On 18 August 2028, EV, SLI and industrial batteries (over 2 kWh) must for the first time declare how large a share of their cobalt, lithium, nickel and lead comes from recycled material. Three years later, on 18 August 2031, the first minimum thresholds take effect: 16% cobalt, 6% lithium, 6% nickel and 85% lead must come from recycled sources. In 2036, the thresholds rise further.
That sounds simple, until you ask the question: How do you prove it?
Cobalt from a recycling plant in Germany can be mixed with virgin cobalt from a mine in Congo, refined in China, shipped to a cathode factory in Poland, and end up in a battery pack in Sweden. The physical molecule cannot be told apart. And yet the Battery Regulation requires you to be able to document exactly what percentage of the cobalt in each battery comes from recycled sources, and that an independent third party can verify it.
The answer is called mass balance. This article explains what it is, how Article 8 works, and which documentation chain you need to build to declare recycled content credibly and lawfully.
- →2028 deadline: EV, SLI and industrial batteries (over 2 kWh) must declare the recycled content of cobalt, lithium, nickel and lead from 18 August 2028. From 2031, minimum thresholds take effect. Non-compliance means loss of market access in the EU.
- →Mass balance is the only realistic documentation model. Physical segregation is technically impossible; book and claim is not approved. Mass balance requires auditable accounting according to ISO 22095 at every tier of the supply chain.
- →Verification is carried out by a notified body, not by the manufacturer itself. Notified bodies have limited capacity, and the 2028-2031 period will be heavily booked.
- →A 10-year audit trail. The documentation must remain auditable throughout the battery's life, even if suppliers drop out or systems are replaced. It is an information architecture, not a folder of PDFs.
Article 8: what does the Battery Regulation require?
Article 8 of the Battery Regulation (EU) 2023/1542 contains two layers of requirements that take effect in phases:
The declaration obligation. From 18 August 2028, the technical documentation for EV, SLI and industrial batteries (over 2 kWh) must contain information on how large a share of the cobalt, lithium, nickel and lead in the active materials comes from recycled sources, stated per battery model and per production batch and plant. For LMT batteries, the same obligation applies from 18 August 2033.
Minimum thresholds. From 18 August 2031, the same battery categories must contain at least 16% cobalt, 6% lithium, 6% nickel and 85% lead from recycled sources. In 2036, the thresholds rise to 26% cobalt, 12% lithium and 15% nickel, while lead remains at 85%.
"Recycled sources" is defined broadly: it includes both post-consumer waste (finished products that have reached end of life) and pre-consumer waste from production (such as discarded materials from the battery factory). Both sources count, but must be documented separately.
The declaration must be included in the battery passport, and it must be verified by a notified body before the battery can be placed on the market in the categories concerned.
Why mass balance and not just segregation?
In practice, there are three ways to document the content of recycled material in a complex supply chain, defined in the international standard ISO 22095:2020, which governs chain of custody models:
1. Physical segregation (identity preservation)
Recycled material is kept completely separate from virgin material throughout the supply chain. Each batch can be traced back to a specific source. Advantage: maximum credibility. Disadvantage: technically and economically unrealistic for the vast majority of battery materials, because refineries and smelters cannot run separate production streams for small quantities.
2. Mass balance
Recycled and virgin material are mixed physically, but kept separate in the accounting. If a refinery receives 100 tonnes of cobalt (of which 30 tonnes from recycled sources), up to 30 tonnes of the finished refined cobalt can be shipped with a "30% recycled content" attribution, even though it is physically a mixture. Advantage: technically realistic and widely established. Disadvantage: requires strict accounting and an independent audit.
3. Book and claim
Certificates for recycled content are traded independently of the physical material, like CO₂ allowances. Advantage: maximum market flexibility. Disadvantage: no physical link between certificate and product, which is why the model is not accepted for the Battery Regulation's recycled content declarations.
For batteries, mass balance is in practice the only usable model. It is established in the industry through ISO 22095, recognised by suppliers such as Umicore (cobalt refining) and BASF (cathode material), and audited by the same notified bodies that will verify the battery passport's declarations.
The central consequence: a battery passport declaration of "16% recycled cobalt" does not mean that every single cobalt atom in the battery comes from a recycled battery. It means the manufacturer can document that a quantity of mass balance-certified recycled cobalt corresponding to 16% of the total cobalt content has been purchased in the supply chain, and that this documentation can be audited.
The documentation chain required
For a mass balance declaration to be approved by a notified body, each tier of the supply chain must provide documentation that fits together. This is where the complexity lies, and where most manufacturers underestimate the scope.
A typical chain for cobalt from recycled battery material looks like this:
Recycling plant. Receives spent batteries, extracts cobalt-bearing materials, and issues mass balance certificates for the recovered cobalt. The plant itself must be certified to ISO 22095 or a sector-specific standard, and its accounting period must be continuous.
Refinery. Smelts and purifies cobalt from both recycled and virgin sources. The mass balance certificate is passed on in proportion to the incoming quantity, but the physical product is a mixture. The refinery must maintain accounts showing that it never issues more certified recycled cobalt than it receives.
Cathode/active material producer. Buys refined cobalt and incorporates it into the cathode material (typically NMC or LFP). The mass balance certificate is allocated to specific production batches, which can then be traced to battery cell producers.
Cell manufacturer. Receives cathode material with a mass balance attribution and produces cells. The allocation follows in the form of data points per batch.
Battery pack producer (OEM). Assembles cells into battery packs, allocates mass balance data to each pack, and enters the declaration in the battery passport for the specific product.
Each tier of the chain must be able to present auditable documentation covering at least 10 years back, in line with the Battery Regulation's general documentation period. It is not a certificate file; it is a coherent data architecture that ties supplier certificates, production batches, purchase orders and battery models together.
Verification by a notified body
The verification itself is carried out by a notified body, an accredited third-party body designated by the authorities to assess conformity with the Battery Regulation. The verification process typically includes:
- Audit of the mass balance accounting. A sample-based review of whether incoming and outgoing quantities balance over a defined period (typically monthly or quarterly).
- Verification of the supply chain. Confirmation that upstream suppliers are themselves certified, and that their certificates are valid and cover the quantities concerned.
- Traceability to battery model and batch. Demonstration that a specific mass balance attribution can be linked to a specific battery model and production batch, not just to the company in general.
- Periodic re-verification. Verification is not a one-off event. It must be repeated at regular intervals, typically annually or in the event of significant changes in the supply chain.
For manufacturers with several product lines and suppliers, verification can grow into an extensive project, especially if the accounting is spread across different systems or exists in unstructured formats (PDF declarations, emails, spreadsheets).
There is a further time factor many underestimate: notified bodies are limited in number, and each can only handle a certain number of verifications in parallel. As the 2028 deadline approaches, capacity across the EU's pool of notified bodies will be under pressure at the same time. Manufacturers that only sign an agreement in 2027 risk waiting in line, while competitors that established the relationship and pre-tested the documentation earlier get their batteries approved and placed on the market without interruption.
Where are the traps?
Three mistakes recur among manufacturers that have just started addressing the recycled content requirements:
Trap 1: Treating supplier declarations as sufficient documentation. A PDF declaration from a supplier stating that "our cobalt contains 30% recycled content" is not a mass balance attribution. It is an undocumented claim. A notified body will ask for the underlying mass balance certificate, the ISO 22095 accreditation and the audit documentation, which the supplier may not be able or willing to share.
Trap 2: Mixing mass balance attribution across product lines. If a manufacturer receives mass balance cobalt in one production period and uses it in two different battery pack models, the allocation must be explicit. A battery passport declaring 16% recycled content without the allocation being traceable to the specific model and batch fails verification.
Trap 3: Underestimating the 10-year documentation. The battery passport follows the battery throughout its life, which for EV batteries can be 10-15 years. The recycled content declaration must remain verifiable throughout this period, which means supplier certificates, production data and audit trails must be archived in a structured way. It is not a compliance deliverable; it is an information architecture obligation.
Timeline: what happens when?
The recycled content requirements unfold over a long schedule, but the early milestones are already close:
- 18 August 2028: The declaration obligation takes effect for EV, SLI and industrial batteries (over 2 kWh). Manufacturers must be able to document the recycled content of cobalt, lithium, nickel and lead in the technical documentation and in the battery passport.
- 18 August 2031: Minimum thresholds take effect: 16% cobalt, 6% lithium, 6% nickel, 85% lead. Batteries that do not meet the thresholds cannot be placed on the market.
- 18 August 2033: The declaration obligation is extended to LMT batteries.
- 18 August 2036: The thresholds rise: 26% cobalt, 12% lithium, 15% nickel, 85% lead.
For a manufacturer with a new battery model launching in 2027 or 2028, the supply chain work must be in place now. Mass balance certification at suppliers takes 6-12 months to set up from scratch. The audit procedures at notified bodies must be run in. And the underlying documentation structure must be designed before the first batch is produced, not retrofitted afterwards.
What the battery passport does differently
The recycled content declaration is one of the most data-heavy sections of the digital battery passport. It combines several types of information that have traditionally lived in separate systems, and this is where the vast majority of manufacturers hit a wall. Purchasing data sits in the ERP. Mass balance certificates sit as PDFs in quality management. Production batches sit in the MES. Audit trails from notified bodies arrive as reports in emails.
The battery passport requires this data to be merged and presented as one consistent declaration per battery, and to remain auditable for 10 years. That is the architectural challenge: not collecting the individual pieces of data, but structuring them so they can be navigated by a notified body during an audit, and by a recycler a decade later. A central compliance platform (a single source of truth) is in practice the prerequisite for making this feasible.
The manufacturers that build the battery passport structure now are at the same time building the documentation chain that makes recycled content verification feasible. Conversely, manufacturers that wait with the battery passport work until 2027 will find themselves with both a compliance deadline and a disorganised data landscape at the same time.
What you can do now
For manufacturers of EV, SLI and industrial batteries, four steps are worth taking already in 2026:
- Map your current supply chain for the four metals. Which suppliers are certified to ISO 22095? Which can issue mass balance certificates? Which cannot, and what is your alternative supplier?
- Set up a data structure that ties purchasing, certificates, production and product data together. An existing system can rarely handle this in isolation; typically data from ERP, MES and the quality management system must be consolidated in a compliance platform.
- Agree the verification process with a notified body early. Notified bodies have limited capacity, and the 2028-2031 period will be heavily booked. Establishing the relationship and pre-testing the documentation a year before the deadline is a competitive advantage.
- Design for a 10-year audit trail. The documentation structure must be able to remain unchanged for 10 years, even if a supplier drops out, a refinery changes owner, or a new ERP is rolled out.
Recycled content is not just an environmental metric. It is a legal requirement for market access, an audit obligation over 10 years, and one of the most complex data points in the whole battery passport. The manufacturer that sees it as three separate things will discover that it is in fact one integrated architecture, and that the architecture must be designed now.
