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Manufacturing thin‐film components is crucial for achieving high‐efficiency and high‐power thermal batteries (TBs). However, developing binders with low‐gas production at the operating temperature range of TBs (400–550 °C) has proven to be a significant challenge. Here, we report the use of acrylic acid derivative terpolymer (LA136D) as a low‐volatile binder for thin‐film cathode fabrication and studied the chain scission and chemical bond‐breaking mechanisms in pyrolysis. It is shown LA136D defers to random‐chain scission and cross‐linking chain scission mechanisms, which gifts it with a low proportion of volatile products (ψ, ψ = 39.2 wt%) at even up to 550 °C, well below those of the conventional PVDF (77.6 wt%) and SBR (99.2 wt%) binders. Surprisingly, LA136D contributes to constructing a thermal shock‐resistant cathode due to the step‐by‐step bond‐breaking process. This is beneficial for the overall performance of TBs. In discharging test, the thin‐film cathodes exhibited a remarkable 440% reduction in polarization and 300% enhancement in the utilization efficiency of cathode materials, while with just a slight increase of 0.05 MPa in gas pressure compared with traditional "thick‐film" cathode. Our work highlights the potential of LA136D as a low‐volatile binder for thin‐film cathodes and shows the feasibility of manufacturing high‐efficiency and high‐power TBs through polymer molecule engineering. [ABSTRACT FROM AUTHOR]