Sustainable Supercapacitors Based on Polypyrrole-Doped Activated Biochar from Wood Waste Electrodes Tekijä Lima, Ravi Moreno Araujo Pinheiro dos Reis, Glaydson Simões Lassi, Ulla Lima, Eder Claudio Dotto, Guilherme Luiz de Oliveira, Helinando Pequeno