Theorem: j d eta/dj - b = 0 for Tafel eta = a + b ln(j) (log-rate slope identity)

Theorem (Tafel-slope-derivative canonical): for eta = a + b ln(j), differentiating w.r.t. j gives d eta/dj = b/j, hence j d eta/dj - b = 0 identically. Canonical sympy pins: a_0, b, j = sp.symbols('a_0 b j', positive=True); eta = a_0 +…