Overcoming the Interfacial Challenges of LiFePO4 in Inorganic All-Solid-State Batteries

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 LiFePO4 (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 have yet to be reported. In this work, the compatibility of LFP with two types of solid-state electrolytes, Li6PS5Cl (LPSCl) and Li2ZrCl6 (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 sulfide-based 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

A 5V-class Cobalt-free Battery Cathode with High Loading Enabled by Dry Coating

Transitioning toward more sustainable materials and manufacturing methods will be critical to continue supporting the rapidly expanding market for lithium-ion batteries. Meanwhile, energy storage applications are demanding higher power and energy densities than ever before, with aggressive performance targets like fast charging and greatly extended operating ranges and durations. Due to its high operating voltage and cobalt-free chemistry, the spinel-type LiNi0.5Mn1.5O4 (LNMO) cathode material has attracted great interest as one of the few next-generation candidates capable of addressing this combination of challenges. However, severe capacity degradation and poor interphase stability have thus far impeded the practical application of LNMO. In this study, by leveraging a dry electrode coating process, we demonstrate LNMO electrodes with stable full cell operation (up to 68% after 1000 cycles) and ultra-high loading (up to 9.5 mAh/cm2 in half cells). This excellent cycling stability is ascribed to a stable cathode-electrolyte interphase, a highly distributed and interconnected electronic percolation network, and robust mechanical properties. High-quality images collected using plasma focused ion beam scanning electron microscopy (PFIB-SEM) provide additional insight into this behavior, with a complementary 2-D model illustrating how the electronic percolation network in the dry-coated electrodes more efficiently supports homogeneous electrochemical reaction pathways. These results strongly motivate that LNMO as a high voltage cobalt-free cathode chemistry combined with an energy-efficient dry electrode coating process opens the possibility for sustainable electrode manufacturing of cost-effective and high-energy-density cathode materials