Hydroxylated boron nitride-enabled erythritol composite phase change material with highly increased thermal conductivity and compensated heat storage density loss

The high heat storage density of erythritol, originated from the hydrogen bonds formed by its hydroxyl structures, makes it a promising phase change material (PCM) in the medium temperature range. To further speed up the heat charging/discharging rates, increased thermal conductivity of erythritol can be realized by doping highly thermally-conductive fillers. However, the addition of fillers also reduces significantly the heat storage density as a penalty. To address this compromise issue, here we propose to use hydroxylated boron nitride nanosheets (-OH BNNSs) as the fillers. The creation of great number of hydrogen bonds between the hydroxyl groups on BNNS and the matrix PCM that is rich in hydroxyl structures builds up an additional heat conduction path and serves as a compensation for the loss of heat storage density. We show that the thermal conductivity of erythritol can be increased to 1.25 W/m center dot K at the loading of only 2 wt% -OH BNNSs. More importantly, compared with the loss of 12.7 % and 12.5 % caused by adding h-BN and BNNSs at the same loading, the loss of heat storage density of erythritol caused by -OH BNNSs is only 7.7 %, with the supercooling behavior of erythritol being also suppressed as an extra bonus.