Adsorbed Water on Nano-Silicon Powder and Its Effects on Charge and Discharge Characteristics as Anode in Lithium-Ion Batteries

Yoshida, Shuhei; Masuo, Yuta; Shibata, Daisuke; Haruta, Masakazu; Doi, Takayuki; Inaba, Masaaki

doi:10.1149/2.01111701jes

Cited by 14 publications

(14 citation statements)

References 22 publications

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“…While the bulk oxidation mediates the overall capacity of the Si material, as seen by the changes in specific capacity (Figure 9), the surface chemistry plays an important role in binder interactions, 24−26 SEI formation, 27−29 and the adsorption of water to the Si surface. 30 The surface of the unprocessed NA 70−130 Si particles was identified to contain a mix of Si− H, geminal, silanol, and siloxane sites. The NMP had minimal effect on these surface species, but after water processing, the Si−H, geminal, and siloxane sites were largely converted to silanol groups, which is common among a fully hydrated silica surface.…”

Section: ■ Discussionmentioning

confidence: 99%

Si Oxidation and H₂ Gassing During Aqueous Slurry Preparation for Li-Ion Battery Anodes

Hays

Wood

et al. 2018

J. Phys. Chem. C

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Si has the possibility to greatly increase the energy density of Li-ion battery anodes, though it is not without its problems. One issue often overlooked is the decomposition of Si during large scale slurry formulation and battery fabrication. Here, we investigate the mechanism of H 2 production to understand the role of different slurry components and their impact on the Si oxidation and surface chemistry. Mass spectrometry and in situ pressure monitoring identifies that carbon black plays a major role in promoting the oxidation of Si and generation of H 2 . Si oxidation also occurs through atmospheric O 2 consumption. Both pathways, along with solvent choice, impact the surface silanol chemistry, as analyzed by 1 H− 29 Si cross-polarization magic angle spinning nuclear magnetic resonance (MAS NMR) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR FTIR). An understanding of the oxidation of Si, during slurry processing, provides a pathway toward improving the manufacturing of Si based anodes by maximizing its capacity and minimizing safety hazards.

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Section: ■ Discussionmentioning

confidence: 99%

Si Oxidation and H₂ Gassing During Aqueous Slurry Preparation for Li-Ion Battery Anodes

Hays

Wood

et al. 2018

J. Phys. Chem. C

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“…[29][30][31][32][33][34][35]. Such processing exposes the materials to moisture, resulting in numerous complications [36][37][38] associated with the hydrolysis of lithium salts [39][40][41][42][43] and of the carbonate solvents. 44,45 Introduction of moisture, and electrochemical or chemical generation of corrosive acids near the positive electrodes, are a particular concern for oxide materials cycled at voltages >4.5 V vs Li/Li + .…”

Section: LImentioning

confidence: 99%

Chemical Weathering of Layered Ni-Rich Oxide Electrode Materials: Evidence for Cation Exchange

Shkrob

Gilbert

Phillips

et al. 2017

J. Electrochem. Soc.

153

160

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Lithiated ternary oxides containing nickel, cobalt, and manganese are intercalation compounds that are used as positive electrodes in high-energy lithium-ion batteries. These oxides undergo changes, when they are stored in humid air or exposed to moisture, that adversely affect their electrochemical performance. There is a new urgency to better understanding of these "weathering" mechanisms as manufacturing moves toward a more environmentally benign aqueous processing of the positive electrode. Delithiation of the oxide and the formation of lithium salts (such as hydroxides and carbonates) coating the surface, are known to occur during moisture exposure. The redox reactions which follow this delithiation are believed to trigger all the other transformations. In this article we suggest another possibility: namely, the proton -lithium exchange. We argue that this hypothesis provides a simple, comprehensive rationale for our observations, which include contraction of the c-axis (unit cell) lattice parameter, rock salt phase formation in the subsurface regions, presence of amorphous surface films, and the partial recovery of oxide capacity during electrochemical relithiation. The detrimental effects of water exposure need to be mitigated before aqueous processing of the positive electrode can find widespread adoption during cell manufacturing. Improving the performance of lithium-ion batteries (LIBs) for electrically powered vehicles gives urgency to the development of high-capacity, high-voltage electrode materials, and layered Ni-rich oxides are presently among the most technological advanced materials that allow operation above +4.0 V vs Li + /Li. 1 Such materials (also known as NCMxyz materials) have the general composition of LiNi x/10 Co y/10 Mn z/10 O 2 , where x+y+z = 10. In these ternary oxides, the manganese stays in the Mn 4+ state during cell cycling, and the capacity mainly originates from the Ni 2+ /Ni 3+ and Ni 3+ /Ni 4+ redox couples. The monolayers of octahedra containing transition metal (TM) ions form a structural scaffold with the layers of mobile Li + ions placed in between. The crystalline material retains the structure of the progenitor material of the family, viz. α-LiCoO 2 , 2 with the unit cell belonging to the rhombohedral R(-3)m space group. During electrochemical cycling, the lithium ions intercalate into (and deintercalate from) the layered crystals as the redox state of (mainly the) nickel ions changes to provide the overall charge neutrality.In this study, we examine one such material, NCM523, which represents a particular trade-off between the cycling rate (that improves with Co content), safety (that improves with Mn content), and capacity (that increases with Ni content).1 The safety concerns mainly relate to the thermal and chemical stability, including oxidation of the organic electrolyte by catalytic centers at the oxide surface 3 and phase transitions in the delithiated material that occur when a significant fraction of nickel ions is reduced to Ni 2+ ions and molecular oxygen ...

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“…We reported that a higher drying temperature of 180°C gives higher coulombic efficiencies for Si-LP anode. 36 It should be noted that the amount of adsorbed water is approximately proportional to the specific surface area of Si materials in Fig. 9.…”

Section: Ceaseless Electrolyte Decomposition and Sei Growthmentioning

confidence: 88%

“…36 Figure 9 shows the relationships between the content of adsorbed water and BET specific surface areas of various Si and carbon powder materials. 36 Here the samples were dried at 120°C for 1 h in N 2 , and the adsorbed water was measured by heating the samples at 250°C in N 2 . Generally graphite and Si anodes were dried at 100-120°C under vacuum before assembling the cells.…”

Section: Ceaseless Electrolyte Decomposition and Sei Growthmentioning

confidence: 99%

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Silicon Nano-flake Powder as an Anode for The Next Generation Lithium-ion Batteries: Current Status and Challenges

et al. 2017

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Silicon is electrochemically alloyed and de-alloyed with Li at potentials close to Li + /Li and is widely recognized as the most promising candidate for the anode of LIBs with a high energy density (250-300 Wh kg −1 ) in the next generation. The most serious issue of Si anode is poor capacity retention owing to large volume changes during charging and discharging. We developed Si LeafPowder ® with a nano-flake structure to overcome the poor capacity retention. However Si anodes still have some problems such as large irreversible capacity, ceaseless electrolyte decomposition, swelling of the electrode, etc. for use in high-energy density LIBs in the next generation. In this article, these problems and the challenges to mitigate them are overviewed based on our resent data obtained by Si nano-flakes (Si LeafPowder ® ).

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Adsorbed Water on Nano-Silicon Powder and Its Effects on Charge and Discharge Characteristics as Anode in Lithium-Ion Batteries

Cited by 14 publications

References 22 publications

Si Oxidation and H₂ Gassing During Aqueous Slurry Preparation for Li-Ion Battery Anodes

Si Oxidation and H₂ Gassing During Aqueous Slurry Preparation for Li-Ion Battery Anodes

Chemical Weathering of Layered Ni-Rich Oxide Electrode Materials: Evidence for Cation Exchange

Silicon Nano-flake Powder as an Anode for The Next Generation Lithium-ion Batteries: Current Status and Challenges

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Adsorbed Water on Nano-Silicon Powder and Its Effects on Charge and Discharge Characteristics as Anode in Lithium-Ion Batteries

Cited by 14 publications

References 22 publications

Si Oxidation and H2 Gassing During Aqueous Slurry Preparation for Li-Ion Battery Anodes

Si Oxidation and H2 Gassing During Aqueous Slurry Preparation for Li-Ion Battery Anodes

Chemical Weathering of Layered Ni-Rich Oxide Electrode Materials: Evidence for Cation Exchange

Silicon Nano-flake Powder as an Anode for The Next Generation Lithium-ion Batteries: Current Status and Challenges

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Product

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About

Si Oxidation and H₂ Gassing During Aqueous Slurry Preparation for Li-Ion Battery Anodes

Si Oxidation and H₂ Gassing During Aqueous Slurry Preparation for Li-Ion Battery Anodes