Features
- The parameter "Ambient temperature [K]" can now be given as a function of position `(y,z)` and time `t`. The "edge" and "current collector" heat transfer coefficient parameters can also depend on `(y,z)` ([3257](https://github.com/pybamm-team/PyBaMM/pull/3257))
- Spherical and cylindrical shell domains can now be solved with any boundary conditions ([3237](https://github.com/pybamm-team/PyBaMM/pull/3237))
- Processed variables now get the spatial variables automatically, allowing plotting of more generic models ([3234](https://github.com/pybamm-team/PyBaMM/pull/3234))
- Numpy functions now work with PyBaMM symbols (e.g. `np.exp(pybamm.Symbol("a"))` returns `pybamm.Exp(pybamm.Symbol("a"))`). This means that parameter functions can be specified using numpy functions instead of pybamm functions. Additionally, combining numpy arrays with pybamm objects now works (the numpy array is converted to a pybamm array) ([3205](https://github.com/pybamm-team/PyBaMM/pull/3205))
- Half-cell models where graphite - or other negative electrode material of choice - is treated as the positive electrode ([3198](https://github.com/pybamm-team/PyBaMM/pull/3198))
- Degradation mechanisms `SEI`, `SEI on cracks` and `lithium plating` can be made to work on the positive electrode by specifying the relevant options as a 2-tuple. If a tuple is not given and `working electrode` is set to `both`, they will be applied on the negative electrode only. ([3198](https://github.com/pybamm-team/PyBaMM/pull/3198))
- Added an example notebook to demonstrate how to use half-cell models ([3198](https://github.com/pybamm-team/PyBaMM/pull/3198))
- Added option to use an empirical hysteresis model for the diffusivity and exchange-current density ([3194](https://github.com/pybamm-team/PyBaMM/pull/3194))
- Double-layer capacity can now be provided as a function of temperature ([3174](https://github.com/pybamm-team/PyBaMM/pull/3174))
- `pybamm_install_jax` is deprecated. It is now replaced with `pip install pybamm[jax]` ([3163](https://github.com/pybamm-team/PyBaMM/pull/3163))
- Implement the MSMR model ([3116](https://github.com/pybamm-team/PyBaMM/pull/3116))
- Added new example notebook `rpt-experiment` to demonstrate how to set up degradation experiments with RPTs ([2851](https://github.com/pybamm-team/PyBaMM/pull/2851))
Bug fixes
- Fixed a bug where the JaxSolver would fails when using GPU support with no input parameters ([3423](https://github.com/pybamm-team/PyBaMM/pull/3423))
- Make pybamm importable with minimal dependencies ([3044](https://github.com/pybamm-team/PyBaMM/pull/3044), [#3475](https://github.com/pybamm-team/PyBaMM/pull/3475))
- Fixed a bug where supplying an initial soc did not work with half cell models ([3456](https://github.com/pybamm-team/PyBaMM/pull/3456))
- Fixed a bug where empty lists passed to QuickPlot resulted in an IndexError and did not return a meaningful error message ([3359](https://github.com/pybamm-team/PyBaMM/pull/3359))
- Fixed a bug where there was a missing thermal conductivity in the thermal pouch cell models ([3330](https://github.com/pybamm-team/PyBaMM/pull/3330))
- Fixed a bug that caused incorrect results of “{Domain} electrode thickness change [m]” due to the absence of dimension for the variable `electrode_thickness_change`([3329](https://github.com/pybamm-team/PyBaMM/pull/3329)).
- Fixed a bug that occured in `check_ys_are_not_too_large` when trying to reference `y-slice` where the referenced variable was not a `pybamm.StateVector` ([3313](https://github.com/pybamm-team/PyBaMM/pull/3313)
- Fixed a bug with `_Heaviside._evaluate_for_shape` which meant some expressions involving heaviside function and subtractions did not work ([3306](https://github.com/pybamm-team/PyBaMM/pull/3306))
- Attributes of `pybamm.Simulation` objects (models, parameter values, geometries, choice of solver, and output variables) are now private and as such cannot be edited in-place after the simulation has been created ([3267](https://github.com/pybamm-team/PyBaMM/pull/3267)
- Fixed bug causing incorrect activation energies using `create_from_bpx()` ([3242](https://github.com/pybamm-team/PyBaMM/pull/3242))
- Fixed a bug where the "basic" lithium-ion models gave incorrect results when using nonlinear particle diffusivity ([3207](https://github.com/pybamm-team/PyBaMM/pull/3207))
- Particle size distributions now work with SPMe and NewmanTobias models ([3207](https://github.com/pybamm-team/PyBaMM/pull/3207))
- Attempting to set `working electrode` to `negative` now triggers an `OptionError`. Instead, set it to `positive` and use what would normally be the negative electrode as the positive electrode. ([3198](https://github.com/pybamm-team/PyBaMM/pull/3198))
- Fix to simulate c_rate steps with drive cycles ([3186](https://github.com/pybamm-team/PyBaMM/pull/3186))
- Always save last cycle in experiment, to fix issues with `starting_solution` and `last_state` ([3177](https://github.com/pybamm-team/PyBaMM/pull/3177))
- Fix simulations with `starting_solution` to work with `start_time` experiments ([3177](https://github.com/pybamm-team/PyBaMM/pull/3177))
- Fix SEI Example Notebook ([3166](https://github.com/pybamm-team/PyBaMM/pull/3166))
- Thevenin() model is now constructed with standard variables: `Time [s]`, `Time [min]`, `Time [h]` ([3143](https://github.com/pybamm-team/PyBaMM/pull/3143))
- Error generated when invalid parameter values are passed ([3132](https://github.com/pybamm-team/PyBaMM/pull/3132))
- Parameters in `Prada2013` have been updated to better match those given in the paper, which is a 2.3 Ah cell, instead of the mix-and-match with the 1.1 Ah cell from Lain2019 ([3096](https://github.com/pybamm-team/PyBaMM/pull/3096))
- The `OneDimensionalX` thermal model has been updated to account for edge/tab cooling and account for the current collector volumetric heat capacity. It now gives the correct behaviour compared with a lumped model with the correct total heat transfer coefficient and surface area for cooling. ([3042](https://github.com/pybamm-team/PyBaMM/pull/3042))
Optimizations
- Improved how steps are processed in simulations to reduce memory usage ([3261](https://github.com/pybamm-team/PyBaMM/pull/3261))
- Added parameter list support to JAX solver, permitting multithreading / GPU execution ([3121](https://github.com/pybamm-team/PyBaMM/pull/3121))
Breaking changes
- The parameter "Exchange-current density for lithium plating [A.m-2]" has been renamed to "Exchange-current density for lithium metal electrode [A.m-2]" when referring to the lithium plating reaction on the surface of a lithium metal electrode ([3445](https://github.com/pybamm-team/PyBaMM/pull/3445))
- Dropped support for i686 (32-bit) architectures on GNU/Linux distributions ([3412](https://github.com/pybamm-team/PyBaMM/pull/3412))
- The class `pybamm.thermal.OneDimensionalX` has been moved to `pybamm.thermal.pouch_cell.OneDimensionalX` to reflect the fact that the model formulation implicitly assumes a pouch cell geometry ([3257](https://github.com/pybamm-team/PyBaMM/pull/3257))
- The "lumped" thermal option now always used the parameters "Cell cooling surface area [m2]", "Cell volume [m3]" and "Total heat transfer coefficient [W.m-2.K-1]" to compute the cell cooling regardless of the chosen "cell geometry" option. The user must now specify the correct values for these parameters instead of them being calculated based on e.g. a pouch cell. An `OptionWarning` is raised to let users know to update their parameters ([3257](https://github.com/pybamm-team/PyBaMM/pull/3257))
- Numpy functions now work with PyBaMM symbols (e.g. `np.exp(pybamm.Symbol("a"))` returns `pybamm.Exp(pybamm.Symbol("a"))`). This means that parameter functions can be specified using numpy functions instead of pybamm functions. Additionally, combining numpy arrays with pybamm objects now works (the numpy array is converted to a pybamm array) ([3205](https://github.com/pybamm-team/PyBaMM/pull/3205))
- The `SEI`, `SEI on cracks` and `lithium plating` submodels can now be used on either electrode, which means the `__init__` functions for the relevant classes now have `domain` as a required argument ([3198](https://github.com/pybamm-team/PyBaMM/pull/3198))
- Likewise, the names of all variables corresponding to those submodels now have domains. For example, instead of `SEI thickness [m]`, use `Negative SEI thickness [m]` or `Positive SEI thickness [m]`. ([3198](https://github.com/pybamm-team/PyBaMM/pull/3198))
- If `options["working electrode"] == "both"` and either `SEI`, `SEI on cracks` or `lithium plating` are not provided as tuples, they are automatically made into tuples. This directly modifies `extra_options`, not `default_options` to ensure the other changes to `default_options` still happen when required. ([3198](https://github.com/pybamm-team/PyBaMM/pull/3198))
- Added option to use an empirical hysteresis model for the diffusivity and exchange-current density ([3194](https://github.com/pybamm-team/PyBaMM/pull/3194))
- Double-layer capacity can now be provided as a function of temperature ([3174](https://github.com/pybamm-team/PyBaMM/pull/3174))
- `pybamm_install_jax` is deprecated. It is now replaced with `pip install pybamm[jax]` ([3163](https://github.com/pybamm-team/PyBaMM/pull/3163))
- PyBaMM now has optional dependencies that can be installed with the pattern `pip install pybamm[option]` e.g. `pybamm[plot]` ([3044](https://github.com/pybamm-team/PyBaMM/pull/3044), [#3475](https://github.com/pybamm-team/PyBaMM/pull/3475))