Ultralight and High Thermal Conductive Current Collector Derived from Polyimide for Advanced LIBs

Abstract

Currently, the thermal runaway of lithium-ion batteries (LIBs) has become one of its most concerned safety hazards. Therefore, battery cells with high safety and energy density have become the important goal for the development of LIBs. In this work, the ultralight and high thermal conductivity of the Cu@graphene-like thermal film (shortened as Cu@GTF) composite current collector with a sandwich structure was derived from polyimide and prepared by the vacuum evaporation method. Compared with the commercial copper foil, the Cu@GTF showed a smaller areal density of <7.0 mg/cm2 (vs 17.50 mg/cm2 of commercial Cu foil) and a higher thermal conductivity of >550 mm2/s (vs 164 mm2/s of Cu foil). Considering its lighter mass, higher thermal conductivity, and reasonable electrical conductivity, the Cu@GTF as a current collector may become a favorable competitor of the commercial Cu foil to meet people’s needs for high safety, energy, and performance of LIBs.

Developments, Novel Concepts, and Challenges of Current Collectors: From Conventional Lithium Batteries to All‐Solid‐State Batteries

“…Moreover, the composite current collectors with a sandwich structure are reported to be able to avoid thermal runaway in LIBs which have become a favourable competitor of commercial metal foils to meet the needs for high safety, energy, and performance of LIBs. [77,78] What's more, Ye et al [78] prepared an ultralight polyimide-based current collector (9 μm thick, specific mass 1.54 mg cm À 2 ) by sandwiching a polyimide embedded with triphenyl phosphate flame retardant between two thin Cu layers (~500 nm), full cells equipped with the 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.…”

Pea-Pod-like Carbon Microspheres Encapsulated by Graphene-like Carbon Nitride for Enhanced Thermal Conductivity in Polyimide Films

“…One common strategy to upgrade the heat transfer capacity of PI film was proposed by integrating one-dimensional (1D) or two-dimensional (2D) highly thermally conductive filler such as carbon nanotube (CNT), Ag nanowires (AgNW), boron nitride (BN), and graphene into the PI matrix constructing an effective heat path. − For instance, Cao et al fabricated PI/BNNS nanocomposites with the resultant thermal conductivity of 4.25 W m –1 K –1 by adding 12.4 vol % BNNS. Dong et al obtained BNNS-AgNW/PI nanocomposite by hot-pressing treatment to regulate the oriented distribution of BNNS and realize the role of AgNW as a thermally conductive bridge to enhance in-plane thermal conductivity to 4.75 W m –1 K –1 .…”