BATTERY PACK, WIRELESS POWER TRANSMISSION SYSTEM AND HEARING AID

To provide a battery pack, wireless power transmission system and hearing aid, capable of ensuring stable charging and discharging of a secondary cell while achieving high connection reliability.SOLUTION: A battery pack 1 includes: a secondary cell 2 having a positive electrode surface 13 and a negative electrode surface 14; a circuit board 20 having a battery-side negative electrode terminal 45 electrically connected to the secondary cell 2; and a first lower-side adhesive layer 73 bonding the negative electrode surface 14 to the battery-side negative electrode terminal 45. The first lower-side adhesive layer 73 contains resin and conductive filler dispersed to the resin, thereby adjusting a tensile storage elastic modulus at 23°C of the first lower-side adhesive layer 73 to at least 1 GPa.SELECTED DRAWING: Figure 1 【課題】接続信頼性の向上を図ることができながら、二次電池の安定した充放電を確保することができる電池パック、無線電力伝送システムおよび補聴器を提供すること。【解決手段】電池パック１に、正極面１３および負極面１４を有する二次電池２と、二次電池２と電気的に接続される電池側負極端子４５を備える回路基板２０と、負極面１４と電池側負極端子４５とを接着する第１下側接着層７３とを備える。第１下側接着層７３に、樹脂と、樹脂に分散する導電性フィラーとを含有させ、第１下側接着層７３の２３℃における引張貯蔵弾性率を１ＧＰａ以上に調整する。【選択図】図１