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The uneven electrochemical reactions of lithium (Li) metal anode is one of the main reasons that hinder its application in rechargeable high energy density batteries. Great progress has been achieved in homogenizing electrochemical reactions of Li metal anode in lab‐scale coin cells, however, it cannot be directly applied to pouch cells, where undesirable defects or side reactions are significantly aggravated. With carbonate electrolyte, multi‐layered negative and positive electrodes (8 × 11 cm), 1.2 Ah sulfurized polyacrylonitrile (SPAN)||Li pouch cell lost all its capacity after 40 cycles under a current of 600 mA, although its counterpart with coin cell configuration showed much higher capacity retention of 94% under the same test condition. Severe corrosion with uneven, porous, dendritic Li deposits is observed for pristine Li electrode in a pouch cell, especially in the near‐tap and the central regions with close connection with the current collector due to the locally amplified current densities. In contrast, Li/Li–Sn alloy composite electrode displays uniform and dense Li plating behavior over the entire test area with significantly suppressed parasitic reactions and gas evolution. As such, a 1.2 Ah SPAN||Li/Li–Sn cell displays much higher capacity retention than SPAN||Li cell (87% for 100 cycles vs. 0 for 40 cycles). [ABSTRACT FROM AUTHOR]

The recycling of LiFePO 4 from degraded lithium-ion batteries (LIBs) from electric vehicles (EVs) has gained significant attention due to resource, environment, and cost considerations. Through neutron diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy, we revealed continuous lithium loss during battery cycling, resulting in a Li-deficient state (Li 1- x FePO 4 ) and phase separation within individual particles, where olive-shaped FePO 4 nanodomains (5-10 nm) were embedded in the LiFePO 4 matrix. The preservation of the olive-shaped skeleton during Li loss and phase change enabled materials recovery. By chemical compensation for the lithium loss, we successfully restored the hybrid LiFePO 4 /FePO 4 structure to pure LiFePO 4 , eliminating nanograin boundaries. The regenerated LiFePO 4 (R-LiFePO 4 ) exhibited a high crystallinity similar to the fresh counterpart. This study highlights the importance of topotactic chemical reactions in structural repair and offers insights into the potential of targeted Li compensation for energy-efficient recycling of battery electrode materials with polyanion-type skeletons.

Lithium-ion batteries (LIBs) are currently dominating the portable electronics market and supplying power for electric vehicles and grid-level storage. However, lithium loss in the formation cycle at the anode side reduces the energy density of state-of-the-art LIBs with carbon anode materials. This situation will be even more severe for future LIBs using high-capacity Si-based anode materials. In this study, a transition metal-based nanocomposite with built-in lithium source was synthesized, featuring Fe nanodomains with a size of ∼5 nm uniformly dispersed in a hybrid Li 2 O and LiF matrix with intimate contact between them. The Fe/LiF/Li 2 O nanocomposite released a high Li-ion capacity of 550 mA h/g based on a multielectron inverse conversion reaction during the first-cycle charge process and exhibited better ambient stability than the counterpart with a pure Li 2 O matrix and also a lower lithium-extraction voltage and faster reaction kinetics than the counterpart with a pure LiF matrix. Serving as an additive to various cathodes (e.g., LiCoO 2 , LiFePO 4 , and LiNi 1- x - y Co x Mn y O 2 ), the Fe/LiF/Li 2 O nanocomposite showed excellent lithium compensation effect. Using 4.8 wt % Fe/LiF/Li 2 O additive based on the total mass of the electrodes, a LiNi 0.8 Co 0.1 Mn 0.1 O 2 |SiO-graphite full cell with a high cathode mass loading of 20 mg/cm 2 exhibited a high reversible capacity of 2.9 mA h/cm 2 at 0.5 C after 100 cycles which is a 15% increase in comparison to the counterpart without the prelithiation additive. After the Fe/LiF/Li 2 O nanocomposite was immersed into the electrolyte and rested for 72 h, the content of iron metal in the electrolyte was negligible, indicating that this prelithiation additive was stable in the electrolyte and would not cause any side reactions, such as the shuttle of iron ions during cycling. The high "donor" Li-ion capacity, good ambient stability, and its compatibility with existing cathode materials and battery fabrication processes make the Fe/LiF/Li 2 O nanocomposite a promising cathode prelithiation additive to offset the initial lithium loss and improve the energy density of LIBs.