Bifunctional In Situ Polymerized Interface for Stable LAGP‐Based Lithium Metal Batteries

Abstract

All‐solid‐state lithium metal batteries (ASSLMBs) have attracted intensive research attention since their incomparable energy density and the further advance of ASSLMBs is severely dependent on the development of solid electrolytes. Unfortunately, as one of the most studied solid electrolytes, the practical applications of (NASICON)‐type Li1.5Al0.5Ge0.5P3O12 (LAGP) electrolyte is hindered by not only its inferior interfacial contact with electrodes but also its undesirable instability toward Li metal anodes. In this work, a bifunctional in situ formed poly(vinylene carbonate) (PVCA)‐based buffer layer is introduced between the LAGP electrolyte and the metallic Li anode to improve interface compatibility and the electrolyte stability. The improved interface contact between LAGP and electrodes and the enhanced stability of LAGP enable ASSLMBs with excellent electrochemical performance. The Li/LAGP/Li symmetric cell with the PVCA‐based interlayer can maintain a low overpotential of 80 mV for 800 h at 0.05 mA cm–2. Inspiringly, the as‐assembled ASSLMBs with LiFePO4 as the cathode also present excellent cyclic stability with a high initial discharge capacity of 150 mAh g–1 at 0.5 C and superior capacity retention of 96% after 200 cycles.

Improving the Stability of Lithium Aluminum Germanium Phosphate with Lithium Metal by Interface Engineering

“…A higher LiF/Li 2 O 2 ratio is observed in the Li 1s spectrum of cycled LAGP@Al 2 O 3 50 after 1060 s etching, implying a gradient distribution of LiF/Li 2 O 2 in the SEI layer. F 1s spectra in Figure 7 e,f originate from Li x PF y and LiF, which could be ascribed to the decomposition of the small addition of liquid electrolyte (LiPF 6 in EC:DEC) [ 37 ]. The LiF/Li x PF y ratio becomes larger for the LAGP@Al 2 O 3 50 after 1060s etching, which also indicates the compositional variation in the SEI layer along with the depth.…”

“…Sun et al [ 30 ] adopted the atomic layer deposition (ALD) technique to coat ultrathin aluminum oxide (Al 2 O 3 ) on the surface of Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP), and the Li/LATP interface was significantly stabilized at 0.01 mA cm −2 . Currently, most Li/LAGP/Li symmetrical cells show a long cycle time at a low current density of 0.1 mA cm −2 [ 1 , 3 , 25 , 26 , 28 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ], making it hard to meet the demand for practical applications. Improving the electrochemical stability of LAGP at higher current densities is an urgent task in the development of high-energy-density ASSLBs [ 38 ].…”

In Situ‐Formed LiF‐Rich Multifunctional Interfaces toward Stable Li10GeP2S12‐Based All‐Solid‐State Lithium Batteries

“…[1][2][3][4][5][6] Meanwhile, highionic-conductivity solid electrolyte layer and stable anode/electrolyte interface are crucial for achieving high-performance all-solid-state lithium batteries. [7][8][9][10][11] Among available solid electrolytes, sulfide electrolyte Li 10 GeP 2 S 12 (LGPS) has achieved multifunctional interface consists of three functional components, including LiF, carbon particles and thin CF bond top-layer, which efficiently prevent the side reactions between Li and LGPS and promote smooth lithium plating on the Li metal surface, as well as enable homogenous Li + flux and fast Li + transfer kinetics, ensuring a stable Li/LGPS interface and endowing the symmetric lithium cell with prolonged cycling stability and increased critical current density of 1.9 mA cm -2 . Moreover, the assembled Li@LiF/LGPS/LiCoO 2 all-solid-state cells show superior rate performances and cycling stability with a capacity retention of 80.9% after 300 cycles at 0.1 C under 25 °C.…”

“…[ 1–6 ] Meanwhile, high‐ionic‐conductivity solid electrolyte layer and stable anode/electrolyte interface are crucial for achieving high‐performance all‐solid‐state lithium batteries. [ 7–11 ] Among available solid electrolytes, sulfide electrolyte Li 10 GeP 2 S 12 (LGPS) has achieved an extremely high ionic conductivity of 12 mS cm –1 , making it an attractive candidate for all‐solid‐state lithium batteries. [ 12,13 ] Nevertheless, severe thermodynamic instability between LGPS and Li metal trigger spontaneous reaction between Li metal and LGPS, [ 14,15 ] resulting in an unstable mixed ionic/electronic conductive interphase composed of Li 3 P, Li 2 S, and Ge/Li‐Ge alloy, [ 16,17 ] which induces continuous reaction.…”

A lithiophilic AlN-modified copper layer for high-performance lithium metal anodes

“…Utilizing the porous composite electrode with large specic surface areas, 15,16 increasing lithium deposition sites and reducing current density could realize the uniform lithium deposition, but the volumetric energy density of the electrode is sacriced, and large specic surface area will lead to more side reactions. Besides, protective coating layers composed of polymers, [17][18][19][20] inorganic materials [21][22][23] and their mixtures [24][25][26][27] are applied to suppress the lithium dendrites and improve the brittleness of SEI, but the transport kinetics of lithium ions in the modied layer still needs to be increased to alleviate the space charge layer. Therefore, it is essential to construct fast ion transport channels in the protective coating layer to ensure the rapid transport of lithium ions particularly.…”