Nuclear engineering

Electrical engineering

Physics

Current (fluid)

Automotive engineering

Electrode

Organic chemistry

Current density

Engineering physics

Energy storage

Endocrinology

Civil engineering

Engineering

Physical chemistry

Composite material

Power (physics)

Chemistry

Materials science

Fire retardant

Current collector

Polyimide

Lithium (medication)

Layer (electronics)

Fire safety

Battery (electricity)

Quantum mechanics

Electrolyte

Energy density

Medicine

Thermal runaway

FOIL method

Nature Energy

Inactive components and safety hazards are two critical challenges in realizing high-energy lithium-ion batteries. Metal foil current collectors with high density are typically an integrated part of lithium-ion batteries yet deliver no capacity. Meanwhile, high-energy batteries can entail increased fire safety issues. Here we report a composite current collector design that simultaneously minimizes the ‘dead weight’ within the cell and improves fire safety. An ultralight polyimide-based current collector (9 μm thick, specific mass 1.54 mg cm−2) is prepared by sandwiching a polyimide embedded with triphenyl phosphate flame retardant between two superthin Cu layers (~500 nm). Compared to lithium-ion batteries assembled with the thinnest commercial metal foil current collectors (~6 µm), batteries equipped with our composite current collectors can realize a 16–26% improvement in specific energy and rapidly self-extinguish fires under extreme conditions such as short circuits and thermal runaway. Batteries need to be energy-dense as well as safe. Yi Cui and team develop an ultralight polyimide-based current collector with embedded fire retardants that enables lithium-ion batteries with much-enhanced safety and energy density.

Ultralight and fire-extinguishing current collectors for high-energy and high-safety lithium-ion batteries