BiVO4-PEDOT Photoelectrochemical Capacitor for Compact Energy Storage

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Solution Overview

Problem

Existing photoelectrochemical capacitors (PEC capacitors) suffer from separate electrodes that hinder space and weight savings due to their non-integrated design.

Innovation Solution

An integrated photoelectrochemical capacitor is constructed using bismuth vanadate (BiVO4) and poly(3,4-ethylenedioxythiophene) (PEDOT) layers on fluorine-doped tin oxide (FTO) glass, bonded with epoxy and connected with copper tape, utilizing pulsed laser deposition and electrochemical deposition methods.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If separate electrodes are used for energy conversion and storage, then functional performance is achieved, but device space and weight increase

Engineering Contradiction:

Improveenergy conversion and storage performanceVSAvoiddevice weight

Core Design Contradiction:

ReliabilityVSWeight of stationary object

Solution Approach 1:

The patent combines the energy conversion function (BiVO4 photoanode) and energy storage function (PEDOT electrode) into a single integrated photoelectrochemical capacitor structure. The BiVO4 layer and PEDOT layer are deposited on opposite sides of the same FTO glass substrate, merging two separate electrode functions into one unified device, thereby reducing overall device weight while maintaining both energy conversion and storage capabilities

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If separate electrodes are used for energy conversion and storage, then functional performance is achieved, but device space increases

Engineering Contradiction:

Improveenergy conversion and storage performanceVSAvoiddevice area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent integrates both energy conversion and storage functions within a single FTO glass substrate structure. The BiVO4 photoanode and PEDOT electrode are deposited on opposite sides of the same substrate, sharing common structural support and electrical connection pathways, thereby minimizing the device footprint while maintaining dual functionality

Inventive Principle:

Principle #5Merging (Combining)

3Weight of stationary object

If integrated design is implemented, then space and weight are reduced, but manufacturing complexity increases

Engineering Contradiction:

Improvedevice weightVSAvoidmanufacturing process complexity

Core Design Contradiction:

Weight of stationary objectVSDevice complexity

Solution Approach 1:

The manufacturing process is divided into distinct sequential steps: first depositing BiVO4 on one side of the FTO substrate, then depositing PEDOT on the opposite side. This segmentation of the manufacturing process into separate, manageable stages reduces overall complexity despite the integrated final structure, allowing each material to be deposited using optimized independent procedures

Inventive Principle:

Principle #1Segmentation

4Area of stationary object

If integrated design is implemented, then space and weight are reduced, but manufacturing precision requirements increase

Engineering Contradiction:

Improvedevice areaVSAvoiddeposition thickness control

Core Design Contradiction:

Area of stationary objectVSManufacturing precision

Solution Approach 1:

The patent specifies precise thickness ranges for each layer (BiVO4: 70-1000 nm, PEDOT: controlled via electrochemical deposition parameters) and treats each deposition process as a separate, independently controllable step. This allows precise control of each material's thickness without the compounding complexity that would arise from attempting to deposit multiple materials simultaneously, thereby maintaining manufacturing precision while achieving integration

Inventive Principle:

Principle #1Segmentation

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 integrated design achieves efficient energy conversion and storage, enabling rapid charging and discharging capabilities with a calculated capacitance of approximately 40 mF/cm2 under simulated sunlight.

Implementation Method 1

when BiVO4 is exposed to radiation with energy equal to or higher than the bandgap energy, electrons are excited from the valence band to the conduction band

Methodology Applied

Scientific EffectPhotoexcitation: Photoelectric Effect

Implementation Method 2

The PEDOT layer, is electrochemically deposited on - onto another FTO glass - the second glass layer. The electrodeposition process is carried out in an aqueous solution of 3,4-ethylenedioxythiophene (EDOT)

Methodology Applied

Scientific EffectElectrochemical deposition: Electrodeposition

Implementation Method 3

These holes migrate towards the surface and are consumed in the oxidation of water

Methodology Applied

Scientific EffectPhotoelectrochemical oxidation: Photo-oxidation

Data Source

PatentEP4462973B1Integrated photoelectrochemical capacitor and method for obtaining an integrated photoelectrochemical capacitor

Publication Date: 2026.01.14 POLITECHNIKA GDANSKA

Figure 1~2

AI summary

Integrated photoelectrochemical capacitor based on bismuth vanadate BiVO4 and poly(3,4-ethylenedioxythiophene) (PEDOT) is characterized in that it comprises a BiVO4 layer, preferably with a thickness ranging from 70 to 1000 nm, deposited on fluorine-doped tin oxide (FTO) conductive glass on one side, and an electrochemically deposited PEDOT layer on FTO glass on the other side, wherein both FTO glass layers are bonded together on the non-conductive side using resin, preferably epoxy, and the conductive sides are connected using tape.