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Li, Sipei

Publications and source records attributed to Li, Sipei.

4 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Integrated rocksalt–polyanion cathodes with excess lithium and stabilized cycling

Co- and Ni-free disordered rocksalt cathodes utilize oxygen redox to increase the energy density of lithium-ion batteries, but it is challenging to achieve good cycle life at high voltages >4.5 V (versus Li/Li + ). Here, in this study, we report a family of Li-excess Mn-rich cathodes that integrates rocksalt- and polyanion-type structures. Following design rules for cation filling and ordering, we demonstrate the bulk incorporation of polyanion groups into the rocksalt lattice. This integration bridges the two primary families of lithium-ion battery cathodes—layered/spinel and phosphate oxides—dramatically enhancing the cycling stability of disordered rocksalt cathodes with 4.8 V upper cut-off voltage. The cathode exhibits high gravimetric energy densities above 1,100 Wh kg -1 and >70% retention over 100 cycles. This study opens up a broad compositional space for developing battery cathodes using earth-abundant elements such as Mn and Fe.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Polymer-Stabilized Liquid Metal Nanoparticles as a Scalable Current Collector Engineering Approach Enabling Lithium Metal Anodes

Dendrites and dead lithium formation over prolonged cycling have long been challenges that hinder the safe implementation of metallic Li anodes. In this study, we employ polymer-stabilized liquid metal nanoparticles (LM-P NPs) of eutectic gallium indium (EGaIn) to create uniform Li nucleation sites enabling homogeneous lithium electrodeposition. Block copolymers of poly(ethylene oxide) and poly(acrylic acid) (PEO-b-PAA) were grafted onto the EGaIn surface, forming stabilized, well-dispersed NPs. Using a scalable spray coating approach, LM-P NPs were fabricated on copper current collectors, providing lithiophilic PEO sites and interactive carboxyl groups to guide Li deposition. The Li-EGaIn alloying process greatly reduced the Li + diffusion barrier, enabling fast Li transport through the coating layer, resulting in decreased nucleation overpotential. Therefore, about five times lower Li nucleation overpotential was obtained on the LM-P modified Cu with an optimal composition of the polymers than the bare Cu substrates. DFT computations was used to reveal the binding properties between the LM-P layer and Li. Due to the regulated Li plating/stripping process, as-obtained 30 μm Li anodes paired with LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM8 11 ) with a negative/positive electrode capacity (N/P) ratio ~ 10 exhibited stable cycling performance at 0.5C for over 250 cycles, with an average Coulombic efficiency of 99.55%. Ultrathin Li (1 μm) anodes with an N/P ratio ~ 0.6 were also demonstrated in Li|LiFePO 4 cells, which examined the stabilization of Li by LM-P NPs and monitored practical loadings of Li anodes that are close to anode-free systems.

25 ENERGY STORAGE↗
DOE OSTI2021

Ultra-high-voltage Ni-rich layered cathodes in practical Li metal batteries enabled by a sulfonamide-based electrolyte

By increasing the charging voltage, a cell specific energy of >400 Wh kg-1 is in principle achievable with LiNi0.8Mn0.1Co0.1O2 in lithium-metal batteries (LMBs). However, stable cycling of high-nickel cathodes at ultra-high voltages is extremely challenging. Here we report that a rationally designed sulfonamide-based electrolyte enables stable cycling of commercial LiNi0.8Co0.1Mn0.1O2 with a cut-off voltage up to 4.7 V in LMBs. In contrast to commercial carbonate electrolytes, the electrolyte not only suppresses side reactions, intergranular cracking, transition-metal dissolution, and impedance growth on the cathode side, but also enables highly reversible Li metal stripping and plating leading to compact morphology and low pulverization. Our LMB delivers a specific capacity >230 mAh g-1 and an average Coulombic efficiency >99.65% over 100 cycles. Even under harsh testing conditions, the 4.7 V LMB can retain >88% capacity for 90 cycles, demonstrating significant advances in practical LMBs.

36 MATERIALS SCIENCE↗