Artificial Solid Electrolyte Interphase Layer for Lithium Metal Anode in High-Energy Lithium Secondary Pouch Cells

Abstract

Lithium secondary batteries have attracted considerable attention due to their great potential to achieve ultrahigh energy density for future use. However, the Li metal anode suffers dendrite formation during repeated stripping/plating, hindering its practical realization. Herein, for the first time, an artificial solid electrolyte interphase layer, lithium phosphorus oxynitride (LiPON), is introduced for the lithium anode, and the viable application in highenergy lithium secondary pouch cell is probed. LiPON is stable with lithium and in the air, which can protect the lithium from the side reaction with H 2 O and O 2 effectively. In low-energy batteries, the LiPON layer can enhance the efficiency of lithium deposition/dissolution and prolong the lifespan of the batteries. Further on, the discharge capacities of the lithium secondary cells with an energy density over 350 Wh kg −1 deploying LiPON-coated Li anodes drop fast, and the batteries are prone to severe polarization leading to the termination of life. Nonuniform current density resulting from the cracks caused by the large mass of lithium stripping/plating is ascribed to being the decisive factor shortening the life of batteries. Generally speaking, more and further exploration should be focused on the modification of the large-area lithium anode to accomplish high-energy-density lithium batteries for practical applications.

Toward the Sustainable Lithium Metal Batteries with a New Electrolyte Solvation Chemistry

“…The pouch‐type Li|NCMA73 battery with Mg(NO 3 ) 2 additive delivers unprecedented stable cycle performance up to 1300 cycles with a capacity retention of 80% (Figure 3c). Notably, compared with previously reported pouch‐type LMB using carbonate‐based electrolyte ( Table 1 ), [ 20,24–31 ] the proposed strategy manifested great competitiveness in terms of long‐term cycling. Particularly, the positive effect of Mg(NO 3 ) 2 additive was also confirmed in LiPF 6 salt‐based electrolyte (Figure S8, Supporting Information), which is the most commonly used as the salt in commercial LIBs.…”

“…The formation of a Li–Mg alloy on Li metal surface is in good agreement with previous reports. [ 27 ] Herein, the formed Mg and Li–Mg alloy should be thin, because the solubility of the formed LiNO 3 (i.e., Mg(NO 3 ) 2 + Li electrode → LiNO 3 + Mg/Li electrode ) is extremely low, which limits the progress of this spontaneous reaction. This point is very important and interesting, because not only does it result in a protective Li–Mg layer, but also it maintains a large proportion of the Mg 2+ in the electrolyte to affect the Li + solvation structure, facilitating Li deposition.…”

Comparative performance of ex situ artificial solid electrolyte interphases for Li metal batteries with liquid electrolytes

“…Moreover, Li 3 PO 4 coating films had high mechanical strength. Additionally, the amorphous solid-state electrolyte Lithium phosphorous oxynitride (LiPON) was studied as ASEI, owing to its high ionic conductivity and chemical stability against Li metal ( Kozen et al., 2017 ; Liu et al., 2018 ).…”

“…The main disadvantages of LCO are its poor thermal stability, the high cost of Co and, more importantly, ethic and health concerns associated with Co extraction ( Sharma and Manthiram, 2020 ). By assembling a pouch cell with 2.24 mAh/cm 2 LCO and a Li metal anode coated with a thin film (2 μm) of LiPON via sputtering, ∼80% capacity was retained in 100 cycles at 0.1C ( Liu et al., 2018 ).…”

A Perspective on interfacial engineering of lithium metal anodes and beyond

“…This is significantly higher than the diffusion coefficient of Li in bulk Li metal (7.65 × 10 -11 cm 2 s -1 ) 30 . Li metal, and dendrites eventually formed 46,47 . For interfacial coatings that favor Li plating underneath, there likely exists a current density threshold for effective dendrite suppression.…”