Ni‐rich cathodes are considered feasible candidates for high‐energy‐density Li‐ion batteries (LIBs). However, the structural degradation of Ni‐rich cathodes on the micro‐ and nanoscale leads to severe capacity fading, thereby impeding their practical use in LIBs. Here, it is reported that 3‐(trimethylsilyl)‐2‐oxazolidinone (TMS‐ON) as a multifunctional additive promotes the dissociation of LiPF6, prevents the hydrolysis of ion‐paired LiPF6 (which produces undesired acidic compounds including HF), and scavenges HF in the electrolyte. Further, the presence of 0.5 wt% TMS‐ON helps maintain a stable solid–electrolyte interphase (SEI) at Ni‐rich LiNi0.7Co0.15Mn0.15O2 (NCM) cathodes, thus mitigating the irreversible phase transformation from layered to rock‐salt structures and enabling the long‐term stability of the SEI at the graphite anode with low interfacial resistance. Notably, NCM/graphite full cells with TMS‐ON, which exhibit an excellent discharge capacity retention of 80.4%, deliver a discharge capacity of 154.7 mAh g−1 after 400 cycles at 45 °C.
Nickel-rich
layered oxides are currently considered the most practical
candidates for realizing high-energy-density lithium metal batteries
(LMBs) because of their relatively high capacities. However, undesired
nickel-rich cathode–electrolyte interactions hinder their applicability.
Here, we report a satisfactory combination of an antioxidant fluorinated
ether solvent and an ionic additive that can form a stable, robust
interfacial structure on the nickel-rich cathode in ether-based electrolytes.
The fluorinated ether 1,1,2,2-tetrafluoroethyl-1H,1H,5H-octafluoropentyl ether (TFOFE)
introduced as a cosolvent into ether-based electrolytes stabilizes
the electrolytes against oxidation at the LiNi0.8Mn0.1Co0.1O2 (NCM811) cathode while simultaneously
preserving the electrochemical performance of the Li metal anode.
Lithium difluoro(bisoxalato)phosphate (LiDFBP) forms a uniform cathode–electrolyte
interphase that limits the generation of microcracks inside secondary
particles and undesired dissolution of transition metal ions such
as nickel, cobalt, and manganese from the cathode into the electrolyte.
Using TFOFE and LiDFBP in ether-based electrolytes provides an excellent
capacity retention of 94.5% in a Li|NCM811 cell after 100 cycles and
enables the delivery of significantly increased capacity at high charge
and discharge rates by manipulating the interfaces of both electrodes.
This research provides insights into advancing electrolyte technologies
to resolve the interfacial instability of nickel-rich cathodes in
LMBs.
The previous counting methods trained by the density map regression scheme fail to precisely count the number of birds in crowded bird images of various scales. This is due to the coarseness of the manually created target density maps. In this paper, we propose a new counting scheme, called DAM counting, which generates our-first-proposed density activation map (DAM). DAM is a CNN perspective density map that has high activation values where the network focuses on for precise counting of birds. The network is trained to autonomously learn where and how much the DAM should be activated so that the sum of all values in the DAM estimates the number of birds. Moreover, our DAM counting scheme incorporates two segmentation regularizers that enable precise counting of birds with various scales and appearance. Our DAM counting scheme can effectively substitute the existing density map regression scheme, bringing in a remarkable increase in the counting accuracy. We also propose the first crowded bird dataset, called CBD-6000, which is very valuable for crowded bird counting research.
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