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The evolution of surface film on aspect of chemical composition and thickness is monitored on a nickel-doped manganese spinel positive electrode (LNMO, LiNi 0.5 Mn 1.5 O 4 ) for lithium-ion batteries. In the first charging from 4.2 to 4.9 V (vs. Li/Li + ), large amount of lithium fluoride (LiF) deposits at lower potentials (4.2 V) but it is removed when the electrode potential moves to the charging end (4.9 V). The phenomenon of LiF deposition at lower potentials and removal at higher potentials is repeated in the continuing cycles, but the overall LiF concentration becomes progressively lower for the surface films to be enriched by the carboncontaining organic species in the later cycles. Due to the highly resistive nature of LiF, the film resistance shows a strong correlation with the LiF concentration in the films. From the finding that LiF formation is the most significant at 4.2 V in every cycle, under which circumstances LNMO itself is fully lithiated to provide lithium source for LiF formation, hydrogen fluoride (HF) attack on the LNMO surface has been proposed to be the major route for LiF formation.

All-solid-state batteries (ASSBs) are viewed as promising next-generation energy storage devices, due to their enhanced safety by replacing organic liquid electrolytes with non-flammable solid-state electrolytes (SSEs). The high ionic conductivity...

The n-doped poly(phenanthrenequinone) is electrically conductive to be successfully used as the binder for nano-silicon negative electrodes.

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One approach to increase the energy density of all-solid-state batteries (ASSBs) is to use high-voltage cathode materials. The spinel LiNi0.5Mn1.5O4 (LNMO) cathode is one such example, as it offers a high reaction potential (close to 5 V). Moreover, it is a Co-free cathode system, which makes it an environmentally friendly and a low-cost alternative. However, several challenges must be addressed before it can be properly adopted in ASSB technologies. Herein, we reveal that lithium argyrodite (Li6PS5Cl), a sulfide solid-state electrolyte (SSE), possesses intrinsic chemical incompatibility with the LNMO cathode. We demonstrate the necessity of using a halide SSE, Li3YCl6 (LYC), through careful analysis of the LNMO/SSE interface. Moreover, we emphasize the necessity of applying a protective coating layer to LNMO particles, even when halide SSEs are used. Furthermore, the chemical phenomena involving LYC in the oxidative environment of LNMO are analyzed, including a comparison between coated and uncoated LNMO particles.

All-solid-state batteries (ASSBs) are one of the most promising systems to enable long-lasting and thermally resilient next-generation energy storage. Ideally, these systems should utilize low-cost resources with reduced reliance on critical materials. Pursuing cobalt-and nickel-free chemistries, like LiFePO 4 (LFP), is a promising strategy. Morphological features of LFP essential for improved electrochemical performance are highlighted to elucidate the interfacial challenges when implemented in ASSBs, since adoption in inorganic ASSBs has yet to be reported. In this work, the compatibility of LFP with two types of solid-state electrolytes, Li 6 PS 5 Cl (LPSCl) and Li 2 ZrCl 6 (LZC), are investigated. The potential existence of oxidative decomposition products is probed using a combination of structural, electrochemical, and spectroscopic analyses. Bulk and interfacial characterization reveal that the sulfidebased electrolyte LPSCl decomposes into insulative products, and electrochemical impedance spectroscopy is used to quantify the resulting impedance growth. However, through utilization of the chloride-based electrolyte LZC, high-rate and stable electrochemical performance is achieved at room temperature.