Ion‐Conducting, Electron‐Blocking Layer for High‐Performance Solid Electrolytes

Abstract

Lithium metal batteries bring greater promise for energy density, often relying on solid‐state electrolytes to meet critical benchmarks. However, Li dendrite formation is a prevailing problem that limits the cycle life and Coulombic efficiency of solid‐state Li metal batteries. For the first time, a thin (<100 nm) layer of electronically insulating, ionically conducting lithium phosphorus oxynitride (LiPON) is applied using atomic layer deposition between a Li anode and garnet Li7La3Zr2O12 (LLZO). The performance of a conformal LiPON layer as an electron barrier in symmetric Li‐LLZO cells is observed through potential step chronoamperometry, galvanostatic cycling, electron microscopy, and various spectroscopic techniques. The LiPON‐coated LLZO achieves 100 times lower electronic conductance than LLZO alone. Cycling carried out at 0.1 mA cm−2 for 100 cycles demonstrates that suppression of electron pathways into the bulk solid electrolyte improves the cycle life of a lithium metal cell. These findings suggest an electronic conductivity effect in solid‐state electrolytes. A strategy is demonstrated to design thin‐film (LiPON)‐modulated bulk solid‐state electrolytes (LLZO) capable of maintaining high ionic conductivity and electrochemical stability while reducing the effective electronic conductivity, which results in significantly decreased dendrite formation, improved cycle life, and greater interfacial integrity between the electrolyte and a Li anode.

Mesoporous Carbon as Conductive Additive to Improve the High‐Rate Charge/Discharge Capacity of Lithium‐Ion Batteries

“…Electrochemical impedance spectroscopy (EIS) is the most common method to measure the ionic conductivity. [43,44] Sandwich symmetric cells with conductive additives inserting into two stainless steel pieces are assembled to measure the ionic conductivity (Figure 2a). All the EIS plots of BMC-1400, CNT, and Super-P show straight lines in the whole first quadrant (Figure 2b).…”

Fast‐Charging Solid‐State Lithium Metal Batteries: A Review

“…The coating layer can effectively inhibit the contact reaction between garnet electrolyte and electrode materials, and reduce the interface resistance from 1710 to 1 Ω cm −2 ( Figure a). Hitz et al [ 166 ] also used ALD method to coat a thin layer of lithium phosphorus oxynitride (LiPON) between the lithium anode and garnet LLZO (Figure 11b). This coating can not only improve the wettability of Li metal but also reduce the electronic conductance of the interface by 100 times, while the ion conductivity maintains high.…”

“…Reproduced with permission. [ 166 ] Copyright 2021, Wiley‐VCH GmbH. c) The manufacturing process of Li‐C 3 N 4 composite and the interfacial contact comparison of Li–garnet SSE interface.…”

“…b) Schematic diagram of coating an ion-conducting, electron-blocking layer by ALD method. Reproduced with permission [166]. Copyright 2021, Wiley-VCH GmbH.…”

The Influence of Surface Chemistry on Critical Current Density for Garnet Electrolyte

“…In addition, we believe such ion-conducting and electron-blocking interlayers can help to enhance the CCD. [36] The lithiophilicity, ASR, and CCD for the four groups are summarized in Figure 6. For the control group, during exposure to air, Li 2 CO 3 accumulates greatly.…”