Polypropylene Carbonate-Based Adaptive Buffer Layer for Stable Interfaces of Solid Polymer Lithium Metal Batteries

Abstract

Solid polymer electrolytes (SPEs) have the potential to enhance the safety and energy density of lithium batteries. However, poor interfacial contact between the lithium metal anode and SPE leads to high interfacial resistance and low specific capacity of the battery. In this work, we present a novel strategy to improve this solid–solid interface problem and maintain good interfacial contact during battery cycling by introducing an adaptive buffer layer (ABL) between the Li metal anode and SPE. The ABL consists of low molecular-weight polypropylene carbonate , poly­(ethylene oxide) (PEO), and lithium salt. Rheological experiments indicate that ABL is viscoelastic and that it flows with a higher viscosity compared to PEO-only SPE. ABL also has higher ionic conductivity than PEO-only SPE. In the presence of ABL, the interface resistance of the Li/ABL/SPE/LiFePO4 battery only increased 20% after 150 cycles, whereas that of the battery without ABL increased by 117%. In addition, because ABL makes a good solid–solid interface contact between the Li metal anode and SPE, the battery with ABL delivered an initial discharge specific capacity of >110 mA·h/g, which is nearly twice that of the battery without ABL, which is 60 mA·h/g. Moreover, ABL is able to maintain electrode–electrolyte interfacial contact during battery cycling, which stabilizes the battery Coulombic efficiency.

Modulating Nanoinhomogeneity at Electrode–Solid Electrolyte Interfaces for Dendrite‐Proof Solid‐State Batteries and Long‐Life Memristors

“…In fact, PPC has already been reported as a superb buffer layer in both solid‐state batteries and in liquid lithium metal batteries. [ 59–61 ] For example, Yang and co‐workers used PPC between PEO and Li and observed better contact and slower interfacial degradation. [ 61 ] Yue et al also reported similar results where they show PPC could enhance the compatibility of composite polymer electrolytes and Li.…”

“…[ 59–61 ] For example, Yang and co‐workers used PPC between PEO and Li and observed better contact and slower interfacial degradation. [ 61 ] Yue et al also reported similar results where they show PPC could enhance the compatibility of composite polymer electrolytes and Li. [ 62 ] In this work, we take a step further and show that, with the unique property of PPC, it can serve as a superb interphasial layer to block dendrites in polycrystalline ceramic solid electrolytes via the homogenizing effect.…”

In-situ construction of a Mg-modified interface to guide uniform lithium deposition for stable all-solid-state batteries

“…The large volume changes of the anode during the Li plating/stripping process is also detrimental for the interface integrity, leading to insufficient cycling [30][31][32][33][34]. Therefore, approaches including polymer structural modification [35,36], optimizing the structure and proportion of Li salts [37,38], introducing organic plasticizers [39,40], and inorganic fillers [41,42] have been extensively explored for constructing a healthy anode/electrolyte interface between PEO-LiTFSI and Li metal.…”

Lithium Ion Conduction in Diblock Polymer Electrolyte with Tethered Anion

“…Further improvement in the transference number (i. e., closer to unity) may be possible with a lower molecular weight PEG or stabilization of lithium metal SEI. An improved SEI, such as by the introduction of propylene carbonate oligomers [21] or other SEI‐forming organic and inorganic additives (e. g., fluoroethylene carbonate, LiNO 3 and LiBOB [22] ) would stabilize the electrode‐electrolyte interface and series resistance. Nevertheless, a higher lithium ion transference number value was measured with both plasticizers showing that the tethered anion approach holds promise for mitigating voltage droop problems.…”