A mismatch electrical conductivity skeleton enables dendrite–free and high stability lithium metal anode

Abstract

The lithium metal anode is regarded as ideal for high-energy rechargeable batteries. Unfortunately, the uncontrolled lithium dendritic growth and the infinite volume expansion upon cycling result in low Coulombic efficiency, fast capacity decay and safety issues. Herein, a mismatch electrical-conductivity framework has been designed as a stable host to regulate lithium deposition behaviour. Due to the ionic conductivity of the lithiophilic layer and the electron conductivity of hollow carbon nanofibres (HCF), lithium metal is preferentially deposited into and encapsulated by the HCF, resulting in greatly improved electrochemical performance. The heat generation upon lithium storage and release in the Al 2 O 3 coated HCF (A–HCF) during cycling is lower compared to the plating/stripping on copper foil. The A-HCF electrodes show high Coulombic efficiency (97%) upon 500 cycles employing a conventional, alkyl carbonate-based electrolyte, demonstrating improved reversibility of Li plating/stripping. Complete cells assembled employing LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NMC811)-based positive electrodes exhibit high capacity retention (94%) after 120 cycles at 1 C, delivering a high energy density (363 Wh per kg of NMC811). Even upon cycling at 5 C rate, the cells, employing less than three times excess lithium, deliver a very high capacity (133 mAh per g of NMC811) for 50 cycles. The mismatch electrical conductivity skeleton effectively regulates the lithium deposition behavior, guiding the Li metal uniform plating on the inside and along the surface of the hollow nanofibers and by this restraining dendritic Li formation as well as decreasing heat generation during cycling. • Effect of a mismatch electrical conductivity framework host (A-HCF) with plentiful cavities to regulate Li deposition behavior. • Li storage mechanism and deposition morphology. • Li storage upon long-term cycling. • Heat generation upon Li storage and release by microcalorimetry. • Electrochemical performance of Li metal cells.