-temperature reliability

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent optimizes the compositional parameters of the cathode material by adjusting the ratios of LiCoO2/NCM to LFP, as well as controlling particle size distribution and doping concentrations. These parameter changes enable the material to maintain high capacity while improving cycle stability at temperatures above 45°C

Inventive Principle:

Principle #35Parameter changes

2Productivity

If lithium cobalt oxide or lithium nickel cobalt manganese oxide is used, then charging speed is improved, but capacity loss at high temperature increases

Engineering Contradiction:

Improvecharging speedVSAvoidcapacity retention at 45°C or higher

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The composite cathode material combines the fast charging capability of LiCoO2 or NCM with the thermal stability of LFP. The synergistic effect allows the battery to accept fast charging currents while maintaining structural integrity and capacity retention at elevated temperatures

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent creates a heterogeneous structure where different regions of the cathode material have specialized functions: LFP domains provide thermal stability and structural framework, while LiCoO2/NCM domains provide fast ion transport channels for rapid charging, achieving both fast charging and high-temperature reliability

Inventive Principle:

Principle #3Local quality

3Quantity of substance

If existing cathode materials are used, then energy storage capacity is improved, but charging and discharging time increases

Engineering Contradiction:

Improveenergy storage capacityVSAvoidcharging and discharging time

Core Design Contradiction:

Quantity of substanceVSLoss of time

Solution Approach 1:

The cathode material is segmented into multiple phases with different functions: LFP segments provide high capacity storage, while LiCoO2/NCM segments provide fast ion transport pathways. This segmentation allows simultaneous achievement of high energy capacity and fast charging/discharging rates

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces conductive carbon coatings and surface modifiers as intermediaries that facilitate rapid electron and ion transport between the high-capacity LFP domains and the external circuit, reducing charging/discharging time while preserving energy storage capacity

Inventive Principle:

Principle #24Intermediary (Mediator)

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 new electrode materials demonstrate improved capacity retention and charging/discharging behavior at high temperatures, with enhanced cycle stability and C-rate capacity, addressing the limitations of existing materials.

Implementation Method 1

Lithium ion secondary batteries are modern devices for storing energy

Methodology Applied

Scientific EffectIon transport: Diffusion

Implementation Method 2

carbon in electrically conductive modification

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS10446833B2Electrode material including lithium transition metal oxide, lithium iron phosphate, further iron-phosphorous compound. and carbon, and lithium battery including the same

Publication Date: 2019.10.15 BASF SE

AI summary

Electrode materials comprising (a) at least one compound of general formula (I) Li(1+x)[NiaCObMncM1d](1-x)O2 (I) the integers being defined as follows: x is in the range of from 0.01 to 0.05, a is in the range of from 0.3 to 0.6, b is in the range of from zero to 0.35, c is in the range of from 0.2 to 0.6, d is in the range of from zero to 0.05, a+b+c+d=1 M1 is at least one metal selected from Ca, Zn, Fe, Ti, Ba, Al, (b) at least one compound of general formula (II) LiFe(1-x)M2yPO4 (II) y is in the range of from zero to 0.8 M2 is at least one element selected from Ti, Co, Mn, Ni, V, Mg, Nd, Zn and Y, that contains at least one further iron-phosphorous compound, in form of a solid solution in compound (b) or in domains, (c) carbon in electrically conductive modification.