Lithium Ion Battery with TEAM: Nancy Dudney, Mat. Sci. and Tech. Div., Oak Ridge National Lab, njdudney@ornl.gov (865)576 4874 Integrated Abuse Tolerant ORNL: Michael Naguib, Srikanth Allu, Electrode Features Srdjan Simunovic, Jianlin Li, and Hsin Wang GM: Mei Cai, Mahmoud Abdelhamid, Fang Dai Technology Overview Goal: Design abuse tolerant component Current Status to prevent rapid failure in the event of Status : Concept proven in full cell (experiment collision or other mechanical abuse . and modeling). Fabricating early prototypes. • Next Technical: Choose best prototype in small Implemented component at the cell level full Li-ion cells with abuse tests (with minimum impact on the cost and Next Development : Fund extended effort (2yr.) energy density) • Identify practical manufacturing. Demonstrate Reduce need for heavy and expensive performance with larger batteries and realistic battery protection abuse test. Help needed: Partner for component fabrication Isolate the damage and Partner for battery assembly. upon impact • Project Statistics Limit the current • . Limit the heat Award Amount $450,000 • Minimize damage July, 2014 – June, 2015 Award Timeline • Maintain partial function – to drive Next Stage Target Phase 1, $4M over 2 year home • materials fabrication Collaborations • battery assembly & testing Sought
Concept - mechanically damaged area of battery is separated from the rest of cell, isolating potential short circuits. • Crushed or penetrated area of battery is isolated from the remaining capacity. ► limit current through short ► limit local heating, avoid thermal runaway ► minimize added cost, added weight ► maintain good performance and reliability Voltage profile of formation cycles from a full coin cell • Baseline battery 4 ► pouch single layer (63 mAh) 3 Voltage (V) ► LiNi 0.5 Mn 0.3 Co 0.2 O 2 (532)/ graphite 2 ► electrolyte LiPF 6 (DEC+EC) Voltage_C1 (V) Voltage_D1 (V) Voltage_C2 (V) Voltage_D2(V) 1 0 0 50 100 150 200 Capacity (mAh/g) 2
Proof of concept - abuse tolerant electrode Compare standard and modified batteries Large single layer vacuum sealed pouch of LMNC vs graphite • Use steel dart for internal short circuit • Monitor temperature (IR camera) and OCV (battery tester) observation modified standard battery (63 mAh) modified standard cathode cathode anode anode OCV for slow discharge; 0 volts when internal short <10mV after 5 shorted hours ∆ T max for 2°C at 4 sec 19°C at 3 internal short sec OCV OCV
Proof of concept - abuse tolerant electrode Compare standard and modified batteries 1.0 sec after shorting with steel dart Modified battery Standard battery 35.0° 27.6 ° dart dart 23.0 ° 23.1 °
Simulation of battery discharge • Mimic short by quickly bringing current collectors to the same potential, in this case each to 1.2V vs Li. • Isolated area of modified battery shows no Fully charged cell discharge at 10 sec. next to, but isolated from shorted area • Realistic current upon short 1.6 4 experiment 1.2 3 Current, A Volt Li Concentration 0.8 2 cathode anode 0.4 1 0 0 58 60 62 64 66 68 70 current (C-rate) Time, s colors represent simulation Li content distance 5 time (sec)
Test prototypes of abuse tolerant electrodes • Impact testing of dry cells – Simple tests with external 3V battery – Three prototype designs tested to date 1 Ω – Single cell, electrodes and separator, no electrolyte • Drop test of large ball electrode battery impact against smaller metal or design fabrication test ceramic ball standard shorted • Next steps modified1 (engineer easier to Gen1 current electrode) implement shorted – Alternate designs and Gen-2 prototypes modified 2 likely damage (replace component) impractical isolated – Stacked layers for multi- modified 3 possible damage cell battery evaluation (low cost additive) isolated
Status at 6 months - summary • Major accomplishments • Established proof of concept with full batteries • Reduced current and heat from internal short, but not fully isolated. • Developed analytical model specific for our concept • Fabricated early prototypes of the abuse tolerant component • Lessons learned • Proof of concept was more complex than anticipated. • Mechanism preventing full isolation has not been identified. • Experimental scope for remaining 6 months • Evaluate alternative abuse-tolerant component design • Test in dry multi-cell stack • Incorporate into full Li-ion battery • Program goal – extend R&D (2 years), lead to commercial product • Collaborations for R&D – component fabrication, battery assembly
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