Na 0.72 [L i0.24 Mn 0.76 ]O 2 , with reversible anionic redox reaction (ARR) and Mn 3+ / Mn 4+ redox, delivers the highest energy density (700 Wh/kg, 270 mAh/g, 1.5-4.5 V) among all Na cathode materials reported to date, surprisingly showing suppressed phase transition and low-strain characteristics. Our findings break the traditional cognition that ARR could only help increase the capacity. It is demonstrated in this work that ARR also plays a key role in stabilizing the structure to induce an even higher capacity with low strain.

Nickel-rich layered materials LiNi 1-x-y Mn x Co y O 2 are promising candidates for high energy density lithium-ion battery cathodes. Unfortunately, they suffer from capacity fading upon cycling, especially with high voltage charging. It is critical to have mechanistic understanding of such fade. Herein, synchrotron-based techniques (including scattering, spectroscopy, and microcopy) and finite element analysis were utilized to understand the LiNi 0.6 Mn 0.2 Co 0.2 O 2 material from structural, chemical, morphological, and mechanical points of view. The lattice structural changes are shown to be relatively reversible during cycling, even when 4.9V charging was applied. However, local disorder and strain were induced by high voltage charging. Nano-resolution 3D transmission X-ray microscopy data analyzed by machine learning methodology reveals that high-voltage charging induced significant oxidation state inhomogeneities in the cycled particles. Regions at the surface have rock-salt type structure with lower oxidation state and build up the impedance while regions with higher oxidization state are scattered in the bulk and are likely deactivated during cycling. In addition, the development of micro-cracks is highly dependent on the pristine state morphology and cycling conditions. Hollow particles seem to be more robust against stress-induced cracks than the solid ones, suggesting that morphology engineering can be effective in mitigating the crack problem in these materials. The engineering support from D. Van Campen, V. Borzenets and D. Day for the TXM experiment at beamline 6-2C of SSRL is gratefully acknowledged. The work done at Brookhaven National Laboratory was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Vehicle Technology Office of the U.S. Department of Energy through the Advanced Battery Materials Research (BMR) Program, including Battery500 Consortium under contract DE-SC0012704. This research used beamlines 7-BM and 28-ID-2 of the National Synchrotron Light Source II, a U.S.

Successfully commercialized poly(ethylene oxide) (PEO)based solid polymer batteries (SPBs) are expected to continuously play a key role in the next generation of high-energy density lithium-ion battery technologies. However, the introduction of high-voltage cathodes, accompanied by safety concerns such as PEO decomposition and the associated gas release, is worthy of more attention. This study employs in situ DEMS to study the gassing behavior of LiCoO 2 |PEO-LiTFSI|Li SPBs. The experiments, together with theory calculations, reveal that a surface catalytic effect of LiCoO 2 is the root cause of the unexpected H 2 gas release of PEO-based SPBs at 4.2 V. The surface coating of LiCoO 2 with a stable solid electrolyte Li 1.4 Al 0.4 Ti 1.6 (PO 4 ) 3 (LATP) can mitigate such a surface catalytic effect and therefore extend the stable working voltage to >4.5 V. The crossover effect of HTFSI, which is generated at the cathode side due to oxidation/dehydration of PEO and reacts with lithium at the anode side, is proposed to explain the H 2 generation behavior.

Cathode electrolyte interphase (CEI) layer plays an essential role in determining the electrochemical performance of Li-ion batteries (LIBs), but the detailed mechanisms of CEI formation and evolution are not yet fully understood. With the pursuit of LIBs possessing a high energy density, fundamental investigations on the CEI have become increasingly important. Herein, X-ray photoelectron spectroscopy (XPS) is employed to fingerprint CEI formation and evolution on three of the most prevailing high-voltage cathodes including layered Li1.144Ni0.136Co0.136Mn0.544O2 (LR-NCM), Li2Ru0.5Mn0.5O3 (LRMO), and spinel LiNi0.5Mn1.5O4 (LNMO). The influences of crystal structure, chemical constitution and cut-off voltage on CEI composition are clarified. Among these cathodes, the spinel cathode exhibits the most stable CEI layer throughout the battery cycle. While the layered cathodes based on the 4d transition metal Ru favor CEI formation upon contacting the electrolyte. Most importantly, anionic redox reaction (ARR) activation at high voltages is verified to dominate CEI evolution in subsequent cycles. The distinct CEI behaviors in diverse cathodes can be attributed to a series of entangled processes, including electrolyte/Li salt decomposition, CEI component dissociation and dissociated CEI species redeposition. Based on these findings, rational guidelines are provided for the interface design of high-voltage LIBs.

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BackgroundRecent population structure studies of T. gondii revealed that a few major clonal lineages predominated in different geographical regions. T. gondii in South America is genetically and biologically divergent, whereas this parasite is remarkably clonal in North America and Europe with a few major lineages including Types I, II and III. Information on genotypes and mouse virulence of T. gondii isolates from China is scarce and insufficient to investigate its population structure, evolution, and transmission.Methodology/Principal FindingsGenotyping of 23 T. gondii isolates from different hosts using 10 markers for PCR-restriction fragment length polymorphism analyses (SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico) revealed five genotypes; among them three genotypes were atypical and two were archetypal. Fifteen strains belong to the Chinese 1 lineage, which has been previously reported as a widespread lineage from swine, cats, and humans in China. Two human isolates fall into the type I and II lineages and the remaining isolates belong to two new atypical genotypes (ToxoDB#204 and #205) which has never been reported in China. Our results show that these genotypes of T. gondii isolates are intermediately or highly virulent in mice except for the strain TgCtwh6, which maintained parasitemia in mice for 35 days post infection although it possesses the uniform genotype of Chinese 1. Additionally, phylogenetic network analyses of all isolates of genotype Chinese 1 are identical, and there is no variation based on the sequence data generated for four introns (EF1, HP2, UPRT1 and UPRT7) and two dense granule proteins (GRA6 and GRA7).Conclusion/SignificanceA limited genetic diversity was found and genotype Chinese 1 (ToxoDB#9) is dominantly circulating in mainland China. The results will provide a useful profile for deep insight to the population structure, epidemiology and biological characteristics of T. gondii in China.