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Lithium metal batteries (LMBs) outperform lithium-ion batteries in the aspect of energy density as they use lithium metal as the anode that has extremely high energy density and low potential. However, the development of LMBs is hampered by uncontrollable Li plating morphology and inferior Coulombic efficiency (CE) during cycling. In the past decade, electrolyte development has been recognized as one of the most effective strategies to tackle these two challenges. Much progress has been made through designing advanced electrolytes, especially ether-based electrolytes, in developing LMBs. Herein, we focus on summarizing the use of additives in ether-based electrolytes to enable high-performance LMBs. The impact of additives in electrolytes on lithium metal anode (LMA) protection, cathode protection, extreme temperature operation, and fast charging for LMBs are systematically discussed. The review reveals the significance of additive engineering in developing advanced electrolytes for high-energy–density LMBs. [ABSTRACT FROM AUTHOR]

A single-ion conducting polymetric artificial solid electrolyte interphase (SICP-ASEI) is rationally designed to improve the cycling performance of Li-metal batteries (LMBs) under high charging rate. The SICP with high cationic transport number (0.84) is obtained by polymerization of LiSTFSI and polyethylene (ethylene glycol) methacrylate following by chemical crosslinking. The LMBs with SICP-ASEI can achieve improved energy efficiency and prolonged cell lifetime, including (i) high cycling stability (over 1000 h cycling) and limited polarization voltage (< 95 mV at ± 1 mA cm−2) on symmetrical cells and (ii) high-capacity retention of 84.3% after 200 cycles at 1 C and over 102 mAh g−1 at high charging rate of 2 C on full cell coupled with high-mass-loading cathode. [ABSTRACT FROM AUTHOR]

Reactive flash synthesis simplifies the processing of complex ceramics such as alumina doped lithium lanthanum zirconate. Low temperatures and short processing times obviate the loss of lithium while producing dense single-phase ceramics. Here we show the synthesis of non-stoichiometric compositions of this ceramic which increases the ionic conductivity by a factor of more than three. The non-stoichiometry refers to non-equilibrium lithium/lanthanum ratio, and to the addition of boron to produce excess lithium-ion vacancies. The results open the possibility of using non-stoichiometry as a concept, and RFS as the tool, for the discovery of new compositions that enhance lithium-ion conductivity. [ABSTRACT FROM AUTHOR]

We show that foreign second phase particles incorporated into the lithium metal-ceramic-electrolyte interface catalyze nucleation of voids, which, at first, lead to higher voltage and then to voltage collapse in constant current experiments. Voltage increases because voids grow the area-specific resistance. The collapse is caused by dendrites. Cell manufacture in high class clean room environments is recommended for the sake of reliability and increased performance. [ABSTRACT FROM AUTHOR]

We show a systematic correlation between temperature, critical current density (CCD), and ASR. The ASR declines while the CCD increases with temperature. The behavior is consistent with a void nucleation model for cell failure. Void nucleation is driven by the cell voltage: a lower ASR reduces the voltage which helps to raise the critical current density. The voids are postulated to be precipitated by local concentrations of electrochemical currents which pull lithium into the electrolyte leaving behind a void in the lithium layer across from the interface. We also report on a possible method for reducing the non-uniformity of current flow across the interface by introducing a layer of silver at the interface. It has the effect of increasing the CCD to 3.5 mA cm−2 at elevated temperature. [ABSTRACT FROM AUTHOR]

The local current at a constriction can be higher than the average current, which can lower the engineering value of the critical current density in lithium-ion cells. We show that X-ray Computed Tomography can be used to image the extent and the length scale of this constriction. The constriction is seen by comparing the in-plane thickness profile of the lithium metal at the anode before, and then at the cathode after full discharge. Remarkable discrepancy between these two images highlights the nature of the constriction. [ABSTRACT FROM AUTHOR]