title: Synthesis and properties of some doped lithium transition-metal phosphates

authors: Butt, Garrett Phillip

abstract: Four structurally related materials; LiNiPO₄, LiCoPO₄, Li₃Fe₂(PO₄)₃ and Li₃V₂(PO₄)₃, were synthesised, characterised and evaluated as potential cathode materials for lithium secondary batteries. 

The materials were synthesized using mainly solid-state techniques. Structural characterisation was performed using powder XRD with Rietveld refinement and Raman spectroscopy. Results showed that the pure forms of LiNiPO₄, LiCoPO₄ and Li₃Fe₂(PO₄)₃ could be synthesised in air at various temperatures. Li₃V₂(PO₄)₃ required a reducing atmosphere of 2%H₂/98%N₂ to achieve phase purity. Attempts were made to substitute all four materials with aliovalent dopants. Li₃Fe₂(PO₄)₃ and Li₃V₂(PO₄)₃ underwent a phase change depending on dopant content to a higher ionic conducting phase. 

AC impedance spectroscopy was used to determine conductivity of the materials. In general the phosphates are poor conductors. There was a significant increase in conductivity when substituting the transition metal Ti⁴⁺ for M³⁺ in Li₃Fe₂(PO₄)₃ and Li₃V₂(PO₄)₃, and V³⁺ for Co²⁺ in LiCoPO₄. 

The four materials and their highest conducting doped analogues were evaluated as cathodes in coin type lithium cells to determine their viability in Li secondary batteries. LiCoPO₄ showed a first discharge capacity of 130 mAh/g at 4.6V, but could be cycled over only a limited number of charge-discharge cycles owing to electrolyte instability at the high oxidation potentials (>5V) required for full charge. LiNiPO₄ could not be charged at all to accessible voltages. Ti doped Li₃Fe₂(PO₄)₃ had a relatively low discharge capacity of 60 mAh/g. Li₃V₂(PO₄)₃ and Ti doped Li₃V₂(PO₄)₃ showed a discharge capacity of 130 and 110 mAh/g respectively, although the Ti doped Li₃V₂(PO₄)₃ showed better cycling characteristics. Therefore, although aliovalent doping could increase the total conductivity of the phosphate materials, the accessible capacities of these materials remained limited.

text: Synthesis and properties of some doped lithium transition-metal phosphates Four structurally related materials; LiNiPO₄, LiCoPO₄, Li₃Fe₂(PO₄)₃ and Li₃V₂(PO₄)₃, were synthesised, characterised and evaluated as potential cathode materials for lithium secondary batteries. 

The materials were synthesized using mainly solid-state techniques. Structural characterisation was performed using powder XRD with Rietveld refinement and Raman spectroscopy. Results showed that the pure forms of LiNiPO₄, LiCoPO₄ and Li₃Fe₂(PO₄)₃ could be synthesised in air at various temperatures. Li₃V₂(PO₄)₃ required a reducing atmosphere of 2%H₂/98%N₂ to achieve phase purity. Attempts were made to substitute all four materials with aliovalent dopants. Li₃Fe₂(PO₄)₃ and Li₃V₂(PO₄)₃ underwent a phase change depending on dopant content to a higher ionic conducting phase. 

AC impedance spectroscopy was used to determine conductivity of the materials. In general the phosphates are poor conductors. There was a significant increase in conductivity when substituting the transition metal Ti⁴⁺ for M³⁺ in Li₃Fe₂(PO₄)₃ and Li₃V₂(PO₄)₃, and V³⁺ for Co²⁺ in LiCoPO₄. 

The four materials and their highest conducting doped analogues were evaluated as cathodes in coin type lithium cells to determine their viability in Li secondary batteries. LiCoPO₄ showed a first discharge capacity of 130 mAh/g at 4.6V, but could be cycled over only a limited number of charge-discharge cycles owing to electrolyte instability at the high oxidation potentials (>5V) required for full charge. LiNiPO₄ could not be charged at all to accessible voltages. Ti doped Li₃Fe₂(PO₄)₃ had a relatively low discharge capacity of 60 mAh/g. Li₃V₂(PO₄)₃ and Ti doped Li₃V₂(PO₄)₃ showed a discharge capacity of 130 and 110 mAh/g respectively, although the Ti doped Li₃V₂(PO₄)₃ showed better cycling characteristics. Therefore, although aliovalent doping could increase the total conductivity of the phosphate materials, the accessible capacities of these materials remained limited.

year: 2000

title: Minimum drain setback distances to protect New Zealand wetlands: tool development

authors: Blyth, James

abstract: This report documents the development of a Wetland Drain Setback Tool (WDST) for New Zealand freshwater wetlands. The purpose of this tool is to assess the potential effects of historical and new drains on wetland ecosystems and provide guidance on appropriate setback distances to protect these ecosystems from adverse effects due to lowered water levels.

The WDST directly supports the implementation of the National Environmental Standards for Freshwater (NES-F), which were established in 2020 to protect and restore wetlands. These standards prohibit earthworks or modifications to the water cycle within or near wetlands unless exempted for specific reasons like wetland restoration. However, there is a lack of national guidance on acceptable water level declines for different wetland types.

The specific goals of this project were to develop and evaluate the viability of the WDST for New Zealand conditions and recommend subsequent steps for its development. The project involved five key steps:

1. Development of a conceptual model to evaluate how drain systems affect wetland hydrology.
2. Representation of the drain-wetland model in numerical software.
3. Collection of site-specific data to refine and validate the numerical modeling approach.
4. Application of conceptual and numerical models to a hypothetical drain development scenario.
5. Development of two national-scale datasets on hydraulic conductivity and Land Surface Recharge to provide input data in the absence of site measurements.

The conceptual model simplifies wetland hydrology affected by drainage, reducing the need for complex modeling at each wetland. Numerical modeling was done using COMSOL Multiphysics, integrating complex governing equations like groundwater flow.

Site-specific data collection and model calibration were carried out at wetlands in different regions. Satisfactory model calibrations were achieved, indicating the suitability of the drainage model for predicting water level responses.

A hypothetical land development scenario near a wetland on the Kāpiti Coast was tested to demonstrate how the WDST could be applied. Various scenarios indicated lateral setback distances to ensure minimal change in wetland water levels.

Overall, the report concludes that a national tool to estimate drainage effects near wetlands is feasible. It recommends further refinement, including verification at additional wetlands and data collection for input parameters. The tool could potentially be developed into a web-based application, supported by technical guidance material, to assist users in protecting wetland ecosystems through appropriate drainage setback distances.

text: Minimum drain setback distances to protect New Zealand wetlands: tool development This report documents the development of a Wetland Drain Setback Tool (WDST) for New Zealand freshwater wetlands. The purpose of this tool is to assess the potential effects of historical and new drains on wetland ecosystems and provide guidance on appropriate setback distances to protect these ecosystems from adverse effects due to lowered water levels.

The WDST directly supports the implementation of the National Environmental Standards for Freshwater (NES-F), which were established in 2020 to protect and restore wetlands. These standards prohibit earthworks or modifications to the water cycle within or near wetlands unless exempted for specific reasons like wetland restoration. However, there is a lack of national guidance on acceptable water level declines for different wetland types.

The specific goals of this project were to develop and evaluate the viability of the WDST for New Zealand conditions and recommend subsequent steps for its development. The project involved five key steps:

1. Development of a conceptual model to evaluate how drain systems affect wetland hydrology.
2. Representation of the drain-wetland model in numerical software.
3. Collection of site-specific data to refine and validate the numerical modeling approach.
4. Application of conceptual and numerical models to a hypothetical drain development scenario.
5. Development of two national-scale datasets on hydraulic conductivity and Land Surface Recharge to provide input data in the absence of site measurements.

The conceptual model simplifies wetland hydrology affected by drainage, reducing the need for complex modeling at each wetland. Numerical modeling was done using COMSOL Multiphysics, integrating complex governing equations like groundwater flow.

Site-specific data collection and model calibration were carried out at wetlands in different regions. Satisfactory model calibrations were achieved, indicating the suitability of the drainage model for predicting water level responses.

A hypothetical land development scenario near a wetland on the Kāpiti Coast was tested to demonstrate how the WDST could be applied. Various scenarios indicated lateral setback distances to ensure minimal change in wetland water levels.

Overall, the report concludes that a national tool to estimate drainage effects near wetlands is feasible. It recommends further refinement, including verification at additional wetlands and data collection for input parameters. The tool could potentially be developed into a web-based application, supported by technical guidance material, to assist users in protecting wetland ecosystems through appropriate drainage setback distances.

year: 2023-07-01

title: Balancing openness with Indigenous data sovereignty: An opportunity to leave no one behind in the journey to sequence all of life

authors: Cartney, Ann M. Mc

abstract: The field of genomics has benefited greatly from its "openness" approach to data sharing. However, with the increasing volume of sequence information being created and stored and the growing number of international genomics efforts, the equity of openness is under question. The United Nations Convention of Biodiversity aims to develop and adopt a standard policy on access and benefit-sharing for sequence information across signatory parties. This standardization will have profound implications on genomics research, requiring a new definition of open data sharing. The redefinition of openness is not unwarranted, as its limitations have unintentionally introduced barriers of engagement to some, including Indigenous Peoples. This commentary provides an insight into the key challenges of openness faced by the researchers who aspire to protect and conserve global biodiversity, including Indigenous flora and fauna, and presents immediate, practical solutions that, if implemented, will equip the genomics community with both the diversity and inclusivity required to respectfully protect global biodiversity.

text: Balancing openness with Indigenous data sovereignty: An opportunity to leave no one behind in the journey to sequence all of life The field of genomics has benefited greatly from its "openness" approach to data sharing. However, with the increasing volume of sequence information being created and stored and the growing number of international genomics efforts, the equity of openness is under question. The United Nations Convention of Biodiversity aims to develop and adopt a standard policy on access and benefit-sharing for sequence information across signatory parties. This standardization will have profound implications on genomics research, requiring a new definition of open data sharing. The redefinition of openness is not unwarranted, as its limitations have unintentionally introduced barriers of engagement to some, including Indigenous Peoples. This commentary provides an insight into the key challenges of openness faced by the researchers who aspire to protect and conserve global biodiversity, including Indigenous flora and fauna, and presents immediate, practical solutions that, if implemented, will equip the genomics community with both the diversity and inclusivity required to respectfully protect global biodiversity.

year: 2022