Aqueous Sodium-Ion Cathode Composition for Higher Capacity

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Solution Overview

Problem

Existing aqueous sodium ion secondary batteries have limited electrochemical capacity compared to conventional lithium ion batteries.

Innovation Solution

The use of a sodium-containing transition metal polyanion, specifically Na3-xMPO4CO3 (where M is Fe, Mn, Ni, or Co, and x is 0 or more and 2 or less), as the cathode active material in an aqueous sodium ion secondary battery, along with an aqueous electrolytic solution containing NaClO4, to enhance electrochemical performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a conventional aqueous electrolytic solution is used in a sodium ion secondary battery, then the battery can be manufactured at low cost using water, but the electrochemical capacity is limited to around 120 mAh/g

Engineering Contradiction:

Improveelectrochemical capacityVSAvoidelectrolytic solution cost

Core Design Contradiction:

Quantity of substanceVSEase of manufacture

Solution Approach 1:

The invention changes the chemical composition parameters of the cathode active material by introducing a specific polyanion structure with delocalized electrons, which fundamentally alters the electrochemical capacity from 120 mAh/g to over 130 mAh/g while maintaining aqueous electrolyte compatibility

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite cathode active material comprising a polyanion with delocalized electrons combined with sodium transition metal phosphate, creating a novel material system that achieves high electrochemical capacity in aqueous electrolyte while maintaining cost-effectiveness

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If a sodium transition metal polyanion with specific composition is used as cathode active material, then the electrochemical capacity exceeds 130 mAh/g, but the material structure becomes more complex

Engineering Contradiction:

Improveelectrochemical capacityVSAvoidcathode active material structure

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The invention optimizes the polyanion structure by controlling the delocalization of electrons and specifying the sodium content range (x = 0 to 2), which achieves high electrochemical capacity while maintaining a relatively simple and manufacturable crystal structure

Inventive Principle:

Principle #35Parameter changes

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

This configuration achieves a higher electrochemical capacity compared to conventional aqueous sodium ion secondary batteries, with discharge capacities exceeding 130 mAh/g in initial cycles.

Implementation Method 1

charge and discharge by reversible intercalation/deintercalation of Na cation occurs

Methodology Applied

Scientific EffectIntercalation/Deintercalation: Absorption (physical)

Implementation Method 2

electrolytic solution is an aqueous electrolytic solution containing at least one member selected from the group consisting of Na2SO4, NaNO3 and NaClO4

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Data Source

PatentUS12322761B2Aqueous sodium ion secondary battery

Publication Date: 2025.06.03 TOSOH CORP

AI summary

To provide an aqueous sodium ion secondary battery which can achieve a high electrochemical capacity as compared with a known sodium ion secondary battery having an aqueous electrolytic solution.An aqueous sodium ion secondary battery includes a cathode, an anode, an electrolytic solution and a separator, wherein the cathode has at least a cathode active material containing at least a sodium transition metal polyanion represented by the formula Na3-xMPO4CO3 (M is at least one member selected from the group consisting of Fe, Mn, Ni and Co, and x is 0 or more and 2 or less), and the electrolytic solution is an aqueous electrolytic solution.