Search

Li-ion batteries (LIBs) are one type of more and more widely used devices for energy storage and power supply in which cathode materials are playing a relatively more decisive role at current stage. In this review, we start with pioneeringly commercialized LiCoO2 (LCO) with a layered rhombohedral structure (space group R 3 ¯ m ) to discuss novel sequentially emerging LCO-derived layered oxides from the perspectives of both cobalt content reduction and performance improvement. Emphasis is placed on the improvement of high-voltage performance of LCO and Co-reduced/free layered oxides, including Co-reduced high-nickel layered oxides, Co-free Li-rich layered oxides, and Ni-based layered oxides cathodes, and their underlying mechanisms via different strategies. Also, possibly matched carbon and silicon-based anode materials are briefly discussed. The common issues and prospects of the layered oxides cathodes and their potential anodes are summarized and commented on. This review can help understand the emergence logics of novel layered oxides with gradually vanishing cobalt involved, provide insights about the underlying mechanisms of performance enhancement pertaining to particular strategies, and even inspire the discovery of novel cathode materials with high performance and low cost. [ABSTRACT FROM AUTHOR]

LiCoO2 (LCO) with a high theoretical capacity of 274 mAh g–1 can rarely achieve a high practical capacity even at an upper cutoff voltage of 4.6 V due to severe structural instability and interface side reactions. Herein, an in situ strategy of gas–solid modifications during synthesis is proposed to improve the performance of LCO using sulfocompound‐contained expanded graphite (EG) as templates. In situ generated SO2 gas from EG enables the Co‐coating of coherent spinel LixCo2O4 and Li2SO4 and the trace doping of high‐valence S mainly in the near‐surface regions via its reactions with the precursors. The modified LCO possesses excellent structural reversibility, interfacial stability, slight dissolution of Co2+, high diffusion coefficients of Li+, and low O 2p band top. This endows LCO with remarkably improved high‐voltage performance, 222 and 143 mAh g‐1 at 0.1 and 20 C, respectively, and 88% capacity retention over 100 cycles at 1 C for LCO/Li half cells between 2.8 and 4.6 V, and 202 mAh g–1 at 1 C and 87% capacity retention over 1000 cycles between 2.8 and 4.5 V for LCO/graphite full cells. This study provides a unique, simple, and upscalable strategy for performance improvement of electrode materials. [ABSTRACT FROM AUTHOR]

Biomasses receive much attention as carbon sources for anodes of high‐energy lithium‐ion batteries and cathodes of lithium‐sulfur batteries due to their low costs, easy availability and potentially high capacities which unfortunately deliver unsatisfactory performances normally. However, biomasses used as silicon instead of carbon‐dominated sources have never been touched before. Here, we report a facile preparation of nitrogen and phosphorus heteroatoms co‐doped hierarchically porous and cross‐linked SiOx/C composite nanosheet architectures from catkins without the introduction of alien Si (N/P‐SiOx/C‐NSs) using chemical exfoliation and treatments. This unique structure composed of novel multiple‐phase composites is revealed to show superior fast kinetics and ultra‐long cycle life with about 340 mAh g−1 and almost no capacity decay after 10000 cycles at 10 A g−1, far beyond those of conventional carbon and SiOx‐based anode materials. The superior performance is closely related to excellent electronic conduction arising from the cross‐linkage architecture, well‐graphitized carbon and uniform co‐doping of nitrogen and phosphorus, rapid ionic transport kinetics from rich hierarchical pores, and outstanding stability from the rigid nanosheet networks. This study sets a precedent of catkins as silicon instead of conventional carbon‐only sources for anode materials, which can largely enhance the role of biomasses in energy storage. [ABSTRACT FROM AUTHOR]

Detrimental rock‐salt and/or spinel surface phases parasitic to Ni‐rich layered oxides with high theoretical capacity are quite formidable which are reported to be eliminated only through alien element dopings and/or surface modifications. Herein, these surface phases are directly eliminated successfully during the synthesis of pristine LiNi0.8Co0.2O2 and LiNi0.9Co0.1O2 using an expanded graphites (EGs) template approach, accompanied by the formation of unique 3D porous structures. The elimination of surface phases may be ascribed to the 3D porous structures formed during the calcination processes at both low and high temperatures, which enables the access of sufficient oxygen to individual nanoparticles and thus promotes the oxidization of Ni2+ to Ni3+ to reduce Li/Ni disordering. Both LiNi0.8Co0.2O2 and LiNi0.9Co0.1O2 show excellent rate capability, long‐term cycling stability, and high initial Coulombic efficiencies (ICEs), such as 210.4 (149) and 222.6 (133) mAh g−1, ICEs of 94.9% and 93.8% at 0.1 C (20 C), and capacity retentions of 74% after 500 cycles at 1 C and 76% after 300 cycles at 1 C, respectively, far better than those synthesized using a conventional sol–gel recipe. This study provides a simple and novel platform for directly synthesizing detrimental surface phases free and chemically stoichiometric Ni‐rich layered oxides with high performance. [ABSTRACT FROM AUTHOR]

Abstract Background Cancers arise through an evolutionary process in which cell populations are subjected to selection; however, to date, the process of bladder cancer, which is one of the most common cancers in the world, remains unknown at a single-cell level. Results We carried out single-cell exome sequencing of 66 individual tumor cells from a muscle-invasive bladder transitional cell carcinoma (TCC). Analyses of the somatic mutant allele frequency spectrum and clonal structure revealed that the tumor cells were derived from a single ancestral cell, but that subsequent evolution occurred, leading to two distinct tumor cell subpopulations. By analyzing recurrently mutant genes in an additional cohort of 99 TCC tumors, we identified genes that might play roles in the maintenance of the ancestral clone and in the muscle-invasive capability of subclones of this bladder cancer, respectively. Conclusions This work provides a new approach of investigating the genetic details of bladder tumoral changes at the single-cell level and a new method for assessing bladder cancer evolution at a cell-population level.

LiCoO2 (LCO) with a high theoretical capacity of 274 mAh g–1 can rarely achieve a high practical capacity even at an upper cutoff voltage of 4.6 V due to severe structural instability and interface side reactions. Herein, an in situ strategy of gas–solid modifications during synthesis is proposed to improve the performance of LCO using sulfocompound‐contained expanded graphite (EG) as templates. In situ generated SO2 gas from EG enables the Co‐coating of coherent spinel LixCo2O4 and Li2SO4 and the trace doping of high‐valence S mainly in the near‐surface regions via its reactions with the precursors. The modified LCO possesses excellent structural reversibility, interfacial stability, slight dissolution of Co2+, high diffusion coefficients of Li+, and low O 2p band top. This endows LCO with remarkably improved high‐voltage performance, 222 and 143 mAh g‐1 at 0.1 and 20 C, respectively, and 88% capacity retention over 100 cycles at 1 C for LCO/Li half cells between 2.8 and 4.6 V, and 202 mAh g–1 at 1 C and 87% capacity retention over 1000 cycles between 2.8 and 4.5 V for LCO/graphite full cells. This study provides a unique, simple, and upscalable strategy for performance improvement of electrode materials. [ABSTRACT FROM AUTHOR]

Commercialized lithium cobalt oxide (LCO) only shows a relatively low capacity of ≈175 mAh g -1 despite a high theoretical capacity of ≈274 mAh g -1 . As an effective and direct strategy, increasing its charge cutoff voltage can, in principle, escalate the capacity, which is however precluded by the irreversible phase transition, oxygen loss, and severe side reactions with electrolytes normally. Herein, an in situ sulfur-assisted solid-state approach is proposed for one-pot synthesis of long-term highly stable high-voltage LCO with a novel compound structure. The coating of coherent spinel Li x Co 2 O 4 shells on and the gradient doping of SO 4 2- polyanions into LCO are in situ realized simultaneously in terms of gas-solid interface reactions between metal oxides and generated SO 2 gas from sulfur during synthesis. At 4.6 V, this LCO shows the discharge capacities of 232.4 mAh g -1 at 0.1 C (1 C = 280 mA g- 1 ), 215 mAh g -1 at 1 C and 139 mAh g -1 even at 20 C and the capacity retentions of 97.4% (89.7%) after 100 (300) cycles at 1 C. This approach is facile, low-cost and up-scalable and may provide a route to improve the performance of LCO and other electrode materials greatly., (© 2022 Wiley-VCH GmbH.)