diff --git a/CHANGELOG.md b/CHANGELOG.md
index 727ea6f..3cfc058 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@
 ## [Unreleased](https://github.com/NREL/BATMODS-lite/)
 
 ### New Features
+- Check bounds of intercalation fraction before calculating exchange current density ([#19](https://github.com/NREL/BATMODS-lite/pull/19))
 - Update `materials` module with new LFP properties, from ICI ([#18](https://github.com/NREL/BATMODS-lite/pull/18))
 - Use `CubicSpline` interpolations for LFP properties ([#15](https://github.com/NREL/BATMODS-lite/pull/15))
 - Add degradation parameters for the electrolyte (applies to P2D only) ([#14](https://github.com/NREL/BATMODS-lite/pull/14))
diff --git a/images/coverage.svg b/images/coverage.svg
index 0f4e1dd..03df345 100644
--- a/images/coverage.svg
+++ b/images/coverage.svg
@@ -1,5 +1,5 @@
-<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="116" height="20" role="img" aria-label="coverage: 92.36%">
-	<title>coverage: 92.36%</title>
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="116" height="20" role="img" aria-label="coverage: 92.03%">
+	<title>coverage: 92.03%</title>
 	<linearGradient id="s" x2="0" y2="100%">
 		<stop offset="0" stop-color="#bbb" stop-opacity=".1"/>
 		<stop offset="1" stop-opacity=".1"/>
@@ -15,7 +15,7 @@
 	<g fill="#fff" text-anchor="middle" font-family="Verdana,Geneva,DejaVu Sans,sans-serif" text-rendering="geometricPrecision" font-size="110">
 		<text aria-hidden="true" x="315.0" y="150" fill="#010101" fill-opacity=".3" transform="scale(.1)" textLength="510">coverage</text>
 		<text x="315.0" y="140" transform="scale(.1)" fill="#fff" textLength="510">coverage</text>
-		<text aria-hidden="true" x="875.0" y="150" fill="#010101" fill-opacity=".3" transform="scale(.1)" textLength="450">92.36%</text>
-		<text x="875.0" y="140" transform="scale(.1)" fill="#fff" textLength="450">92.36%</text>
+		<text aria-hidden="true" x="875.0" y="150" fill="#010101" fill-opacity=".3" transform="scale(.1)" textLength="450">92.03%</text>
+		<text x="875.0" y="140" transform="scale(.1)" fill="#fff" textLength="450">92.03%</text>
 	</g>
 </svg>
diff --git a/src/bmlite/materials/_graphite.py b/src/bmlite/materials/_graphite.py
index 7b2fe1e..3631809 100644
--- a/src/bmlite/materials/_graphite.py
+++ b/src/bmlite/materials/_graphite.py
@@ -1,3 +1,5 @@
+from numbers import Real
+
 import numpy as np
 
 
@@ -93,6 +95,15 @@ def get_i0(self, x: float | np.ndarray, C_Li: float | np.ndarray,
 
         c = Constants()
 
+        # Avoid floating point errors
+        if isinstance(x, Real):
+            if (x < 0 and self.alpha_c < 1) or (x > 1 and self.alpha_a < 1):
+                raise ValueError('x is out of [0, 1] during i0 calculation')
+        elif isinstance(x, np.ndarray):
+            if ((any(x.flatten() < 0) and self.alpha_c < 1)
+               or (any(x.flatten() > 1) and self.alpha_a < 1)):
+                raise ValueError('x is out of [0, 1] during i0 calculation')
+
         i0 = 2.5 * 0.27 * np.exp(-30e6 / c.R * (1 / T - 1 / 303.15)) \
             * C_Li**self.alpha_a * (self.Li_max * x)**self.alpha_c \
             * (self.Li_max - self.Li_max * x)**self.alpha_a
diff --git a/src/bmlite/materials/_lfp.py b/src/bmlite/materials/_lfp.py
index 970cef5..c638e70 100644
--- a/src/bmlite/materials/_lfp.py
+++ b/src/bmlite/materials/_lfp.py
@@ -1,3 +1,5 @@
+from numbers import Real
+
 import numpy as np
 
 
@@ -101,6 +103,15 @@ def get_i0(self, x: float | np.ndarray, C_Li: float | np.ndarray,
 
         c = Constants()
 
+        # Avoid floating point errors
+        if isinstance(x, Real):
+            if (x < 0 and self.alpha_c < 1) or (x > 1 and self.alpha_a < 1):
+                raise ValueError('x is out of [0, 1] during i0 calculation')
+        elif isinstance(x, np.ndarray):
+            if ((any(x.flatten() < 0) and self.alpha_c < 1)
+               or (any(x.flatten() > 1) and self.alpha_a < 1)):
+                raise ValueError('x is out of [0, 1] during i0 calculation')
+
         i0 = 0.27 * np.exp(-30e6 / c.R * (1 / T - 1 / 303.15)) \
            * C_Li**self.alpha_a * (self.Li_max * x)**self.alpha_c \
            * (self.Li_max - self.Li_max * x)**self.alpha_a