Rechargeable Lithium Metal Batteries with an In‐Built Solid‐State Polymer Electrolyte and a High Voltage/Loading Ni‐Rich Layered Cathode

Abstract

Solid‐state batteries enabled by solid‐state polymer electrolytes (SPEs) are under active consideration for their promise as cost‐effective platforms that simultaneously support high‐energy and safe electrochemical energy storage. The limited oxidative stability and poor interfacial charge transport in conventional polymer electrolytes are well known, but difficult challenges must be addressed if high‐voltage intercalating cathodes are to be used in such batteries. Here, ether‐based electrolytes are in situ polymerized by a ring‐opening reaction in the presence of aluminum fluoride (AlF3) to create SPEs inside LiNi0.6Co0.2 Mn0.2O2 (NCM) || Li batteries that are able to overcome both challenges. AlF3 plays a dual role as a Lewis acid catalyst and for the building of fluoridized cathode–electrolyte interphases, protecting both the electrolyte and aluminum current collector from degradation reactions. The solid‐state NCM || Li metal batteries exhibit enhanced specific capacity of 153 mAh g−1 under high areal capacity of 3.0 mAh cm−2. This work offers an important pathway toward solid‐state polymer electrolytes for high‐voltage solid‐state batteries.

Interface Issues and Challenges in All‐Solid‐State Batteries: Lithium, Sodium, and Beyond

“…Then, the thick NCM layer invades the current collector and the dissolved aluminum fragments diffuse and accumulate on top of the NCM layer. [ 79 ] Adding LiDFOB or LiBOB salts could be beneficial to enhance interface stability through the formation of a highly stable interface layer.…”

Stamping Flexible Li Alloy Anodes

“…[ 1–5 ] It is also an indispensable component for Li‐metal batteries to reach the projected high energy densities. [ 6–9 ] Such promise comes from its high theoretical capacity (3861 mAh g –1 ) and lowest redox potential (‐3.04 V vs the standard hydrogen electrode, SHE) among other anode candidates. [ 10 ] In practice, to match the capacity of a typical commercial cathode, [ 8,11–13 ] an areal capacity of ≈3 mAh cm –2 is required for Li anode, which translates to a thickness of only ≈15 µm.…”

“…[ 6–9 ] Such promise comes from its high theoretical capacity (3861 mAh g –1 ) and lowest redox potential (‐3.04 V vs the standard hydrogen electrode, SHE) among other anode candidates. [ 10 ] In practice, to match the capacity of a typical commercial cathode, [ 8,11–13 ] an areal capacity of ≈3 mAh cm –2 is required for Li anode, which translates to a thickness of only ≈15 µm. [ 14 ] However, due to the poor Columbic efficiency during Li plating/stripping, at least a twofold oversupply of Li is needed to ensure the long cycle life of the anode.…”

Structure Design of Cathode Electrodes for Solid‐State Batteries: Challenges and Progress

“…Aluminum fluoride was not only able to initiate the ring‐opening polymerization of 1,3‐dioxolane but also beneficial in constructing stable cathode–electrolyte interphase. [ 139 ] The interphase with LiF enrichment effectively facilitated stability of ether‐based electrolyte and thus practical cycling of Ni‐rich oxides cathode. It was found some lithium salt could also be the medium to accomplish the in situ coating which preserves the high‐voltage compatibility.…”