Method to calculate theoretical efficiency

[aabills]

Description

Please include a summary of the change and which issue is fixed. Please also include relevant motivation and context. List any dependencies that are required for this change.

Implements integral of VdQ to calculate theoretical maximum energy. Useful for defining battery efficiency. Submitted PR due to discussion with @tinosulzer

Fixes # (issue)

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.

• [ x] 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: $ pre-commit run (see CONTRIBUTING.md for how to set this up to run automatically when committing locally, in just two lines of code)
• All tests pass: $ python run-tests.py --all
• The documentation builds: $ python run-tests.py --doctest

You can run unit and doctests together 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

Patch coverage: 100.00% and no project coverage change.

Comparison is base (124efe5) 99.68% compared to head (617549c) 99.68%.

❗ Current head 617549c differs from pull request most recent head 0fa49e2. Consider uploading reports for the commit 0fa49e2 to get more accurate results

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #2777   +/-   ##
========================================
  Coverage    99.68%   99.68%           
========================================
  Files          272      272           
  Lines        19007    19027   +20     
========================================
+ Hits         18948    18968   +20     
  Misses          59       59           

Impacted Files	Coverage Δ
...s/full_battery_models/lithium_ion/electrode_soh.py	100.00% <100.00%> (ø)

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[valentinsulzer]

Looks good, some formatting changes, also what is 26.8 ?