CURRENT AND FUTURE PROPAGATION TEST AND THE EMBEDDING IN PRODUCT SAFETY THOMAS TIMKE, JRC

Transcription

1 CURRENT AND FUTURE PROPAGATION TEST AND THE EMBEDDING IN PRODUCT SAFETY THOMAS TIMKE, JRC

2 SOLARWATT COMMITMENT Safety Not negotiable Lifetime & Performance Current main topic in Germany Complete sharing with DIN, IEC, VDE AR, funding requirements and standards in other countries Input for test methods but no competition via it might burn somewhere else 2

3 For what reason ever something (safety critical) happens inside a cell means not to know enough about it. To test propagation with a thermal runaway is the resulting worst case approach. To be closer to the cell means to test closer to reality (which does not exclude thermal runaways).

4 A Li-ion battery is safe enough, if you sleep next to it despite knowing all possible effects TT

5 Published November 2014 Online available free of charge Key points as input in future IEC and DIN EN norms Complements the state of the art Propagation test mandatory Current status: Several systems in tested and under redesign & testing No update necessary until now Testing Guide available from BVES Basis for VDE-AR-E Future standards and activities IEC ed2. Lithium Ion core knowledge as input for the DIN standardization roadmap

6 Global SHORT OVERVIEW APPLICATION RULE AND SAFETY GUIDELINE VDE-AR-E :2017 & Safety Guideline for Li-Ion-Home storage V1.0 EU Product Safety Directive Transport Recyling. EU Germany Closed Gaps in standards Battery- Safety (DIN) EN 62619* DIN EN EU conformity (CE) EMD- Directive (DIN) EN x* LV Directive (DIN) EN * e.g. GGVSEB ADR + UN38.3 e.g. Battery law Battery- Directive IEC 62619* IEC 61000* IEC * UN Model- Regulation + UN38.3 National standards *possible standards

7 Cell temperature MAIN GAP CLOSED: PRELIMINARY DAMAGE BY CELL OUTSIDE ITS SPECIFIED REGION. Closed Gaps in standards Example NMC/G C Cell voltage V 1. Battery-Design 2. Environment No cell shall leave its operating region Worst Case: All cells fail e.g. because of battery overcharge 3.cell-internal failure: during proper operation Worst Case: Thermal runaway and propagation

8 CELL RISK SCHEME VDE-AR-E :2017 Table A.3 cell characteristics for risk evaluation 1 Option Likelyhood and/oder severity reducing Likelyhood and/oder severity increasing Cell manufacturing Fully automated Partially manual Energy density Low (e.g. <130 Wh/kg) High (e.g.. >190 Wh/kg) Single cell capacity Low (e.g. <50 Ah) High (e.g. >100 Ah) CID and/or PTC for parallel cells Ceramic layer between anode and cathode Thermal conductivity of cell housing or packaging Sealing, material of cell housing or packaging Cycle stability ( under consideration of cell type) Yes Yes High High Quality low/no humidity transfer High No No Low Low quality, side reactions Low

9 THE HONEST POUCH CELLS. Nearly every quality or design problem shows Sheet cutting and/or packaging problem Potential short circuit between anode and aluminum cathode layer Source: KIT

10 INSIDE

11 THE HONEST POUCH CELLS. Nearly every quality or design problem shows Homogeneous inhomogeneity Source: KIT

12 OTHER ISSUES Fingerprints on electrodes and separator from cells with (at least partial) manual production

13 OUR INTERNAL BATTERY RULES Preface cell safety During Analysis and relevant abuse tests, single or inside the battery, no chemical and/or thermal reaction shall be shown or appear likely, which damages one or more components in a way, that a cell internal failure over the life time happens or must be expected which causes more than minor venting (actually not even that)

14 IT STARTS WITH A GOOD CELL 53 Ah, SK Innnovation.. separator with ceramic coating 14

15 MYRESERVE BATTERY MODULE 2,4 kwh 24,9 kg Logistikoptimiertes Format 15

16 BATTERY MODULE WITH INTEGRATED SAFETY MECHANISMS Module Fuse Module Relais

17 SK 53 Ah (Pouch, NMC/Graphite) SAE-J 2464 Penetration, clause (100% SoC, Nail diameter: 3 mm Speed: 8 cm/s, Result: Hazard Level 3)

18 SK 53 Ah (Pouch, NMC/Graphite) SAE-J 2464 Penetration, clause (100% SoC, Nail diameter: 3 mm Speed: 8 cm/s, Result: Hazard Level 3)

19 SK 53 Ah (Pouch, NMC/Graphite) SAE-J 2464 Penetration, clause (100% SoC, Nail diameter: 3 mm Speed: 8 cm/s, Result: Hazard Level 3)

20 SK 53 Ah (Pouch, NMC/Graphite) SAE-J 2464 Penetration, clause (100% SoC, Nail diameter: 3 mm Speed: 8 cm/s, Result: Hazard Level 3)

21 SK 53 Ah (Pouch, NMC/Graphite) SAE-J 2464 Penetration, clause (100% SoC, Nail diameter: 3 mm Speed: 8 cm/s, Result: Hazard Level 3)

22 SK 53 Ah (Pouch, NMC/Graphite) SAE-J 2464 Penetration, clause (100% SoC, Nail diameter: 3 mm Speed: 8 cm/s, Result: Hazard Level 3-4

23 SK 53 Ah (Pouch, NMC/Graphite) SAE-J 2464 Penetration, clause (100% SoC, Nail diameter: 3 mm Speed: 8 cm/s, Result: Hazard Level 3)

24 SK 53 Ah (Pouch,NMC/Grafit) T( C) Penetration spot Ca. 13 A, 52 Watt, 300 mω T( C) Tabs

25 KNOWN OR UNKNOW CELL BACKGOUND? Reasonable battery safety is only possible if the cell is not considered as a black box with worst case potential QM Sharing Safety-experiences in TCs Documentation Product tests according to relevant standards and beyond limits Safety- and Lifetime-characterization of the cell until failures happen Selection of the test lab (accreditation, engineer, equipment, ) Selection cell manufacturer + Audit by the cell manufacturer

26 PROGNOSIS: TWO PARALLEL PROPAGATION TEST APPROACHES Requirement: No external fire from the battery system or no battery case rupture after a TR of one cell in the stack Propagation test with (mandatory) thermal runaway But: At least one cell vents. Thus, the gas must be considered in the risk analysis, because there is no test yet, which considers the realistic and possible failures of a cell. More stabile cells need to be treated harsher to initiate a thermal runaway. Current research: E.g. more standardized thermal runaway initiation Advanced propagation tests with validated cell failures Requirement: probably stricter + different safety level considering (no)venting, heat, secondary effects Goal: Propagation tests with cell (type) specific failures and their suitable consideration in risk analysis. Current research: Pre-tests for more (not necessarily completely) realistic cell specific failures. Until enough experience with advanced propagation tests has been gained, it is crucial to continue with the current tests!

27 time POSSIBLE CELL MARKET TENDENCY It is likely that the energy density including its reactivity is increased until the paths for battery design will separate. Some cell manufacturers might follow this path Some manufacturers stay under this limit or might reduce the reactivity after an overshoot * and work on increased energy density in combination with stability. They will be the suppliers for non-energy density driven applications like stationary, industrial trucks etc. Li-ion cell chemistries without potential to increase the energy density might get under price pressure because of higher material demand per kwh. energy density & reactivity * Cell energy density roadmap

28 OVERCOMING SOME ADDITIONAL GAPS Functional Safety <-> Electro chemistry (appropriate risk analyses including separate consideration of likelihood and severity) EMC (as part of functional safety) <-> BMS requirements Li-ion batteries tested as apparatuses according to similarly matured standards as inverters (e.g. IEC ).

29 store safely