Nickel metaphosphate Ni(PO3)2 as a conversion positive electrode for lithium-ion batteries
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Open Access
Type
ArticleAbstract
Lithium storage schemes based on conversion chemistry have been used in a large variety of negative electrodes achieving capacities 2-3 times higher than graphite. However, to date, relatively few positive electrode examples have been reported. Here, we report a new conversion ...
See moreLithium storage schemes based on conversion chemistry have been used in a large variety of negative electrodes achieving capacities 2-3 times higher than graphite. However, to date, relatively few positive electrode examples have been reported. Here, we report a new conversion positive electrode, Ni(PO3)2, and systematic studies on its working and degradation mechanisms. Crystalline Ni(PO3)2 undergoes an electrochemistry-driven amorphisation process in the first discharge to form a fine microstructure, consisting of Ni domains with ~2 nm wide that form a percolating electron-conducting network, embedded in a glassy LiPO3 matrix. P does not participate electrochemically, remaining as P5+ in [PO3]- throughout. The electrode does not recrystallise in the following first charge process, remaining amorphous over all subsequent cycles. The low ionicity of the Ni-[PO3] bond and the high Li+ conductivity of the LiPO3 glass lead to high intrinsic electrochemical activity, allowing the micro-sized Ni(PO3)2 to achieve its theoretical capacity of 247 mAh/g. The performance of the Ni(PO3)2 electrode ultimately degrades due to the growth of larger and more isolated Ni grains. While the theoretical capacity of Ni(PO3)2 is itself limited, it sheds new light on the underlying chemical mechanisms of conversion cathodes, an important new class of electrode for solid-state batteries.
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See moreLithium storage schemes based on conversion chemistry have been used in a large variety of negative electrodes achieving capacities 2-3 times higher than graphite. However, to date, relatively few positive electrode examples have been reported. Here, we report a new conversion positive electrode, Ni(PO3)2, and systematic studies on its working and degradation mechanisms. Crystalline Ni(PO3)2 undergoes an electrochemistry-driven amorphisation process in the first discharge to form a fine microstructure, consisting of Ni domains with ~2 nm wide that form a percolating electron-conducting network, embedded in a glassy LiPO3 matrix. P does not participate electrochemically, remaining as P5+ in [PO3]- throughout. The electrode does not recrystallise in the following first charge process, remaining amorphous over all subsequent cycles. The low ionicity of the Ni-[PO3] bond and the high Li+ conductivity of the LiPO3 glass lead to high intrinsic electrochemical activity, allowing the micro-sized Ni(PO3)2 to achieve its theoretical capacity of 247 mAh/g. The performance of the Ni(PO3)2 electrode ultimately degrades due to the growth of larger and more isolated Ni grains. While the theoretical capacity of Ni(PO3)2 is itself limited, it sheds new light on the underlying chemical mechanisms of conversion cathodes, an important new class of electrode for solid-state batteries.
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Date
2021Source title
Batteries and SupercapsVolume
4Publisher
WileyFunding information
ARC DP200100959Rights statement
"This is the peer reviewed version of the following article: Q. Xia, M. Avdeev, S. Schmid, H. Liu, B. Johannessen, C. D. Ling, Batteries & Supercaps 2021, 4, 195, which has been published in final form at https://doi.org/10.1002/batt.202000164. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited."Faculty/School
Faculty of Science, School of ChemistryShare