Polymer Electrolyte Layer in Li-Ion Batteries for Low-Temperature Cycling

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Solution Overview

Problem

Existing battery technologies face challenges in improving cycle characteristics, particularly at low temperatures, where lithium precipitation on the negative electrode surface can lead to decreased performance and reduced cycle life.

Innovation Solution

Incorporating a polymer electrolyte layer between the negative electrode and the separator in a lithium ion secondary battery, which helps in suppressing lithium precipitation and maintaining electronic conductivity by allowing the electrolyte to contain a negative electrode active material in the voids of the electrode layers, thereby enhancing cycle characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional battery structure without polymer electrolyte layer is used, then the structure is simple and easy to manufacture, but lithium precipitation occurs on the negative electrode surface at low temperatures leading to poor cycle characteristics

Engineering Contradiction:

Improvecycle characteristicsVSAvoidbattery structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The battery structure is segmented by introducing a polymer electrolyte layer as a distinct component between the negative electrode and separator. This segmentation allows the polymer electrolyte to specifically address lithium precipitation issues without redesigning the entire battery structure, thus improving cycle characteristics while maintaining manufacturing feasibility.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The polymer electrolyte layer acts as an intermediary between the negative electrode and separator. It mediates the interaction by providing a protective interface that prevents direct contact between lithium and the negative electrode surface, thereby suppressing lithium precipitation and improving cycle characteristics without complicating the overall battery structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Duration of action of stationary object

If no polymer electrolyte layer is used, then the battery structure is simpler, but lithium precipitation on the negative electrode surface decreases performance and cycle life

Engineering Contradiction:

Improvecycle lifeVSAvoidbattery structure

Core Design Contradiction:

Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The polymer electrolyte layer is introduced in advance as a preventive measure against lithium precipitation. By establishing this protective layer before lithium deposition occurs, the battery structure is prepared to prevent performance degradation and extend cycle life, rather than attempting to address precipitation issues after they arise.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The polymer electrolyte layer serves as a cushioning layer that absorbs and mitigates the harmful effects of lithium precipitation before it can significantly degrade performance. This beforehand cushioning protects the negative electrode surface, thereby extending cycle life without requiring complex structural modifications.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If lithium precipitation is allowed to occur, then the battery structure remains simple, but performance decreases and cycle life is reduced

Engineering Contradiction:

Improveperformance stabilityVSAvoidbattery structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention converts the potential harm of lithium precipitation into a benefit by using the polymer electrolyte layer to control and direct lithium deposition. Instead of allowing uncontrolled precipitation that degrades performance, the polymer electrolyte guides lithium deposition in a controlled manner, thereby improving performance stability while maintaining a relatively simple battery structure.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 solution effectively improves cycle characteristics by preventing lithium precipitation and maintaining conductivity, even at low temperatures, leading to increased battery performance and longevity.

Implementation Method 1

lithium precipitation on the negative electrode surface can lead to decreased performance and reduced cycle life

Methodology Applied

Scientific EffectLithium precipitation: Precipitation

Implementation Method 2

maintaining electronic conductivity by allowing the electrolyte to contain a negative electrode active material in the voids of the electrode layers

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Data Source

PatentEP3331084B1Battery, battery pack, electronic device, electric vehicle, electricity storage device and electric power system

Publication Date: 2025.01.15 MURATA MFG CO LTD

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Figure 3A~3B

AI summary

A battery, including: a positive electrode; a negative electrode; and an electrolyte layer containing a negative electrode active material.