Issue 1244 algebraic j

[valentinsulzer]

Description

Add an option to make the interfacial current density a state with an algebraic equation

Fixes #1244

Type of change

Please add a line in the relevant section of CHANGELOG.md to document the change (include PR #) - note reverse order of PR #s. If necessary, also add to the list of breaking changes.

• New feature (non-breaking change which adds functionality)
• Optimization (back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)

Key checklist:

• No style issues: $ flake8
• All tests pass: $ python run-tests.py --unit
• The documentation builds: $ cd docs and then $ make clean; make html

You can run all three at once, using $ python run-tests.py --quick.

Further checks:

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works

[codecov]

Codecov Report

Merging #1280 (136a31f) into develop (0e6c78c) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff            @@
##           develop    #1280   +/-   ##
========================================
  Coverage    98.09%   98.09%           
========================================
  Files          270      270           
  Lines        15150    15155    +5     
========================================
+ Hits         14861    14866    +5     
  Misses         289      289           

Impacted Files	Coverage Δ
...m/models/full_battery_models/base_battery_model.py	99.67% <100.00%> (+<0.01%)	⬆️
...ybamm/models/full_battery_models/lead_acid/full.py	100.00% <100.00%> (ø)
...dels/full_battery_models/lead_acid/higher_order.py	98.09% <100.00%> (ø)
...ybamm/models/full_battery_models/lead_acid/loqs.py	100.00% <100.00%> (ø)
...bamm/models/full_battery_models/lithium_ion/dfn.py	100.00% <100.00%> (ø)
...bamm/models/full_battery_models/lithium_ion/spm.py	100.00% <100.00%> (ø)
...amm/models/full_battery_models/lithium_ion/spme.py	100.00% <100.00%> (ø)
...dels/submodels/interface/kinetics/base_kinetics.py	100.00% <100.00%> (ø)
...dels/submodels/interface/kinetics/butler_volmer.py	100.00% <100.00%> (ø)
...models/submodels/interface/kinetics/no_reaction.py	100.00% <100.00%> (ø)
... and 1 more

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[brosaplanella]

Looks good, just some minor comments. Thanks Tino!

[brosaplanella]

Linked to my previous comment, how come here we use "none" instead of "false"?

[valentinsulzer]

It is a bit arbitrary but I am basically using "false" if the other option is "true" and "none" otherwise, except for "surface form". "There is no convection" -> "convection: none" vs "We don't use the surface form" -> "surface form: false"