Boron-Coated LiNiCoMnO2 Cathode for Low-Temperature Output

Solution Overview

Problem

Current nonaqueous electrolyte secondary batteries, particularly those using lithium-nickel-cobalt-manganese composite oxide as the positive electrode material, face challenges in achieving high output characteristics across a wide temperature range, from extremely low to high temperatures, and are difficult to produce on an industrial scale.

Innovation Solution

A positive electrode active material comprising lithium-nickel-cobalt-manganese composite oxide with a boron compound on its surface, formed through a method involving crystallization, lithium mixing, firing, boron mixing, and heat treatment, which enhances the material's performance by reducing resistance and improving capacity and cycle characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If lithium-nickel-cobalt-manganese composite oxide is used as positive electrode material, then thermal stability and capacity are improved, but output characteristics deteriorate due to high resistance

Engineering Contradiction:

Improvethermal stabilityVSAvoidoutput characteristics

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The patent applies local quality by adding boron specifically to the surface of the lithium-nickel-cobalt-manganese composite oxide particles. This creates a boron-containing layer on the particle surfaces that improves conductivity and output characteristics without altering the bulk composition and thermal stability properties of the composite oxide.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the surface chemical composition parameter by introducing boron elements onto the particle surfaces through a specific heat treatment process. This parameter change enhances electronic conductivity and reduces resistance, thereby improving output characteristics while maintaining the original bulk material properties.

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If lithium-nickel-cobalt-manganese composite oxide is used as positive electrode material, then capacity is improved, but resistance increases leading to poor output characteristics

Engineering Contradiction:

ImprovecapacityVSAvoidresistance

Core Design Contradiction:

Quantity of substanceVSPower

Solution Approach 1:

The patent applies local quality by adding boron specifically to the surface of the lithium-nickel-cobalt-manganese composite oxide particles. This creates a boron-containing layer on the particle surfaces that improves conductivity and output characteristics without altering the bulk composition and thermal stability properties of the composite oxide.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the surface chemical composition parameter by introducing boron elements onto the particle surfaces through a specific heat treatment process. This parameter change enhances electronic conductivity and reduces resistance, thereby improving output characteristics while maintaining the original bulk material properties.

Inventive Principle:

Principle #35Parameter changes

3Power

If complex multi-step production process is used to add boron compound, then output characteristics are improved, but manufacturing complexity increases

Engineering Contradiction:

Improveoutput characteristicsVSAvoidproduction process complexity

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The patent merges the boron addition step with the existing firing process. By adding boron compounds to the green body before firing and utilizing the firing step to simultaneously sinter the material and form the boron-containing surface layer, the process integrates multiple functions into existing steps, reducing overall process complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent applies preliminary action by pre-mixing boron compounds with the lithium-nickel-cobalt-manganese composite oxide before the firing step. This preliminary preparation ensures uniform distribution of boron elements, which then form the desired surface layer during the subsequent firing process, simplifying the overall manufacturing流程.

Inventive Principle:

Principle #10Preliminary action

4Power

If boron compound is added to lithium-nickel-cobalt-manganese composite oxide, then resistance is reduced and output characteristics are improved, but production difficulty increases

Engineering Contradiction:

ImproveresistanceVSAvoidproduction difficulty

Core Design Contradiction:

PowerVSEase of manufacture

Solution Approach 1:

The patent merges the boron addition step with the existing firing process. By adding boron compounds to the green body before firing and utilizing the firing step to simultaneously sinter the material and form the boron-containing surface layer, the process integrates multiple functions into existing steps, reducing overall process complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent applies preliminary action by pre-mixing boron compounds with the lithium-nickel-cobalt-manganese composite oxide before the firing step. This preliminary preparation ensures uniform distribution of boron elements, which then form the desired surface layer during the subsequent firing process, simplifying the overall manufacturing流程.

Inventive Principle:

Principle #10Preliminary action

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 proposed solution results in a positive electrode active material with low resistance and high output characteristics across a wide temperature range, suitable for use in portable electronics and electric vehicles, and can be easily produced on an industrial scale.

Implementation Method 1

the boron compound being present on at least part of the surface of the primary particles

Methodology Applied

Scientific EffectSurface modification: Coatings

Implementation Method 2

a crystallization step of obtaining particles of nickel-cobalt-manganese composite hydroxide

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Implementation Method 3

a firing step of firing the resulting lithium mixture by retaining the resulting lithium mixture in an oxidizing atmosphere at a firing temperature from 800°C to 1000°C for 5 to 20 hours

Methodology Applied

Scientific EffectFiring: Sintering

Implementation Method 4

a heat-treatment step of subjecting the boron mixture to heat treatment in an oxidizing atmosphere at a temperature from 300°C to 580°C

Methodology Applied

Scientific EffectHeat treatment: Heat Treatment

Data Source

PatentEP3151317B1Positive electrode active material for nonaqueous electrolyte secondary batteries, production method thereof, and nonaqueous electrolyte secondary battery including said material

Publication Date: 2021.11.24 SUMITOMO METAL MINING CO LTD

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AI summary

Provided is a positive electrode active material that can be used to fabricate a nonaqueous electrolyte secondary battery having excellent output characteristics not only in an environment at normal temperature but also in all temperature environments from extremely low to high temperatures. A positive electrode active material for nonaqueous electrolyte secondary batteries, the positive electrode active material includes a boron compound and lithium-nickel-cobalt-manganese composite oxide of general formula (1) having a layered hexagonal crystal structure. The lithium-nickel-cobalt-manganese composite oxide includes secondary particles composed of agglomerated primary particles. The boron compound is present on at least part of the surface of the primary particles, and contains lithium. Li1+sNixCoyMnzMotMwO2 ... (1)