Hydrothermal Carbon Anode for Sodium-Ion Battery SEI Inhibition

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Solution Overview

Problem

Sodium-ion batteries face challenges with long charge and discharge times, irreversible capacity loss due to the formation of a solid electrolyte interface (SEI) layer on the anode, and safety concerns compared to lithium-ion batteries, which are becoming scarce and hazardous.

Innovation Solution

The use of hydrothermal carbon (HTC) nano-structures as anodes in sodium-ion batteries, combined with a pyromellitic acid stabilizer in the electrolyte to inhibit SEI layer formation, and a method to produce HTC from biomass materials, reducing environmental impact and improving charge capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional anodes are used in sodium-ion batteries, then the battery can operate, but irreversible capacity loss occurs due to SEI layer formation on the anode surface

Engineering Contradiction:

Improvebattery capacity retentionVSAvoidcapacity loss

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

A solid electrolyte inter-phase (SEI) inhibitor is introduced as an intermediary substance in the electrolyte composition. This inhibitor acts as a mediator that prevents the harmful formation of SEI layer on the anode surface, thereby eliminating irreversible capacity loss while maintaining battery operation. The inhibitor specifically targets and blocks the mechanism causing capacity degradation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The harmful SEI layer formation process is effectively removed from the battery system through the use of SEI inhibitor. By extracting or eliminating this detrimental side reaction, the battery achieves reversible capacity retention without the progressive degradation that would otherwise occur with conventional anodes.

Inventive Principle:

Principle #2Taking out (Extraction)

2Object-affected harmful factors

If biomass material is converted to HTC nano-structures through hydrothermal processing, then environmentally friendly anodes are produced, but the process requires strong acid pretreatment and heating

Engineering Contradiction:

Improveenvironmental impactVSAvoidprocessing temperature

Core Design Contradiction:

Object-affected harmful factorsVSTemperature

Solution Approach 1:

The biomass conversion process utilizes hydrothermal processing, which involves phase transition of water to supercritical or near-supercritical state. This phase transition enables the breakdown of biomass into HTC nano-structures at relatively moderate temperatures and pressures, creating environmentally friendly anodes while managing the thermal requirements through controlled phase change.

Inventive Principle:

Principle #36Phase transitions

Solution Approach 2:

The process employs parameter changes by adjusting temperature, pressure, and acid concentration to optimize the conversion of biomass to HTC. By carefully controlling these parameters, the process achieves effective biomass carbonization with reduced environmental impact, balancing the harsh conditions needed for conversion against the goal of sustainability.

Inventive Principle:

Principle #35Parameter changes

3Quantity of substance

If sodium-ion batteries are used instead of lithium-ion batteries, then cost and availability improve, but charge and discharge times increase

Engineering Contradiction:

Improvesodium availabilityVSAvoidcharge time

Core Design Contradiction:

Quantity of substanceVSLoss of time

Solution Approach 1:

The battery employs localized optimization by using HTC nano-structures with specific porous characteristics and surface properties tailored for sodium ion transport. This local quality enhancement at the anode level improves charge kinetics, reducing charge time while maintaining the cost and availability advantages of sodium-ion technology over lithium-ion.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The HTC anode utilizes porous nano-structures that provide extensive surface area and optimized ion transport pathways. This porous architecture accelerates sodium ion diffusion and reaction kinetics, thereby reducing charge and discharge times while maintaining the economic benefits of using abundant sodium instead of lithium.

Inventive Principle:

Principle #31Porous materials

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 enhances charge capacity, stability, and safety of sodium-ion batteries by preventing SEI buildup, making them safer and more efficient than conventional sodium-ion cells, while being environmentally friendly and reducing the risks associated with lithium-ion batteries.

Implementation Method 1

stabilizing the sodium-ion battery cell by adding a solid electrolyte inter-phase (SEI) inhibitor in mixture with the electrolyte

Methodology Applied

Scientific EffectSolid electrolyte inter-phase (SEI) inhibition:

Implementation Method 2

heating the biomass in a strongly acidic environment to form a slurry, and filtering the slurry to separate hydrolysis products from other byproducts. The hydrolysis products are subjected to a hydrothermal process to provide a porous nano-structured carbon material

Methodology Applied

Scientific EffectHydrothermal carbonization:

Data Source

PatentUS9985315B1Hydrothermal carbon anode, polymer stabilized, sodium-ion cell

Publication Date: 2018.05.29 CATERPILLAR INC

AI summary

An electrical power cell includes a cathode capable of accepting sodium ions, an anode comprising one or more hydrothermal carbon (HTC) nano-structures, and an electrolyte in contact with the anode and the cathode, the electrolyte comprising a solid electrolyte inter-phase (SEI) inhibitor.