IEC TS 62607-4-11:2026

IEC TS 62607-4-11 ®
Edition 1.0 2026-03
TECHNICAL
SPECIFICATION
Nanomanufacturing - Key control characteristics -
Part 4-11: Nano-enabled energy storage - Dispersion stability of nano-carbon
materials for the electrodes of lithium-ion capacitors: zeta potential method
ICS 07.120  ISBN 978-2-8327-1134-7

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or
by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either
IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC copyright
or have an enquiry about obtaining additional rights to this publication, please contact the address below or your local
IEC member National Committee for further information.

IEC Secretariat Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

IEC publications search - IEC Products & Services Portal - products.iec.ch
webstore.iec.ch/advsearchform Discover our powerful search engine and read freely all the
The advanced search enables to find IEC publications by a publications previews, graphical symbols and the glossary.
variety of criteria (reference number, text, technical With a subscription you will always have access to up to date
committee, …). It also gives information on projects, content tailored to your needs.
replaced and withdrawn publications.
Electropedia - www.electropedia.org
The world's leading online dictionary on electrotechnology,
IEC Just Published - webstore.iec.ch/justpublished
Stay up to date on all new IEC publications. Just Published containing more than 22 500 terminological entries in English
details all new publications released. Available online and and French, with equivalent terms in 25 additional languages.
once a month by email. Also known as the International Electrotechnical Vocabulary
(IEV) online.
IEC Customer Service Centre - webstore.iec.ch/csc
If you wish to give us your feedback on this publication or
need further assistance, please contact the Customer
Service Centre: sales@iec.ch.
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
3.1 General related terms . 6
3.2 Key control characteristics measured according to this document . 7
4 Measurement principle and sample preparation method . 7
4.1 Measurement principle . 7
4.2 Sample preparation method . 9
4.2.1 Materials . 9
4.2.2 Chemicals. 10
4.2.3 Apparatus . 10
4.2.4 Detailed sample preparation procedure . 10
4.3 Measurement system . 10
4.4 Description of measurement equipment / apparatus . 11
4.5 Calibration standards . 11
4.6 Ambient conditions during measurement . 11
5 Measurement procedures – Detailed protocol . 11
5.1 General . 11
5.2 Minimum required measurement parameters . 13
5.3 General measurement procedure for ζ . 13
5.4 Size of particles . 13
5.5 Minimal specifications of ζ measurement analyser . 13
6 Results to be reported . 13
6.1 General . 13
6.2 Product/sample identification . 14
6.3 Test conditions . 14
6.4 Measurement-specific information . 14
6.5 ζ and dispersion stability . 14
Annex A (informative) Application, worked examples . 15
A.1 Example 1 – Results . 15
A.2 Example 2 – Results . 17
A.3 Theory of ζ . 26

Figure 1 – Pictorial visualization of factors associated with ζ. 8
Figure 2 – Schematic of ζ measurement setup . 10
Figure 3 – Mechanism of ζ analyser for electrophoresis . 12
Figure A.1 – ζ distributions for single-walled carbon nanotubes (SWNTs) functionalized
with different surfactants and their concentrations in deionized (DI) water solution . 15
Figure A.2 – Histograms of average values of ζ distributions SWNTs that are shown in
Figure A.1 . 16
Figure A.3 – Optical images for SWNTs that are shown in Figure A.1 . 17
Figure A.4 – Histograms of ζ values (in mV) for initially dispersed samples of SWNTs,
graphene oxide, carbon black, and graphite in DI water and with various surfactants at
different concentrations as shown in Table A.2 . 19
Figure A.5 – Histograms of ζ values for SWNTs, GO, carbon black, and graphite in DI
water and with various surfactants at different concentrations, measured 5 days after
initial dispersion . 20
Figure A.6 – Histograms of ζ values for initially dispersed samples of SWNTs, GO,
carbon black, and graphite in DI water and with various surfactants at different
concentrations, with corresponding dispersion images . 20
Figure A.7 – Histograms of ζ values for SWNTs, GO, carbon black, and graphite in DI
water and with various surfactants at different concentrations, measured 5 days after
initial dispersion, with corresponding dispersion images . 21
Figure A.8 – Histograms of ζ values in different solvents for each nano-carbon material
(SWNTs, GO, carbon black, and graphite) in initially dispersed samples, with
corresponding dispersion images . 22
Figure A.9 – Histograms of ζ values in different solvents for each nano-carbon material
(SWNTs, GO, carbon black, and graphite) measured 5 days after initial dispersion, with
corresponding dispersion images . 23
Figure A.10 – Histograms of ζ changes over time for SWNT in different solvents,
comparing initially dispersed samples with measurements taken 5 days later, with
corresponding dispersion images . 24
Figure A.11 – Histograms of ζ changes over time for GO in different solvents,
comparing initially dispersed samples with measurements taken 5 days later, with
corresponding dispersion images . 25
Figure A.12 – Histograms of ζ changes over time for carbon black in different solvents,
comparing initially dispersed samples with measurements taken 5 days later, with
corresponding dispersion images . 25
Figure A.13 – Histograms of ζ changes over time for graphite in different solvents,
comparing initially dispersed samples with measurements taken 5 days later, with
corresponding dispersion images . 26
Figure A.14 – Plot showing the interatomic forces versus distance. 27
Figure A.15 – Decrease of electrical repulsion with increasing ion concentration (C) . 27
Figure A.16 – Steric and electrostatic stabilization mechanisms of colloidal dispersions . 28
Figure A.17 – Schematic to represent inter-dependency between charged particles and
ζ data. 29

Table 1 – Stability establishment based on ζ values . 9
Table A.1 – Average values of ζ and pH of SWNTs that are shown in Figure A.1 . 16
Table A.2 – pH values for initially dispersed samples of SWNTs, GO, carbon black,
and graphite in DI water and with various surfactants at different concentrations . 18
Table A.3 – ζ values for initially dispersed samples of SWNTs, GO, carbon black, and
graphite in DI water and with various surfactants at different concentrations . 18
Table A.4 – ζ values for SWNTs, GO, carbon black, and graphite in DI water and with
various surfactants at different concentrations, measured 5 days after initial dispersion . 19

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Nanomanufacturing - Key control characteristics -
Part 4-11: Nano-enabled energy storage - Dispersion stability of
nano-carbon materials for the electrodes of lithium-ion capacitors:
zeta potential method
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as "IEC Publication(s)"). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC TS 62607-4-11 has been prepared by IEC technical committee 113: Nanotechnology for
electrotechnical products and systems. It is a Technical Specification.
The text of this Technical Specification is based on the following documents:
Draft Report on voting
113/934/DTS 113/951/RVDTS
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Specification is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts in the IEC 62607 series, published under the general title Nanomanufacturing -
Key control characteristics, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
INTRODUCTION
Zeta potential (ζ), a key parameter in colloidal dispersion systems, is defined as the potential
difference between the slipping plane and dispersion medium. This potential reflects the
interaction between charged particles in suspension and is directly influenced by the distance
between the particle surface and the bulk fluid where the mobile phase interacts with the
stationary fluid layer.
In industrial contexts, ζ serves as a critical measure for determining the stability of colloidal
systems. Its utility extends across various sectors, such as pharmaceuticals, wastewater
treatment, and food production, where the control of colloidal stability is essential for product
performance. High ζ values typically indicate strong electrostatic repulsion between particles,
minimizing aggregation and ensuring system stability. Conversely, low ζ values suggest a
dominance of attractive forces, potentially leading to flocculation or coagulation.
Given its broad relevance, the method for measuring ζ has become indispensable in ensuring
the quality and functionality of colloidal formulations. This document explores the principle of ζ
and its measurement, while emphasizing its industrial applications and the associated
requirements for different sectors.

1 Scope
This part of IEC 62607 specifies the dispersion stability by using the zeta potential (ζ) method
for nano-carbon materials for lithium-ion capacitors. This document describes not only the
dispersion stability of nano-carbon materials but also the effect of different surfactants as well
as the evaluation method for testing long-term dispersion stability using ζ. This document
describes:
– Dispersion stability of nano-carbon materials using ζ for lithium-ion capacitors using carbon
nanomaterials as electrodes
– Effect of different surfactants
– Evaluation of long-term dispersion stability using the ζ method
2 Normative references
There are no normative references in this document.
3 Terms and definitions
3.1 General related terms
3.1.1
zeta potential
𝜻𝜻
potential difference between the slipping plane and dispersion medium
3.1.2
dispersion
system in which distributed particles of one material are dispersed in a
continuous phase of another material
3.1.3
colloid
mixture in which one substance consisting of microscopically dispersed insoluble particles is
suspended throughout another substance
3.1.4
nano-carbon materials
carbon nanomaterials
morphologically confined objects, generally formed in nanometre size either in zero, one, or two
dimensions, which are made up of carbon atoms with conjugated 𝜋𝜋-electron systems at their
surfaces
Note 1 to entry: Examples include fullerenes, carbon nanotubes, graphene, graphene oxide, carbon nanofibers,
carbon blacks, and carbon onions, etc.
3.1.5
surfactant
compound that lowers the surface tension (or interfacial tension) between two liquids, between
a gas and a liquid, or between a liquid and a solid
3.1.6
electric double-layer
EDL
spatial distribution of electric charges that appears on and at the vicinity of the surface of an
object when it is placed in contact with a liquid
3.1.7
Stern layer
first (internal) layer that is comprised of a layer of ions charged oppositely to the surface which
attach to the surface of the electric double-layer, which forms at a charged surface in an ionic
solution
3.1.8
slipping plane
abstract plane in the vicinity of the liquid/solid interface where liquid starts to slide relative to
the surface under influence of a shear stress
3.1.9
surface charge
charge on an interface per area due to specific adsorption of ions from the liquid bulk, or due
to dissociation of the surface groups
3.1.10
stability of colloidal dispersion
stability which is defined in terms of its ability to contain its chemical and physical
configurations, such as composition, formulation, and arrangement, over a period of time or
under different physiological conditions (e.g., temperature, light, humidity, polarity, pH, etc.)
3.2 Key control characteristics measured according to this document
3.2.1
key control characteristic
material property or intermediate product characteristic which can affect safety or compliance
with regulations, fit, function, performance, quality, reliability, and subsequent processing of the
final product
Note 1 to entry: The measurement of a key control characteristic is described in a standardized measurement
procedure with known accuracy and precision.
Note 2 to entry: It is possible to define more than one measurement method for a key control characteristic if the
correlation of the results is well-defined and known.
Note 3 to entry: In ISO TC 16949 the term "special characteristic" is used for a KCC. The term key control
characteristic is preferred since it emphasizes the relevance of the parameter for the quality of the final product.
Note 4 to entry: The terms "key performance indicator" or "property" shall not be used to indicate the special
meaning of key control characteristics concerning blank detail specification.
3.2.2
magnitude and sign of zeta potential
indications of the colloidal system's stability, with a high potential (positive or negative)
providing electrostatic repulsion to prevent aggregation, while a low potential allows attractive
forces to dominate, leading to coagulation or flocculation
4 Measurement principle and sample preparation method
4.1 Measurement principle
The zeta potential (ζ) is the potential difference between the slipping plane and dispersion
medium, where the mobile fluid is separated from the one that remains attached to the surface
of colloidal particles, as shown in Figure 1.
Figure 1 – Pictorial visualization of factors associated with ζ
The electro-kinetic potential in colloidal dispersions is known as zeta potential (ζ). The Greek
symbol zeta (ζ), which stands for "potential", is frequently used in the literature on colloidal
chemistry. ζ is often expressed in terms of volt (V), or more commonly, millivolt (mV). ζ is the
electric potential in the interfacial double layer (DL) at the position of the sliding plane
concerning a point in the bulk fluid distant from the interface, according to theory. ζ, then, is the
potential difference between the stationary fluid layer associated with the dispersed particle
and the dispersion medium.
The position of the slipping plane affects ζ, which is brought on by the net electrical charge
present in the area it bounds. Thus, it is widely used for quantification of the magnitude of the
charge. However, ζ is not equal to the Stern potential or electric surface potential in the double
layer, because these are defined at different locations. Applying such equality presumptions
should be done with care. ζ, however, is frequently the sole route available for characterizing
double-layer features.
The stability behaviour of colloidal particles refers to their ability to remain dispersed in a fluid
without aggregating or settling over time, and it is influenced by several factors, including the
size, shape, charge, and concentration of the part
...